@@LordOfThePancakes You might want to edit your comment once the offensive thing gets removed so people don't think you're calling out the top-level commenter.
Dude, i love videos like this. I need to rewatch portions of the video multiple times to understand wtf is the abstract concept that's being explained and i realize that whoever the guy making these animations and montages is, his work is definitely ultra helpful in so many situations.
Rofl. I have a minor in physics and still an easily 1/3 videos are so over my head they require multiple rewatches. The level of information provided in this channel is wild
@@thehobo00I think very few people can get all this on the first go around. Our brains evolved to deal with a pretty simple environment after all, not to deal with the insanity of space 😅
I do that all the time with videos like this, sometimes 4 or 5 times, and often fail to "intuitively come up with some kind of "analogy/dot connecting" image anyways. 🙂
A qbit can only ever approach the limit of true naughty or existence in its entirety would cease to exist as it would become evil and destroy and tortyure everything in existence with its infinite computational power and pure naughtiness. Not like I'd know 😅
"Oh, wicked, bad, naughty Qubit! She has been setting a light to our firewall, which, I've just remembered, is Grail shaped. It's not the first time we've had this problem."
I really like the firewall idea, and I kinda hope we end up finding evidence for that. It's a very cool idea to consider, that black holes are actual holes as in the space inside just doesn't exist, and it's also just incredibly funny. Like: "Our calculations say all kinds of impossible things should happen inside a black hole, but those things are impossible so they shouldn't be happening!" "Don't worry, the interior doesn't exist so those things aren't happening."
Can confirm. I’ve been forced by multiple governments to send encoded messages to Bob, and now they are poking me about that black hole business. Ugh, I hate Bob, he always gets the more fun job :/
YES YES YES!! PLEASE GIVE BOB AND ALICE ENOUGH ENTANGLED PARTICLES TO EACH COLLAPSE INTO THEIR OWN BLACKHOLES ASAP!! You guys are killing it!! Thankyou Matt and crew, you guys hands down make some of the best content on here! Cheers!
I must not know enough about the actual definition of equivalence, it sounds like Alice's "hey I noticed a firewall" observation that breaks it is similar to looking out the window on the Vomit Comet and noticing that I'm in an airplane & not a distant gravity-less part of space.
Yeah, I didn't follow that. If i think im free floating through space, and then i notice my feet are burning off in a star, im gonna know i mustve been free falling in that star's gravitational field rather than floating in space with no gravity. The star's heat is an effect of the thing causing the gravitational pull just like the firewall's heat is an effect of the thing causing the gravitational pull. Quite possible there's some additional catch with the equivalence principal that I'm not getting though.
There's a difference. From the plane window, you are detecting something- the ground- because the ground is sending something up to you: the photons that enable you to see it. In freefall there should be nothing to detect at the "firewall" of the black hole, because no signal can come from the black hole itself.
I'm in Leonard Susskind's ER = EPR interpretation camp that basically says the following: - An outside observer sees the expected slowing down to infinitesimal rate of motion and dimming we would expect at the EH - If the outside observer waits long enough, they will see the BH evaporate away until there is only a stellar remnant of some sort left - The falling observer crosses the EH and notices nothing out of the ordinary; they fall further toward the singularity in time and when "reaching" the moment of singularity, emerges in the distant future at the moment the BH has evaporated, and there is no BH in existence anymore, nor a "naked singularity", just a stellar remnant of some kind (what ever is left from the evaporation process when it re-emerges from the retreating and disappearing EH - remember, the EH is not a real physical entity) - Thus, the outside observer will (in theory) after a long, indeterminate, but finite, stretch of time see the falling observer fade in again and move away from what once was a BH, while the falling observer simply will be in free fall and not ever even notice that they fell into the BH in the first place Of course, in reality, the chances of the falling observer to emerge again while still alive are slim; they probably have starved by then, unfortunately they forgot to supply an indeterminate amount of cheeseburgers for sustenance until they appear again. The outside observer will have a theoretical supply of cheeseburgers and might survive for a while, but die of boredom in the meantime.
I agree with this, this sounds far more plausible than the silly firewall idea. The firewall sounds like a cheap solution trying to plug up a gap in knowledge. There's little difference between the firewall and "god did it" in my mind. But I also don't think the falling observer would starve to death, considering the immense gravity and time dilation that occurs, if the observer is falling into a large enough BH (so that they don't get spaghettified), they will also be so massively time dilated that by the time they emerge from the BH only a few moments will have passed for the falling observer.
In vanilla General Relativity, the infalling observer _will always_ reach the singularly at the black hole's center of mass in a finite, and rather quick, amount of proper time (on the infalling observer's own clock). Depending on the size of the black hole, it may happen within milliseconds, or take a couple of days for the largest black holes known to exist. The black hole evaporates a very long time _after_ everything that ever fell into it has reached the physical singularly at the center. You can't see Hawking radiation while you are in free-fall, falling into the black hole. You must be maintaining a constant distance away from the black hole, i.e. continuously accelerating away from the black hole, in order to observe any Hawking radiation. (It's like Unruh radiation.) So... um... if you fall into a black hole, you don't miraculously escape at the last second.
@@juliavixen176 That is a misinterpretation. First of all, there is no such thing as "proper time". There is time passing for an outside observer, and time passing for an inside observer. Those are two distinct inertial systems, and none of them is "proper". The infalling person is subjected to a lot of gravitational time dilation, so what is a short span of time for them is a very long time viewed from the outside. The second misinterpretation is that you seem to neglect the internal geometry of the black hole; you might want to take a look at Leonard Susskind's lecture on exactly this case. On your last point, in this model, the singularity is a point of time in the future; in this future, the singularity finishes evaporating and the singularity is the point in time when evaporation is finished. This is no cop out. Remember that time-like and space-like dimensions switch their roles inside of black holes; you are free to move anywhere you want, but everywhere you go is in your future, and at the end of this future is the inevitable singularity. The novel thing about Susskind's approach is that the singularity isn't real, and instead the black hole is a travel shortcut through positive time (so, no dinosaur tourism, unfortunately).
That's how I have been thinking about it too, but in my mind the infalling subject never cross the EH as that would mean it would reach the speed of light and well, we know what it takes for anything massive to get to that speed. So, to me is like one of the Simpsons intro variations where the family is trying to reach an ever receding couch. We know the Simpsons carry infinite wisdom and can predict the future, so maybe that intro is about this and a representation of BH evaporation. The lucky one would travel to a distant future and immediately crushed at the surface of whatever remnant is left as it would have the Schwarzschild radius.
I once saw a picture of soap stretched out and a rubber band place in it and the soap surface inside of the band popped. It pulled the rubber band taut and left a hole there, and I'd wondered if it wasn't possible for black holes to be like this. Cool to see this idea come up here.
We were trying to solve the paradox of an absolute coordinate system in the universe only to find out that none even exists. We were trying to solve how the force of gravity works only to find out that its not even a force. I wouldn't even be surprised anymore if us trying to solve how the interior of a black hole works ends up with the conclusions that there simply is no interior to begin with.
I feel proud to watch this video and not be completely confused about the topic being discussed. Matt/PBS Spacetime Crew have done a good job at building our knowledge up enough to tackle these subjects.
Same for me here. I fee like have watched a sufficient amount of videos that I could explain most of the notions to a layperson. It meansPBS is doing a great job :)
Appreciate the amount of work scientists are doing, debating themselves and others over these topics that can have unseen outcomes for humanity. Or at the very pave the way to answer some of our oldest questions not just about gravity. This was such a fascinating video.
Infinities in the math, and paradoxes, are a sure indicator that you need to investigate and rethink. One of my profs told me that as an undergraduate and it stuck with me. Firewalls seem a good indicator that our conception of what happens to information at the event horizon begs more work
Most people don't know that Einstein said that singularities are not possible. In the 1939 journal "Annals of Mathematics" he wrote - "The essential result of this investigation is a clear understanding as to why the Schwarzchild singularities (Schwarzchild was the first to raise the issue of General Relativity predicting singularities) do not exist in physical reality. Although the theory given here treats only clusters (star clusters) whose particles move along circular paths it does seem to be subject to reasonable doubt that more general cases will have analogous results. The Schwarzchild singularities do not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light." He was referring to the phenomenon of dilation (sometimes called gamma or y) mass that is dilated is smeared through spacetime relative to an outside observer. It's the phenomenon behind the phrase "mass becomes infinite at the speed of light". A 2 axis graph illustrates the squared nature of the phenomenon, dilation increases at an exponential rate the closer you get to the speed of light. A "time dilation" graph illustrates the same phenomenon, it's not just time that gets dilated. Dilation will occur wherever there is an astronomical quantity of mass because high mass means high momentum. This includes the centers of very high mass stars and the overwhelming majority of galaxy centers. The "missing mass" needed to explain galaxy rotation curves/dark matter is dilated mass. Dilation does not occur in galaxies with low mass centers because they do not have enough mass to achieve relativistic velocities. It has been confirmed in 6 very low mass galaxies including NGC 1052-DF2 and DF4 to have no dark matter, in other words they have normal rotation rates
Special Relativity math works for both sub light speed and super luminal speed. Mater of fact, superluminal particles would be called tachyons if they existed. The problem is, they have immaginary mass so we say these solutions are not real. So, what if the event horizon and volume inside a black hole where equally not real solutions? Lets look at the pauli exclusion principle. It prevents any two fermions from occupying the same quantum state. And all matter is made up of fermions. If it is that "no two fermions can be compressed to a volume that is equal to what would be their event horizon" is equlivent to , the same quantum state, then there are not only no eventhorizons, but then there no true black holes, and there are no gravitational singularities, and there is no more information paradox. Apparent black holes would be Just balls of supper dense matter that appear to look like black holes from a distance. But upclose they would ocupy a volume that is a little larger than what would be an event horizon, but would not have an event horizon, and hawking radiation would instead entangle with the highly compressed matter, or the matter's energy just tunnels out carrying quantum entangled information with it. Gravity is preserved as a spacetime warpage rather than a a grand unified therory of everything while equliventciy is preserved in general relativity, and finally plays nice with quantum dynamics within possible solutions matter can exist in, without event horions. But if black holes are infact real with real eventhorizons, then infalling matter would increase a black hole's event horizon diameter. Hawking radiation sitting just above it would be engulfed by the new event horioz, and if there were entangled information, then wouldn't it be engulfed by the expanded eventhorizon? Maybe if there is a firewall then the expanded firewall moves quantum entangled information just a little further away preserving it from entering the event horizon.
Remember that maths includes concepts and paradoxes that are not real in our universe. This firewall solves a problem that is not proven to exist. I assume the firewall has no observations to support it and may cause problems for the varying mass (growth) of Black Holes. Hawking radiation has not even been proven to exist.
8:58 it's not clear to me why a qubit at the event horizon must be entangled twice, with a particle outside (Hawking radiation) and another inside the BH. Are the two particles inside and outside the BH the two virtual particles originated initially? And the 3rd one at the EO must exist because otherwise the space-time fabric outside the EO can't be hold together? This is a blurred part in my opinion.
Love this content! It almost seems like a black hole firewall implies that *nothing* exists beyond it… but time teleporting blackholes sound fun. Hopefully we will one day we will be able to (safely) observe them directly.
Could you explain more about how exactly the firewall hypotheses violates the equivalence principle? I do understand that a 20 minute popular-sciency explanation-by-analogue is inherently flawed and to actually "get it" I'd have to do the hard work and study physics for years, but knowing that doesn't solve my bafflement. Is there any additional explanation that would clear my confusion at least a bit? Specifically, this is what I did not understand: If I am trying to figure out whether my weightlessness is because I'm falling towards the Earth surface or because I'm in deep space, then the Equivalence Principle says I can't do that. If I was falling towards the Earth then I will naturally observe the test result of hitting the ground hard, but even then the Equivalence Principle argues that I still could have been gently floating in the deep space and it was the Earth that accelerated towards me. The "hitting ground" is no problem to the Equivalence Principle because it's just a matter of the environment being the way it is. There's a "thing" and I happen to hit it or it happens to hit me, both being equivalent and true descriptions of the physical reality. And that's my confusion now. How is the black hole firewall different? Why can't it be a "thing" that exists just like the Earth surface? The episode clearly implies that there is a genuine and fundamental difference and that the Equivalence Principle gets violated, and I believe that. I just did not get the why. Any help?
@@hassassinator8858 “black holes explained - from birth to death”. 8 years ago. It’s the “very quick death” scenario. They don’t explain at all, they just say “you would hit a firewall and be terminated” Really bad science communication tbh. I had wondered wtf they meant ever since I watched it all those years ago th-cam.com/video/e-P5IFTqB98/w-d-xo.htmlsi=zm6r4ZnDNjhAkBgb
Thank you! Finally I understand 1) why the paradox is really a paradox and 2) why, when a seemingly arbitrary amount of 50% of the black hole has evaporated, the information becomes, in principle, recoverable. I've heard lots about this and everyone has these convoluted, esoteric explanations (even you, Sean Carroll!)
Great vid - just ordered a hoodie from the store, can't wait to get it! This one really made my head spin. If I understand correctly, there is presently no concept for how exactly the firewall itself works - rather it is simply the required amount of energy that must be present on the horizon in order to break the entanglement between the virtual particle pair generated from random quantum fluctuations. So, assuming what I stated above is correct. A quick side note, as I understand it, when quantum fluctuations generate a pair of virtual particles, these particles normally annihilate immediately with no further observable effects (with the exception of the casimir effect and hawking radiation or other related special conditions). However, when a pair of normal particle's annihilate (for example an electron and a positron) the annihilation event emits a high energy photon as dictated by conservation of energy. So, I'm assuming that since a photon is not emitted when virtual particle's generated by a quantum fluctuation annihilate it's because energy is already conserved because they together reached "zero point energy" via annihilating back into the vacuum. If that's true then (I admit, this is a big IF), how is energy conserved if one of the virtual particle's escape as hawking radiation and the other goes down into the abyss of a blackhole? Is there any chance that the point on the horizon where the annihilation would've normally taken place manifest's the firewall to satisfy conservation? Maybe more specifically, when a new particle is absorbed into the blackhole when it cross's this point left by fluctuation event it is taken instead (hence, "completely thermalized")? In my head this kind of make's sense, but I would appreciate someone explaining why I'm wrong (obviously, there has to be a reason this isn't true - I just don't know what it is) Otherwise, other than to satisfy the condition of breaking entanglement of the produced pair on the horizon, is there any proposed "mechanism" of the firewall on the horizon talked about in this video? Thanks for the excellent content as always.
