@@PaulMSutter I must agree with Clulesskid. The whole thing could have been compressed into a few sentences, kind of like how relativistic moving objects compress the forward direction.
He answered the question while claiming he couldn't answer the question. If time does not apply to light then light does not experience time. If something doesn't apply to an object then that object does not experience whatever that something is
You're allowed to ask but there's no answer. It's like dividing by zero. You're allowed to ask what 1 divided by 0 equals but there's no valid answer for that question. Or even better, it's like asking what's 12 + purple? Not only is there no valid answer, there's no way to even evaluate that question.
@@Bob-sq1us You're missing the subtle but important nuance. It's not that difficult to pay attention for more than 1 minute so that you might get a deeper understanding. It's not that time has stopped for a photon of light. It's not that time is standing still for a photon. That would imply that light exists within a framework that includes time. Time never started in the first place for a photon. Time as we know it doesn't exist for light. It's like asking what 1 divided by zero equals. You can't say it equals 1 (time is flowing) or 0 (time is not flowing). The answer is undefined. There is no answer.
You are so good that you make me doubt your logic ... If frame of reference can't go in the speed of light, it doesn't mean that light can't be it's own frame of reference outside relativity I mean if relativity can't answer this question, it's a limit of the theory and not of light
@@PaulMSutter Hi a slightly different perspective and question on time. In the presence of Gravity (& hence matter) time slows down relatively speaking like near a black hole. So how fast does time run when no gravity is present like out in the middle of space away from any galaxies? How would we perceive this from our frame of reference, is it possible we would experience it as space expanding? Given that speed of light is constant if time is (relatively) running faster for C to remain constant from our frame of reference it would have to travel further otherwise it would appear to be travelling faster. If space/time is compressed by gravity does it un-compress to some natural state in the total absence (or at least approaching zero) of gravity? Cheers.
@@PaulMSutter In a nuclear reactor, we see Vavrilov-Čerenkov-Radiation because light itself suddenly travels faster than light when entering the water. If however light has, even in massless state, to "slow down" anywhere AND we can observe Vavrilov-Čerenkov-Radiation (as shown in dozens of videos here), c and v_lux must be different, v_lux < c. As there IS no absolute vacuum, it could be argued that light never can reach 1.0̅ c, always being slowed down by some minute ε. In this case, the theory indeed should apply to photons (or "gravitons"/gravitational waves ϗtp.), as they DO seem, outside a THEORETICAL absolute vacuum, to always travel with v=c-ε where ε>0. So I'm not convinced the argument that the theory breaks down for 1.0̅ c applies here.
Growing up I was always taught "The power of the question", ie ask the right question... Seems more poingent in this vid... I'm new to these vids and thoroughly enjoying the content. Thank you
Mind blown!!! This makes me wonder if light is part of the fabric of the universe, or a function of it. Your content is my favorite on TH-cam. It is your excellent ability to explain these concepts that makes me see how difficult these scientific questions are. Do you ever wonder if as science progresses will we just stack up unanswerable questions like cord wood? Either we find something more powerful than special relativity or we are at a dead-end. Special relativity will have to be replaced, but it works so perfectly I worry if it will ever happen.
Movement in space relative to what? If a clock is in orbit passing overhead, for 1/2 the duration it’s moving toward you and away the other, relative to the ground. But the earth is moving through the solar system, again in different directions relative to other pints, in a corkscrew. Take that all the way through position in the galaxy, the galactic movement in the universe and speed relative to the center of the universe, if there is such a point.
"Movement in space relative to what?" To **YOU** To the observer!!!! EVERYTHING IS RELATIVE TO THE OBSERVER!!! Why is that so difficult for you to grasp? Who cares what the total ultimate movement of the earth through the universe is, it is at a constant velocity and so counts for zero in every equation of relevance. Whomever the observer is, wherever the observer is, that is the zero motion point for all measurements. ::facepalm:: Goddamn, Fucking DUH! That's why it is called "RELATIVITY", for fucks sake! Einstein was right... only two things are infinite. The universe and human stupidity. And he's wasn't sure about the universe.
Questions that seem to be nonsense are often the key to deeper understanding. Black hole event horizons were thought to be singularities, but questioning the assumption proved quite useful.
A photon/anti-photon pair created by pair creation through quantum fluctuations at the event horizon of a black hole produces Hawking radiation when the photon escapes to the far field and the anti-photon is absorbed into the black hole. How does that anti-photon decrease the energy content of the black hole to evaporate it since to the best of my understanding the anti-photon has positive energy…but negative frequency? Furthermore a photon with negative frequency and one with positive frequency are identical. Is the issue that allows the anti-photon to annihilate positive energy in any way related to the stoppage of time at the event horizon? Otherwise, the black hole just gets more energetic over time from this influx of anti-photons.
Just saw your comment on light and time. I tried to summarize it for my sister and I came out with this. The inability to travel at light speed, resembles, somewhat, a postulate in Euclid. It can't be an axiom, because it is not self evident, though Maxwell may make this so to some. If one tries to put light in with time then one is trying to explain a postulate using theorems proved by using the postulate. As in geometry, leave axioms and postulates alone; don't try to explore them using their children, as it were. Also the math doesn't allow it: 1/ 0 = infinity or whatever.
Not only there is no concept of time but there is no concept of space either to the photon. Because the space shrinks in the direction of travel so much that it's length becomes zero at the speed of light. So photon has no time and no space.
And that's essentially why physicists have run into problems when they've pushed the limits of our understanding of the universe and tried to apply it to the singularity of a black hole or right at the moment of creation when t=0.
Another - related - question though: Say we discover a giant mirror ten lightyears from Earth, and this mirror is somehow in alignment with Earths trajectory. When pointing our telescopes towards the mirror and finding Earth there, are we looking twenty years into our own past?
Yup. A bit more tbh. Also, remember to aim correctly, it's ten years away after all :) Also its gravity too would affect us ten years later-beautiful calculations of space curvature too !
So... when asked my favourite comedic physics question, which is something like, "If we're traveling in a vehicle going the speed of light, and we turn our headlights on, do they do any good?" what should I say? From the video, it's "not a question we can ask." But hey, what if??? Paul Sutter Truly Rocks, OMG!!!
It would be interesting to hear a discussion on the Big Bang and Inflation, relative to this precept. There was "nothing", then a bang, and everything everywhere, just was. The universe was populated. So, perhaps time was "different" just after the BB?
There is a moment in one of Feinman's lectures given in New zealand where he is trying to explain quantum electrodynamics to a ley audience and he at one point talks about particles moving through space along all possible paths and he stops himself and sheepishly corrects himself telling the audience that the particles don't move through space/time, they do particle things and space and time is the place where they do them.
Wow only 19k subscribers?? What the? You deserve so many many more. I know you'll get there though. Your so smart and an awesome great teacher too. Everyone would be so much smarter if they just watched your videos. Thats all you need ppl, is to watch Paul M Sutter and you'll have an EXTREMELY wrinkly brain 😝😝 I gotta say tho, this one really got me. I thought i had it but then i lost it. Pretty difficult for me to grasp. Anyway once again, great video teacher. My number one love in life is space science. So thank you for making these videos and spreading your smartness haha! Have a lovely day. ❤
I guess it depends how you look at it. Certainly, we can't travel at the speed of light; we have mass! But we can observe the emission and absorption of light quanta, which are events in our framework of understanding time, or pretty much what our understanding of time hinges on in the first place. We can use light to knock electrons out of semiconductor plates and then travel back to that plate the long way around, driving devices in the circuit (some of which will purpousfully emit light ok I'm rambling)
Compared the the speed of light, humans and other animals are about as slow as plants. That's why our lifetimes seem long to us, but are a blink of the eye to the universe.
It would seem that it does not experience time in the way that we understand or don't understand it. But it does oscillate within itself or its own field(s) so that internal movement seems to impart some property or type of "light-time" to it.
A more simple way to explain why the photon DOES experience time would be to say that in the same manner that if you move at 50% the speed of light, you look at the clock on your hand- It's still ticking normally because it's in the same reference frame as you right? So in the same way, that hypothetical photon is also looking at the clock on their hand and there's a reference frame therefore there's spacetime experience (if there was consciousness, of course). This no longer hold when the universe is very *VERY* old, and no physical matter left with mass. No reference frames anymore. And only then time and distance lose their meaning. Check out Penrose's Conformal Cyclic ... thing..
Since someone mentioned speed of light being slower in materials (let's say water), I thought of this question: Cherenkov radiation is considered to be equivalent to sonic boom for the light when particles go faster than light. But we know speed of light in materials (water) also depends on the wavelength of the photons, and more importantly, gravitational field doesn't even care about that material, and still keeps going at C. So, how does those FTL particles know they are going faster than light? Which energy wavelength is slowing them down? What interactions happen in there?
I think from our perspective we are always moving at that slowest speed through space, just as light is always moving at the speed of light. It's from an external perspective that the speed of our movement through time shifts.
Very well explained. I don't disagree with any of it but there is a school of thought about the relationship between light and time which fits with relativity (as explained) and it asks the question: Why is the speed of light not infinite? The answer turns out to be that light needs time to propagate light-wave frequencies (wave-crest intervals). Therefore, if 'c' was infinite there would be no light. So light does have a relationship with time. This seems to mean that you can think of the frequency of light-waves as a ticking clock relative to the frequency of the light emitted. The clock must have a variable tick to coincide with the actual frequency of the wavelength. This also means that white light is made up of a series of clocks all ticking at different speeds (wavelengths). It also raises the question of whether relative time is actually a product of light itself? It also explains why you cannot travel faster than 'c' and the relationship of the spectrum of light with distance and velocity (and time), so v=s/t. BTW: It is also a neat explanation of time-dilation if time itself is a product of light and relative-velocity (or relative motion).
