How the Quantum Eraser Rewrites the Past | Space Time | PBS Digital Studios
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Causality is meant to move in one direction: forward. But the Quantum Eraser experiment seems to reverse causality. How and why can this happen and what are the implications of this experiment on how we understand Quantum Mechanics and our greater universe?
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A Delayed Choice Quantum Eraser
Kim, Yu, Kulik, Shih & Scully, 2000, Physical Review Letters v.84 p.1
arxiv.org/abs/quant-ph/9903047v1
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This is the most absurd thing I've ever tried to wrap my head around in my entire life. Thank you
Same.
This describes my thoughts perfectly xD
Its true
@@madcow5833 Thank you for this
Why take anything down because it has been debunked? There is still usefull information here and it shows the process of science. There is also nothing on the internet that has an obligation to be truthfull to you.
Dammit i told you the universe wasn't ready for offical release yet.
The universe has't been officially released, this is a leaked version.
just like no man's sky :/
I'm just glad we're not getting all the 404 errors that plagued the first leak.
nonamae2009 oh god i don't want to be reminded of those
+Smerlin and i had beeb told we were out of beta and releasing on time...
I really like the transactional interpretation for explaining this. In it particles only appear after a three part process where an emitter sends out an offer wave (psi), then receives confirmation waves (psi*) from every possible future absorber and non deterministically "chooses" a single confirmation wave, which then creates something almost like a standing wave in spacetime that transfers energy, spin, momentum, etc from emitter to absorber. Which we perceive as a particle at a timelike interval. The mutual atemporal interaction between both emitter and detector is required for a particle to exist in the first place.
So when you have entangled wave packets moving through the delayed choice experiment, as a single offer wave, the potential properties of "future" particles stemming from that offer wave are basically doled out to suitable absorbers in the system as you measure. Which explains all the seemingly retrocausal weirdness.
Which is also why when you measure the spin of an entangled particle the spin of the other instantly changes. The possibility of it being one or the other became finalized as soon as it was measured since measuring itself is what caused potential properties to manifest from possible ones into actual events at timelike intervals.
This comment is criminally underappreciated.
1k likes from me to you.
@@hillarysemails1615 Sir. You are not authorized to give 1k likes here. We restricted your contribution to a number of 1 like.
😆😁😇@@Blacksoul444
You are 100% right about that one - quote: "Physicists DO LOVE a good MYSTERY!" ...even more than answers!
PS. ...maybe that's why each answer they provide us with discloses a 100 new questions...
I like to tell kids learning physics is like fighting a hydra
@@douglaswinters9695 every time you cut a head, another 2 show up sprout in its place ?
When you are not looking at it, this comment describes the answer to the quantum eraser problem.
*insert elitest comment saying how wrong you are*
p.s. I hav no idea
Hahahahh
Every time I look it must be invisible. It must be outside the range of human senses. Can my dog see it?
i got a reason to stare at my phone with my eyes closed.
Parakmi I lol good one :)
...yeah. I'll be watching this one a few more times.
I feel you brother, this shit is too valuable not to learn
I don't know how I got this far in life not knowing this. I'll never look at the world the same way again, innocence lost. I feel so much older and wiser knowing this. I'm ready to take on the world now, look out world I know some real shit now. I don't have a clue what the fuck it means, but I know it :)
I'm on my 5th go
You have to watch this many times because the meaning keeps changing. ;)
It took a while but after seeing it multiple times and really thinking about it , It breaks your mind!
I'm both profoundly shocked, and in wonderland. This is fascinating and provoking. Everything I love in life, thank you for uploading all those videos
Debunked
I remember opening and closing a fridge and every time wondering if the light was always on..then i found the button switch and the magic died forever.
Dgaf brapman 😅👍🏻 me too
Haha same. I use 2 try open the fridge fast or slow or sneak look at it. Found out there was a fuckn botton and found how stupid I looked haha
Excellent comment.
There is no fridge
Hidden variable
"Could it get any weirder? This is quantum mechanics. So, yeah." That made my day.
It can and is 😂
I love how the presenter, with his facials expression, is also like "What?? This doesn't make any sense", lol
Mindblowing. This looks to be the most complex problem to root cause. This is where rational understanding has to be leveled up.
Or the experiment
Proof that universe has a parental control," You're are not that evolved to take this yet".
nope its complex variable that doesnt allow to see its properties
Excellent comment.
Underrated comment🍆
#BlameIsAnInteger
Pass it on. #Dust
The creators of the simulator have control systems in place
You kinda represented the data in the study wrong. The pattern that is created by the double slit experiment doesn't change when you turn any of the detectors on or off. The reason why they talked about the pattern changing was they used the detectors to create a list of which photons went through which slit. They were able to get an interference pattern when they only looked at the data of photons which went through one slit. When the data from both slits is put together the pattern disappears.
This is absolutely right. We glossed over some details, but will expand on this in an upcoming video.
This is super important information, especially when it comes to interpreting what the results mean.
Lol you call that "some details"? You should be ashamed to call yourself scientists.
+SemperAugustusBubble Dude, they are going to talk more on it in a later video, wait for that before you say shit like that
hahahah
Here’s some food for thought: Perhaps the central illusion here is the passage of time (in the before-during-after sense). Einstein and others have posited the notion of “block time” or “block universe” in which past, present, and future are concurrent.