Watching these Space Time videos makes me miss working on Quantum Computation back when I was getting my degree. It was hard, but the end result was fun.
8:50 "Without entanglement there is no space" seems to refer to Leonard Susskind's (and someone else's, Maldacena?) theories relating entanglement to the "spatility" of space. I would love to hear PBS Space Time do an episode on this, it seems like exactly the sort of explanation you are good at.
Another thing worth revisiting is the kugelblitz video -- how does this work if a black hole forms around you, rather than you falling in? The space disappears? Does it happen faster than the speed of light?
What I always asked myself is whether Hawking Radiation completely throws the possibility of falling into a black hole off the table. Since it is said that a black hole will evaporate in a *finite* amount of time, wouldn't that mean that the time dialation near the event horizon can become so great that the actual black hole would shrink just before one would enter? Would that also imply a trip to the vastly distant future where the black hole completely evaporated, or became small enough to tear the traveller to pieces?
Moreover, the event horizon never forms, since the same thing happens to the first particle that tries to form the event horizon. I hope that the "mainstream" black hole community will eventually understand that straightforward conclusion. I'm repeating this since 20 years, and I'm happy to see some commentors getting to the same trivial result.
@@geraldeichstaedt I think we've got enough evidence that we can assume BH-like objects exist. The question here is if there is any time-like path from outside the event horizon that crosses the horizon before it evaporates in the far-but-finite future.
@@johngregor6743 Black Holes aren't black because event horizon, they're black because extreme time dilation which redshifts all radiation so it becomes Hawking radiation. And Event Horizon is, actually, perfect term: it's true meaning is last thing that can happen to you in THIS Universe - is crossing this Event Horizon. It's the last event in the universe for that poor falling observer.
@@johngregor6743 I don't think that there is any time-like path manifested in real black hole physics. From an experimental point of view, the event horizon is inaccessible by definition. So, all evidence we have, is that of a compact mass that obeys General Relativity to the accuracy of our measurements and that doesn't appear to enter a steady state once it's collapsing. Crossing the event horizon within finite time in terms of an exterior frame of reference would question General Relativity and essentially state that the singularity reaches up to the supposd event horizon, if we take the Penrose theorem as a basis to define a singularity as a region where General Relativity and related theories are violated. But this would question the notion of an event horizon itself since it's based on the notion of a continuous spacetime and a GR-ish physical settings, and hence the notion of a black hole in any classical sense.
No because from the reference frame of the infalling observer, the equivalence principle still holds: this means that he doesnt feel any gravitional anomaly and thus no time dilation. However you can see that there is infact such time dilation but only from an outside frame of reference: infact an outside observe communicating with an infalling one, would know that their respective clocks tick at different rates, but this is only "observable" by the outsider observer. So an infalling observer would simply pass through the event horizon without noticing anything strange and in a finite time
A somewhat related question I haven’t been able to find an answer to: When falling into a black hole, as you approach the event horizon, would the time dilation be such that as you approach and reach light speed the external universe’s clock appear to move infinitely quickly? As a consequence of this would you then witness the heat death of the universe above you? This produces a dilemma as it has been theorised that black holes should decay slowly via Hawking radiation, would this not occur instantly as apparent external time approaches infinity? Is it possible that this would mean that before you can ever actually cross the event horizon of a black hole that it would evaporate?
@@geraldeichstaedt I suppose that even the quintessential event horizon that defines a black hole forms infinitely far into our future as an external observer as anything that reaches it would witness the same temporal distortion, not just you as an observer approaching it.
Here’s an idea: The “firewall” that Bob encounters is actually/also the entire evaporative history (via Hawking Radiation) of the BH. For Alice, this encounter plays out over the long remaining lifespan of the BH. For Bob, it happens in an instant. The difference in perception is due to the extreme gravitational time dilation near the EH.
That's a good idea, but unfortunately the time dilation doesn't work that way. If you freely fall into a black hole, you do not experience a sped up view of the outside universe, nor of the black hole evaporating. That only happens if you hover just above the horizon (which would require an enormous acceleration.) In other words the time dilation means the faraway observer sees your light get infinitely redshifted, and not that you see everything infinitely blueshifted (again unless you hover there.) The reason is because redshift/blueshift is related to the change in energy of photons reaching you, but if you are freefalling, the photons gained the same amount of energy that you did, so you see no shift at all.
@@watsisname I say it's relative. I'm not sure you would experience colour shift at that distance. I think the effect on you would be relative and that your biggest concern would approaching light speed.
@@watsisname ooh, I hadn't considered that. Essentially the photonic frame of reference around a black hole will be accelerating towards the hole along with the observer...
@@watsisname It's not the shift of the photons that matters, it's the *quantity* and *density*. The universe will not redshift, but it will still explode behind you - and the black hole will explode in front of you - so yes, you would hit a firewall as photons pile up on you to a ludicrious degree - not that you'd care, as your total height from head to toe is now ~1 plank length.
Just had a striking observation that the firewall must be on both sides of the event horizon or for it to not be seen at all, the only alternative is the fire wall is exactly the photons/energy that's orbiting the blackhole precisely at the event Horizon but this is only possible if it's an infinitely thin line and I feel like nothing exactly fits that description except electrons... perhaps the quantum uncertainty principle and thus the probability cloud becomes 100% exactly on that boundary and 0% everywhere else and that is your firewall. Only electrons as far as I know are described as point like and once you confine the probability cloud to an infinitely thin line that is the boundary you get a firewall. This would mean the boundary is NOT visible as 100% of the boundaries energy which may be infinite by the implications of this description is exactly orbiting the blackhole, none of it escapes in any other direction to hit a retina or detection device and thus space appears locally uniform. You approach it at the speed of light so like a vacuum decay, you never see it. You just cease to exist in an instant every infinitely thin slice of you crossing that boundary being obliterated by the firewall is now traveling towards the singularity at the speed of light meaning every infinitely thin slice of you crossing it can never warn the rest of your body to transmit any information about its existence outward.
Thanks for another great video. I have a question that I have begun thinking about after hearing several times that nothing can cross the event horizon (in finite time), because it will seem to be frozen in time above the horizon for an outside observer. (And there light from it that do escape becomes to red shifted as to become invisible, i.e. black, as in a black hole.) But what then when two black holes collide, as measured to happen (now several times) by LIGO, when the two holes orbits each other at extreme speeds just before they collide and causes gravity waves for us to detect with LIGO. If it should take forever to reach the event horizon, what is it then that causes those two black holes to merge in an instant? (Or do they not really collide, but only get close enough to stop spinning fast enough for us to detect because their time is slowed down very fast when getting close enough to each other? Just thought of this last par while typing.) Have no idea if any of this makes sense of if there are any problems or I just overlook a simple explanation. But is seems that the collision of black holes goes against the idea that nothing can fall all the way into a black hole as seen by an outside observer... Which we are when detecting the gravity waves of two black holes merging. Thanks in advance for a good explanation, either here or in a new video ;-)
How would the firewall explain the very formation of the black hole? I mean, it's technically possible to make a neutron star very close to the mass of becoming a black hole, and then trow a few more neutron to transform it into a black hole, where does all that volume, information, mass, energy, disappear, if the space-time itself stop existing? And is it instantaneously, like all the quantum information of all the particles that were making the volume just before it turned into a black hole, suddenly appear on the event horizon? Also, I'm still not sure I understand the whole particle-antiparticle hawking radiation, like AFAIK, both particles and anti-particles have mass, then how come the mass of the black hole gets smaller and smaller as it "eats" those particles? And, if something crazy like negative-mass particles exists, how they decide to only go inside the black hole and never in the hawking radiation? Or is simply a matter of energy, like if this firewall exists, it takes double the energy to break a virtual particle pair, and then half of it goes outside.
It's very easy, actually. All this mass of a collapsing object becomes this firewall. No black holes exist, they just didn't formed yet. They all in a process of their collapse and they'll finish only when Universe (or Space-Time) ends. Or never, if there's no ending of space-time. And Hawking radiation is just regular EM radiation which becomes extremely redshifted by time dilation near extremely dense collapsing object. No virtual particles needed. Also, I don't see any equivalence breaking paradox there: a falling observer never enters a BH from the perspective of distant observer, because time dilation will send this event to the end of time. And falling observer just leaves distant observer's Universe by travelling to the end of time. In other words, it's not just space dividing the Universe outside BH from the Universe inside, it's also time, bacause space-time is one thing.
@@user-zz6fk8bc8u No one knows how the horizon actually forms. Maybe it forms inside, at the very center of a collapsing object, and then expands. It is basically the region of extremely curved space time, because of insane mass concentration.
One thing I've wondered for a while about black holes, and maybe some of you can clear up this confusion, is: Since time stops at the event horizon (for the outside observer), if you fall into a black hole, the outside observer should "see" you simultaneously hitting everything that's fallen in before you, and being hit by everything that'll fall in after you, exactly when you cross the horizon (which he'll never actually see because 1) it's in the infinite future and 2) redshift; but it seems to me that that's the correct extrapolation from what he does see) Doesn't that mean that while you fall in, you'd in turn see the outside universe speed up, getting UVshifted to the point where it annihilates you as you get close to the horizon?
What you are seeing here is the stated limitations of relativity. Mr Einstein clearly states that the theory of relativity is limited and breaks at and beyond an event horizon or singularity. It's a bit like the idea of a photon traveling at the speed of light experiencing no time. Einstein clearly states that you can't use time dilation for a photon or massless object. The speed of light 'c' is an event horizon. Relativity will work up to 99.999999... % of 'c' but fails at 'c' due to weird mathematical infinities. > So, at any event horizon be it a black hole, the event horizon of causality 'c' or a particle that occupies a singular (singularity) in any "now moment, relativity cannot work and they have to move to Quantum field theory of Quantum mechanics to offer descriptions :) > So, you are just discovering the limitations of the theory of relativity :)
@@FLPhotoCatcher I'm here to nip this irrevelant comment chain in the bud. Keep your eyes on the prize y'all and don't throw things off for other viewers.
@@LordOfThePancakes 1. Guy is gender neutral 2. Matt's pronouns are very clearly displayed in the end card of almost of every episode, it would be wrong to NOT use his preferred pronouns due to YOUR ignorance of them.
How will one see if there is a firewall? As the only particles out of it are hawking radition. Is there a way of knowing wheater a particle is entangled with other by only seeing the first particle? 13:46
If nothing can cross the event horizon, how can a black hole grow? How can two black holes merges? We have observed the merger of two black holes via the gravitational waves generated by the merger, so this phenomenon exists.
Every science channel must have at least one video about black holes . . . . and i love it 😊 Our known cosmos is full of incredible wonders, particels, time distortions, quantum fields, negative multiverse impacts, and we may never fully understand the science behind it, but we will work on it
I don't quite understand why the firewall would break the equivalance principle. Doesn't the surface of a planet act in the same way? It's just a physical barrier as far as I recon, which doesn't interfere with the spatial properties around the black hole. What am I missing here?
As far as I understand it, there is supposed to be nothing special about crossing the event horizon. There’s no temperature increase. But the firewall would definitely be hot but for no apparent reason so the equivalence principle is broken.
@@louislesch3878I think it means that more like such intense firewall of energy would create its own gravitationl effects such that when you free-fall towards the event horizion, you will feel this "effective" gravitational force
It's not a physical barrier though. It's a feature of space itself. You're in a gravitational field and logically you should keep falling but you can't, because space ended.
8:35 "these pairs of swallowed and radiated things have to be entangled with each other" - but the swollen thing has effectively negative mass, by swallowing it the black hole becomes less massive. It does not continue to exist inside the black hole so we can count 3 particle instead of 2. It is similar to a particle which escapes by tunnel effect, it does not create an entangled twin inside the well
@@Boritis I don't know does it make sense to speak about the properties of this swollen particle, I think about it as a fictional - but the result is one particle disappears inside the horizon and one particle is radiated away, so there is nothing inside to be entangled with the radiated particle
Purely as a layman, it makes me wonder if the firewall is equivalent to the holography argument ie. the firewall is the 2D manifestation of the blackhole's 3D interior. I guess a region in spacetime where the fabric becomes so distorted space behaves like time and vice versa, would probably have some odd properties like violating equivalence. But again, way out of my depth a few videos ago lol Or, maybe the firewall only appears if you try to accelerate near the horizon, and disappears if you remain in freefall straight through the horizon. I suppose it could be similar to BH complementarity in that way.
What if there's no 3D-interior after all? What if space-time becomes so distorted so it becomes 2-dimensional? But with 2 time-like dimensions instead of one.
@@Boritis maybe that's exactly what the 2D hologram would be like. It's hard enough to imagine an infinitely far away surface that's encoding the entire 3D volume of the universe in lock step with us, maybe it'd be just as weird to consider a "3D interior" if we started our considerations at the surface.
So what does breaking the entanglement physically do? Like what is the mechanism here which would generate the firewall? And where is that energy coming from? It feels like violating unitarity is the less radical problem provided it is only violated along causally discontinuous spacetime
I don't think the firewall violates the equivalence principle. The equivalence principle simply says that being in a gravitational field is equivalent to being in an *inertial* frame. It doesn't say you also have to feel like you're moving slowly relative to other stuff. If you're right next to the event horizon, you may feel like you're in an inertial frame, but you're also experiencing extreme time dilation/ length contraction relative to a distant observer. The equivalence principle analog of this would be traveling at a constant speed at nearly the speed of light. And guess what you'd be staring at? A completely identical firewall made by the CMB radiation. This points to the idea that Hawking radiation and the CMB are deeply related in some way.
Agreed. Key point in equivalence principle is 'locally'. The locality becomes smaller the greater acceleration. While Alice won't be able to fall smoothly lol point like particle will. It's ridiculous so called scientists make silly mistakes like that. Yeah and also the greater the acceleration in absence of gravity the bigger Unruh effect. So don't see what's surprising it's the same around bh? If anything equivalence holds 😂
@Nat-oj2uc That's an interesting point about unruh radiation, though, as you say, it's only visible when you're accelerating. So, I don't think that would satisfy the equivalence principle, though the CMB would be extremely blueshifted at constant high speed. I think a lot of people seem to miss the caveats that go along with the equivalence principle. You mentioned the locality one, but another one is the non equivalence of relative speed. Let's say you are in a rocket ship at a constant acceleration. If you do experiments inside of the rocket ship, it would seem like you are standing on a massive body, but only if you don't look out the window! It's the same thing as being in free fall vs being in deep space. It seems the same until you look out the window and you see the ground coming up at you!