Here is my argument I feel light must experience time ever so slightly because there is a limit to its speed, If truly light did not experience time it would probably move instantaneous as this would correlate with the fact that all time as it observes it stands still but as we know a photon that has traveled a light year has left different conditions from its place of origin so time did move since its departure, therefore if light could perceive time it would observe a change that is extremely slight but it would be there, I think the limitation to its speed is the key factor. Perhaps a good way to test if light experiences time is to test if light can change its state without interaction and how long this will take, if it changes through travel then this could count as an experience of time.
What I've always wondered when trading between speed in space and speed in time, why is the speed of light finite? Is it possible to construe a theory in which the maximum of movement in time (the speed of light) depends on the maximum of space (the extent of the observable universe)? So as older the universe gets, the slower the speed of light will become. All we would technically experience is some mysterious acceleration for very far distances.
this is a bit of a tricky one, because the speed of light 'just is'. the speed itself is derived from a couple other fundamental constants, and we don't understand the origins of our fundamental constants...
That's a question I've wondered but never saw a proper answer for. Thanks for the explanation. So if you're going 99.99999etc... the speed of light, and could measure light that you emitted somehow, it would still appear to move away from you at the speed of light? If you're going the speed of light (not possible i know) , would light you emit still move away from you at the speed of light? Is that the question that can't be asked, doesn't make sense, or is it just that we don't have the understanding or math to answer that?
I'll make a guess here, but I think you should ask this question from the point of an inertial frame of reference. if you go at the speed of light, I think the inertial reference would see you running side by side with light, wich is impossible, cuz nothing can go side by side with light.
Well presented and well spoken, but I just had to pause you at 1:06 to relay what I heard another channel say: Because motion is also relative, then the time dilation does not work -- if a spaceship is moving away from Earth at relativistic speed (not accelerating), then it can also be seen (with a different frame of reference) that the Earth is moving away from the spaceship at relativistic speed, so whose clock is running slower??
So, I've been watching this channel for a while now and my understanding of this topic is like following and please correct me if I'm wrong. So we measure the speed of light based on our human units which we just agreed to use. Then we can measure the speed of light using some tools that are made out of mater, but the mater itself uses force carrier particles to interact with itself, and they move at the speed of light. so if the tool is moving at 0% of the speed of light or 99.99999999999999999999999999999999% of the speed of light, the atoms of it are still communicating with each other at the speed of light! so that is why when an object is moving at relativistic speeds, the physical interactions of that object actually slow down because it takes longer for the part of that object to communicate with one and other with force carriers or in other words, there is a lag for them to realize each other's existence and behavior. What we perceive as time is our atoms communicating with each other at the speed of the constant, which is the speed of light. So when we ask how the light experiences the time, what that means is how the light experiences its own speed? so that doesn't make any sense! And that's why this question is wrong.
And yet here we are - beams of light experiencing their own speed, as mass is merely trapped energy. ;) I've always imagined that's the whole point of asking how light experiences time - to simply note that it doesn't. Ergo from its own perspective light does not exist, because light cannot have a perspective. The interesting bit of the question, then, is 'what makes us different than a beam of light that allows us to have a perspective?' The bog standard answer is that we have mass, but mass is confined energy, and the energy and the interactions confining it all happen at the speed of light. So we are travelling at the speed of light in that sense.
@@mikicerise6250 this makes me think that interacting with the Higgs field is just a direction (freedom of movement) that higher energy (I dislike the next term) packets can travel in as a way to *fit* in 3+1 D.
The way I understand the explanation is that if you could ride next to a beam of light then the relative speed between you and the photon would be 0 which is disallowed because the speed of light is always supposed to be 300 000 km/s. I guess one could still try to imagine it but this video’s explanation is the clearest I have heard it explained.
innertubez speed and travelling photon this is two different things. In theory, if you jump to table of reference of the specific photon, then if you turn on flash light that photons will go in speed of light in that table of reference. What is a photon? It’s a portion of energy. It’s photon only when it’s moving. If you jump to it’s table of reference then you will see nothing ( not physical, only in theory) because table of reference of the photon haven’t space, it’s a pint. If you jump to it you will see only spark of energy. Exactly the same when photon jump to our table of reference, when hit and stop on something.
If the concept of a multiverse where different universes have different laws and constants is real, is the speed of light one of those that could change, or is it a universal constant?
Paul, this topic is my favourite mind worm that I think about way too much. May I ask two questions? First please could you explain the difference between light not experiencing time and light not being within time? I fail to see a meaningful distinction. Second, I use my understanding of light's 'timelessness' to support my belief in a block universe where the future already exists (I'm sure I don't need to go into details to explain this further but I'm willing to if you want me to) ... any comment or criticism of this view that you can share would be fantastic. Thanks.
It's interesting, when you say "block universe" where the future present and past "already exists" .. the word "exists" uses a reference of time. If you mean that they exist "all at once", to say that is to talk about a reality in which things have to reference time as part of it's nature. I think what Paul is saying is that, to something like a photon that travels at the speed of light, this framing of the question cannot inherently contain any reference of time.
Well, I dont have a physics background at all but I would think if there was a way to measure light at point A and point B and there was a change in temperature from point A to point B then yes, light did experience time because time had to occur in order to allow the drop of the light temperature. Just my thought- thanks for the video- interesting concept overall.
Hey paul got a question for you, I read a writing about some stars those orbit blackholes like sag A, surpasses speed of light when they passing very close to the blackhole. Is this possible?
Time seems to move forward for your reference frame because you are on a geodesic path toward a time singularity. Eventually, all reference frames go to the same singularity as time contracts and space dialtes ... as the universe is really a 'time hole'. The more mass you have, the slower your movement along that temporal geodesic. Things with less mass or no mass like light will look like they move faster than you through time. But really, time itself is just a higher spacial dimension that light traverses all at once. Light would experience the 'block universe ', and if we had no mass, we would too. If we could 'ride along with light' as you say, we would see the entire history of our lives all at once. But things with more mass can stop passing through time completely if there is enough in small enough space to form a black hole. The expansion of the universe and the redshift of light is basically an illusion caused by space dilating as we experience the accelerating contraction of time from our light cone.
It's almost as if the closer you get to that speed the closer you are getting to the speed of time itself, and when you reach it you are no longer moving in space, but time. Like the way time and space switch places beyond an event horizon. Maybe we are in an event horizon ourselves.
Yes. Light travels as fast as the medium through which it is traveling. A different material or substance with a different index of refraction (if that makes sense) would mean the light ray can be slowed down or speed up ⚽️ *it is weird
I'm watching these like a ton of times as I feel exactly the same way. Half my battle is aligning my thinking to Paul's so question isn't completely kindagarten
So a photon being emitted and absorbed in a plasma like the inside of a star or the early universe, experiences the same time as a photon travelling across the galaxy from a distant star to my retina? Are we still effectively in a plasma state that's been stretched out?
So according to the time dilation formula, t = delta T0 / sqrt. Rather than, 0.9999999c for v, if you could plug in 1c for v, you'd end up with c/c which is 1 then you'd have 1-1 which is 0 and the sqrt of 0 is 0 and lastly you'd be dividing by zero which is obviously not allowed. So the time of t (from the formula) is asymptotically approaching infinity. That means, as I said before, a photon sees the entire future events of the universe unfold instantaneously until time itself becomes meaningless. And after this, who knows what might happen. Maybe according to Roger Penrose, a new universe could be born since the maxed out entropy state is essentially the same as a pre- big bang state.
Here is a somewhat related question. Given that different frames of reference will measure the age of the universe as having different values. Is there a frame (or frames) of reference with a maximum meassured value for the age of the universe? If there is, can this be considered a universal stationary frame of reference?
TL;DR: I'm fairly confident you can't actually be stationary relative to space-time, at least not truly stationary. I might be on a different track from you, but I have wondered what the most "stationary" position could be. The closest I could think of would be if you could somehow suspend yourself in the middle of a substantial void like Bootes with as close to no relative movement to the nearest gravity wells as possible. At that point you should be pretty close to stationary relative the local space-time around you and in turn get a higher value, but even then it wouldn't be particularly meaningful as it is still going to be the 99.99...%c problem in reverse, you can always push it further, but you'll never get to the destination. I'm pretty sure that the only way to achieve true 0 speed would be to exist in an entirely isolated universe with only the observer. Even with that, the observer itself couldn't really contain anything more than the plank level of energy/mass otherwise it should at least interact with itself causing some form of movement. Of course, if this existed and the observer truly was stationary, it would also negate the concept of space and time in that universe, making the concept of being stationary or any form of observation taking place irrelevant.
@@venoltar - You are probably correct that it is not possable to actually be in the "stationary frame". It is still interesting if it is possable to compute how such a frame would relate to an observers frame of referance AND all observers agree on the same "stationary frame".
@@johnbennett1465 Your next challenge would be compensating for the expansion of space-time itself. You could feasibly have two separate observers at identical levels of "stationary" who are also rapidly moving away from each other.
time is what is experienced between two events. so in case of a photon even if it's created and absorbed right away dont mind the interactions, speed changes and so on i would say yes it dose cause creation > time > absorption.