To this I would add that, rather than “parallel” universes/realities, such a block universe might contain all possible trajectories and events in superposition - in other words, the firing/ slit passage/ measurement is all just one unitary event. Moreover, the detection display also exists in both wave and particle (and other?) format concurrently - the one emerging trajectory being the one that is observed/attended to (sort of in the way that a sculptor “attends” to particular molecules in a block of granite to reveal a statue).
In this scenario, there need be no wave function collapse (physical alteration). It would simply be the “collapse” or focus of attention by the observer on one possible trajectory.
An interesting/challenging implication of this would be that the appearance of cause-and-effect is also illusory - simply being events and phenomena that co-emerge when one particular world line is attended to.
The above might also illuminate the perennial question “do people have free will?” Along any particular world-line set, the opportunity-choice-outcome is one concurrent, co-emergent phenomenon. Yet the fact that we have a double-slit “paradox” suggests that choice is involved in regard to which world-line set the observer attends to.
WOW that was amazing! Thank you for sharing this video, I really enjoyed the topic.
This is by far...the most important program you have ever done.
"Physicists hate being outsmarted by the universe." 😂
wll physicists outsmarted their selves.
This interpretation is based on a logical fallacy.
arxiv.org/pdf/1112.4522.pdf
@@nickolasgaspar9660 Quantum Mechanics are based on empirical data anyways.
Shortly said: It is made up from theoretical facts.
@@ethhics Sure, but the interpretations of the quantum eraser is factually wrong.
@@ethhics btw ''theoretical facts'' is an oxymoron. We use facts to construct our theories.
Yet the universe kicks everyone's teeth in after the experiment.
I love this so much; in throwing out the Copenhagen Interpretation in favor of Everett's MW Interpretation this seems a much simpler effect - when we effectively entangle with this system determines whether or not we see a double-slit pattern or an interference pattern recorded. If we entangle with the system at the point of the two slits then our later measurement will absolutely be one where photons moved through one slit or the other. We've already opened Schrödinger's box and it's state is now defined because we've entangled with it. However if we don't open Schrödinger's box, we don't entangle with the system until after the double-slit filter, then it's state won't be defined until it's measured at the detector - causing the box to open and it's state finally defined as our interference pattern.
Both results are absolutely the result of entanglement. It just depends on when we become entangled with it. If you measure the pattern after we entangle at the point of the double-slit you'll get a double slit pattern; if measuring the pattern is your point of entanglement you'll get the interference pattern.
The absolute hidden beauty of this experiment is that it proves that WE entangle with this experiment's system and will do so for every other experiment we devise.
Each like gets us closer to home time travel 😂
Nice reply. See mine above. That's the nub, isn't it? The observer has to be entangled with each particle. But is it before or after? There's something going on with apparent determinacy at the point of interaction.
Collapsing the wave function is really poor terminology. Decohering target entanglement through interaction would be more accurate. This implies reversing the interaction could recohere an entangled state, which seems sensible.
Its like the universe is preventing the existence of a paradox
Maybe the screen becomes the detector...and influences whether a particle is reflected or passes through.
Voila, no retro-explanation required.
That makes me wonder🤔. What would happen at the eraser end if the Which-Way polarizers are added?
Exactly. That's why I believe time travel has no paradoxes, because from the universe's perspective there is no such thing.
@@Hallowed_Ground And what if we are the universe and do not end in the tip of our fingers?
@@fabriciopereira9366 You have it there. There is no such thing as "separation." We are all, everywhere, everywhen, part of that which began as One, then expanded, to try to understand what it meant to be not alone.
Man, this was part of the start of a very weird journey. 4 years later still weird and getting weirder
“An entangled pair...”
I had surgery for that in 9th grade...
I did too...but in 6th grade. Very young for that problem
Quantum physics also gets my nuts in a twist.....
Ah.. the strangulated hernia..
Lol you guys 🤣
5th grade for me
I keep coming back to this video.
This is the only good explanation I've seen. Thanks!
Alright then, keep your secrets.
Philosophical implications came to my mind when they talked about splitting photons. Are we supposed to have photon halves?
@@bethanyudonome4219 How so? were not supposed to have anything. Things just are, photons are photons and by splitting them were not violating any laws of physics or anything
@@benl8962 also by cloning you're not violating any laws of physics. I said a moral dilemma, not a physical law. Morals, Ethics- do you have any?
@@bethanyudonome4219 yeah alright, but you havent answered my question. Why is it a moral dilemma to split a photon? Nobody gets hurt by doing so....
@@bethanyudonome4219 like wtf, you are questioning my morals because i dont see a problem with splitting photons?
Wow, this is mind blowing, I always wanted to know what Peter Dicklage would look like if he wasn't a dwarf.
Made me laugh out loud
And still attractive, in spite of the added height, ay?
human?
Really great explanation Matt. One of my favorites.
Matt lied to you. The conclusions that Matt presents have been debunked.
This is Awesome. Such a wonderful rabbit hole to go down. Thank you
What the actual fuck universe
For some reason this seems to somewhat support the "simulated universe" theory, where our universe is a simulated one, and it does not simulate to the quantum level, instead reverting to computational "shortcuts". It would actually simulate things with more detail when it is being observed, I.E. when we are testing it. I feel like these differing results are the result of the universe going into a sort of "low-resolution" mode, similar to many games only rendering the things the player is looking at, and replacing textures with simpler, less intensive textures at larger distances. Of course, this entire thing is a theory, and simply being capable of wondering if we are in a simulated universe may prove we are not in one... my brain hurts!!!