It IS both eerie and beautiful :) I did some thought experiments on it decades back and it wasn't so much that it didn't exist, it just seamed to be reversed (kind of turning the sphere inside out). So it kind of put the center of the sphere (the singularity) on the inside edge of the event horizon. The "space" between the outer edge of the event horizon, and the center just below the event horizon was still there, but it gave the impression (from the external view) that a large spherical chunk of space time had gone missing (I kind of viewed it as an illusion of excessively warped space-time) :)
That point about the singularity expanding to the event horizon gave me a few ideas. Half of what's on this channel goes over my head without a repeat watch, and these ideas might have already been addressed or shown to be impossible with info in other videos I don't remember, but who knows. What if a star/stellar mass collapsing into a black hole is it crossing over the breaking point of a sort of "quantum pressure", not to dissimilar to protons turning into neutrons in neutron stars or even neutron stars into the theoretical "strange stars", where "normal" matter goes from being in a defined yet unknowable state, to being changed into some other, new phase of matter where all possible quantum states are "filled"? In this case it could be not that the forces within the event horizon get even stronger towards the center, but that the body of the black hole is a sort of homogeneous and equal density of "full" space-time, possibly where there is no "real" distinction between the center and near the edge of within the event horizon, and new quantum information flowing in is not destroyed, but is altered in a way that it can cram into an un-claimed quantum state. Given the existence of things like the "Planck Length" and "Planck Temperature", this says to me that all cells on the spreadsheet of quantum information have defined ranges, and therefore, every point of space-time has a defined amount of possible quantum states, and those quantum states could be crammed full by the absurd amount of energy in the process of a collapse. And on top of this "state-cramming", given the sheer energy required in neutron stars to convert protons, and even vastly more energy for that "neutronium" to turn into the theoretical "strange matter", I don't think it's that far off of an idea that the collapse into a black hole could cross this energetic barrier to transform into this new state of matter, possibly one beyond anything we can concieve as of now. A bit of a long shot, but as an extension of this, in regards to hawking radiation and evaporation, is that conversely to the (to my knowledge) typically un-entangled matter that adds to the mass of the black hole, in the pairs that form near this boundry, the in-falling half bounces off of the surface, alters one of the taken quantum states on the surface (like how observing a particle changes its information, the thing that makes it never fully knowable), and that which it interacted with cannot change into one of the other quantum states taken within, so that information which *has* to change because it was interacted with changes into an information state that is available, and the only available states it can take are *outside* of the event horizon, thus performing the process of evaporation. Think of it like the "death by 1000 cuts" but it's "Death By Eleventy Bajillion Hawking Pairs Tea-Bagging The Surface Of The Black Hole". Another way this could work is that (some of?) the information of the in-falling particle could be in a way "locked" by the escaping particle, destructively (to the black hole) interacting with this "full" matter on the surface, causing this same "nowhere to go but Out" effect, causing of these occupied states to change in a way that forces it to superposition/tunnel to the other side of the event horizon. While this my not be the most accurate descriptor, in this theory, the black hole doesn't destroy information, the black hole IS the information. I spent over an hour writing this comment and re-writing and processing this all, it's almost 4am, I would like a cookie and some sleep now please.
13:01 All right, it's clear y'all need a scale. So who's got the plan for how we send something back and forth between two distant enough places? That will also vary enough over time to with calculatable enough accuracy such that we can measure the change in gravitational pull upon an object that is doing the exact same thing every single time repeatedly for like 500 years give or take. That should probably be enough. Also more than one probably like 50,000 of them
So electron flying through both slits simultaneously fits perfectly into quantum theory, but a qubit being on both sides of the event horizon somehow ruins it?
Yes? Well I mean, insofar as “being in two places at once” is a good description of an electron of being in a superposition of going through one slit and going through the other slit. It is a different sense of “two places at once”. If the qubit was in a superposition of having fallen in and not having fallen in, that probably wouldn’t really be a problem. Like, if you have a photon whose spin is being used to encode a qubit, having that photon be in a superposition of going through one slit and going through the other slit, that’s not an issue. That’s normal. But having two of “the same qubit”, maximally entangled with another qubit, well, that would let you do two different measurements of it, and... that doesn’t work...
As far as I understand it (which might not be very far) the difference is you can theoretically detect the particle both inside and outside the event horizon at the same time, meanwhile the particle moving through both slits can only do so as an (unobserved) wave. Attempting to detect it in both slits simultainously causes the wave function to collapse and it "shows up" in only one of the two slits
Haven't watched the entire video yet. But a qubit is simply two states of information (on or off, hence the affix -bit). While an electron passing through two slits has a lot more information: it has an output of an oscillating probability curve bound by a normal distribution defined by said parameters . Also event horizons are weird. Really weird. Arguably, physics doesn't have a place describing what's happening behind an event horizon.
I studied physics at university level, specialized in high energy physics, also followed cosmology and particle physics classes. But after seeing these Space Time videos I feel like I am a complete nitwit in physics 😂 These videos are so great, I learn really a lot from them! But it will take a lot of time before I fully grasp everything Matt explains.
@johnreder8167 imagine a sheet of paper, now cut a circular "hole" in it, imagine that 2d living beings lives in the paper, to them there is no way to distinguish the shape of the hole to any other circumference of the normal circles in their world, the thing is that we as the 3d beings are seeing the hole from a perpendicular perspective that the 2d beings don't have. the non-continuous space time inside the "firewall black hole" seems to be the same thing, only that this time we are the ones inside the paper.
12:40 Well, the sight of approaching Earth surface and first sensations of getting spattered on it do not violate equivalence principle, why this firewall should?
For a stationary black hole, it would appear to you that you never fall through the event horizon, because any light that has fallen in further than you can never reach you, but the mass can still lense some light to you, as long as that light hasn't yet fallen in further than you. So to an object falling into a stationary black hole, the black hole would appear to shrink away from it, all the way up to the moment when it reaches the Roche limit and the tidal force renders it to quarks. But stationary black holes probably don't exist.
@@kethmarhkfy7luf.263 I think they meant non-rotating black holes (ie: the Schwarzschild metric). I'm not sure their assertion is correct, but I don't think they meant stationary in terms of spatial position.
So, where this black hole firewall take the energy to power up a giant screen of death for octillions of years? Because this sound to me like a quite promising energy source.
That'd imply the "firewall" can even be broken up or harnessed. Then, if both a firewall does exist (it's only a hypothesis) and it being able to be harnessed/broken up... what happens after? How destructive would the information being freely let out be to the universe at large?
You've got very shallow understanding of it. Not that mine is any deeper, but that firewall would be something quantum size thin. And where it would get it's energy is explained in the video. Either way, it's just continuation of quantum physicists making things up just to make their wonky math check out for things they don't understand.
I have absolutely no idea, but my first guess: The energy is the vacuum energy corresponding to the volume of the black hole. If there is not even a vacuum inside, that energy must be somewhere. And as with all vacuum energy there would be no way to "harvest" it. Don't know if that energy will be sufficient though.
I guess from its mass through de-entanglement driven by hawking radiation? So kinda by virtue of being a crazy dense and sufficiently large lump of matter?
So, here's the problem I imagine. You try to plug into the firewall and just end up as part of the firewall yourself... unless you have unlimited energy to propel yourself (or your energy collection device) away from the gravity well, which is pulling space itself inward at relativistic speeds, but then you already have the energy and might not need to harvest the firewall. I'm not sure how to do the math to see if that could even theoretically gain more than what is lost in preventing the fall into the black hole. Interesting to think about, anyway
Hi Matt. Isn’t it obvious that the object falling into the black hole isn’t the same as the light emitted by it or reflected from it? The object falls in but the light slows down so much that to the outside observer it *looks like* the object never falls in. I see no breaking of equivalence or unitarity.
1. If nothing can cross the firewall, then how does a black hole gain mass? 2. What about when black holes merge? Clearly, the event horizons do cross, which would means it MUST be possible to cross the event horizon. In these events, wouldn't it be possible to see the bulk of the material in the accretion disks being annihilated by 2 firewalls? 3. Further, how is this ridiculously powerful energy field being created? What mechanism (that no one has ever measured/seen/theorized before) is creating it? This episode seemed to explain everything in more comprehensible terms than usual, yet, I'm more confused by the subject matter somehow. A TRUE information paradox... :)
1. The mass is the firewall. 2. The merger happens as the event horizons meet, they don't cross. 3. The energy is all matter moving at near light speed as it approaches the event horizon. 4. I don't know what I'm talking about.
To expand on @knurlgnar24's answer to 1, the gravitational field outside of of a spherical shell of mass is exactly the same as if the mass were collapsed to a central singularity. So if black holes have firewalls, then all the mass lies on the horizon, but their gravity and appearance are exactly the same according to distant observers.
@@watsisname Knurlgnar's 4th point was that he didn't know what he was talking about (which I understood to be "I'm joking"), so expanding on that seems... questionable? To knurlgnar's point, the mass cannot be the firewall, since the mass is below the event horizon, or at least 'at' the event horizon, and the firewall is supposed to be above that. The whole theory of the firewall is that nothing can get close to the event horizon, since it is destroyed by the firewall - literally the point of the firewall theory. Therefore, if all mass is converted to energy by the firewall before it can be absorbed into the event horizon, it cannot add to the mass of the black hole. To your point, the mass being at the center (the singularity) or the event horizon is immaterial. The question was, "If nothing can cross the firewall, then how does a black hole gain mass?" The firewall would eliminate any future growth of a black hole by destroying all matter before it reached the event horizon, meaning there can be no growth (as we understand it).
@@madnessbydesignVria I honestly don't have credentials to answering these questions, but my understanding of the 'firewall' is that since no outside observer can ever witness anything falling past an event horizon then it means anything falling into the event horizon is in the infinite future which means it can never happen even if the observer falling witnesses it without time dialation. Logically this must mean that nothing can ever pass the event horizon. Given that Hawking radiation is a thing then that means nothing falling into the event horizon can ever reach or pass it even in their reference frame. That means the 'firewall' must be real. And, yes, I don't know what I'm talking about.
Thanks for this episode which I have been asking about for years now. The comments are asking about how the firewall is spontaneously generated in the first place. In my opinion, and keep in mind that all astrophysical (actual) black hoes are rotating, if spacetime is thought of as 3D surface tension of a 4D fluid, just for argument’s sake, then once a black hole forms, say from a collapsing star, the angular momentum of the star is retained and the vortex keeps going so much so that there is substantial interstitial shear at all elevations in the black hole. This shreds spacetime so that it’s effectively quantum foam but macroscopic. In my opinion, the firewall solves these paradoxes and will eventually have to drive theoretical physics to these same conclusions. It doesn’t even break GR, it’s just an expansion of it.
This is a fascinating idea, which leads to a few questions. If there is nothing inside a firewall, does that mean the firewall IS the black hole? How does it grow over time? What happens if the black hole collides with something much larger? Does it bounce off, break up, stilll consume the bigger object, or something else? Are there different size limits?
hello, Mr Matt, my idea for antigravity engine: The concept is based on the following principles: 1. A tokamak reactor is used to create a plasma of fusing atoms. 2. The energy released from fusion reactions is utilized to strengthen the magnetic field around the plasma. 3. This enhanced magnetic field accelerates the plasma to near-light speeds. 4. At these extreme velocities, the plasma reaches a new state of matter, where added energy manifests as additional mass. 5. This new state of matter generates a significant perpendicular force. 6. When the tokamak is charged with this 5th state of matter at a specific point, the resulting perpendicular force exceeds Earth's gravitational pull. 7. The system, entangled with the 5th state of matter, disconnects from Earth's gravitational field, effectively achieving antigravity. This concept represents a potential unification of quantum physics and general relativity, offering a novel approach to antigravity technology. what do you think?
Too expensive to build and maintain and use it, just use rocket and jet engine or turbofan engine , or helicopter stuff, much more simpler, more reliable , actually practical in real life Actually do something useful
You've got me curious about a possible connection between event horizon barriers and those perhaps lesser barriers at the limits of a solar system, or even potentially of a star or planet (like ours). Thank you for the "food for thought."
3:40 the firewall could un violate equivalence if there's a preferred background reference frame similar to the cmb co moving reference frame when gravitational lensing changes the nature of diversity of firewall types without making them any less firewall.
I wonder idk like 2years ago, about similar thing. That is "probing" (so to say) black hole with entangled particles. I know that it is not really the same stuff as described in this video, but still. I'm kinda happy I came up with it before it was published on PBS. Btw lovely episode!
Just about every Black Hole Information Paradox video on TH-cam seems to forget that: 1) From the outside observer’s perspective, it takes a falling object infinite time to reach the event horizon, but meanwhile the bh is sloooowly evaporating as Hawking radiation, so the latter process will finish first. And therefore 2) Due to time dilation, the Hawking radiation looks like an explosion of gamma rays to the falling object’s perspective. If that observer survives the Hawking gamma storm, it will still see the black hole radiating away all of it mass and vanishing before it gets even close to the event horizon.
Yeah... this has always been my intuition of the situation... due to extreme time dilation near the mass of the black hole, wouldn't the outside observer experience waaaayyyy more time than the falling object? Like, the object is still "falling" / "chasing the horizon", but from the outside, so much time has passed that the black hole evaporation is significant
watch the recent videos on black hole complementarity and the information paradox if you want to see these mentioned. also, no, time doesn't speed up to infinity for infalling matter, because the time dilation outside the event horizon of most black holes isn't extreme enough for that.
@@april5054 Never said it speeds up infinitely, only that it would take infinite time to an outside observer. Not the same. But the point is moot because the event horizon is shrinking away as the faller approaches anyway.
@@jerrysstories711 like i saide, the time dilation is too slow for the event horizon to even come close to shrinking away from the infalling matter. black holes don't evaporate on timescales that short, or theyd all be gone by now. anyway, they're growing right now.
A bit of a tangent, but an insightful tangent appears when one appreciates that at the Event Horizon, there is a steep gravitational gradient. Gravitational gradients (steep or not so steep) affect local timekeeping. In the Hawking Radiation scenario, the pair of virtual particles are maximally entangled, meaning they are oscillating at their characteristic de Broglie frequency. At the instant of the birth of a pair of virtual particles, they are jointly oscillating in perfect phase-locked synchrony. But as they separate along the black hole's gravitational gradient, they drift out of phase with each other: they necessarily decohere with their increasing separation distance. Now apply that same thinking to a pair of entangled particles (or qubits) in a Bell test experiment. Due to the ubiquitous presence of gravitational gradients (e.g. those affecting the Earth's tides), the Bell test particles also drift out of perfect phase-locked synchrony; they ineluctably decohere with separation distance. Bell left this phenomenon out of his mathematical model, assuming that timekeeping was uniform along the axis of separation. If you add gravitational gradients back into the underlying model for the derivation of Bell's Inequality, you don't get that his presumptive hidden variable, λ(x,t) is an odd-function, integrating to zero. Rather you get a non-zero "beat frequency" term arising from taking a gravitational path integral. This discrepancy suffices to explain why the Bell Inequality doesn't apply to time-varying (oscillating) characteristics in a cosmos suffused with gravitational gradients. The not-so-hidden variable is time itself (and any characteristic (like phase of the de Broglie wavelength) that is a function of distance and time. The (essentially random) phase of the Bell test particles suffices to explain why Bell test experiments do not obey his inequality, due to decoherence arising from differential timekeeping, thanks to gravitational gradients.