If light were only subject to space, and not time, then it would be able to travel all space instantly, which is not happening, light needs time to travel over such great distances, like from one star to another.
At the beginning of the video spoke of the universe having no 'universal time', and whilst this is true, there has to be a point in the universe that is extremely close to a 'maximum flow of time' (or speed of ageing) in terms of how quickly time can flow. Just as absolute zero is a theoretical limit, so wouldn't there be a theoretical maximum time speed? For example, an extremely slow moving hydrogen atom sitting alone in the middle of a super void. Wouldn't this atom be experiencing the maximum flow of time (or ageing) that is possible within a universe that contains matter? Doesn't that suggest that there is a maximum speed to how quickly something can age?
I think it's a matter of perspective. If you move at the speed of light, the only light reaching you is "standing still". So it should appear that time has stopped around you. Or not.
Impressed by the charm and radiance of a photon when an electron asked the photon out on a date, you know what the photon said??? "I really don't have time!!" The electron wanted the photon to stop for a little chat and see if it could change its mind, the photon said: " I just can't stop!!"
From a photon's perspective : Light is a wave of energy quanta we call photons , that oscillate at a frequency f = 1/T . If the time is standing still from the photon's perspective, T=0 , then the frequency f = 1/0 that is f=0. Is it logical to deduce that from a photon's perspective there is no oscillations therefore there is no wave, therefore there is no photon ? If the photon doesn't exist from its own perspective but it does from our own perspective , what does that mean ? Does it mean that our mind creates the reality ? Same goes for yourself moving at the speed of light , nothing that depends on time will exist from your perspective . No electrons , no atoms , no molecules, etc. Can you then say that everything would be "normal" from your perspective ? How can it be normal ? You cease to exist from your perspective .....
From a photon's perspective whether it crosses the room or crosses the universe, it travels nowhere and takes no time to do it. An electron changes its energy state on the surface of a star and 100 years later an electron in your retina changes its energy state by an identical amount. It's an instantaneous cosmic handshake between two points in spacetime and nothing can get in the way of it. Once that photon sets off it will complete its journey. Don't believe me? Just go outside tonight and look up at the stars. There. There it was. That photon was just travelling for 100 years, but from its perspective, the moment it was created it formed an instantaneous link with your eye. This is the way I see it. To me it feels like the universe is just one immutable blob of past, present and future spacetime.
I believe, if you were riding the "Oh my god particle" (99.99999999999999999999951% of C) then 1 second in a frame at that speed is ~10^11 seconds in our slow moving frame like Earth right? In our frame, universe is ~10^17 seconds old and one year is ~10^7 seconds. So riding that particle, in under one year (in your frame), you'd have been able to watch the entire universe unfold around you from the big bang to now.
So I've repeated this concept to others, that "light doesn't experience time", and it sounds like you're saying, not *exactly* that that's wrong, but rather that the answer is undefined, which okay, annoying, but I can live with it. Two questions; one, does any property of a photon change, from it's perspective, during it's non-existent "lifetime", and two, if yes, then is it possible light doesn't travel at the speed of light? ie could we tell if it was moving at 99.9999999......% the speed of causality instead of precisely at our universe's fundamental maximum speed?
I know this is going to sound like an uneducated "question to answer a question" observation of matters, but here goes: if light experienced time wouldn't we notice the effects of time on the light emitted by similar cosmological phenomenon at varying distances? For example wouldn't a type Ia supernova in the Andromeda Galaxy convey the effects of light age as opposed to one in the Large Magellanic Cloud if light, in fact, experienced time?
Looking at this another way, these "infinities" are our clue to the unified field theory that cosmologists struggle with. Whether it's the non-locality of quanta or the effective non-locality of light due to its lack of aging, the answer is there.
1:10 "And the faster you go in space the slower you go in time..." That is too general / imprecise. The faster you move away or past a place, the slower will your clock be relative to all the clocks in that place, but it will look normal to you (the second hand will tick at just the same rate as before), and the clocks in that place you are moving away from or past will look normal to the 'people' in that place. But see my comment at 1:06, namely, that because velocity/speed (not acceleration) is also relative, it can be equally seen as if you are 'stationary' and the other place is either moving away from you or past you. Both yours and that place's clocks can't be the slow ones. This disproves Einstein's time dilation and length contraction right away.
It is possible to ride with a piece of light, because the duration of the travel is zero and the distance travelled is zero, meaning that the speed of light would be 0/0, which is an indeterminable value that can assume any value of your choice, including c. Hence light does not experience time.
@@PaulMSutter Rocket having only a little bit more mass than the universe does, as current physics states. Some people commenting have forgotten about the part "current physics" though. Love all your work ofc ! (who wouldn't)
Redshift is a phenomena that you observe from your frame of reference, and has no bearing on the (non-existant/described by special relativity) "perspective" of light. Light has no perspective, this is an unphysical question according to special relativity.
If time is relevant to an observer. If moving at the speed of light you experience time normally but someone watching you would see you moving in slow motion. If this is the case light does experience time. Because time is relevant. And changes depending on movement but not for outside observers.
So... does light experience change? I’d have thought that if a photon transitions from one state to another state or some part of it changes, like, isn’t that how we gauge the passage of time based on what changes we can observe? From a photons perspective, if it undergoes change, would it not then experience time in some manner?
Photon doesn’t change states, unlike other particles with inertial mass, like an electron. As far as I know, electron does have a quantum spin, but it can’t change the orientation of the said spin.
7:20 " ... light doesn't know what time is ... " Does light know what space is? Or put another way, if light doesn't have time does light have extent, distance?
The better way to think about it is that we simply have no idea what light experiences because the postulates used to construct the theories we use to talk about time and space do not apply to light. Remember, if you are going .9999999c you still measure light as going speed c. This is an axiom used to derive every result of Special Relativity. But if you are going speed c, this can't be true, as you must always be at rest in a frame moving at your own speed. So the right thing to say is special relativity just doesn't apply to light speed frames, it makes no statements one way or another, and we have no language or way to understand anything about "what it is like" to be in a light speed reference frame. All these loose mystical statements about "light has no time" or "there is no space for light" are just imaginative science fiction at best.
It isn't the wrong question. It takes asking what may seem absurd questions and creating wild thought experiments to eventually come to absurd answers. It was a variation of this very thought experiment that eventually drove Einstein to both of his most influential and successful works in all of science the special theory of relativity and the general theory of relativity.
That's right, it's impossible to travel at the speed of light. Because then you won't know what 1 second is. And there will be no perception whatsoever. And you can't do an experiment to see if you've reached the speed of light.
Paul Sutter; Duality in time? If clock time doesn't exist for a photon of light going at the speed of light then there must be a duality in time. One energy in time that binds the photon to exist and the other that is relative to clock time, relative to a mathematical space-time scaffolding. which is from our conscious perspective, over and in time? Questions for you? What is the CAUSE of the speed of light? Why does a massless particle ACCELERATE to the speed of light? Why is there a LIMIT to the speed of light? Why can TACYONS go faster than the speed of light? Thanks!
WE define the Frequency of each photon as the number of "times" that WE observe it to "wiggle" in what we call "one Second" of time. But if the photon does not even comprehend the existence of "Time", how does it even conceptualise its own frequency? How does a blue photon differ from a green photon if neither of them has a definition of time?
How about this: When something is traveling at the speed of light, there is no concept of time at all. There is no concept of movement either. The photons would just come into existence and disappear always at the very same point in space, would never travel anywhere and would never experience any time at all. I don't know how one should interpreter the space time for such things, but I think it would be missing at least those two dimensions, time and the direction where it would be traveling at. Anyone agree me with this? This is the only way I can make sense of how to things look at the perspective of a particle moving at the speed of light.
take an observable event eg a rock falling into a puddle or a meteor hitting Mars, this event or "image" travels to an observer at c . Non physicist logic suggests that the observer must also be travelling at c . to observe the event in its enterity. does this mean we are already travelling at c ? Also take 3 equidistant points A is the observer, B and C are distant stars. between A and B is clear space but between A and C is a black hole. an event, eg a supernova at B or C should take the same amount of time to be visible to the observer, however point C events "image " can be distorted/deflected by gravitational lensing due to the black hole meaning it would appear to be at a further distance than point B To the observer the speed of light would seem to be variable ?? Are these valid questions ?
Do photons have spin? Can they experience quantum entanglement? If so, does a photon actually need to travel through space or time in order to transmit information?
This question has bothered me so much since I watched Neil Tyson giving that same "photon does not experience time" theory. Your explanation atleast gives me the satisfaction that the approach is incorrect. What the universe is from the perspective of light can't be known from relativity because in that theory, light will always travel at c for u. It never will be at rest.
I think you messed up at the end there. If the question is: does light experience time? Then the answer is no, by your explanation. The incorrect question is: how does light experience time?
Two questions... How is there not a universal time if it only takes conversion? I experience time at my speed, then I can look at another object, see the speed, and calculate what the time it is for that object. Second, from the sun to earth it takes 8 minutes, that means I can know where it is 4 minutes in, specifically halfway between earth and the sun, so how does it not experience time?
Funny question: let's say you were moving so fast, length contraction shortened the entire universe to 1 plank length width, then you move just a little bit faster. Does the universe shrink under a plank length? Does the universe just stop shrinking and stays (essentially) 2D?
That's the wrooooong question to ask. xD That has got to be where quantum weirdness just fully takes over. You move just a little bit faster and next thing you know you're a blue whale falling towards the ground.