Hey Matt, that is 100% what I've thought for most of my life. I've said it many times but have never worded it in such an easily digestible way as you did. Very nice.
how does being capable of wondering prove that?
Matthew Smith it's not a theory, it's a hypothesis. It's also an untestable hypothesis, so think about it all you want but I wouldn't invest too much into this idea. Also us being able to think about something is not evidence. It's like when religious people say that since the idea of God is in our head therefore God exists. It's circular logic and bad science.
no worries, its just a glitch in the matix
Damn programmers, trying to make performance optimizations that end up being noticed.
Simulating a quadrilion photons as a wave is exactly how simulations are programmed
@@JZSIX very creepy stuff.. seems to point to the universe being a program with subatomic optimizations.
Hey I know Matt says it's like the wave function goes back in time if we are looking at it. However, I know that there are beam splitters and prisms being used, I know that light actually slows down when it goes through a prism, would it possibly be the reason that it looks like it goes back in time is actually just some of the light being slowed down by going through the prism and some of it 'hits' the detector without being interfered with (compared to the light that goes through the prism?)
If there is a way to observe a large number(let's say 1%) of all photons then we are essentially stress testing the universe.
@@taichiwinchester1102 Crash the simulation!
It just blew my mind. Quantum physics and it's applications in molecular r electronic structure determination have always been my interest. Thank you for making a video on such a beautiful topic. Keep it up.
Mind blown, thanks for the explanation sir.
My new found favorite Space Time topic. I’ve watched this video three times (minimum needed for me to fully comprehend all of Matt’s brilliant insights). Hope to see more regarding this in the future.
Quantum Mechanics:
1. Build the experiment from your brain
2. The experiment will now build your brain
3. Blow your brains out
Po
Yeah brain no likey 😂 raise that consciousness!!
Yesss I knew it!!! I heard of an experiment like this where a wave instantaneously transformed into particle only when observed but no one knew why, and I thought that maybe the method of observing the wave/particle influenced how the wave/particle acted but I could never find anything else on it for years ( I was 8 when I first heard about the experiment )
Sadly this experiment and most channels are lying to you. Watch Sabine Hossenfelder who debunks their bullshit.
@@Anonimowany1 I know, but the concept remains the same in that by viewing or measuring an experiment you may affect the outcome and even if the methods used in this experiment are outdated it’s still an interesting concept
The double slit experiment
@@timpowers6876 yes… that’s what it’s about…
Great summary... Thanks
Hello simulation runners. Just a humble request to fix the bug before it gets wider attention.
Agents have been dispatched.
Simulation is defined as hypocrisy, meaning your mind is perceptively the only source of any simulation. So fix yourself first, attack the source. Hypocrites at least know they are simulating, but the ignorant simulator is a hypocrite without realizing, without understanding of that which is the correct path. Which is more dangerous? Legalism creates simulators, which are controlled by elite hypocrites.
Ok I will go fix it
It is not a bug, it is meant to be this way so that the computer can save some ram by not having to render something real within the program unless it is being observed
@@MrHHVV hahaha, good one....wait what?!
Schrodinger's window:
It is both snowing and not snowing until you look through the window. It's how I survive the winter.
Thanks for waiting Matt. Much appreciated.
truly and actually mind blowing
I swear: Quantum physics is just a giant middle finger to anyone who wants this shit to make any kind of sense.
Scientists just love the middle finger from nature. It is what spurs them on to achieve the impossible.
God is trolling hard.
God reminds brilliant minds just who their daddy is in a spiritual sense.
Pretty much yeah.
QM is like trying to read a book where you can only see half the letters of a word, one word at a time, and you only get to look at a single page once.
and the book is in another language that no one knows how to read it...
Of all the things I've learned from Space Time, this one blew my mind!
The clearest illustration (via animated graphics) of the delayed choice and quantum eraser experiments I've seen yet.
This video is pretty good too: th-cam.com/video/0ui9ovrQuKE/w-d-xo.html
Thankyou.... you explained this complex topic in a wonderfully easy to understand way. Thanks so much. I am delivering an audio presentation on this soon and you have really helped me out.
The detector affects the particle, it has to slow it down which sort of irons out the interference pattern into 2 bands. It has to because no matter how many particles you send through the slits they will only ever hit the detector behind the slit, but the interference pattern suggests that there is a possibility of a particle can hit where band 7 is or band 1
Quantum physics: the science that makes no sense at all and gives you the middle finger saying deal with it bitch......
Like religion
+Cams250
Thanks for this unpredicted twist, we will transfer you to someone who gives a damn....
+Madridy1996 Lol you mad? the example is ironic.
+Cams250
You had to bring it didn't you!
Madridy1996 Round one, FIGHT!
Last time I was this early the universe was still orange
This is actually good.
Woah, this is the only clever one I've seen
I don't get it. 😢
+Ismael Ochoa
orange = visible wavelength, that's a LOT less red shifted than the 3K radiation of today. A LOT less red shifted cosmic background radiation means a LONG time ago.
best comment I've read in a long time!
I just want to thank Siddharth for the making me feel " special" part.. Fun apart THANK YOU!
It seems to me that part of the problem is our illusion of time moving in one direction. It seems more like time happens simultaneously, as dual causality is also a thing, where the past affects the future and the future affects the past. While I will admit my math skills are a little weak to prove this, I do think the answer to this conundrum lies in our perspective of time.