I am not convinced there is a paradox at play here. If i sat a qubit on my desk and put a mirror across the room from it, i would be able to see the qubit by looking both directly at it, and by looking at its reflection in the mirror. No one would claim the qubits been duplicated - i can just either look at it directly, or at an image if it. In the same way, when the qubit falls into a black hole and the last light to interact with it gets caught in the event horizon, im not look at the _actual_ qubit on the event horizon. Im looking at an image of it in the very last moment before it passed the threshold. Edit: heres an analogy - say i was on a spaceship orbiting a black hole, and im holding some object, but i have my eyes closes and have no idea what it is. I throw the object in, and once I’m good and sure its passed through the event horizon i open my eyes, look and the event horizon and see the object was a lit lightbulb. However, the object was actually a flashing lightbulb. If i was inside the black hole id be able to look directly at the lightbulb and see this additional piece of information, but since the impression caught on the event horizon is just a snapshot of the object, the information is lost to the outside world. To me this busts the paradox - the actual nature of the object would continue to exist below the event horizon, but would not above it.
"If i sat a qubit on my desk and put a mirror across the room from it" Would you see the qubit in the mirror, or a photon carrying the information of the qubits position. A qubit and a photon are separate objects... well actually a qubit isn't even an object, but I'm sure you get what I am saying :)
This is not the case because you are assuming that the infalling observer is the "main/preferenced" frame of reference between the two: who is to say then that the actual real qubit is the one outside stuck on the horizon, visible by the outside observer?. In relativity, the concept of simultianeity of events is not the same as that of classical physics, but even if two observers observe the same event (that would be simultaneous in a classical framework) but at different proper times, they are still observing the same event. The fact that both observers disagree on the simultaneity of the event doest mean that one of them is wrong and is actually seeing a "snapshot" of the event, a.k.a. a "false" or "late" information of that event. They are indeed seeing the same event, at the same time except that due special relativity its not at the same time from their different perspective. There's no "preferred" reference frame, so your metaphor with the mirror is not correct here and the paradox still exists. The qubit stuck on the even horizon is not a "snapchat", nor is the qubit already inside the event horizon: both are equally as real as they get in each reference frame. I know it sounds weird and counter -intuitive but thats special relativity for you
@@StefSubZero270 "I know it sounds weird and counter -intuitive but thats special relativity for you" Yeah, that why many of us don't like it. It places the reality of an object into the position of the observer (human). All reality is then a disassociated photon and the original object become some abstract non reality.
@@StefSubZero270 "The qubit stuck on the even horizon is not a "snapchat", nor is the qubit already inside the event horizon: both are equally as real as they get in each reference frame" You can pretend that the object has not gone through the event horizon, but that's a bit like looking at a star and pretend that it hasn't moved since the photons were emitted. The only difference with the black hole is that you can't tell if an object has gone through or if it's still floating just above the horizon. But in practice we know that based on other information. E.g. we know that a lightbulb has no ability to counteract gravity like a rocket might.
You already cannot cross it. In the reference frame of a distant observer, you take forever to cross it, that is not an illusion, you just asymptotically approach it. So you either take forever to cross it or hawking radiations if real destroys the black hole before you cross it. From your falling perspective this time is finite, but the black hole evaporates before you enter it, or if you enter it, there is no outside anymore, because infinite time has passed outside.
Something that I never understood is that 2 things related to the firewall paradox is exactly what I would expect to see even from the most basic description of black holes, and yet I've never heard someone mentioning them: -firewall: if from a distant POV I see the BH evaporating in a finite time, and from that same POV I never see alice crossing the EH, doesn't that mean that also from Alice POV she never crosses the EH? And if we see the whole mass of a BH evaporating in billions of years, shouldn't Alice see the same mass evaporate in just the few minutes/seconds of her fall? Isn't this a powerful firewall? -"the interior of the black hole might not even exist": if from a distant POV the BH evaporates in a finite time, shouldn't it also evaporate from Alice POV in a finite time? Shouldn't it evaporate from any reference frame, included any reference frame of any particle falling into the black hole? Doesn't tha mean that a Black hole evaporates before even forming? Or maybe that just before turning into a BH, the matter falling into it "evaporate"? No BH => no paradoxes. An this would not violate our observations because from a distant observer, an object that is *almost* a black hole would be indistinguishable from a "complete" BH. Does someone know where this logic is wrong?
I repeat this since 20 years, and I'm glad that in the meanwhile some people appear to understand. If there is Hawking radiation, there is no classical black hole in our cosmology. Same if General Relativity holds always (meaning that there are no singularities, hence no closed event horizon by reversing the Penrose Theorem; without GR, black holes wouldn't make much sense anyway), and/or if the second law of thermodynamics is always true by contradicting the no-hairs theorem.
*Summary: Black Hole Firewall Paradox* * *[**0:00**] Introduction:* The video sets up the scenario of jumping into a black hole and introduces the idea of firewalls. * *[**1:38**] The Problem:* Black holes present a fundamental conflict between Einstein's theory of General Relativity and Quantum Mechanics. This is known as the black hole information paradox. * *[**1:45**] Information Paradox:* Black holes seem to both destroy information (by swallowing it) and preserve it (through Hawking radiation), contradicting a core principle of quantum mechanics called "unitarity". * *[**4:13**] Entanglement & Monogamy:* Quantum entanglement plays a crucial role. For Hawking radiation to work, particles need to be entangled both within the black hole and with the escaping radiation. This violates the principle of "monogamy of entanglement" - a qubit can't be maximally entangled with two things at once. * *[**10:29**] Firewall Solution:* One proposed solution is the existence of a "firewall" - a high-energy barrier at the event horizon that prevents anything from entering the black hole. This preserves unitarity. * *[**11:55**] Equivalence Principle at Risk:* However, firewalls directly contradict the equivalence principle of general relativity, which states that freefall should be indistinguishable from the absence of gravity. * *[**15:00**] No Easy Answers:* The video explores various attempts to resolve this paradox, including black hole complementarity, modified quantum field theories, and even the possibility that black hole interiors don't exist as we understand them. * *[**16:29**] The Search Continues:* The black hole firewall paradox highlights the limitations of our current understanding of physics and motivates the search for a unified theory of quantum gravity. i used gemini 1.5 pro to summarize the transcript
"A lot of energy is needed to break entanglement" Okay, but need and exists is two different things. As presented on the video, there is no explanation to where this necessary energy would come from. It doesn't seem to be emerging from the theory itself and rather being "there is a firewall because a firewall would solve this problem"
@@drdca8263 A supermassive black hole could be formed from something with an extremely low density and temperature, and its horizon may form long before collapse leads to extreme temperature or pressure.
We don’t enter the black hole. The black hole grows around us. We are frozen there until the end of time, or when Hawking-radiation disintegrates us. Side-note: it resolves the information paradox.
My (developing) theory is like this, plus a wrinkle: Alice never enters the black hole, she's stuck on the event horizon squashed down to 2D, but within the black hole there's a 3D version of her that does enter, a la the holographic universe theory that EVERYTHING is both on the edge of the universe in 2D and inside it in 3D. Black holes are therefore little bubble universes. The string theory fuzzy black holes could be a different picture of this same thing. I certainly can't prove this, but it's the most consistent description to me.
You mention logical arguments but what are they that also avoid the problem of the 'excluded middle' while not invalidating the methodology used to reach this conclusion? Can't we always have a deeper level of explanation/physics that intervenes in the middle? Is that not the very aspect by which the discipline has progessed?
Reminds me of your video on Unruh radiation, it's as if the firewall isn't a literal static field of energy and more just the point at which acceleration caused by the black hole becomes so intense "observers" (is that the right word?) are destroyed by high levels of Unruh radiation
9:29 i loled what happens to this firewall when the black hole rotates. does it turn into a firewall energy gradient since your talking about plank lengths that determine the qbits that loose there entanglement. at what point would that gradient be sufficient to breath the entanglement? also why does Juan Maldacena look like a prequel photo to a james bond villan?
9:16 why is the virtual particle on the surface paired with a vp in thw hawking cloud outside the black hole if it is created entangled with the one inside? I don't understand that bit. I thought particles are created entangled and only in pairs, or did I miss something?
I love this channel! I consider myself a midwit: I'm interested in mathematics and physics and willing to put in quite some time, but my IQ is too low to keep up with uni lectures. So this is - besides Veritasium - exactly the amount of information I am able to process at once. Thanks a lot!
I've always thought about that if a SMBH Event Horizon wouldn't begin spaghettification until closer to the singularity, could we send a probe into a Black Hole that had a trailing tether back outside the Event Horizon (to send data from the probe). Could we then send data from inside the Event Horizon to outside of it? Also could we send a long item into the Black Hole a certain percentage of the length, then attempt to retrieve the item with winch or retro rockets?
I would love to see an episode about how the stuff inside of a black hole becomes the evaporative radiation. Or about what we’d expect to see where a black hole has finished evaporating
Great video, as always, but can you guys consider getting a teleprompter that is attached to the camera right above the lens? That way it would look like he's talking to us, rather than slightly off screen to the right of the camera? I know they make those and this isn't the type of video that works better not looking at the camera. Just a suggestion, thanks!
12:03 The equivalence principle, when stated in this manner, is not actually true because there is no gravitational field that does not have a centre of gravity. Imagine yourself in an elevator cabin in space. To figure out whether you are falling in a gravitational field, simply place two apples in front of you spaced apart. If the apples move towards each other (we can neglect their mutual gravitational attraction) then you are free falling. The distance between the apples reduces in this case because they are moving both towards the same gravitational centre (and if they could reach it, they'd end up in the same spot).
I've always been attracted to the idea that a black hole is basically a very high energy elementary particle. I don't know enough physics to know if that is at all sensible. I made it barely through quantum II in college. But in my lay opinion, I always liked the idea. I really wanted to take GR but was told that there was no way I could handle the math and there was no sense in auditing the class if I couldn't do the math. I really wanted to audit the coass though.
I feel like a student who skipped the entire semester but then showed up to the final lecture before the exams
I minored in physics and I feel the same way. Is it really April 1? Maybe SpaceTime is playing a joke on us?
I have that very nightmare roughly once a month.
I think that's the basic concept of the channel. Lol
@@Jerler91is there any person out there besides the host who saw this video who understands what he is talking about
Welcome to SpaceTime
15:57 So basically like that one scene from the Simpsons where Moe throws Barney out of the Bar only for him to just appear behind him?
The Simpsons are always first
Yes.
Duff Beer acts as the Higgs Boson
@@mavelous1763LMFAO
It's doing that thing again!
“So you’ve decided to jump into a black hole…” sounds like the general motto of 2024.
M8… The subtle racism isn’t necessary.
@@henrythegreatamerican8136you’re disgusting
Yet it is one of the most stupid sentences to be pronounced
@@LordOfThePancakes You might want to edit your comment once the offensive thing gets removed so people don't think you're calling out the top-level commenter.
@@LordOfThePancakesIt's not racism.
Dude, i love videos like this. I need to rewatch portions of the video multiple times to understand wtf is the abstract concept that's being explained and i realize that whoever the guy making these animations and montages is, his work is definitely ultra helpful in so many situations.
Rofl. I have a minor in physics and still an easily 1/3 videos are so over my head they require multiple rewatches. The level of information provided in this channel is wild
@@eskamobob8662 Okay good. I thought I was just dumb for not getting a lot of these topics first time lol
ChatGPT has allowed me to enjoy this channel in a way I couldn't before.
@@thehobo00I think very few people can get all this on the first go around. Our brains evolved to deal with a pretty simple environment after all, not to deal with the insanity of space 😅
I do that all the time with videos like this, sometimes 4 or 5 times, and often fail to "intuitively come up with some kind of "analogy/dot connecting" image anyways. 🙂
A new phrase has entered my list of things that will remain in my mind rent-free: naughty qubit
A qbit can only ever approach the limit of true naughty or existence in its entirety would cease to exist as it would become evil and destroy and tortyure everything in existence with its infinite computational power and pure naughtiness. Not like I'd know 😅
"Oh, wicked, bad, naughty Qubit! She has been setting a light to our firewall, which, I've just remembered, is Grail shaped. It's not the first time we've had this problem."
Well, it turned out it wasn't naughty, after all ;)
Best. Stripper name. Ever.
I really like the firewall idea, and I kinda hope we end up finding evidence for that. It's a very cool idea to consider, that black holes are actual holes as in the space inside just doesn't exist, and it's also just incredibly funny. Like: "Our calculations say all kinds of impossible things should happen inside a black hole, but those things are impossible so they shouldn't be happening!" "Don't worry, the interior doesn't exist so those things aren't happening."
The Fuzzball episode is a good addition to this. It basically postulates what you say here.
The black hole will evaporate before you fall in so it doesn't matter.
There's literally no way to get any evidence about anything out of a black hole, lol.
i find alot of these episodes are a bit beyond my knowledge and intelligence but i have still learned alot. thanks Matt and crew
Never name your kids Alice, The are cosmologists lurking round every corner.
cryptographers and computer security people will be after her too.
@@KellyClowers bob is also in danger
They should let Eve do the task, she is better at extracting hidden information
Can confirm. I’ve been forced by multiple governments to send encoded messages to Bob, and now they are poking me about that black hole business.
Ugh, I hate Bob, he always gets the more fun job :/
YES YES YES!! PLEASE GIVE BOB AND ALICE ENOUGH ENTANGLED PARTICLES TO EACH COLLAPSE INTO THEIR OWN BLACKHOLES ASAP!! You guys are killing it!! Thankyou Matt and crew, you guys hands down make some of the best content on here! Cheers!
"Because of the laws of physics, we cannot print an unlimited number of shirts".
Print?
@@PetraKann The logos are printed.
@@nanohatakamachi1066 logos?
Are?
@@Mb63360??
I must not know enough about the actual definition of equivalence, it sounds like Alice's "hey I noticed a firewall" observation that breaks it is similar to looking out the window on the Vomit Comet and noticing that I'm in an airplane & not a distant gravity-less part of space.