I think why are we not able to put the speed of light in all the formula given by lorentz transformation because it may be same thing as 6/2=3 (defined) 6/1=6 (defined) But 6/0 =(undefined) Means may be speed of light is like putting zero in denominator.
The speed of light is equivalent to the speed of causality. Cause always precedes affect. The speed of causality is 1 planck length in 1 planck time. "T", can never be a zero or a negative number.
I have been investigating propagating Electromagnetic fields for many years. My investigations revealed that these fields and the information in these fields propagate nearly instantaneously when they are created and reduce to the speed of light as they propagate into the farfield. According to Albert Einstein, if the speed of light is not a constant, then his theories of Special and General Relativity are wrong. This can be seen in Einstein's time dilation result due to a moving observer: t=r t' and the length contraction result: L=L'/r, where t and L are reference to the stationary frame, and t' and L ' are reference to the moving frame, and r is the Relativistic gamma factor: r =1/Sqrt(1-(v/c)^2). These results are easily derived using Einstein's light clock thought experiment using simple algebra. But if propagating EM fields with infinite speed near the source are used in the derivation, then c = Infinity, and r=1. If propagating EM fields far from the source are used, then c = the speed of light, and r= the standard Relativistic gamma factor. What comes out of this is that the effects on time and space are completely different depending on whether one uses propagating fields near or far away from the source, which can't be true since time and space are real. So the conclusion must be that Einstein's Relativity is wrong and time and space do not change with respect to moving reference frames, Galilean Relativity is correct, and that Einstein's equations just enable us to back calculate to the correct answer, givin the time delays observed by the propagating EM fields used in measuring the effects. But these results do not account for the time dilation observed by moving atomic clocks in airplane experiments, but can be accounted for using variable light speed theory (VLS), origionally proposed by Einstein, and later improved by Robert Dicky in 1957. In this theory, spacetime is not curved by gravity as suggested by General Relativity, instead Newtons theory of gravity is correct and the many other known effects of gravity are due to the affect of gravity on the of light speed. For instance the observed bending of light by mass, which caused General Relativity to be accepted, can be explained, by the gravity generated by the mass, changing the speed of light, causing the light to bend around the mass. This effect is analogous to the bending of light in glass. Since lasers are used in atomic clocks to measure time, then the observed time dilation in atomic clocks in moving airplanes can be explained as due to the effects of light speed changes in the clocks due to changes in gravitation as the plane goes up and down. It should also be noted that several researchers have shown the relation E=mc^2 can be derived without Relativity using Newtonian mechanics, and the Michelson Morley experiment can be explained using the Doppler effect, ref Nathan Rapport 2021 In summary, this research shows that Einstein's theories are wrong and that time and space do not change with respect to moving observers, Galilean Relativity is correct, Newtons theory of gravity is correct, and many of the other effects of gravity can be explained as gravity simply changing the speed of light. The importance of this research is that it completely changes our understanding of time and space and gravity, and simplifies our theories. Perhaps this new understanding will finally enable researchers to finally unite Gravitational theory with quantum mechanics which have been incompatible since scientists accepted Einstein's theories for Special and General Relativity. For instance, Relativity is incompatible with quantum entanglement, which requires communication faster than light, but can perhaps can be explained by superluminal propagating fields between entangled particles. It should be mentioned that this superluminal effect is also observed in the propagating gravitational fields generated by an oscillating mass using Newtonian gravitational theory, and is nearly infinite near the source and reduces to speed of light far from the source. This matches very well with observations of the stability of the planets, which would not be possible if gravity propagates at light speed, and was origionally proposed by Simone Laplace in his famous book: Mécanique Céleste in the late 1700's, where he estimated the speed of gravity to be 7x10^6 times greater than the speed of light.
@@PaulMSutter It's ok, given enough time there will be one. We just need to get into space and start building those dyson swarms. After that, it will be a child's play. Let just hope that by that time, people will not forget this idea. Or reinvent it again. Thanks for the episode.
Semantics. You can still say that light does not experience time since time does not apply to a photon. So can it experience something that does not exist to it? The answer is no.
This is a great question as it takes into account the spacetime continuum which Einstein proved can not be handled separated. If you come to the realization that a photon does not experience the flow of time at all (not stating time is obsolete for a photon), space would just be a 2D view of the whole universe from beginning to end. The way I see it is that we denote c as the constant of the speed of light is just from our egocentric point of view as humans. Ergo, this is a wrong view on the constante c. It is comparable with e.g. historical views that the earth was the center of the universe. Please do not get me wrong! I am a huge fan of Einstein and I am not trying to challenge his brilliance what we know as GR. However, I think he was on his way of using his own theories and creativity to come up with that F = ma is the same as E = mc2. If only the universe as a whole would be in motion. He was a mathematician and could have proven this, Gödel was an even better mathematician and solved Einstein’s field equations. Gödel worked out the equations and found a way for our universe to be in a stationary motion. I am just a kid with a huge fantasy... I know technically acceleration is velocity divided by time and c is just a velocity. However, if the universe is in motion, the constante c could be the velocity of the universe with inertia being the experience of time. The dimensions of space AND TIME do not exist for photons (emitted and absorbed instantaneously). So, acceleration and velocity are the same for photons as these particles do not travel spatially from A to B. As soon as they originated at A they are also absorbed at B, and therefore are experiencing time as standing still. Ergo, no time flow at all from their perpective. Step back: Lorentz was on the right track that with the use of the Maxwell equations there had to be a constant which could not be infinite. Einstein mixed it all together and came up with relativity. In the process also defining the spacetime continuum. Absolute brilliance. The thing that I am stuck with is that Einstein, at the end of his life, knew that time is just an illusion. The past, present and future are all in the same moment. This all has to do with what Einstein already discovered that space and time are inseparable from each other and that motion in spacetime affected ‘the experience’ of time as being relative as well. So, in other words c is the constant velocity which our universe is moving. So, Gödel’s solution on Einstein’s field equations. If we flip it, we may also state that light has no inertia (as it has no mass; Newton). As light has no inertia, velocity or motion are obsolete. Ergo, no velocity or motion is needed to cover any distance (space) over any amount of time. It is all the other way around! Light does not have a velocity or speed. A photon is instantaneously emitted and absorbed. It is the inertia of the universe creating the illusion that light has to travel some distance in a given amount of time (length contraction). It is due to the constant stationary motion of the universe the spacetime continuum is created. Imagine an image of a road at night shot by a camera with a long shutter speed. On this road there is just one car driving with its lights on. With the long shutter speed, the light emitted by the car is smeared out in one line. Suppose you take the same picture and set the shutter time very very short making the light of the car just one pixel on the image. It is all the same photons emitted at very instant moment the picture was taken, but due to inertia (shutter speed) of the film itself (spacetime continuum) it created a line what objects with mass experience as the flow of time (length contraction). This could help understand what Einstein meant with the legendary words: “we know that the distinction between past, present and future is only a stubbornly persistent illusion”. It is the same as Newton viewed the apple falling from the tree. But asked himself: could it be that the earth is (also) falling to apple?
Mind blown.
In addition to it being my wife’s favorite comeback. “Son, that was the wronggggggggggg question to ask.
Basically :)
8 minutes just to be told that we're not allowed to ask that question.
And you watched the whole thing!
@@PaulMSutter I must agree with Clulesskid. The whole thing could have been compressed into a few sentences, kind of like how relativistic moving objects compress the forward direction.
He answered the question while claiming he couldn't answer the question. If time does not apply to light then light does not experience time. If something doesn't apply to an object then that object does not experience whatever that something is
You're allowed to ask but there's no answer. It's like dividing by zero. You're allowed to ask what 1 divided by 0 equals but there's no valid answer for that question. Or even better, it's like asking what's 12 + purple? Not only is there no valid answer, there's no way to even evaluate that question.
@@Bob-sq1us You're missing the subtle but important nuance. It's not that difficult to pay attention for more than 1 minute so that you might get a deeper understanding.
It's not that time has stopped for a photon of light. It's not that time is standing still for a photon. That would imply that light exists within a framework that includes time.
Time never started in the first place for a photon. Time as we know it doesn't exist for light. It's like asking what 1 divided by zero equals. You can't say it equals 1 (time is flowing) or 0 (time is not flowing). The answer is undefined. There is no answer.
You are so good that you make me doubt your logic ... If frame of reference can't go in the speed of light, it doesn't mean that light can't be it's own frame of reference outside relativity
I mean if relativity can't answer this question, it's a limit of the theory and not of light
That's exactly it! The theory breaks down at the speed of light
@@PaulMSutter Hi a slightly different perspective and question on time. In the presence of Gravity (& hence matter) time slows down relatively speaking like near a black hole. So how fast does time run when no gravity is present like out in the middle of space away from any galaxies? How would we perceive this from our frame of reference, is it possible we would experience it as space expanding? Given that speed of light is constant if time is (relatively) running faster for C to remain constant from our frame of reference it would have to travel further otherwise it would appear to be travelling faster. If space/time is compressed by gravity does it un-compress to some natural state in the total absence (or at least approaching zero) of gravity? Cheers.
@@PaulMSutter In a nuclear reactor, we see Vavrilov-Čerenkov-Radiation because light itself suddenly travels faster than light when entering the water.
If however light has, even in massless state, to "slow down" anywhere AND we can observe Vavrilov-Čerenkov-Radiation (as shown in dozens of videos here), c and v_lux must be different, v_lux < c.