That makes sense, especially when you consider that photons are supposed to have no time. So playing around with them in our time may just mean for them that different body parts of the whole four dimensional existence is touched in their single moment which is it eternity for it (excuse the metaphorical time words for a non-time being photon)
@@michael5764so photons are this 4d all knowing entity that exist everywhere in time. Sounds so far fetched. Infact continuity of time itself breaks down and all math that derives itself from this continuity. 😅.
How the what does the what?!
Probably the most curious title yet!
... By the end of the video, I had far more questions than I came in with. =_=
+YuTe3712 That's science for ya
+YuTe3712 That's the fun part of quantum mechanics.
its just faster than light information exchange which he says re-writes past maybe. tl:dr if you will
+YuTe3712
That's not untypical for science
"Without the nonsense mysticism" - I love you so much.
I just wrote almost the exact same comment. I love you too now.
I am sorry, we have operating quantum computers, and from their operation, it seems the correct answer is the multiple worlds interpenetration. That the particle going through the second slit, is a particle located in another dimension. And not to mention Dr. Hammeroffs work, he had shown, the bing in consciousness is the collapse the the wave function in Micro Tubules. I know there is not a lot of transnational research, however there should be. Photo synthesis, cannot operate without QM either.
@@stage274 In the multiple worlds interpretation, there is no wave function collapse :/
Ironic.
What if after your interference screen displays a wave, you block one path that makes the erasing possible? Would then the particle that hits the interference screen be a wave and the one that hits the detector be a particle, or would a wave pattern never occur in the first place because the particle "knows" about your intention?
Love this! Ty
I came across this in Brian Greens book, The Fabric Of The cosmos. Had a hard time understanding it there. But thanks to you it’s crystal clear now.
Thank you
In the quantum eraser experiment, say we increased the distance from the double slit to the A/B and C/D detector setups to let's say 10 light minutes to a light year and put a 50/50 probability fission event at the end (like in Schrödinger's thought experiment) to choose which of A/B or C/D setup to use and which to move out of the way or block.
What patterns would we observe at the interference screen?
Could we predict the future 10 min / a year ahead, predict the fission event by observing a pattern on the nearby interference screen?
@Pupsi: Yes, why isn't that an obvious question to ask (?) What's the answer (?) Let's say it takes 1 second for the particle to reach the interference screen . . . but 5 seconds to reach detectors A and B. So what appears on the interference screen at 2 seconds (?)
@@QED_ I might be wrong on this one but I think it's not possible to extract any conclusive or.. "predictive" data from the interference screen at shorter time frames. I'm just guessing the way the experiment is actually done is to shoot individual particles one at a time for a long period and then compile a BIG amount of data at the end to see the patterns from the chaos. One particle hitting the interference screen won't tell anything, it'll just look like a random point. The time to shoot enough particles and to process the data from the interference screen needs way more time than 3 seconds (5 sec - 2 sec) IF the experiment is done this way. Don't know how else it would be done though.
So what appears on the interference screen at 2 seconds? I'm thinking it seems just random at THAT moment..... until long long after when the data analysis is done
@@Pupsi Well suppose in theory we could increase the time to reach detectors A and B to over the time it takes to fire enough photons, then what?
@@oaksnice please title
I believe in multiverse theory, so instead it’s causal, if we would ever eventually detect which slit it went through, we are forced down the ‘no interference pattern’ branch, and if we don’t, then we’re forced down the ‘interference pattern” path, no backwards time travel information for me here unfortunately
I'm wondering if the Wheeler-Feynman Emitter/Absorber Theory could possibly help explain this. Is there any chance that we are seeing interference patterns across the time dimension in these experiments?
mind blown
Excellent video & explanation. Please talk about "reality" the latest thinking.
Even the universe gets stuck with spaghetti code
Jesus saves, but God doesn't debug.
Wow. That response is amazing.
then i guess the other guy hits the delete key :P
Sounds like string theory,James Gates...and digital physics Ed Fredkin,Nick Bostrom,Sandra Postel,Tom Campbell Bruce Lipton interview,Pam Grout,
LOL
this is one of those videos that I'll have to watch several times. :/
nah, its a bunch of bologna and you know it!
We are unable to single handedly compute all that we know because not only can our processor not handle it but our memory bank along with our ability to observe it in open tabs just like a computer does, is very minimal ( unless you are obsessed with it and disciplined enough to study it day and night which I have yet to do properly ).
it's not easy to organize the mind in terms of folders, because our subconscious does that job on its own.
I was thinking the same thing. I'll have to watch this a few times...
I spent half the day at it, and I'm still at it.
I think for the first time I'm beginning to understand entanglement half-decently. Thank you. I know the video wasn't really about that, but this experiment just kind of made it all click in my head.
Well then im sorry to tell you but this video is just clickbait
Try "The delayed choice quantum eraser, Debunked" by Sabine Hossenfelder here on YT
She is an actual scientist and will explain why this video is just total nonsense
@@platzpropeller858 I watch Sabine s lot. I've also read Feynman's lectures. I'll go watch Sabine's vid, but it wasn't the quantum eraser that made it click specifically. It was everything prior to that, and how it mixed with previous content from Feynman, mostly. Sabine is great though.
Edit: watched Sabine's vid and funny enough this was my original assumption on how it worked. If he meant it actually "changed the past", I misunderstood and took that as a simplified shorthand. To elaborate on what I got out of this in a quick way, waveform collapse is similar to measuring a single vector out of n vectors that make up the wave. A useful (but inaccurate) way to think of this is as if we measured x vector, but we can understand it was measurable due to n - x vectors making up the wave.