Yeah, I didn't follow that. If i think im free floating through space, and then i notice my feet are burning off in a star, im gonna know i mustve been free falling in that star's gravitational field rather than floating in space with no gravity. The star's heat is an effect of the thing causing the gravitational pull just like the firewall's heat is an effect of the thing causing the gravitational pull.
Quite possible there's some additional catch with the equivalence principal that I'm not getting though.
Glad you made this comment because I am wondering the same thing
There's a difference. From the plane window, you are detecting something- the ground- because the ground is sending something up to you: the photons that enable you to see it. In freefall there should be nothing to detect at the "firewall" of the black hole, because no signal can come from the black hole itself.
I believe that's because the ground outside of the plane is not in your local patch of space-time.
@@levybenathome You would see all the light falling into the black hole behind you though.
I'm in Leonard Susskind's ER = EPR interpretation camp that basically says the following:
- An outside observer sees the expected slowing down to infinitesimal rate of motion and dimming we would expect at the EH
- If the outside observer waits long enough, they will see the BH evaporate away until there is only a stellar remnant of some sort left
- The falling observer crosses the EH and notices nothing out of the ordinary; they fall further toward the singularity in time and when "reaching" the moment of singularity, emerges in the distant future at the moment the BH has evaporated, and there is no BH in existence anymore, nor a "naked singularity", just a stellar remnant of some kind (what ever is left from the evaporation process when it re-emerges from the retreating and disappearing EH - remember, the EH is not a real physical entity)
- Thus, the outside observer will (in theory) after a long, indeterminate, but finite, stretch of time see the falling observer fade in again and move away from what once was a BH, while the falling observer simply will be in free fall and not ever even notice that they fell into the BH in the first place
Of course, in reality, the chances of the falling observer to emerge again while still alive are slim; they probably have starved by then, unfortunately they forgot to supply an indeterminate amount of cheeseburgers for sustenance until they appear again. The outside observer will have a theoretical supply of cheeseburgers and might survive for a while, but die of boredom in the meantime.
I agree with this, this sounds far more plausible than the silly firewall idea. The firewall sounds like a cheap solution trying to plug up a gap in knowledge. There's little difference between the firewall and "god did it" in my mind.
But I also don't think the falling observer would starve to death, considering the immense gravity and time dilation that occurs, if the observer is falling into a large enough BH (so that they don't get spaghettified), they will also be so massively time dilated that by the time they emerge from the BH only a few moments will have passed for the falling observer.
In vanilla General Relativity, the infalling observer _will always_ reach the singularly at the black hole's center of mass in a finite, and rather quick, amount of proper time (on the infalling observer's own clock). Depending on the size of the black hole, it may happen within milliseconds, or take a couple of days for the largest black holes known to exist.
The black hole evaporates a very long time _after_ everything that ever fell into it has reached the physical singularly at the center.
You can't see Hawking radiation while you are in free-fall, falling into the black hole. You must be maintaining a constant distance away from the black hole, i.e. continuously accelerating away from the black hole, in order to observe any Hawking radiation. (It's like Unruh radiation.)
So... um... if you fall into a black hole, you don't miraculously escape at the last second.
@@juliavixen176 Nobody said anything about miraculous last moment escapes... I think you misread.
@@juliavixen176 That is a misinterpretation.
First of all, there is no such thing as "proper time". There is time passing for an outside observer, and time passing for an inside observer. Those are two distinct inertial systems, and none of them is "proper".
The infalling person is subjected to a lot of gravitational time dilation, so what is a short span of time for them is a very long time viewed from the outside. The second misinterpretation is that you seem to neglect the internal geometry of the black hole; you might want to take a look at Leonard Susskind's lecture on exactly this case.
On your last point, in this model, the singularity is a point of time in the future; in this future, the singularity finishes evaporating and the singularity is the point in time when evaporation is finished. This is no cop out. Remember that time-like and space-like dimensions switch their roles inside of black holes; you are free to move anywhere you want, but everywhere you go is in your future, and at the end of this future is the inevitable singularity. The novel thing about Susskind's approach is that the singularity isn't real, and instead the black hole is a travel shortcut through positive time (so, no dinosaur tourism, unfortunately).
That's how I have been thinking about it too, but in my mind the infalling subject never cross the EH as that would mean it would reach the speed of light and well, we know what it takes for anything massive to get to that speed.
So, to me is like one of the Simpsons intro variations where the family is trying to reach an ever receding couch. We know the Simpsons carry infinite wisdom and can predict the future, so maybe that intro is about this and a representation of BH evaporation.
The lucky one would travel to a distant future and immediately crushed at the surface of whatever remnant is left as it would have the Schwarzschild radius.
"extra impossible" brand new expression in my vocabulary.. love it ! 😍
"It's not just impossible, it's *extra* impossible"™
Right up there with "sufficiently unique".
I once saw a picture of soap stretched out and a rubber band place in it and the soap surface inside of the band popped. It pulled the rubber band taut and left a hole there, and I'd wondered if it wasn't possible for black holes to be like this. Cool to see this idea come up here.
these recent episodes are fire.. love the content.
We were trying to solve the paradox of an absolute coordinate system in the universe only to find out that none even exists.
We were trying to solve how the force of gravity works only to find out that its not even a force.
I wouldn't even be surprised anymore if us trying to solve how the interior of a black hole works ends up with the conclusions that there simply is no interior to begin with.
I feel proud to watch this video and not be completely confused about the topic being discussed. Matt/PBS Spacetime Crew have done a good job at building our knowledge up enough to tackle these subjects.
Same for me here. I fee like have watched a sufficient amount of videos that I could explain most of the notions to a layperson. It meansPBS is doing a great job :)
Appreciate the amount of work scientists are doing, debating themselves and others over these topics that can have unseen outcomes for humanity. Or at the very pave the way to answer some of our oldest questions not just about gravity. This was such a fascinating video.
Infinities in the math, and paradoxes, are a sure indicator that you need to investigate and rethink. One of my profs told me that as an undergraduate and it stuck with me. Firewalls seem a good indicator that our conception of what happens to information at the event horizon begs more work
I think that's what the entire video just said, yes.
Most people don't know that Einstein said that singularities are not possible. In the 1939 journal "Annals of Mathematics" he wrote -
"The essential result of this investigation is a clear understanding as to why the Schwarzchild singularities (Schwarzchild was the first to raise the issue of General Relativity predicting singularities) do not exist in physical reality. Although the theory given here treats only clusters (star clusters) whose particles move along circular paths it does seem to be subject to reasonable doubt that more general cases will have analogous results. The Schwarzchild singularities do not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light."
He was referring to the phenomenon of dilation (sometimes called gamma or y) mass that is dilated is smeared through spacetime relative to an outside observer. It's the phenomenon behind the phrase "mass becomes infinite at the speed of light". A 2 axis graph illustrates the squared nature of the phenomenon, dilation increases at an exponential rate the closer you get to the speed of light. A "time dilation" graph illustrates the same phenomenon, it's not just time that gets dilated.
Dilation will occur wherever there is an astronomical quantity of mass because high mass means high momentum. This includes the centers of very high mass stars and the overwhelming majority of galaxy centers. The "missing mass" needed to explain galaxy rotation curves/dark matter is dilated mass.
Dilation does not occur in galaxies with low mass centers because they do not have enough mass to achieve relativistic velocities. It has been confirmed in 6 very low mass galaxies including NGC 1052-DF2 and DF4 to have no dark matter, in other words they have normal rotation rates
Special Relativity math works for both sub light speed and super luminal speed. Mater of fact, superluminal particles would be called tachyons if they existed. The problem is, they have immaginary mass so we say these solutions are not real. So, what if the event horizon and volume inside a black hole where equally not real solutions?
Lets look at the pauli exclusion principle. It prevents any two fermions from occupying the same quantum state. And all matter is made up of fermions. If it is that "no two fermions can be compressed to a volume that is equal to what would be their event horizon" is equlivent to , the same quantum state, then there are not only no eventhorizons, but then there no true black holes, and there are no gravitational singularities, and there is no more information paradox. Apparent black holes would be Just balls of supper dense matter that appear to look like black holes from a distance. But upclose they would ocupy a volume that is a little larger than what would be an event horizon, but would not have an event horizon, and hawking radiation would instead entangle with the highly compressed matter, or the matter's energy just tunnels out carrying quantum entangled information with it.
Gravity is preserved as a spacetime warpage rather than a a grand unified therory of everything while equliventciy is preserved in general relativity, and finally plays nice with quantum dynamics within possible solutions matter can exist in, without event horions.
But if black holes are infact real with real eventhorizons, then infalling matter would increase a black hole's event horizon diameter. Hawking radiation sitting just above it would be engulfed by the new event horioz, and if there were entangled information, then wouldn't it be engulfed by the expanded eventhorizon? Maybe if there is a firewall then the expanded firewall moves quantum entangled information just a little further away preserving it from entering the event horizon.
Remember that maths includes concepts and paradoxes that are not real in our universe. This firewall solves a problem that is not proven to exist. I assume the firewall has no observations to support it and may cause problems for the varying mass (growth) of Black Holes. Hawking radiation has not even been proven to exist.
So as Einstein might have said (as Einstein did mention the “Secrets of the OLD ONE”), → THE OLD ONE DOES NOT DIVIDE BY ZERO!
8:58 it's not clear to me why a qubit at the event horizon must be entangled twice, with a particle outside (Hawking radiation) and another inside the BH. Are the two particles inside and outside the BH the two virtual particles originated initially? And the 3rd one at the EO must exist because otherwise the space-time fabric outside the EO can't be hold together? This is a blurred part in my opinion.
*"Out of bounds"* ahh phenomenon
Love this content!
It almost seems like a black hole firewall implies that *nothing* exists beyond it… but time teleporting blackholes sound fun.
Hopefully we will one day we will be able to (safely) observe them directly.
This video was way more understandable some of the previous video. Thanks for the _mostly_clear explaination!!
Could you explain more about how exactly the firewall hypotheses violates the equivalence principle? I do understand that a 20 minute popular-sciency explanation-by-analogue is inherently flawed and to actually "get it" I'd have to do the hard work and study physics for years, but knowing that doesn't solve my bafflement. Is there any additional explanation that would clear my confusion at least a bit? Specifically, this is what I did not understand: If I am trying to figure out whether my weightlessness is because I'm falling towards the Earth surface or because I'm in deep space, then the Equivalence Principle says I can't do that. If I was falling towards the Earth then I will naturally observe the test result of hitting the ground hard, but even then the Equivalence Principle argues that I still could have been gently floating in the deep space and it was the Earth that accelerated towards me. The "hitting ground" is no problem to the Equivalence Principle because it's just a matter of the environment being the way it is. There's a "thing" and I happen to hit it or it happens to hit me, both being equivalent and true descriptions of the physical reality. And that's my confusion now. How is the black hole firewall different? Why can't it be a "thing" that exists just like the Earth surface? The episode clearly implies that there is a genuine and fundamental difference and that the Equivalence Principle gets violated, and I believe that. I just did not get the why. Any help?
Finally I now have an explanation for that throwaway, unexplained line from kurzgesagt’s old black hole video. Been bothering me ever since
Which one?
@@hassassinator8858
“black holes explained - from birth to death”. 8 years ago. It’s the “very quick death” scenario. They don’t explain at all, they just say “you would hit a firewall and be terminated”
Really bad science communication tbh. I had wondered wtf they meant ever since I watched it all those years ago
th-cam.com/video/e-P5IFTqB98/w-d-xo.htmlsi=zm6r4ZnDNjhAkBgb
@@hassassinator8858 black holes explained - from birth to death
I already replied to you but I think my reply got yeeted because I put a link in it
How can a black hole grow if all the matter, energy and radiation get compressed into a singularity?
@Ezekiel903 not sure what you're confused about. singularities have infinite density, not infinite mass. you can add mass to a singularity.
Thank you! Finally I understand 1) why the paradox is really a paradox and 2) why, when a seemingly arbitrary amount of 50% of the black hole has evaporated, the information becomes, in principle, recoverable. I've heard lots about this and everyone has these convoluted, esoteric explanations (even you, Sean Carroll!)
Can you say more about why severing the entanglement requires a high energy?
And where does all that energy come from? If he said it, I missed it
@@wavyarmedmanThat energy would be the firewall
@@laurisiltanen8348 I get that the energy is the firewall. But where does it come from?
IMO that part seems very weird, I'm in the causality/decoherence camp...
Well the energy would come from gravitational potential.
Great vid - just ordered a hoodie from the store, can't wait to get it!
This one really made my head spin. If I understand correctly, there is presently no concept for how exactly the firewall itself works - rather it is simply the required amount of energy that must be present on the horizon in order to break the entanglement between the virtual particle pair generated from random quantum fluctuations.
So, assuming what I stated above is correct. A quick side note, as I understand it, when quantum fluctuations generate a pair of virtual particles, these particles normally annihilate immediately with no further observable effects (with the exception of the casimir effect and hawking radiation or other related special conditions).
However, when a pair of normal particle's annihilate (for example an electron and a positron) the annihilation event emits a high energy photon as dictated by conservation of energy.
So, I'm assuming that since a photon is not emitted when virtual particle's generated by a quantum fluctuation annihilate it's because energy is already conserved because they together reached "zero point energy" via annihilating back into the vacuum.
If that's true then (I admit, this is a big IF), how is energy conserved if one of the virtual particle's escape as hawking radiation and the other goes down into the abyss of a blackhole? Is there any chance that the point on the horizon where the annihilation would've normally taken place manifest's the firewall to satisfy conservation?
Maybe more specifically, when a new particle is absorbed into the blackhole when it cross's this point left by fluctuation event it is taken instead (hence, "completely thermalized")?
In my head this kind of make's sense, but I would appreciate someone explaining why I'm wrong (obviously, there has to be a reason this isn't true - I just don't know what it is)
Otherwise, other than to satisfy the condition of breaking entanglement of the produced pair on the horizon, is there any proposed "mechanism" of the firewall on the horizon talked about in this video?
Thanks for the excellent content as always.
Crazy that you're making these videos about such complex things and so many people are turning up to watch. Great job!
They seek sleep
Watching these Space Time videos makes me miss working on Quantum Computation back when I was getting my degree. It was hard, but the end result was fun.
8:50 "Without entanglement there is no space" seems to refer to Leonard Susskind's (and someone else's, Maldacena?) theories relating entanglement to the "spatility" of space. I would love to hear PBS Space Time do an episode on this, it seems like exactly the sort of explanation you are good at.