As there IS no absolute vacuum, it could be argued that light never can reach 1.0̅ c, always being slowed down by some minute ε.
In this case, the theory indeed should apply to photons (or "gravitons"/gravitational waves ϗtp.), as they DO seem, outside a THEORETICAL absolute vacuum, to always travel with v=c-ε where ε>0.
So I'm not convinced the argument that the theory breaks down for 1.0̅ c applies here.
@@PaulMSutter please anwer damo's question
Growing up I was always taught "The power of the question", ie ask the right question...
Seems more poingent in this vid...
I'm new to these vids and thoroughly enjoying the content. Thank you
Rockin' good work! And just so fun to watch!
What an awesome presentation thank you.
Mind blown!!! This makes me wonder if light is part of the fabric of the universe, or a function of it. Your content is my favorite on TH-cam. It is your excellent ability to explain these concepts that makes me see how difficult these scientific questions are. Do you ever wonder if as science progresses will we just stack up unanswerable questions like cord wood? Either we find something more powerful than special relativity or we are at a dead-end. Special relativity will have to be replaced, but it works so perfectly I worry if it will ever happen.
Very interesting video. This totally makes sense. Thanks.
Movement in space relative to what? If a clock is in orbit passing overhead, for 1/2 the duration it’s moving toward you and away the other, relative to the ground. But the earth is moving through the solar system, again in different directions relative to other pints, in a corkscrew. Take that all the way through position in the galaxy, the galactic movement in the universe and speed relative to the center of the universe, if there is such a point.
Exactly. All movement is relative to other frames. So everyone has different clocks and rulers!
"Movement in space relative to what?"
To **YOU** To the observer!!!! EVERYTHING IS RELATIVE TO THE OBSERVER!!!
Why is that so difficult for you to grasp?
Who cares what the total ultimate movement of the earth through the universe is, it is at a constant velocity and so counts for zero in every equation of relevance.
Whomever the observer is, wherever the observer is, that is the zero motion point for all measurements.
::facepalm:: Goddamn, Fucking DUH!
That's why it is called "RELATIVITY", for fucks sake!
Einstein was right... only two things are infinite. The universe and human stupidity.
And he's wasn't sure about the universe.
@@bigdickpornsuperstar yes, it's relative and only relevant to the observer's frame, but you're being a dick
Fantastic video.
Questions that seem to be nonsense are often the key to deeper understanding. Black hole event horizons were thought to be singularities, but questioning the assumption proved quite useful.
HAPPY NEW YEAR, Spaceman!
by the way , just curious, have you heard The Killers song Spaceman?
Happy new year to you too, and no but I'll give it a listen!
A photon/anti-photon pair created by pair creation through quantum fluctuations at the event horizon of a black hole produces Hawking radiation when the photon escapes to the far field and the anti-photon is absorbed into the black hole. How does that anti-photon decrease the energy content of the black hole to evaporate it since to the best of my understanding the anti-photon has positive energy…but negative frequency? Furthermore a photon with negative frequency and one with positive frequency are identical. Is the issue that allows the anti-photon to annihilate positive energy in any way related to the stoppage of time at the event horizon? Otherwise, the black hole just gets more energetic over time from this influx of anti-photons.
Great question! I've discussed this before - just search my channel for hawking radiation!
Just saw your comment on light and time. I tried to summarize it for my sister and I came out with this. The inability to travel at light speed, resembles, somewhat, a postulate in Euclid. It can't be an axiom, because it is not self evident, though Maxwell may make this so to some. If one tries to put light in with time then one is trying to explain a postulate using theorems proved by using the postulate. As in geometry, leave axioms and postulates alone; don't try to explore them using their children, as it were. Also the math doesn't allow it: 1/ 0 = infinity or whatever.
Not only there is no concept of time but there is no concept of space either to the photon. Because the space shrinks in the direction of travel so much that it's length becomes zero at the speed of light. So photon has no time and no space.
And that's essentially why physicists have run into problems when they've pushed the limits of our understanding of the universe and tried to apply it to the singularity of a black hole or right at the moment of creation when t=0.
Another - related - question though:
Say we discover a giant mirror ten lightyears from Earth, and this mirror is somehow in alignment with Earths trajectory. When pointing our telescopes towards the mirror and finding Earth there, are we looking twenty years into our own past?
Yup. A bit more tbh. Also, remember to aim correctly, it's ten years away after all :) Also its gravity too would affect us ten years later-beautiful calculations of space curvature too !
So... when asked my favourite comedic physics question, which is something like, "If we're traveling in a vehicle going the speed of light, and we turn our headlights on, do they do any good?" what should I say? From the video, it's "not a question we can ask." But hey, what if??? Paul Sutter Truly Rocks, OMG!!!
It would be interesting to hear a discussion on the Big Bang and Inflation, relative to this precept. There was "nothing", then a bang, and everything everywhere, just was. The universe was populated. So, perhaps time was "different" just after the BB?
I’m reading this more slowly in the taxi than on the sofa.
There is a moment in one of Feinman's lectures given in New zealand where he is trying to explain quantum electrodynamics to a ley audience and he at one point talks about particles moving through space along all possible paths and he stops himself and sheepishly corrects himself telling the audience that the particles don't move through space/time, they do particle things and space and time is the place where they do them.
Wow only 19k subscribers?? What the? You deserve so many many more. I know you'll get there though. Your so smart and an awesome great teacher too. Everyone would be so much smarter if they just watched your videos. Thats all you need ppl, is to watch Paul M Sutter and you'll have an EXTREMELY wrinkly brain 😝😝 I gotta say tho, this one really got me. I thought i had it but then i lost it. Pretty difficult for me to grasp. Anyway once again, great video teacher. My number one love in life is space science. So thank you for making these videos and spreading your smartness haha! Have a lovely day. ❤
Haha, thank you! I'm grateful for anyone who will watch! And don't worry about having to do multiple takes on this episode, it took me awhile too!
@@PaulMSutter - Wow thank you for the reply....
@@PaulMSutter, I think you are being persecuted on YT for saying something political.
I guess it depends how you look at it. Certainly, we can't travel at the speed of light; we have mass! But we can observe the emission and absorption of light quanta, which are events in our framework of understanding time, or pretty much what our understanding of time hinges on in the first place. We can use light to knock electrons out of semiconductor plates and then travel back to that plate the long way around, driving devices in the circuit (some of which will purpousfully emit light ok I'm rambling)
So, how do you know how fast you're going?
Compared the the speed of light, humans and other animals are about as slow as plants. That's why our lifetimes seem long to us, but are a blink of the eye to the universe.
It would seem that it does not experience time in the way that we understand or don't understand it. But it does oscillate within itself or its own field(s) so that internal movement seems to impart some property or type of "light-time" to it.
A more simple way to explain why the photon DOES experience time would be to say that in the same manner that if you move at 50% the speed of light, you look at the clock on your hand- It's still ticking normally because it's in the same reference frame as you right? So in the same way, that hypothetical photon is also looking at the clock on their hand and there's a reference frame therefore there's spacetime experience (if there was consciousness, of course).
This no longer hold when the universe is very *VERY* old, and no physical matter left with mass. No reference frames anymore. And only then time and distance lose their meaning. Check out Penrose's Conformal Cyclic ... thing..
Mr. Spaceman, could you do a video on what time is?
Since someone mentioned speed of light being slower in materials (let's say water), I thought of this question: Cherenkov radiation is considered to be equivalent to sonic boom for the light when particles go faster than light. But we know speed of light in materials (water) also depends on the wavelength of the photons, and more importantly, gravitational field doesn't even care about that material, and still keeps going at C. So, how does those FTL particles know they are going faster than light? Which energy wavelength is slowing them down? What interactions happen in there?
What's the slowest you could move in space and thus the fastest in time?
No movement in space -> speed of light through time!
I think from our perspective we are always moving at that slowest speed through space, just as light is always moving at the speed of light. It's from an external perspective that the speed of our movement through time shifts.
Very well explained. I don't disagree with any of it but there is a school of thought about the relationship between light and time which fits with relativity (as explained) and it asks the question: Why is the speed of light not infinite? The answer turns out to be that light needs time to propagate light-wave frequencies (wave-crest intervals). Therefore, if 'c' was infinite there would be no light. So light does have a relationship with time. This seems to mean that you can think of the frequency of light-waves as a ticking clock relative to the frequency of the light emitted. The clock must have a variable tick to coincide with the actual frequency of the wavelength. This also means that white light is made up of a series of clocks all ticking at different speeds (wavelengths). It also raises the question of whether relative time is actually a product of light itself? It also explains why you cannot travel faster than 'c' and the relationship of the spectrum of light with distance and velocity (and time), so v=s/t. BTW: It is also a neat explanation of time-dilation if time itself is a product of light and relative-velocity (or relative motion).
Hey Paul, Is it the wrong question or just non sensical like what's the marital status of the number 5?
Or what's the right question?
Yes, it's like that...the question just doesn't make sense :)
Like - "What's the difference between a duck ?"......"One of it's legs are both the same."
Here is my argument I feel light must experience time ever so slightly because there is a limit to its speed, If truly light did not experience time it would probably move instantaneous as this would correlate with the fact that all time as it observes it stands still but as we know a photon that has traveled a light year has left different conditions from its place of origin so time did move since its departure, therefore if light could perceive time it would observe a change that is extremely slight but it would be there, I think the limitation to its speed is the key factor. Perhaps a good way to test if light experiences time is to test if light can change its state without interaction and how long this will take, if it changes through travel then this could count as an experience of time.