"You can't detect something without messing with it but we found a way to detect it without messing with it"
until we realized that the universe doesn't want to let us win
Because when C or D detect it we don’t know which slit it came through, so yes it was detected but the detection was “erased” by the quantum eraser which unmessed it up
How is this _not_ a glitch in the Matrix.
Because it deliberately let us observe it.
there aren't agents knocking on your door
simulations and programs follow reality I guess, rather than the other way around, since maths is a core property of not just the universe but existence itself...or at least they could...so you've really got to leave your intuitions about living 'in code'
@@jorgepeterbarton not realy
Maths is just the way humans thing.
Dogs and cats dont know of mathmatics nor does a planet or a star yet they existed before humans invented maths...
This is exactly what I was going to write...
gotohell Mathematics is not exclusive to humans. We just define it better. If you put 1 piece of food on one side of a dog and 2 pieces on the other side, which side do you think the dog will choose to go? Even if animals don't realise it, they are doing maths. Maths is just a language used to apply logic. Since logic is a fundamental requirement for self-awareness, it is a core property of the universe. For example Boltzmann brains can spontaneously come into existence purely by entropic chance.
Houseplants can observe us.
Thanks for letting us know.
If you've read "The Day of the Triffids" you already knew this.
I’m glad my prediction turned out to be correct. This is the experiment I had in mind
I'd like to ask a similar question to one that was asked before. Using detectors AB to determine each photon's path results in no interference. You mentioned that this happens even if the photons hit the screen before their entangled twin gets to the detectors. What does the screen look like in that time interval? It should have an interference pattern as the detection is in the future and might as well not happen. But after the detection it will have only the two clusters. Does it change?
It doesn't work that way because the interference pattern you see is from firing single particles over time, Impossible to tell with only one because in reality of the "Interference screen" in real time would show up at 1 dot, you can't see if its a interference pattern or blob with only 1 dot on the screen. In theory lets say one dot didn't show up as a dot and magically showed up as the information of Pattern or Blob, I wonder if it would actually "re-write" time if you could see the screen before the twin reaches the detector and then what the screen says after it actually hits the detector, if it would change. The universe has no business changing the position of particles while your looking, seeing the screen just turns YOU into the detector and oops you collapsed the wave function just by observing it instantaneously, that's what's weird here. It doesn't rewrite time or what happened, with observation collapsing the wave function its impossible, the question you should be asking is, when your not observing are the particles really there or do they just choose to be there when you observe, which ties into these new videos they have about "does consciousness create reality/the universe" so the weird thing is, consciousness/measurement/observation because you can't have measurement without consciousness I consider them all to be the same or alike, if you consider machine measurement to be the offspring/branch of biological/conscious measurement. It was created by it and can only form from it or an observer in our case (us hoomans). So since they are the same they play by the same rules so cameras are like branches of us, forms of measurement discovered/created by us so that's why the universe will still lol "boot in" even when your not there looking and only a machine is, but if its Not a measuring device, who knows if its really there or not. Makes you feel special, if you understand, anyways the key variable in the quantum eraser is the half silvered mirrors, if your Giving each particle the choice of 50% pass or reflect didn't you technically just make another which way "double slit" but in a different way? why not use the special crystals in place of the Half silvered mirrors? Because then it would create two particles from one, the quantum eraser experiment is worthless but the Which way experiment is amazing.
Someone should try the quantum eraser experiment with large distances, and see exactly how far they can go to demonstrate non-locality.
Weston Hettinger makes no difference.. a photon (relatively speaking) only ever appear at their destination instantaneously.. so even the ones that to us have taken millions of years to travel from source to get to us over vast distances .. for the photon this is irrelevant .. relativity! 😉
Donald Piniach .. that’s ok.. it’s just relativity.. as you approach the speed of light (c) time slows down, so imagine if you were actually able to travel at “c” time would effectively reach “0” .. time just stoops.. & stays stopped for you until you reach your destination... but for people living on the surface of earth your journey could have taken millions of years (in earth time)
Here’s a cool video that might help:
th-cam.com/video/AqRQ_93kFKs/w-d-xo.html
@@TimberWolfmanV6 But, I was told you can do this experiment with protons and other non electromagnetic things. If you do it with protons it should not work the same way since you can't send a proton at the speed of light, thusly time moves for them... Very slowly, but still.
@@TimberWolfmanV6 I don't understand why distance will not matter. Speed of light is insignificant on a galactic scale. We just have to dealy the second photon long enough to confirm.. even a few nanoseconds would do.
rupak rokade .. no delay for the photon whether it appears a billion light years from source -or- if it appears only a meter from source .. both from the perspective of the photon are instantaneous regardless of distance.
Suppose I lengthen the path that leads to A,B,C, and D using a pair of fibre optic cables wrapped around the earth 449 times (should be 1 minute to travel at the speed of light).
I arbitrarily switch the paths to C and D on and off. Have I created a system that can send a message 1 minute into the past, by watching for the interference pattern and assigning a 1 or 0 based on whether I see one or not?
But then, if I receive a message like '10101' and one minute later I decide to invert my message and send '010101' instead, haven't I broken causality?
Kevin Laity that's a very good question, I've been wondering the same. any comment from other physics folks round here?