Another thing worth revisiting is the kugelblitz video -- how does this work if a black hole forms around you, rather than you falling in? The space disappears? Does it happen faster than the speed of light?
What I always asked myself is whether Hawking Radiation completely throws the possibility of falling into a black hole off the table. Since it is said that a black hole will evaporate in a *finite* amount of time, wouldn't that mean that the time dialation near the event horizon can become so great that the actual black hole would shrink just before one would enter? Would that also imply a trip to the vastly distant future where the black hole completely evaporated, or became small enough to tear the traveller to pieces?
Moreover, the event horizon never forms, since the same thing happens to the first particle that tries to form the event horizon. I hope that the "mainstream" black hole community will eventually understand that straightforward conclusion. I'm repeating this since 20 years, and I'm happy to see some commentors getting to the same trivial result.
@@geraldeichstaedt I think we've got enough evidence that we can assume BH-like objects exist. The question here is if there is any time-like path from outside the event horizon that crosses the horizon before it evaporates in the far-but-finite future.
@@johngregor6743 Black Holes aren't black because event horizon, they're black because extreme time dilation which redshifts all radiation so it becomes Hawking radiation. And Event Horizon is, actually, perfect term: it's true meaning is last thing that can happen to you in THIS Universe - is crossing this Event Horizon. It's the last event in the universe for that poor falling observer.
@@johngregor6743 I don't think that there is any time-like path manifested in real black hole physics. From an experimental point of view, the event horizon is inaccessible by definition. So, all evidence we have, is that of a compact mass that obeys General Relativity to the accuracy of our measurements and that doesn't appear to enter a steady state once it's collapsing.
Crossing the event horizon within finite time in terms of an exterior frame of reference would question General Relativity and essentially state that the singularity reaches up to the supposd event horizon, if we take the Penrose theorem as a basis to define a singularity as a region where General Relativity and related theories are violated. But this would question the notion of an event horizon itself since it's based on the notion of a continuous spacetime and a GR-ish physical settings, and hence the notion of a black hole in any classical sense.
No because from the reference frame of the infalling observer, the equivalence principle still holds: this means that he doesnt feel any gravitional anomaly and thus no time dilation. However you can see that there is infact such time dilation but only from an outside frame of reference: infact an outside observe communicating with an infalling one, would know that their respective clocks tick at different rates, but this is only "observable" by the outsider observer. So an infalling observer would simply pass through the event horizon without noticing anything strange and in a finite time
I want to thank the patrons of PBSST, because they really enable this excellent work for all of us for absolutely free, so thank you.
thanks for another one PBS team
How about a cash donation instead?
Thanks is a nice but doesn’t really help funding for the program
A somewhat related question I haven’t been able to find an answer to:
When falling into a black hole, as you approach the event horizon, would the time dilation be such that as you approach and reach light speed the external universe’s clock appear to move infinitely quickly?
As a consequence of this would you then witness the heat death of the universe above you?
This produces a dilemma as it has been theorised that black holes should decay slowly via Hawking radiation, would this not occur instantly as apparent external time approaches infinity?
Is it possible that this would mean that before you can ever actually cross the event horizon of a black hole that it would evaporate?
Which event horizon? Doesn't the event horizon form in infinite future, meaning after the black hole vanished?
@@geraldeichstaedt I suppose that even the quintessential event horizon that defines a black hole forms infinitely far into our future as an external observer as anything that reaches it would witness the same temporal distortion, not just you as an observer approaching it.
Here’s an idea: The “firewall” that Bob encounters is actually/also the entire evaporative history (via Hawking Radiation) of the BH. For Alice, this encounter plays out over the long remaining lifespan of the BH. For Bob, it happens in an instant. The difference in perception is due to the extreme gravitational time dilation near the EH.
That's a good idea, but unfortunately the time dilation doesn't work that way. If you freely fall into a black hole, you do not experience a sped up view of the outside universe, nor of the black hole evaporating. That only happens if you hover just above the horizon (which would require an enormous acceleration.) In other words the time dilation means the faraway observer sees your light get infinitely redshifted, and not that you see everything infinitely blueshifted (again unless you hover there.) The reason is because redshift/blueshift is related to the change in energy of photons reaching you, but if you are freefalling, the photons gained the same amount of energy that you did, so you see no shift at all.
@@watsisname I say it's relative. I'm not sure you would experience colour shift at that distance. I think the effect on you would be relative and that your biggest concern would approaching light speed.
@@watsisname ooh, I hadn't considered that. Essentially the photonic frame of reference around a black hole will be accelerating towards the hole along with the observer...
@@watsisname It's not the shift of the photons that matters, it's the *quantity* and *density*. The universe will not redshift, but it will still explode behind you - and the black hole will explode in front of you - so yes, you would hit a firewall as photons pile up on you to a ludicrious degree - not that you'd care, as your total height from head to toe is now ~1 plank length.
Just had a striking observation that the firewall must be on both sides of the event horizon or for it to not be seen at all, the only alternative is the fire wall is exactly the photons/energy that's orbiting the blackhole precisely at the event Horizon but this is only possible if it's an infinitely thin line and I feel like nothing exactly fits that description except electrons... perhaps the quantum uncertainty principle and thus the probability cloud becomes 100% exactly on that boundary and 0% everywhere else and that is your firewall. Only electrons as far as I know are described as point like and once you confine the probability cloud to an infinitely thin line that is the boundary you get a firewall. This would mean the boundary is NOT visible as 100% of the boundaries energy which may be infinite by the implications of this description is exactly orbiting the blackhole, none of it escapes in any other direction to hit a retina or detection device and thus space appears locally uniform.
You approach it at the speed of light so like a vacuum decay, you never see it. You just cease to exist in an instant every infinitely thin slice of you crossing that boundary being obliterated by the firewall is now traveling towards the singularity at the speed of light meaning every infinitely thin slice of you crossing it can never warn the rest of your body to transmit any information about its existence outward.
Thanks for another great video. I have a question that I have begun thinking about after hearing several times that nothing can cross the event horizon (in finite time), because it will seem to be frozen in time above the horizon for an outside observer. (And there light from it that do escape becomes to red shifted as to become invisible, i.e. black, as in a black hole.) But what then when two black holes collide, as measured to happen (now several times) by LIGO, when the two holes orbits each other at extreme speeds just before they collide and causes gravity waves for us to detect with LIGO. If it should take forever to reach the event horizon, what is it then that causes those two black holes to merge in an instant? (Or do they not really collide, but only get close enough to stop spinning fast enough for us to detect because their time is slowed down very fast when getting close enough to each other? Just thought of this last par while typing.) Have no idea if any of this makes sense of if there are any problems or I just overlook a simple explanation. But is seems that the collision of black holes goes against the idea that nothing can fall all the way into a black hole as seen by an outside observer... Which we are when detecting the gravity waves of two black holes merging. Thanks in advance for a good explanation, either here or in a new video ;-)
How would the firewall explain the very formation of the black hole? I mean, it's technically possible to make a neutron star very close to the mass of becoming a black hole, and then trow a few more neutron to transform it into a black hole, where does all that volume, information, mass, energy, disappear, if the space-time itself stop existing? And is it instantaneously, like all the quantum information of all the particles that were making the volume just before it turned into a black hole, suddenly appear on the event horizon?
Also, I'm still not sure I understand the whole particle-antiparticle hawking radiation, like AFAIK, both particles and anti-particles have mass, then how come the mass of the black hole gets smaller and smaller as it "eats" those particles? And, if something crazy like negative-mass particles exists, how they decide to only go inside the black hole and never in the hawking radiation? Or is simply a matter of energy, like if this firewall exists, it takes double the energy to break a virtual particle pair, and then half of it goes outside.
It's very easy, actually. All this mass of a collapsing object becomes this firewall. No black holes exist, they just didn't formed yet. They all in a process of their collapse and they'll finish only when Universe (or Space-Time) ends. Or never, if there's no ending of space-time. And Hawking radiation is just regular EM radiation which becomes extremely redshifted by time dilation near extremely dense collapsing object. No virtual particles needed.
Also, I don't see any equivalence breaking paradox there: a falling observer never enters a BH from the perspective of distant observer, because time dilation will send this event to the end of time. And falling observer just leaves distant observer's Universe by travelling to the end of time. In other words, it's not just space dividing the Universe outside BH from the Universe inside, it's also time, bacause space-time is one thing.
Before the collapse there is already mass inside the sphere which becomes the event horizon - what happens to that?
@@user-zz6fk8bc8u No one knows how the horizon actually forms. Maybe it forms inside, at the very center of a collapsing object, and then expands. It is basically the region of extremely curved space time, because of insane mass concentration.
@@Boritis 🤔 never thought about it that way, thank you
One thing I've wondered for a while about black holes, and maybe some of you can clear up this confusion, is:
Since time stops at the event horizon (for the outside observer), if you fall into a black hole, the outside observer should "see" you simultaneously hitting everything that's fallen in before you, and being hit by everything that'll fall in after you, exactly when you cross the horizon (which he'll never actually see because 1) it's in the infinite future and 2) redshift; but it seems to me that that's the correct extrapolation from what he does see)
Doesn't that mean that while you fall in, you'd in turn see the outside universe speed up, getting UVshifted to the point where it annihilates you as you get close to the horizon?
I agree, and moreover there is no event horizon since the same conclusion applies to the very first particle, as well.
I think it also means, since BH evaporation is observable in finite time, that the evaporation clobbers you from the other side at the same time.
What you are seeing here is the stated limitations of relativity. Mr Einstein clearly states that the theory of relativity is limited and breaks at and beyond an event horizon or singularity. It's a bit like the idea of a photon traveling at the speed of light experiencing no time. Einstein clearly states that you can't use time dilation for a photon or massless object. The speed of light 'c' is an event horizon. Relativity will work up to 99.999999... % of 'c' but fails at 'c' due to weird mathematical infinities.
>
So, at any event horizon be it a black hole, the event horizon of causality 'c' or a particle that occupies a singular (singularity) in any "now moment, relativity cannot work and they have to move to Quantum field theory of Quantum mechanics to offer descriptions :)
>
So, you are just discovering the limitations of the theory of relativity :)
This guy is really smart
You’re really smart too, Evan
This person/persons*
You shouldn’t assume someone else’s gender
@@LordOfThePancakes You shouldn't assume that he's not a guy, and shouldn't assume he would be offended by the word, either way.
@@FLPhotoCatcher I'm here to nip this irrevelant comment chain in the bud. Keep your eyes on the prize y'all and don't throw things off for other viewers.
@@LordOfThePancakes
1. Guy is gender neutral
2. Matt's pronouns are very clearly displayed in the end card of almost of every episode, it would be wrong to NOT use his preferred pronouns due to YOUR ignorance of them.
How will one see if there is a firewall? As the only particles out of it are hawking radition. Is there a way of knowing wheater a particle is entangled with other by only seeing the first particle? 13:46
If nothing can cross the event horizon, how can a black hole grow? How can two black holes merges? We have observed the merger of two black holes via the gravitational waves generated by the merger, so this phenomenon exists.
Every science channel must have at least one video about black holes . . . . and i love it
😊 Our known cosmos is full of incredible wonders, particels, time distortions, quantum fields, negative multiverse impacts, and we may never fully understand the science behind it, but we will work on it
I don't quite understand why the firewall would break the equivalance principle. Doesn't the surface of a planet act in the same way? It's just a physical barrier as far as I recon, which doesn't interfere with the spatial properties around the black hole. What am I missing here?
As far as I understand it, there is supposed to be nothing special about crossing the event horizon. There’s no temperature increase. But the firewall would definitely be hot but for no apparent reason so the equivalence principle is broken.
@@louislesch3878I think it means that more like such intense firewall of energy would create its own gravitationl effects such that when you free-fall towards the event horizion, you will feel this "effective" gravitational force
I was also confused by this. I'm commenting just to get notifications of replies.
It's not a physical barrier though. It's a feature of space itself. You're in a gravitational field and logically you should keep falling but you can't, because space ended.
This has bothered me for years! I'm glad someone's doing a video about it!
Albino u scared of black holes 😊
I miss the answering comment questions segment at the end of a video.
Me too ☹
Saaaame
I don't. Most of the questions were lame. Never watched the answers, it is very dull and boring compared to the actual content of the video.
8:35 "these pairs of swallowed and radiated things have to be entangled with each other" - but the swollen thing has effectively negative mass, by swallowing it the black hole becomes less massive. It does not continue to exist inside the black hole so we can count 3 particle instead of 2. It is similar to a particle which escapes by tunnel effect, it does not create an entangled twin inside the well
Shouldn't a negative-mass particle experience antigravity pull instead of gravity? It should fly away from a black hole with great velosity!
@@Boritis I don't know does it make sense to speak about the properties of this swollen particle, I think about it as a fictional - but the result is one particle disappears inside the horizon and one particle is radiated away, so there is nothing inside to be entangled with the radiated particle
Purely as a layman, it makes me wonder if the firewall is equivalent to the holography argument ie. the firewall is the 2D manifestation of the blackhole's 3D interior.
I guess a region in spacetime where the fabric becomes so distorted space behaves like time and vice versa, would probably have some odd properties like violating equivalence. But again, way out of my depth a few videos ago lol
Or, maybe the firewall only appears if you try to accelerate near the horizon, and disappears if you remain in freefall straight through the horizon. I suppose it could be similar to BH complementarity in that way.
What if there's no 3D-interior after all? What if space-time becomes so distorted so it becomes 2-dimensional? But with 2 time-like dimensions instead of one.
@@Boritis maybe that's exactly what the 2D hologram would be like. It's hard enough to imagine an infinitely far away surface that's encoding the entire 3D volume of the universe in lock step with us, maybe it'd be just as weird to consider a "3D interior" if we started our considerations at the surface.
So what does breaking the entanglement physically do? Like what is the mechanism here which would generate the firewall? And where is that energy coming from?
It feels like violating unitarity is the less radical problem provided it is only violated along causally discontinuous spacetime
"Einstein halp!" 🤣🤣🤣
I don't think the firewall violates the equivalence principle. The equivalence principle simply says that being in a gravitational field is equivalent to being in an *inertial* frame. It doesn't say you also have to feel like you're moving slowly relative to other stuff. If you're right next to the event horizon, you may feel like you're in an inertial frame, but you're also experiencing extreme time dilation/ length contraction relative to a distant observer. The equivalence principle analog of this would be traveling at a constant speed at nearly the speed of light. And guess what you'd be staring at? A completely identical firewall made by the CMB radiation. This points to the idea that Hawking radiation and the CMB are deeply related in some way.