What I've always wondered when trading between speed in space and speed in time, why is the speed of light finite? Is it possible to construe a theory in which the maximum of movement in time (the speed of light) depends on the maximum of space (the extent of the observable universe)? So as older the universe gets, the slower the speed of light will become. All we would technically experience is some mysterious acceleration for very far distances.
this is a bit of a tricky one, because the speed of light 'just is'. the speed itself is derived from a couple other fundamental constants, and we don't understand the origins of our fundamental constants...
@@PaulMSutter Thanks for replying, very good point :)
I heard that Einstein said that from the perspective of light, you (all of us) have been dead for trillions of years (plural).
0:54 - Maybe that's an excuse to be late. Sorry I'm late, but time is relative!
lol. I'll say that to my supervisor if I'm ever late.
That's a question I've wondered but never saw a proper answer for. Thanks for the explanation. So if you're going 99.99999etc... the speed of light, and could measure light that you emitted somehow, it would still appear to move away from you at the speed of light? If you're going the speed of light (not possible i know) , would light you emit still move away from you at the speed of light? Is that the question that can't be asked, doesn't make sense, or is it just that we don't have the understanding or math to answer that?
I'll make a guess here, but I think you should ask this question from the point of an inertial frame of reference. if you go at the speed of light, I think the inertial reference would see you running side by side with light, wich is impossible, cuz nothing can go side by side with light.
Nein Nein Nein Nein Nein Nein Nein Nein Nein Nein Nein Nein :D
yes English 9 sounds like German Nein ^^@@opheliabawles9646
Nein. Nicht nein, neun.
30+ times
Cheer up : )
Nein nein nein nein nein nein nein nein diese Frage stimmt nicht.
Well presented and well spoken, but I just had to pause you at 1:06 to relay what I heard another channel say: Because motion is also relative, then the time dilation does not work -- if a spaceship is moving away from Earth at relativistic speed (not accelerating), then it can also be seen (with a different frame of reference) that the Earth is moving away from the spaceship at relativistic speed, so whose clock is running slower??
So, I've been watching this channel for a while now and my understanding of this topic is like following and please correct me if I'm wrong.
So we measure the speed of light based on our human units which we just agreed to use. Then we can measure the speed of light using some tools that are made out of mater, but the mater itself uses force carrier particles to interact with itself, and they move at the speed of light. so if the tool is moving at 0% of the speed of light or 99.99999999999999999999999999999999% of the speed of light, the atoms of it are still communicating with each other at the speed of light! so that is why when an object is moving at relativistic speeds, the physical interactions of that object actually slow down because it takes longer for the part of that object to communicate with one and other with force carriers or in other words, there is a lag for them to realize each other's existence and behavior.
What we perceive as time is our atoms communicating with each other at the speed of the constant, which is the speed of light. So when we ask how the light experiences the time, what that means is how the light experiences its own speed? so that doesn't make any sense! And that's why this question is wrong.
And yet here we are - beams of light experiencing their own speed, as mass is merely trapped energy. ;)
I've always imagined that's the whole point of asking how light experiences time - to simply note that it doesn't. Ergo from its own perspective light does not exist, because light cannot have a perspective. The interesting bit of the question, then, is 'what makes us different than a beam of light that allows us to have a perspective?' The bog standard answer is that we have mass, but mass is confined energy, and the energy and the interactions confining it all happen at the speed of light. So we are travelling at the speed of light in that sense.
@@mikicerise6250 this makes me think that interacting with the Higgs field is just a direction (freedom of movement) that higher energy (I dislike the next term) packets can travel in as a way to *fit* in 3+1 D.
The way I understand the explanation is that if you could ride next to a beam of light then the relative speed between you and the photon would be 0 which is disallowed because the speed of light is always supposed to be 300 000 km/s. I guess one could still try to imagine it but this video’s explanation is the clearest I have heard it explained.
innertubez speed and travelling photon this is two different things. In theory, if you jump to table of reference of the specific photon, then if you turn on flash light that photons will go in speed of light in that table of reference. What is a photon? It’s a portion of energy. It’s photon only when it’s moving. If you jump to it’s table of reference then you will see nothing ( not physical, only in theory) because table of reference of the photon haven’t space, it’s a pint. If you jump to it you will see only spark of energy. Exactly the same when photon jump to our table of reference, when hit and stop on something.
If the concept of a multiverse where different universes have different laws and constants is real, is the speed of light one of those that could change, or is it a universal constant?
Paul, this topic is my favourite mind worm that I think about way too much. May I ask two questions? First please could you explain the difference between light not experiencing time and light not being within time? I fail to see a meaningful distinction. Second, I use my understanding of light's 'timelessness' to support my belief in a block universe where the future already exists (I'm sure I don't need to go into details to explain this further but I'm willing to if you want me to) ... any comment or criticism of this view that you can share would be fantastic. Thanks.
It's interesting, when you say "block universe" where the future present and past "already exists" .. the word "exists" uses a reference of time. If you mean that they exist "all at once", to say that is to talk about a reality in which things have to reference time as part of it's nature. I think what Paul is saying is that, to something like a photon that travels at the speed of light, this framing of the question cannot inherently contain any reference of time.
When we see something , we see it from the true perspective of light...instantly ,not with delete...!
Well, I dont have a physics background at all but I would think if there was a way to measure light at point A and point B and there was a change in temperature from point A to point B then yes, light did experience time because time had to occur in order to allow the drop of the light temperature. Just my thought- thanks for the video- interesting concept overall.
Hey Paul!
Are you familiar with the work of Klee Irwin of Quantum Gravity Research and if so what do you think of it?
Thirty spokes share the wheel's hub;
It is the center hole that makes it useful.
Hey paul got a question for you, I read a writing about some stars those orbit blackholes like sag A, surpasses speed of light when they passing very close to the blackhole. Is this possible?
It isn't possible
Nah, they get super faster, but not greater than c.
Yes but what about gravitation waves? Can that not effect light? If so light can slow down no?
Time seems to move forward for your reference frame because you are on a geodesic path toward a time singularity. Eventually, all reference frames go to the same singularity as time contracts and space dialtes ... as the universe is really a 'time hole'.
The more mass you have, the slower your movement along that temporal geodesic. Things with less mass or no mass like light will look like they move faster than you through time.
But really, time itself is just a higher spacial dimension that light traverses all at once. Light would experience the 'block universe ', and if we had no mass, we would too. If we could 'ride along with light' as you say, we would see the entire history of our lives all at once.
But things with more mass can stop passing through time completely if there is enough in small enough space to form a black hole.
The expansion of the universe and the redshift of light is basically an illusion caused by space dilating as we experience the accelerating contraction of time from our light cone.
It's like light is the other end of the concept of singularity.
Black holes are said to have infinite density due to its singularity (something like that)
Light, even the fastest moving thing cannot escape it
in the end what i got was, through a lot of science and math we explain we don't want to answer something that does have an answer.
It's almost as if the closer you get to that speed the closer you are getting to the speed of time itself, and when you reach it you are no longer moving in space, but time. Like the way time and space switch places beyond an event horizon. Maybe we are in an event horizon ourselves.
You are on the right track.
See my comment above.
Yes. Light travels as fast as the medium through which it is traveling. A different material or substance with a different index of refraction (if that makes sense) would mean the light ray can be slowed down or speed up ⚽️
*it is weird
Time is the many pieces of light from point A to point B. In our brains, light happens chemically. Our own share of times many pieces.
I definitely understood the entire concept you put across here, but I'm still so temped to just make a comment that's like "duhhhhh"
Feel free!
I'm watching these like a ton of times as I feel exactly the same way. Half my battle is aligning my thinking to Paul's so question isn't completely kindagarten
So a photon being emitted and absorbed in a plasma like the inside of a star or the early universe, experiences the same time as a photon travelling across the galaxy from a distant star to my retina? Are we still effectively in a plasma state that's been stretched out?
So according to the time dilation formula, t = delta T0 / sqrt. Rather than, 0.9999999c for v, if you could plug in 1c for v, you'd end up with c/c which is 1 then you'd have 1-1 which is 0 and the sqrt of 0 is 0 and lastly you'd be dividing by zero which is obviously not allowed. So the time of t (from the formula) is asymptotically approaching infinity. That means, as I said before, a photon sees the entire future events of the universe unfold instantaneously until time itself becomes meaningless. And after this, who knows what might happen. Maybe according to Roger Penrose, a new universe could be born since the maxed out entropy state is essentially the same as a pre- big bang state.
So what would it see if past,future and present don't physical exist and is just a idea we came up with
Here is a somewhat related question. Given that different frames of reference will measure the age of the universe as having different values. Is there a frame (or frames) of reference with a maximum meassured value for the age of the universe?
If there is, can this be considered a universal stationary frame of reference?
TL;DR: I'm fairly confident you can't actually be stationary relative to space-time, at least not truly stationary.
I might be on a different track from you, but I have wondered what the most "stationary" position could be. The closest I could think of would be if you could somehow suspend yourself in the middle of a substantial void like Bootes with as close to no relative movement to the nearest gravity wells as possible. At that point you should be pretty close to stationary relative the local space-time around you and in turn get a higher value, but even then it wouldn't be particularly meaningful as it is still going to be the 99.99...%c problem in reverse, you can always push it further, but you'll never get to the destination.