Could you also use entangled pairs as a type of 'switch'? I.e. If the particle hits an area that would normally be in an interference peak, make the switch spin one way to indicate 1, and store that info. If it hits an area that would normally *not* be in a peak (i.e. indicating noise), make the switch spin a different way to indicate 0. Collect all of the responses and see if they match up to the final result on the screen - is it an even amount of 1s and 0s to indicate detection, or does the data show an interference pattern but the screen show noise?
I don't think you would receive "10101" in the first place, because you later changed it to "010101". This experiment should be done though, even if it's a much smaller scale.
entanglement cannot be used to send messages, both particles must be measured first
As far as I know the measurements on the entangled photon have no effect on the pattern. Or else you could have instant FTL communication between two distant locations by placing the light source half way between them. In fact I believe there is no interference pattern overall in this experiment, which can be explained if entanglement is physically equivalent to measurement. The patterns related to 'erasure' at C and D are obtained by looking only at photons corresponding to just C measurements, or just D measurements. You have to have the measurements to know which photons to look at. The sum of these patterns (which is all you have in the absence of that information) is not itself an interference pattern.
Hey PBS Spacetime, I’m curious. I’ve been watching your videos on quantum mechanics and special+general relativity for a while and I had a question that looped me back to this experiment, but the quantum world is absurdly large so I apologize if there are any obvious misunderstandings of it on my part as I ask this question. The question is, could the results of this experiment not be explained by extra temporal dimensions allowing lateral movement through time (relative to our frame of reference of course)?
These lateral temporal paths could create a spread of possible locations for a particle in our particular experience of the flow of time. This could (if I understand properly) also explain why the act of any distinctly “forward” or “backward” moving particle measuring a particle of unknown temporal trajectory causing the wave function to collapse. Much like particle “spin” aligns itself with the measuring device we use, since we would be measuring temporal trajectory with a collection of forward moving particles, the temporal trajectory would align forward in time in a sense causing the wave function to collapse at whatever point the particle was measured. Further, this could help explain why greater mass decreases uncertainty, as it could explain mass as a forward/backward momentum through time. The more massive the object, the more temporal momentum, and that could create inertia that helps prevent lateral movement through time.
I actually have many other things I believe could be explained by this (dark matter could be matter that moves laterally through time by our reference frame as an example, but would be impossible for us to directly see since it would be measured with a forward/backward reference), but I was wondering if this is something that has been explored already and disproven. Or, perhaps I am positing this with such a poor understanding of the concepts that it isn’t particularly worthwhile to ask?
"the quantum world is absurdly large" 👀
So if you were able make that first half mirror turn on or off meaning that we actually changed between measuring which slit it went into or sending the beam into the quantum eraser. Would the screen on the other end instantly switch between showing an interference pattern vs not showing that? Or does the action of switching if we are measuring the beam have some affect on this?
What would happen if you only had detector A (only detect photons of one slit). What happens with the photons going through the other slit (B)? Would they act as if they were detected since you know they were going through slit B because detector A didn't light up or would you see an interference pattern?
Funny story: this is actually what they did. In the original experiment the researchers didn't bother with detector B (or D3 in the paper). However in order to isolate the photons that traveled down any given path you need coincidence electronics connected to both the screen and the detector. That means that, without detector B, photons associated with that path a indistinguishable from any hits on the screen due to background photons or screen detector noise. However if you could somehow eliminate the noise then theoretically any photons not hitting A, C, or D must have traveled down the B path. That's which-way knowledge, so should leave a non-interference pattern.
So... what if you can't eliminate all noise, but you can give noise an upper bound? Say that you know that less than 10% of the photons hitting the screen is noise. Would you gradually get a more non-interference like result as that percentage approaches zero..? Because surely you can make some estimation of this bound under any well controlled circumstance (even though the percentage might come out high if this elimination is hard to achieve)? Basically: wouldn't it be possible to calculate this upper bound even for experiments that *did* show interference patterns? Implying a gradual transition for the observed results? (We have a bound on how many photons we have which-way knowledge for - but we don't know *exactly* which of the photons we have that knowledge on - only a percentage of total photons.) Interesting implication would be that the amount of noise is directly related to what pattern would be observed.
+PBS Space Time how can you rule out the rule of averages in this is you don't do it with one photon in a magnetically isolated vaceum at a time? the effect could be caused from the screen sending information through the entanglement link or just at light speed with photons or magnetic waves?
on the other hand, if the outcome is retroactive, dies that mean it changed from one outcome to another? was it a wave pattern one instant and a blob the next? is it possible that happened because the link transferred existing and inevitable outcome data and not physical information that can be affected by c ?
+monoham1 err i mean to say, or if the result in the screen and the detection in the detectors happened at the same instance is it possible the information went fatter than c?
Thanks for clearing that up (and also for mentioning it again in the latest video :) ). Sounds super weird but also plausible at the same time^^ I always thought in order to collapse the wave function you have to directly observe the photon. But obviously the information about which path it took is enough since that means you no longer have a set of probabilities.
this episode is really good
Great...now I'll need another video to explain this one.
The description is wrong around 6:11 of the video. If one observes a pile of scattered photons on the interference screen without an interference pattern, it means that the detector A or B has already measured one of the entangled photon pair before the interference screen observations.
two particles are having a secret affair
negative particle: meet you on the other side
positive particle: only if no one sees us
physics.stackexchange.com/questions/490828/can-there-be-interference-between-a-proton-and-an-electron
"Perhaps, this thing we call observation is just entanglement between the observer and the experiment."
nope its entanglemnt with the observer,experiment,particle so that means its reverse results of the outcome it validates through the experiment..