Agreed. Key point in equivalence principle is 'locally'. The locality becomes smaller the greater acceleration. While Alice won't be able to fall smoothly lol point like particle will. It's ridiculous so called scientists make silly mistakes like that. Yeah and also the greater the acceleration in absence of gravity the bigger Unruh effect. So don't see what's surprising it's the same around bh? If anything equivalence holds 😂
@Nat-oj2uc That's an interesting point about unruh radiation, though, as you say, it's only visible when you're accelerating. So, I don't think that would satisfy the equivalence principle, though the CMB would be extremely blueshifted at constant high speed. I think a lot of people seem to miss the caveats that go along with the equivalence principle. You mentioned the locality one, but another one is the non equivalence of relative speed. Let's say you are in a rocket ship at a constant acceleration. If you do experiments inside of the rocket ship, it would seem like you are standing on a massive body, but only if you don't look out the window! It's the same thing as being in free fall vs being in deep space. It seems the same until you look out the window and you see the ground coming up at you!
The thought that spacetime doesn't exist "inside" a black hole is eerie, but also beautiful in a way
It IS both eerie and beautiful :) I did some thought experiments on it decades back and it wasn't so much that it didn't exist, it just seamed to be reversed (kind of turning the sphere inside out). So it kind of put the center of the sphere (the singularity) on the inside edge of the event horizon. The "space" between the outer edge of the event horizon, and the center just below the event horizon was still there, but it gave the impression (from the external view) that a large spherical chunk of space time had gone missing (I kind of viewed it as an illusion of excessively warped space-time) :)
In a way, there is no 'inside'. How can something exist, if there's no space to exist IN, and no time to exist FOR?
Like the eye of a storm.
@@Tasarranso black hole is just a sphere of non-existence/nothingness?
@@Shaunshahriar In that case I think I'd describe it more as a surface/wall rather than a sphere, but yes
That point about the singularity expanding to the event horizon gave me a few ideas. Half of what's on this channel goes over my head without a repeat watch, and these ideas might have already been addressed or shown to be impossible with info in other videos I don't remember, but who knows.
What if a star/stellar mass collapsing into a black hole is it crossing over the breaking point of a sort of "quantum pressure", not to dissimilar to protons turning into neutrons in neutron stars or even neutron stars into the theoretical "strange stars", where "normal" matter goes from being in a defined yet unknowable state, to being changed into some other, new phase of matter where all possible quantum states are "filled"? In this case it could be not that the forces within the event horizon get even stronger towards the center, but that the body of the black hole is a sort of homogeneous and equal density of "full" space-time, possibly where there is no "real" distinction between the center and near the edge of within the event horizon, and new quantum information flowing in is not destroyed, but is altered in a way that it can cram into an un-claimed quantum state. Given the existence of things like the "Planck Length" and "Planck Temperature", this says to me that all cells on the spreadsheet of quantum information have defined ranges, and therefore, every point of space-time has a defined amount of possible quantum states, and those quantum states could be crammed full by the absurd amount of energy in the process of a collapse.
And on top of this "state-cramming", given the sheer energy required in neutron stars to convert protons, and even vastly more energy for that "neutronium" to turn into the theoretical "strange matter", I don't think it's that far off of an idea that the collapse into a black hole could cross this energetic barrier to transform into this new state of matter, possibly one beyond anything we can concieve as of now.
A bit of a long shot, but as an extension of this, in regards to hawking radiation and evaporation, is that conversely to the (to my knowledge) typically un-entangled matter that adds to the mass of the black hole, in the pairs that form near this boundry, the in-falling half bounces off of the surface, alters one of the taken quantum states on the surface (like how observing a particle changes its information, the thing that makes it never fully knowable), and that which it interacted with cannot change into one of the other quantum states taken within, so that information which *has* to change because it was interacted with changes into an information state that is available, and the only available states it can take are *outside* of the event horizon, thus performing the process of evaporation. Think of it like the "death by 1000 cuts" but it's "Death By Eleventy Bajillion Hawking Pairs Tea-Bagging The Surface Of The Black Hole". Another way this could work is that (some of?) the information of the in-falling particle could be in a way "locked" by the escaping particle, destructively (to the black hole) interacting with this "full" matter on the surface, causing this same "nowhere to go but Out" effect, causing of these occupied states to change in a way that forces it to superposition/tunnel to the other side of the event horizon.
While this my not be the most accurate descriptor, in this theory, the black hole doesn't destroy information, the black hole IS the information.
I spent over an hour writing this comment and re-writing and processing this all, it's almost 4am, I would like a cookie and some sleep now please.
If it takes a firewall to break entanglement, why is our quantum computers decohering so quickly?
13:01 All right, it's clear y'all need a scale. So who's got the plan for how we send something back and forth between two distant enough places? That will also vary enough over time to with calculatable enough accuracy such that we can measure the change in gravitational pull upon an object that is doing the exact same thing every single time repeatedly for like 500 years give or take. That should probably be enough. Also more than one probably like 50,000 of them
So electron flying through both slits simultaneously fits perfectly into quantum theory, but a qubit being on both sides of the event horizon somehow ruins it?
Yes?
Well I mean, insofar as “being in two places at once” is a good description of an electron of being in a superposition of going through one slit and going through the other slit.
It is a different sense of “two places at once”.
If the qubit was in a superposition of having fallen in and not having fallen in, that probably wouldn’t really be a problem.
Like, if you have a photon whose spin is being used to encode a qubit, having that photon be in a superposition of going through one slit and going through the other slit, that’s not an issue. That’s normal.
But having two of “the same qubit”, maximally entangled with another qubit,
well, that would let you do two different measurements of it, and... that doesn’t work...
you're confusing the differences between particle-wave duality and the equivalence principal. these are completely unrelated things
As far as I understand it (which might not be very far) the difference is you can theoretically detect the particle both inside and outside the event horizon at the same time, meanwhile the particle moving through both slits can only do so as an (unobserved) wave. Attempting to detect it in both slits simultainously causes the wave function to collapse and it "shows up" in only one of the two slits
@@drdca8263 "That's normal" he says, about quantum field theory. :-)
Haven't watched the entire video yet. But a qubit is simply two states of information (on or off, hence the affix -bit). While an electron passing through two slits has a lot more information: it has an output of an oscillating probability curve bound by a normal distribution defined by said parameters .
Also event horizons are weird. Really weird. Arguably, physics doesn't have a place describing what's happening behind an event horizon.
I studied physics at university level, specialized in high energy physics, also followed cosmology and particle physics classes. But after seeing these Space Time videos I feel like I am a complete nitwit in physics 😂 These videos are so great, I learn really a lot from them! But it will take a lot of time before I fully grasp everything Matt explains.
14:22 huh, so it's like a literal hole in space time, a "black hole"
black holes are spheres, not actual holes
@@johnreder8167Would not any actual hole in four dimensional spacetime necessarily be something three dimensional, such as a sphere or spheroid?
@johnreder8167 imagine a sheet of paper, now cut a circular "hole" in it, imagine that 2d living beings lives in the paper, to them there is no way to distinguish the shape of the hole to any other circumference of the normal circles in their world, the thing is that we as the 3d beings are seeing the hole from a perpendicular perspective that the 2d beings don't have. the non-continuous space time inside the "firewall black hole" seems to be the same thing, only that this time we are the ones inside the paper.
@@johnreder8167a three dimentional sphere can still be a hole in 4 dimentional space-time.
12:40
Well, the sight of approaching Earth surface and first sensations of getting spattered on it do not violate equivalence principle, why this firewall should?
Seconded, I'm having trouble wrapping my head around that.
For a stationary black hole, it would appear to you that you never fall through the event horizon, because any light that has fallen in further than you can never reach you, but the mass can still lense some light to you, as long as that light hasn't yet fallen in further than you. So to an object falling into a stationary black hole, the black hole would appear to shrink away from it, all the way up to the moment when it reaches the Roche limit and the tidal force renders it to quarks.
But stationary black holes probably don't exist.
@@kethmarhkfy7luf.263 I think they meant non-rotating black holes (ie: the Schwarzschild metric). I'm not sure their assertion is correct, but I don't think they meant stationary in terms of spatial position.
I’ve been waiting for you to talk about this. All the current pros studying this all say they have a firewall.
Remember you also get the light amplified by time moving fast so matter moving fast especially light hitting it
So, where this black hole firewall take the energy to power up a giant screen of death for octillions of years? Because this sound to me like a quite promising energy source.
That'd imply the "firewall" can even be broken up or harnessed.
Then, if both a firewall does exist (it's only a hypothesis) and it being able to be harnessed/broken up... what happens after? How destructive would the information being freely let out be to the universe at large?
You've got very shallow understanding of it. Not that mine is any deeper, but that firewall would be something quantum size thin. And where it would get it's energy is explained in the video.
Either way, it's just continuation of quantum physicists making things up just to make their wonky math check out for things they don't understand.
I have absolutely no idea, but my first guess: The energy is the vacuum energy corresponding to the volume of the black hole. If there is not even a vacuum inside, that energy must be somewhere. And as with all vacuum energy there would be no way to "harvest" it. Don't know if that energy will be sufficient though.
I guess from its mass through de-entanglement driven by hawking radiation? So kinda by virtue of being a crazy dense and sufficiently large lump of matter?
So, here's the problem I imagine. You try to plug into the firewall and just end up as part of the firewall yourself... unless you have unlimited energy to propel yourself (or your energy collection device) away from the gravity well, which is pulling space itself inward at relativistic speeds, but then you already have the energy and might not need to harvest the firewall. I'm not sure how to do the math to see if that could even theoretically gain more than what is lost in preventing the fall into the black hole. Interesting to think about, anyway
Hi Matt. Isn’t it obvious that the object falling into the black hole isn’t the same as the light emitted by it or reflected from it? The object falls in but the light slows down so much that to the outside observer it *looks like* the object never falls in. I see no breaking of equivalence or unitarity.
1. If nothing can cross the firewall, then how does a black hole gain mass?
2. What about when black holes merge? Clearly, the event horizons do cross, which would means it MUST be possible to cross the event horizon. In these events, wouldn't it be possible to see the bulk of the material in the accretion disks being annihilated by 2 firewalls?
3. Further, how is this ridiculously powerful energy field being created? What mechanism (that no one has ever measured/seen/theorized before) is creating it?
This episode seemed to explain everything in more comprehensible terms than usual, yet, I'm more confused by the subject matter somehow. A TRUE information paradox... :)
1. The mass is the firewall.
2. The merger happens as the event horizons meet, they don't cross.
3. The energy is all matter moving at near light speed as it approaches the event horizon.
4. I don't know what I'm talking about.
@@knurlgnar24 I was trying to say what you said, but it got too lengthy and convoluted. I love what you said.
To expand on @knurlgnar24's answer to 1, the gravitational field outside of of a spherical shell of mass is exactly the same as if the mass were collapsed to a central singularity. So if black holes have firewalls, then all the mass lies on the horizon, but their gravity and appearance are exactly the same according to distant observers.
@@watsisname Knurlgnar's 4th point was that he didn't know what he was talking about (which I understood to be "I'm joking"), so expanding on that seems... questionable?
To knurlgnar's point, the mass cannot be the firewall, since the mass is below the event horizon, or at least 'at' the event horizon, and the firewall is supposed to be above that. The whole theory of the firewall is that nothing can get close to the event horizon, since it is destroyed by the firewall - literally the point of the firewall theory. Therefore, if all mass is converted to energy by the firewall before it can be absorbed into the event horizon, it cannot add to the mass of the black hole.
To your point, the mass being at the center (the singularity) or the event horizon is immaterial. The question was, "If nothing can cross the firewall, then how does a black hole gain mass?" The firewall would eliminate any future growth of a black hole by destroying all matter before it reached the event horizon, meaning there can be no growth (as we understand it).
@@madnessbydesignVria I honestly don't have credentials to answering these questions, but my understanding of the 'firewall' is that since no outside observer can ever witness anything falling past an event horizon then it means anything falling into the event horizon is in the infinite future which means it can never happen even if the observer falling witnesses it without time dialation. Logically this must mean that nothing can ever pass the event horizon. Given that Hawking radiation is a thing then that means nothing falling into the event horizon can ever reach or pass it even in their reference frame. That means the 'firewall' must be real. And, yes, I don't know what I'm talking about.
Thanks for this episode which I have been asking about for years now. The comments are asking about how the firewall is spontaneously generated in the first place. In my opinion, and keep in mind that all astrophysical (actual) black hoes are rotating, if spacetime is thought of as 3D surface tension of a 4D fluid, just for argument’s sake, then once a black hole forms, say from a collapsing star, the angular momentum of the star is retained and the vortex keeps going so much so that there is substantial interstitial shear at all elevations in the black hole. This shreds spacetime so that it’s effectively quantum foam but macroscopic. In my opinion, the firewall solves these paradoxes and will eventually have to drive theoretical physics to these same conclusions. It doesn’t even break GR, it’s just an expansion of it.
Spacetime itself is an evaporating black hole.
This is a fascinating idea, which leads to a few questions. If there is nothing inside a firewall, does that mean the firewall IS the black hole? How does it grow over time? What happens if the black hole collides with something much larger? Does it bounce off, break up, stilll consume the bigger object, or something else? Are there different size limits?
hello, Mr Matt,
my idea for antigravity engine:
The concept is based on the following principles:
1. A tokamak reactor is used to create a plasma of fusing atoms.
2. The energy released from fusion reactions is utilized to strengthen the magnetic field around the plasma.
3. This enhanced magnetic field accelerates the plasma to near-light speeds.
4. At these extreme velocities, the plasma reaches a new state of matter, where added energy manifests as additional mass.
5. This new state of matter generates a significant perpendicular force.
6. When the tokamak is charged with this 5th state of matter at a specific point, the resulting perpendicular force exceeds Earth's gravitational pull.
7. The system, entangled with the 5th state of matter, disconnects from Earth's gravitational field, effectively achieving antigravity.
This concept represents a potential unification of quantum physics and general relativity, offering a novel approach to antigravity technology.
what do you think?
Too expensive to build and maintain and use it, just use rocket and jet engine or turbofan engine , or helicopter stuff, much more simpler, more reliable , actually practical in real life
Actually do something useful
You've got me curious about a possible connection between event horizon barriers and those perhaps lesser barriers at the limits of a solar system, or even potentially of a star or planet (like ours). Thank you for the "food for thought."
Don't touch the edge is the galactic version of don't drop the soap.
"don't edge the black holes"
Edging a black hole gone wrong and n$fw.
@@n8an811 this comment cracks me up.