I'm pretty sure that the only way to achieve true 0 speed would be to exist in an entirely isolated universe with only the observer. Even with that, the observer itself couldn't really contain anything more than the plank level of energy/mass otherwise it should at least interact with itself causing some form of movement. Of course, if this existed and the observer truly was stationary, it would also negate the concept of space and time in that universe, making the concept of being stationary or any form of observation taking place irrelevant.
@@venoltar - You are probably correct that it is not possable to actually be in the "stationary frame". It is still interesting if it is possable to compute how such a frame would relate to an observers frame of referance AND all observers agree on the same "stationary frame".
@@johnbennett1465 Your next challenge would be compensating for the expansion of space-time itself. You could feasibly have two separate observers at identical levels of "stationary" who are also rapidly moving away from each other.
time is what is experienced between two events. so in case of a photon even if it's created and absorbed right away dont mind the interactions, speed changes and so on i would say yes it dose cause creation > time > absorption.
If light were only subject to space, and not time, then it would be able to travel all space instantly, which is not happening, light needs time to travel over such great distances, like from one star to another.
At the beginning of the video spoke of the universe having no 'universal time', and whilst this is true, there has to be a point in the universe that is extremely close to a 'maximum flow of time' (or speed of ageing) in terms of how quickly time can flow. Just as absolute zero is a theoretical limit, so wouldn't there be a theoretical maximum time speed?
For example, an extremely slow moving hydrogen atom sitting alone in the middle of a super void. Wouldn't this atom be experiencing the maximum flow of time (or ageing) that is possible within a universe that contains matter? Doesn't that suggest that there is a maximum speed to how quickly something can age?
There's no "universal clock" but there is a maximum speed of the passage of time: the speed of light!
I think it's a matter of perspective. If you move at the speed of light, the only light reaching you is "standing still". So it should appear that time has stopped around you. Or not.
Time has stopped around you because the entire future history of the universe just hit you in face. ;)
Impressed by the charm and radiance of a photon when an electron asked the photon out on a date, you know what the photon said???
"I really don't have time!!"
The electron wanted the photon to stop for a little chat and see if it could change its mind, the photon said:
" I just can't stop!!"
From a photon's perspective :
Light is a wave of energy quanta we call photons , that oscillate at a frequency f = 1/T . If the time is standing still from the photon's perspective, T=0 , then the frequency f = 1/0 that is f=0.
Is it logical to deduce that from a photon's perspective there is no oscillations therefore there is no wave, therefore there is no photon ?
If the photon doesn't exist from its own perspective but it does from our own perspective , what does that mean ? Does it mean that our mind creates the reality ?
Same goes for yourself moving at the speed of light , nothing that depends on time will exist from your perspective . No electrons , no atoms , no molecules, etc.
Can you then say that everything would be "normal" from your perspective ? How can it be normal ? You cease to exist from your perspective .....
From a photon's perspective whether it crosses the room or crosses the universe, it travels nowhere and takes no time to do it. An electron changes its energy state on the surface of a star and 100 years later an electron in your retina changes its energy state by an identical amount. It's an instantaneous cosmic handshake between two points in spacetime and nothing can get in the way of it. Once that photon sets off it will complete its journey. Don't believe me? Just go outside tonight and look up at the stars. There. There it was. That photon was just travelling for 100 years, but from its perspective, the moment it was created it formed an instantaneous link with your eye. This is the way I see it. To me it feels like the universe is just one immutable blob of past, present and future spacetime.
I have to rewatch it. I think I might be a little bit more confused
I believe, if you were riding the "Oh my god particle" (99.99999999999999999999951% of C) then 1 second in a frame at that speed is ~10^11 seconds in our slow moving frame like Earth right? In our frame, universe is ~10^17 seconds old and one year is ~10^7 seconds. So riding that particle, in under one year (in your frame), you'd have been able to watch the entire universe unfold around you from the big bang to now.
So I've repeated this concept to others, that "light doesn't experience time", and it sounds like you're saying, not *exactly* that that's wrong, but rather that the answer is undefined, which okay, annoying, but I can live with it. Two questions; one, does any property of a photon change, from it's perspective, during it's non-existent "lifetime", and two, if yes, then is it possible light doesn't travel at the speed of light? ie could we tell if it was moving at 99.9999999......% the speed of causality instead of precisely at our universe's fundamental maximum speed?
Exactly, it's that the question can't be properly posed.
I know this is going to sound like an uneducated "question to answer a question" observation of matters, but here goes: if light experienced time wouldn't we notice the effects of time on the light emitted by similar cosmological phenomenon at varying distances? For example wouldn't a type Ia supernova in the Andromeda Galaxy convey the effects of light age as opposed to one in the Large Magellanic Cloud if light, in fact, experienced time?
If light suffered some sort of "drag" or other effect as it traveled, we would certainly notice!
The speed of light has infinities built in, and instead of thinking from our normal perspective, we should back-calculate everything from there.
Looking at this another way, these "infinities" are our clue to the unified field theory that cosmologists struggle with. Whether it's the non-locality of quanta or the effective non-locality of light due to its lack of aging, the answer is there.
1:10 "And the faster you go in space the slower you go in time..." That is too general / imprecise. The faster you move away or past a place, the slower will your clock be relative to all the clocks in that place, but it will look normal to you (the second hand will tick at just the same rate as before), and the clocks in that place you are moving away from or past will look normal to the 'people' in that place. But see my comment at 1:06, namely, that because velocity/speed (not acceleration) is also relative, it can be equally seen as if you are 'stationary' and the other place is either moving away from you or past you. Both yours and that place's clocks can't be the slow ones. This disproves Einstein's time dilation and length contraction right away.
It is possible to ride with a piece of light, because the duration of the travel is zero and the distance travelled is zero, meaning that the speed of light would be 0/0, which is an indeterminable value that can assume any value of your choice, including c. Hence light does not experience time.
1:25 You can do that? Sweet, I'll pack my bag now. Next stop, Alpha Centauri 👽
Just need a giant rocket :)
@@PaulMSutter Rocket having only a little bit more mass than the universe does, as current physics states. Some people commenting have forgotten about the part "current physics" though. Love all your work ofc ! (who wouldn't)
A light wave must be influenced hence experience time because of redshift.
Are you challenging Einstein?
Redshift is a phenomena that you observe from your frame of reference, and has no bearing on the (non-existant/described by special relativity) "perspective" of light. Light has no perspective, this is an unphysical question according to special relativity.
If time is relevant to an observer. If moving at the speed of light you experience time normally but someone watching you would see you moving in slow motion. If this is the case light does experience time. Because time is relevant. And changes depending on movement but not for outside observers.
Shapiro time delay is a proof that massless light does experience time from spacetime curvature.
What is the speed of light in the reference system moving in the direction of photon with speed of light?
Google minkowski diagram.
So... does light experience change? I’d have thought that if a photon transitions from one state to another state or some part of it changes, like, isn’t that how we gauge the passage of time based on what changes we can observe? From a photons perspective, if it undergoes change, would it not then experience time in some manner?
Photon doesn’t change states, unlike other particles with inertial mass, like an electron.
As far as I know, electron does have a quantum spin, but it can’t change the orientation of the said spin.
7:20 " ... light doesn't know what time is ... " Does light know what space is? Or put another way, if light doesn't have time does light have extent, distance?
The better way to think about it is that we simply have no idea what light experiences because the postulates used to construct the theories we use to talk about time and space do not apply to light.
Remember, if you are going .9999999c you still measure light as going speed c. This is an axiom used to derive every result of Special Relativity. But if you are going speed c, this can't be true, as you must always be at rest in a frame moving at your own speed.
So the right thing to say is special relativity just doesn't apply to light speed frames, it makes no statements one way or another, and we have no language or way to understand anything about "what it is like" to be in a light speed reference frame. All these loose mystical statements about "light has no time" or "there is no space for light" are just imaginative science fiction at best.
It isn't the wrong question. It takes asking what may seem absurd questions and creating wild thought experiments to eventually come to absurd answers. It was a variation of this very thought experiment that eventually drove Einstein to both of his most influential and successful works in all of science the special theory of relativity and the general theory of relativity.
That's right, it's impossible to travel at the speed of light. Because then you won't know what 1 second is. And there will be no perception whatsoever. And you can't do an experiment to see if you've reached the speed of light.
Paul Sutter; Duality in time? If clock time doesn't exist for a photon of light going at the speed of light then there must be a duality in time. One energy in time that binds the photon to exist and the other that is relative to clock time, relative to a mathematical space-time scaffolding. which is from our conscious perspective, over and in time?
Questions for you? What is the CAUSE of the speed of light? Why does a massless particle ACCELERATE to the speed of light? Why is there a LIMIT to the speed of light? Why can TACYONS go faster than the speed of light? Thanks!
WE define the Frequency of each photon as the number of "times" that WE observe it to "wiggle" in what we call "one Second" of time.
But if the photon does not even comprehend the existence of "Time", how does it even conceptualise its own frequency? How does a blue photon differ from a green photon if neither of them has a definition of time?
How about this: When something is traveling at the speed of light, there is no concept of time at all. There is no concept of movement either. The photons would just come into existence and disappear always at the very same point in space, would never travel anywhere and would never experience any time at all. I don't know how one should interpreter the space time for such things, but I think it would be missing at least those two dimensions, time and the direction where it would be traveling at.
Anyone agree me with this? This is the only way I can make sense of how to things look at the perspective of a particle moving at the speed of light.
There are no wrong questions to ask!
take an observable event eg a rock falling into a puddle or a meteor hitting Mars, this event or "image" travels to an observer at c . Non physicist logic suggests that the observer must also be travelling at c . to observe the event in its enterity. does this mean we are already travelling at c ?