You are close. See this talk: th-cam.com/video/dEaecUuEqfc/w-d-xo.html the title "The Quantum Conspiracy: What Popularizers of QM Don't Want You to Know" is purposely ironic, but the talk is serious. Near the end you will see a good explanation. But not entangled with the observer per se, but the experimental setting. No consciousness is required (no Depak Chopra stuff is needed), for that see this article: arxiv.org/abs/1009.2404 "Quantum mechanics needs no consciousness (and the other way around)"
@@agranero6 This talk is made by a guy who is not even a physicist and represents the fringe interpretation of quantum mechanics. It is like Alex Jones talking about quantum mechanics.
@@smrtfasizmu6161I was only concerned with his explanation of the quantum eraser experiment that is clearer and not so "pop resumed" as all pop talks of physics we see. But: 1. As I said the title is a joke. There is no conspiracy and he don't intend that there is one. 2. It is a consensus between Physicists, that conscience is not needed for explaining QM: arxiv.org/abs/1009.2404 (aka von Neuman-Wigner interpretation is bullshit, and the other way around Penrose theory of conciousness too). This is way more than reasonable. 3. What he says is that what he claim is so trivially assumed without noticing that is not usually considered by physicists. 4. There are several articles by "real" physicists describing this idea or variations of it: arxiv.org/abs/1905.09978. arxiv.org/abs/1905.09978
@@smrtfasizmu6161 PS: you can say that any of the 40 or so interpretations that are not the Copenhagen interpretation are fringe interpretations. All my teachers except two never ever discussed any other or allowed discussion in class of any other.
Amazing
Stronger jawed joe jonas explaining science is something i didnt think would happen today
what about time dilation from the point of reference of the photon? moving at the speed of light, a photon must not even feel the effects of time, so an entangled photon being detected should effect the other photon no matter the time, right?
That's an interesting idea I'd like to hear some input on that!
The effect works the same for massive particles, so that doesnt really apply. Besides, even if photons themselves experience no time, they still take time to propagate in our reference frame
Oh man, I just typed my comment and then saw this one! Haha, we're thinking the same thing!! *high five*
I'm a little late on this one. IIRC no observer can move at light speed, so the idea of "from the photon's perspective" doesn't really make sense.
“If you can't explain it to a six year old, you don't understand it yourself.”
- Albert Einstein
"If you're a virgin and you live in your moms basement, you can't be taken seriously".
- Albert Einstein
@Jason Buford that was for him, I tagged a wrong person
“Quantum weirdness dictates that if I cannot find my iPhone it does not exist, unless a relative has moved it - this lead directly to my theory about relative interference”
- Albert Einstein
Jason Buford ..
“My Albert Einstein quote was better than yours Jason Buford”
- Albert Einstein
😆🤣😂
Feynman believed something very similar. That anything could be explained in a simple manner. Then someone (I don't remember who) defied him to explain in a simple manner the spin statistics theorem (that proves that fermions obey the Fermi-Dirac statistics and bosons obey Bose-Einstein statistics). Well after thinking a few days he admitted defeat: there was no simple way to explain the spin statistics theorem in a simple manner.
Thank you
Who said we already didnt...awesomeness!
This tells you that the Universe operates from outside the boundaries of time. Time is something that exists only for us, not for the "place" from which the laws of physics are emerging. Time exists for us because we are subjected to the laws of physics, but the laws of physics are not subjected to the laws of physics so they are not bound by time the way we are. That is why information can go apparently backwards and forward in time, because it is not subjected to time, but creates the time effect for us, it does not obey time, it generates time.
lol no
Exude
lol yes
The study of physics defines itself as looking for timeless agents, since those are the ones with predictive power...no need for experiments to "tell us" that one :P
"Time exists for us because we are subjected to the laws of physics"
Umm...? Time exists for us because the information we receive is not identical with the information driving the actions of the world
(i.e. precisely because our minds are "subjected to" something other than the laws of physics...however that works)
WOW, dude that's some heavy shit, man I gotta sit back and think about that one :/
blob darkass When a tree falls in the forest and there's no one around, does it make any noise ?
Man: "guys i figured out how to work around the observational collapse of a wave!"
Universe: "Hold my beer..."
So what if the detectors are one light hour away from the slits. And they are not even attached. The person operating them will attach them or not - depending on his/her mood. What are we going to see on the screen through this hour? Will the image change after the remote person's action or decision? If so, how much time it will take?
This is exactly what I wanted to know too. It just made me feel that the experiment results as given by this and other similar videos are not entirely true. So far we are only seeing videos and explanations from third parties. Where is the video of the actual original experiment? Why are they not available?
@@boontecklee592 How do they win the Nobel price without something to convince people, that's weird. I agreed with you. All these video only true in a particular case.
By now it is apparent that this episode is not quite right.
The splitters registering at A and B only destroy the interference pattern.
Those at C and D also destroy it. For each (C or D) you only get half a pattern.
When you combine these patterns for C and D you get the patterns for A and B.
Therefore the arguement of going back in time / re-writing the past is not made out.
This is shown by Sabine Hossenfelder in one of her TH-cam videos.
Sean Carroll also makes reference to this point.
A similar arguement is also made in Jim Baggott’s Book ‘The Quantum Story’ chapter 33.
It may be worth doing an update for this episode (assuming not done already).