3:40 the firewall could un violate equivalence if there's a preferred background reference frame similar to the cmb co moving reference frame when gravitational lensing changes the nature of diversity of firewall types without making them any less firewall.
Best channel next to Fraser Cain, SFIA, Cool Worlds and SEA
and Anton Petrov. gotta hand it to the kid for his billion percent efforts daily
I wonder idk like 2years ago, about similar thing. That is "probing" (so to say) black hole with entangled particles. I know that it is not really the same stuff as described in this video, but still. I'm kinda happy I came up with it before it was published on PBS. Btw lovely episode!
Just about every Black Hole Information Paradox video on TH-cam seems to forget that:
1) From the outside observer’s perspective, it takes a falling object infinite time to reach the event horizon, but meanwhile the bh is sloooowly evaporating as Hawking radiation, so the latter process will finish first. And therefore
2) Due to time dilation, the Hawking radiation looks like an explosion of gamma rays to the falling object’s perspective. If that observer survives the Hawking gamma storm, it will still see the black hole radiating away all of it mass and vanishing before it gets even close to the event horizon.
Yeah... this has always been my intuition of the situation... due to extreme time dilation near the mass of the black hole, wouldn't the outside observer experience waaaayyyy more time than the falling object? Like, the object is still "falling" / "chasing the horizon", but from the outside, so much time has passed that the black hole evaporation is significant
watch the recent videos on black hole complementarity and the information paradox if you want to see these mentioned. also, no, time doesn't speed up to infinity for infalling matter, because the time dilation outside the event horizon of most black holes isn't extreme enough for that.
@@april5054 Never said it speeds up infinitely, only that it would take infinite time to an outside observer. Not the same. But the point is moot because the event horizon is shrinking away as the faller approaches anyway.
@@aaphantasiaa I've made this comment to a few black hole videos, and you're the first person who has ever actually gotten it.
@@jerrysstories711 like i saide, the time dilation is too slow for the event horizon to even come close to shrinking away from the infalling matter. black holes don't evaporate on timescales that short, or theyd all be gone by now. anyway, they're growing right now.
A bit of a tangent, but an insightful tangent appears when one appreciates that at the Event Horizon, there is a steep gravitational gradient. Gravitational gradients (steep or not so steep) affect local timekeeping. In the Hawking Radiation scenario, the pair of virtual particles are maximally entangled, meaning they are oscillating at their characteristic de Broglie frequency. At the instant of the birth of a pair of virtual particles, they are jointly oscillating in perfect phase-locked synchrony. But as they separate along the black hole's gravitational gradient, they drift out of phase with each other: they necessarily decohere with their increasing separation distance.
Now apply that same thinking to a pair of entangled particles (or qubits) in a Bell test experiment. Due to the ubiquitous presence of gravitational gradients (e.g. those affecting the Earth's tides), the Bell test particles also drift out of perfect phase-locked synchrony; they ineluctably decohere with separation distance. Bell left this phenomenon out of his mathematical model, assuming that timekeeping was uniform along the axis of separation. If you add gravitational gradients back into the underlying model for the derivation of Bell's Inequality, you don't get that his presumptive hidden variable, λ(x,t) is an odd-function, integrating to zero. Rather you get a non-zero "beat frequency" term arising from taking a gravitational path integral. This discrepancy suffices to explain why the Bell Inequality doesn't apply to time-varying (oscillating) characteristics in a cosmos suffused with gravitational gradients. The not-so-hidden variable is time itself (and any characteristic (like phase of the de Broglie wavelength) that is a function of distance and time. The (essentially random) phase of the Bell test particles suffices to explain why Bell test experiments do not obey his inequality, due to decoherence arising from differential timekeeping, thanks to gravitational gradients.
I am not convinced there is a paradox at play here. If i sat a qubit on my desk and put a mirror across the room from it, i would be able to see the qubit by looking both directly at it, and by looking at its reflection in the mirror. No one would claim the qubits been duplicated - i can just either look at it directly, or at an image if it.
In the same way, when the qubit falls into a black hole and the last light to interact with it gets caught in the event horizon, im not look at the _actual_ qubit on the event horizon. Im looking at an image of it in the very last moment before it passed the threshold.
Edit: heres an analogy - say i was on a spaceship orbiting a black hole, and im holding some object, but i have my eyes closes and have no idea what it is. I throw the object in, and once I’m good and sure its passed through the event horizon i open my eyes, look and the event horizon and see the object was a lit lightbulb.
However, the object was actually a flashing lightbulb. If i was inside the black hole id be able to look directly at the lightbulb and see this additional piece of information, but since the impression caught on the event horizon is just a snapshot of the object, the information is lost to the outside world. To me this busts the paradox - the actual nature of the object would continue to exist below the event horizon, but would not above it.
Convince yourself then.
"If i sat a qubit on my desk and put a mirror across the room from it" Would you see the qubit in the mirror, or a photon carrying the information of the qubits position. A qubit and a photon are separate objects... well actually a qubit isn't even an object, but I'm sure you get what I am saying :)
This is not the case because you are assuming that the infalling observer is the "main/preferenced" frame of reference between the two: who is to say then that the actual real qubit is the one outside stuck on the horizon, visible by the outside observer?. In relativity, the concept of simultianeity of events is not the same as that of classical physics, but even if two observers observe the same event (that would be simultaneous in a classical framework) but at different proper times, they are still observing the same event. The fact that both observers disagree on the simultaneity of the event doest mean that one of them is wrong and is actually seeing a "snapshot" of the event, a.k.a. a "false" or "late" information of that event. They are indeed seeing the same event, at the same time except that due special relativity its not at the same time from their different perspective. There's no "preferred" reference frame, so your metaphor with the mirror is not correct here and the paradox still exists. The qubit stuck on the even horizon is not a "snapchat", nor is the qubit already inside the event horizon: both are equally as real as they get in each reference frame. I know it sounds weird and counter -intuitive but thats special relativity for you
@@StefSubZero270 "I know it sounds weird and counter -intuitive but thats special relativity for you"
Yeah, that why many of us don't like it. It places the reality of an object into the position of the observer (human). All reality is then a disassociated photon and the original object become some abstract non reality.
@@StefSubZero270 "The qubit stuck on the even horizon is not a "snapchat", nor is the qubit already inside the event horizon: both are equally as real as they get in each reference frame"
You can pretend that the object has not gone through the event horizon, but that's a bit like looking at a star and pretend that it hasn't moved since the photons were emitted. The only difference with the black hole is that you can't tell if an object has gone through or if it's still floating just above the horizon. But in practice we know that based on other information. E.g. we know that a lightbulb has no ability to counteract gravity like a rocket might.
Excellent video Matt and team, keep the hard work.
You already cannot cross it. In the reference frame of a distant observer, you take forever to cross it, that is not an illusion, you just asymptotically approach it. So you either take forever to cross it or hawking radiations if real destroys the black hole before you cross it. From your falling perspective this time is finite, but the black hole evaporates before you enter it, or if you enter it, there is no outside anymore, because infinite time has passed outside.
Something that I never understood is that 2 things related to the firewall paradox is exactly what I would expect to see even from the most basic description of black holes, and yet I've never heard someone mentioning them:
-firewall: if from a distant POV I see the BH evaporating in a finite time, and from that same POV I never see alice crossing the EH, doesn't that mean that also from Alice POV she never crosses the EH? And if we see the whole mass of a BH evaporating in billions of years, shouldn't Alice see the same mass evaporate in just the few minutes/seconds of her fall? Isn't this a powerful firewall?
-"the interior of the black hole might not even exist": if from a distant POV the BH evaporates in a finite time, shouldn't it also evaporate from Alice POV in a finite time? Shouldn't it evaporate from any reference frame, included any reference frame of any particle falling into the black hole? Doesn't tha mean that a Black hole evaporates before even forming? Or maybe that just before turning into a BH, the matter falling into it "evaporate"? No BH => no paradoxes. An this would not violate our observations because from a distant observer, an object that is *almost* a black hole would be indistinguishable from a "complete" BH.
Does someone know where this logic is wrong?
I repeat this since 20 years, and I'm glad that in the meanwhile some people appear to understand. If there is Hawking radiation, there is no classical black hole in our cosmology. Same if General Relativity holds always (meaning that there are no singularities, hence no closed event horizon by reversing the Penrose Theorem; without GR, black holes wouldn't make much sense anyway), and/or if the second law of thermodynamics is always true by contradicting the no-hairs theorem.
Who wants to be the first to find out? 😂
Me, no problem
Hells yeah! Lets try it! The CMB would be hot as the big bang!
Me. Im tired of the woke. Id rather jump in a black hole.
Me. Throw me in
I VOLUNTEER AS TRIBUTE
*Summary: Black Hole Firewall Paradox*
* *[**0:00**] Introduction:* The video sets up the scenario of jumping into a black hole and introduces the idea of firewalls.
* *[**1:38**] The Problem:* Black holes present a fundamental conflict between Einstein's theory of General Relativity and Quantum Mechanics. This is known as the black hole information paradox.
* *[**1:45**] Information Paradox:* Black holes seem to both destroy information (by swallowing it) and preserve it (through Hawking radiation), contradicting a core principle of quantum mechanics called "unitarity".
* *[**4:13**] Entanglement & Monogamy:* Quantum entanglement plays a crucial role. For Hawking radiation to work, particles need to be entangled both within the black hole and with the escaping radiation. This violates the principle of "monogamy of entanglement" - a qubit can't be maximally entangled with two things at once.
* *[**10:29**] Firewall Solution:* One proposed solution is the existence of a "firewall" - a high-energy barrier at the event horizon that prevents anything from entering the black hole. This preserves unitarity.
* *[**11:55**] Equivalence Principle at Risk:* However, firewalls directly contradict the equivalence principle of general relativity, which states that freefall should be indistinguishable from the absence of gravity.
* *[**15:00**] No Easy Answers:* The video explores various attempts to resolve this paradox, including black hole complementarity, modified quantum field theories, and even the possibility that black hole interiors don't exist as we understand them.
* *[**16:29**] The Search Continues:* The black hole firewall paradox highlights the limitations of our current understanding of physics and motivates the search for a unified theory of quantum gravity.
i used gemini 1.5 pro to summarize the transcript
"A lot of energy is needed to break entanglement"
Okay, but need and exists is two different things. As presented on the video, there is no explanation to where this necessary energy would come from. It doesn't seem to be emerging from the theory itself and rather being "there is a firewall because a firewall would solve this problem"
100% agree, but if it does exist it could be a great energy source.
Is it so surprising that the surface of a collapsed star would be very hot?
@@drdca8263 A supermassive black hole could be formed from something with an extremely low density and temperature, and its horizon may form long before collapse leads to extreme temperature or pressure.
Yeah, that is the nature of the violation of the equivalence principle. If it came from *something* it would just be an object like the accretion disk
@@watsisname ... hmm, ok, point...
how do they merge then? btw the fire wall software or hardware... so many questions 🤔🤔🤔🤔😉😉😆😆😆😆😆😆
We don’t enter the black hole. The black hole grows around us. We are frozen there until the end of time, or when Hawking-radiation disintegrates us.
Side-note: it resolves the information paradox.
My (developing) theory is like this, plus a wrinkle: Alice never enters the black hole, she's stuck on the event horizon squashed down to 2D, but within the black hole there's a 3D version of her that does enter, a la the holographic universe theory that EVERYTHING is both on the edge of the universe in 2D and inside it in 3D. Black holes are therefore little bubble universes. The string theory fuzzy black holes could be a different picture of this same thing. I certainly can't prove this, but it's the most consistent description to me.
You mention logical arguments but what are they that also avoid the problem of the 'excluded middle' while not invalidating the methodology used to reach this conclusion? Can't we always have a deeper level of explanation/physics that intervenes in the middle?
Is that not the very aspect by which the discipline has progessed?
Reminds me of your video on Unruh radiation, it's as if the firewall isn't a literal static field of energy and more just the point at which acceleration caused by the black hole becomes so intense "observers" (is that the right word?) are destroyed by high levels of Unruh radiation
9:29 i loled what happens to this firewall when the black hole rotates. does it turn into a firewall energy gradient since your talking about plank lengths that determine the qbits that loose there entanglement. at what point would that gradient be sufficient to breath the entanglement? also why does Juan Maldacena look like a prequel photo to a james bond villan?
9:16 why is the virtual particle on the surface paired with a vp in thw hawking cloud outside the black hole if it is created entangled with the one inside? I don't understand that bit. I thought particles are created entangled and only in pairs, or did I miss something?
As always, an excellent lecture! A real pleasure. Thank you and all the SpaceTime team for your work.
I love this channel! I consider myself a midwit: I'm interested in mathematics and physics and willing to put in quite some time, but my IQ is too low to keep up with uni lectures. So this is - besides Veritasium - exactly the amount of information I am able to process at once. Thanks a lot!
I've always thought about that if a SMBH Event Horizon wouldn't begin spaghettification until closer to the singularity, could we send a probe into a Black Hole that had a trailing tether back outside the Event Horizon (to send data from the probe). Could we then send data from inside the Event Horizon to outside of it? Also could we send a long item into the Black Hole a certain percentage of the length, then attempt to retrieve the item with winch or retro rockets?
I hope someday Matt does a video on the Wheele-Feynman absorber theory and how it relates to soft photons
I would love to see an episode about how the stuff inside of a black hole becomes the evaporative radiation. Or about what we’d expect to see where a black hole has finished evaporating
Great video, as always, but can you guys consider getting a teleprompter that is attached to the camera right above the lens? That way it would look like he's talking to us, rather than slightly off screen to the right of the camera? I know they make those and this isn't the type of video that works better not looking at the camera. Just a suggestion, thanks!
12:03 The equivalence principle, when stated in this manner, is not actually true because there is no gravitational field that does not have a centre of gravity. Imagine yourself in an elevator cabin in space. To figure out whether you are falling in a gravitational field, simply place two apples in front of you spaced apart. If the apples move towards each other (we can neglect their mutual gravitational attraction) then you are free falling. The distance between the apples reduces in this case because they are moving both towards the same gravitational centre (and if they could reach it, they'd end up in the same spot).
I'm loving these black hole videos
Interesting as usual. Thank you!
I've always been attracted to the idea that a black hole is basically a very high energy elementary particle. I don't know enough physics to know if that is at all sensible. I made it barely through quantum II in college. But in my lay opinion, I always liked the idea.
I really wanted to take GR but was told that there was no way I could handle the math and there was no sense in auditing the class if I couldn't do the math. I really wanted to audit the coass though.
at 12:13, Doesn't the same gravitational forces that cause spagettification near a black hole already break the Equivalence Principle?