Also take 3 equidistant points A is the observer, B and C are distant stars. between A and B is clear space but between A and C is a black hole. an event, eg a supernova at B or C should take the same amount of time to be visible to the observer, however point C events "image " can be distorted/deflected by gravitational lensing due to the black hole meaning it would appear to be at a further distance than point B To the observer the speed of light would seem to be variable ??
Are these valid questions ?
From our world perspective energy is not created or destroyed but on a universal scale energy is created maintaining a constant density in the vacuum?
Can someone tell me how do we know that light doesn't expirience time. Please.... any link to some webpage or video??
Red Button
Look for the first video under the search:
Light point of view
Do photons have spin? Can they experience quantum entanglement? If so, does a photon actually need to travel through space or time in order to transmit information?
Photons can be entangled! Not through spin but through their polarization state!
This question has bothered me so much since I watched Neil Tyson giving that same "photon does not experience time" theory. Your explanation atleast gives me the satisfaction that the approach is incorrect. What the universe is from the perspective of light can't be known from relativity because in that theory, light will always travel at c for u. It never will be at rest.
I think you messed up at the end there. If the question is: does light experience time? Then the answer is no, by your explanation. The incorrect question is: how does light experience time?
Good Video ⚽️
So time is relative until it seizes to exist at the speed of light. Would it go backwards if FTL is possible?
Yes, it could!
Two questions...
How is there not a universal time if it only takes conversion? I experience time at my speed, then I can look at another object, see the speed, and calculate what the time it is for that object.
Second, from the sun to earth it takes 8 minutes, that means I can know where it is 4 minutes in, specifically halfway between earth and the sun, so how does it not experience time?
Funny question: let's say you were moving so fast, length contraction shortened the entire universe to 1 plank length width, then you move just a little bit faster.
Does the universe shrink under a plank length? Does the universe just stop shrinking and stays (essentially) 2D?
That's the wrooooong question to ask. xD That has got to be where quantum weirdness just fully takes over. You move just a little bit faster and next thing you know you're a blue whale falling towards the ground.
I think why are we not able to put the speed of light in all the formula given by lorentz transformation because it may be same thing as
6/2=3 (defined)
6/1=6 (defined)
But 6/0 =(undefined)
Means may be speed of light is like putting zero in denominator.
if you plugged in c for v in the numerator of the Lorentz transformation it would blow up the formula because you'd be dividing by zero.
The speed of light is equivalent to the speed of causality. Cause always precedes affect. The speed of causality is 1 planck length in 1 planck time. "T", can never be a zero or a negative number.
I have been investigating propagating Electromagnetic fields for many years. My investigations revealed that these fields and the information in these fields propagate nearly instantaneously when they are created and reduce to the speed of light as they propagate into the farfield.
According to Albert Einstein, if the speed of light is not a constant, then his theories of Special and General Relativity are wrong. This can be seen in Einstein's time dilation result due to a moving observer: t=r t' and the length contraction result: L=L'/r, where t and L are reference to the stationary frame, and t' and L ' are reference to the moving frame, and r is the Relativistic gamma factor: r =1/Sqrt(1-(v/c)^2). These results are easily derived using Einstein's light clock thought experiment using simple algebra. But if propagating EM fields with infinite speed near the source are used in the derivation, then c = Infinity, and r=1. If propagating EM fields far from the source are used, then c = the speed of light, and r= the standard Relativistic gamma factor. What comes out of this is that the effects on time and space are completely different depending on whether one uses propagating fields near or far away from the source, which can't be true since time and space are real. So the conclusion must be that Einstein's Relativity is wrong and time and space do not change with respect to moving reference frames, Galilean Relativity is correct, and that Einstein's equations just enable us to back calculate to the correct answer, givin the time delays observed by the propagating EM fields used in measuring the effects.
But these results do not account for the time dilation observed by moving atomic clocks in airplane experiments, but can be accounted for using variable light speed theory (VLS), origionally proposed by Einstein, and later improved by Robert Dicky in 1957. In this theory, spacetime is not curved by gravity as suggested by General Relativity, instead Newtons theory of gravity is correct and the many other known effects of gravity are due to the affect of gravity on the of light speed. For instance the observed bending of light by mass, which caused General Relativity to be accepted, can be explained, by the gravity generated by the mass, changing the speed of light, causing the light to bend around the mass. This effect is analogous to the bending of light in glass. Since lasers are used in atomic clocks to measure time, then the observed time dilation in atomic clocks in moving airplanes can be explained as due to the effects of light speed changes in the clocks due to changes in gravitation as the plane goes up and down. It should also be noted that several researchers have shown the relation E=mc^2 can be derived without Relativity using Newtonian mechanics, and the Michelson Morley experiment can be explained using the Doppler effect, ref Nathan Rapport 2021
In summary, this research shows that Einstein's theories are wrong and that time and space do not change with respect to moving observers, Galilean Relativity is correct, Newtons theory of gravity is correct, and many of the other effects of gravity can be explained as gravity simply changing the speed of light. The importance of this research is that it completely changes our understanding of time and space and gravity, and simplifies our theories. Perhaps this new understanding will finally enable researchers to finally unite Gravitational theory with quantum mechanics which have been incompatible since scientists accepted Einstein's theories for Special and General Relativity. For instance, Relativity is incompatible with quantum entanglement, which requires communication faster than light, but can perhaps can be explained by
superluminal propagating fields between entangled particles.
It should be mentioned that this superluminal effect is also observed in the propagating gravitational fields generated by an oscillating mass using Newtonian gravitational theory, and is nearly infinite near the source and reduces to speed of light far from the source. This matches very well with observations of the stability of the planets, which would not be possible if gravity propagates at light speed, and was origionally proposed by Simone Laplace in his famous book: Mécanique Céleste in the late 1700's, where he estimated the speed of gravity to be 7x10^6 times greater than the speed of light.
There SHOULD BE such thing!
Sorry!
@@PaulMSutter It's ok, given enough time there will be one. We just need to get into space and start building those dyson swarms. After that, it will be a child's play. Let just hope that by that time, people will not forget this idea. Or reinvent it again.
Thanks for the episode.
A photon doesn’t move? We are the ones moving?
Semantics. You can still say that light does not experience time since time does not apply to a photon. So can it experience something that does not exist to it? The answer is no.
Does the concept of space-time still apply at the speed of light?
Humanity can't save us at the speed of light
This is a great question as it takes into account the spacetime continuum which Einstein proved can not be handled separated. If you come to the realization that a photon does not experience the flow of time at all (not stating time is obsolete for a photon), space would just be a 2D view of the whole universe from beginning to end.
The way I see it is that we denote c as the constant of the speed of light is just from our egocentric point of view as humans. Ergo, this is a wrong view on the constante c. It is comparable with e.g. historical views that the earth was the center of the universe. Please do not get me wrong! I am a huge fan of Einstein and I am not trying to challenge his brilliance what we know as GR.
However, I think he was on his way of using his own theories and creativity to come up with that F = ma is the same as E = mc2. If only the universe as a whole would be in motion. He was a mathematician and could have proven this, Gödel was an even better mathematician and solved Einstein’s field equations. Gödel worked out the equations and found a way for our universe to be in a stationary motion. I am just a kid with a huge fantasy... I know technically acceleration is velocity divided by time and c is just a velocity. However, if the universe is in motion, the constante c could be the velocity of the universe with inertia being the experience of time.
The dimensions of space AND TIME do not exist for photons (emitted and absorbed instantaneously). So, acceleration and velocity are the same for photons as these particles do not travel spatially from A to B. As soon as they originated at A they are also absorbed at B, and therefore are experiencing time as standing still. Ergo, no time flow at all from their perpective.
Step back: Lorentz was on the right track that with the use of the Maxwell equations there had to be a constant which could not be infinite. Einstein mixed it all together and came up with relativity. In the process also defining the spacetime continuum. Absolute brilliance. The thing that I am stuck with is that Einstein, at the end of his life, knew that time is just an illusion. The past, present and future are all in the same moment. This all has to do with what Einstein already discovered that space and time are inseparable from each other and that motion in spacetime affected ‘the experience’ of time as being relative as well.
So, in other words c is the constant velocity which our universe is moving. So, Gödel’s solution on Einstein’s field equations. If we flip it, we may also state that light has no inertia (as it has no mass; Newton). As light has no inertia, velocity or motion are obsolete. Ergo, no velocity or motion is needed to cover any distance (space) over any amount of time. It is all the other way around! Light does not have a velocity or speed. A photon is instantaneously emitted and absorbed. It is the inertia of the universe creating the illusion that light has to travel some distance in a given amount of time (length contraction). It is due to the constant stationary motion of the universe the spacetime continuum is created.
Imagine an image of a road at night shot by a camera with a long shutter speed. On this road there is just one car driving with its lights on. With the long shutter speed, the light emitted by the car is smeared out in one line. Suppose you take the same picture and set the shutter time very very short making the light of the car just one pixel on the image. It is all the same photons emitted at very instant moment the picture was taken, but due to inertia (shutter speed) of the film itself (spacetime continuum) it created a line what objects with mass experience as the flow of time (length contraction). This could help understand what Einstein meant with the legendary words: “we know that the distinction between past, present and future is only a stubbornly persistent illusion”.
It is the same as Newton viewed the apple falling from the tree. But asked himself: could it be that the earth is (also) falling to apple?