Love this channel so much ❤❤❤❤❤
I want to be quantum erased
Looks like a good euphimism for a swear word
😂😂😂
I know right.
have you heard of quantum suicide?
I know a guy. Message me if youre interested.
This was most mind blowing video about Quantum retro casuality that I have ever seen by far.👍👍
Two thoughts today. 1) I wish my mom was still alive so I could share this stuff with her. She'd love it. 2) If a particle is just a wobble in its field, some mixture of pilot wave theory and the Copenhagen interpretation is easier to intuit. The wave isn't propagating through time - it just _is_. Time is just another dimension, after all. What the 'measurement' does is tap the wave-function so that it bursts all at once like a bubble. What looks like causality propagating through time is an illusion caused by our perception of time. It's no weirder for the collapse to propagate backward in time than it is for it to propagate sideways in space. I don't know if I'm explaining it very well, but it makes more sense to me now than it did 6 years ago when I watched this the first time.
This gives a rather fascinating idea of the potential nature of the Ultimate Creator of at least our own Universe. We could conceived that potentially there is some Being at the End of Time, Who simply "looks back," and in so doing, essentially writes what we consider to be History. That Being collapses the wave function of all of existence since the beginning of the Great Expansion, simply by being there to observe the final moment of what we consider to be Space-Time.
doesn't that just prove special relativity? I mean, the entangled pair, moving at the speed of light, experience zero time, so that when one behaves as a particle and then the other does as well, they are not changing retroactively because no time as passed for them, only us.
I agree. I’ve been thinking about this stuff for a long time. I think were onto something. The particles almost certainly experience zero time in my opinion it’s the most logical conclusion.
first time ive read this explanation for it, and i gotta say that makes a ton of sense. surprised more people havent talked about this
This is invalid afaik, as even though they are not evolved in time, the distance between them has increased. If you and your friend are imitating each other and suddenly you both are accelerated at the speed of light in opposite direction and are taken far away from each other, you will have no idea you are travelling or anything has changed, but the moment we stop you from your point of view you friend will no longer be able to imitate you, So there is no way your solution *completely* solves the problem. Again this is only my understanding and I can be wrong.
And again electrons also exhibit this property and they are not going at the speed of light.
If somebody can explain this....
The observation thing is still confusing for me. Is it our knowledge about the observation that decides the outcome? If so then what if, in this experiment, the outcomes on these detectors are observed by some conscious person who don't know what to interpret form it. Will the path information be considered as known or unknown. How the result might come in this case. Please clear this doubt.
Why did the photon cross the slit?
Ar Con to get to every side.
To figure out every path possible and choose it?
To exhibit dual nature
To WAVE from the other side , LOL
To bounce one wave and make it's dual nature.
I would be interested to know what pattern we get at the positions the detectors are placed in. So what happens if we switch the detectors to screens. Do we get an interference pattern at C and D but not on A and B??🤔
I wonder if we could build a system that delays the "observation" of the photon long enough to see either the interference pattern or particle interaction and then attempt to measure the path of the particle/wave based upon whether we saw an interference pattern. Essentially bounce a particle around for a few milliseconds inside a system that we cannot measure the path, then once we observe the type of pattern on the screen we observe the path of the particle or choose to not observe the path of the particle by making it pass through something that loses the possibility of determining the path.
Best show ever
Glitch in the matrix
Levi Smith look up ancestor experiments 😂😂
*acenstor simulations
not a glitch - a feature!
Whoa.
I was thinking, the same experimenters did delaying the detector landing after the pattern detection. What happens if we reversed it?
I did know that real particles will know if time is reversed, thus the clock gets broken. The symmetry ensures that the information is carried back in time, through virtual patticles. Another idea is that the observer is using rougher technique for detection while light remains smaller than it.
nice video bro
It's almost like we are experiencing time in reverse.
incredible revelation. how came you to it?
I've wondered that..
if we are *all* Benjamin Buttons... The reason we all think it's "normal" is because we are all experiencing the same thing..
Good thought. Time can travel in many directions. Humans presume it is linear and in one direction.
Nice idea.
The big bang has a singularity expanding out and an observable horizon.
A black hole also has an event horizon collapsing into a singularity.
At the event horizon of a black hole time stops and beyond the horizon time goes backwards. Hypothetically, falling into the singularity in reverse time would appear like a big bang.
The measurement Problem = Double slit delayed choice quantum eraser experiment. It would appear that an event in the future affects an event in the past .
In reverse time = the past is the future correct
I don't understand, and this isn't gonna help me finish my English homework
Actually, when you're not looking, it finishes your homework.
Try to understand this subject is way better than ur English homework tho :)
Bandrewson P look into the actual double slit experiment
Bandrewson P English is descriptive so......... Describe how to understand Maths to yourself. Confuse the TA. One can get away. ......... OK
An ion is structure; 1
An axon is potential energy; 2
A chaon is interaction; 3
An elementon is representation; 5
The basic formulas look like this:
*1+2=3
*2+3=5
*5-3=2
*3-2=1
Really wish I could ask a question on this, what would happen if the eraser was AFTER you seeing what happened on the screen? If it was chosen at random to either observe or not observe but only after you have seen what happened on the screen. Would this mean you could see if it was going to be detected or not ahead of time based on if you got interference or not?
As soon as you see what happens on the screen you've observed it, your question is a paradox with no answer
This has been on my mind every cents I seen it. Weird stuff.