it helps to look at the photon from einsteins perspective. for the photon itself there is no time passing. the entire path was taken in one moment. the photons moment is projected into the world we experience as a line. but from the perspective of the photon there is no before or after in relation to points on the photons way. the entire way is one single moment for the photon. so the 2nd beam spliter is either present in the moment or not. what we experience as paradox can be simply explained by the relativity of simultaneity
No, the photon is just data. It doesn't go two ways, things can't be in two places at once. It's not measured, why waste resources computing it when noone needs the data to render their reality. For "delayed" experiments the same applies.. it was never physically there, only potentially hence the "wave" behaviour. If the data is available in a double slit type detector storage, you get particle behaviour. The behaviour is determined at the measurement stage, there is nothing going back in time. Also, particles don't communicate anything. The underlying system manages them, and they can be in pairs "entangled" as a single thing.. super simple, nothing needs to be communicated. When we measure one thing, the other bit is automatically set.. because we entangled them😉
The second experiment (the "Delayed Choice"), does not necessarily show communication backwards in time either. It shows the same as the first experiment: there is some form of coordination that happens instantaneously. In the Delayed Choice experiment, the photon always takes both paths, also when there is no beam splitter in place. It is just that all the other possible paths disappear instantaneously when the photon is detected. That is the "normal" QM quirk, called the measurement problem. Measuring a photons collapses all possible outcomes into a single one.
But what if those entangled entities are far away enough that the influence dark energy has leaves them traveling at relativistic speeds away from each other? Would that imply time travel? That entanglement would ignore time and space to reach that instant communication. What is considered time travel anyways?
I remember when you questioned how we'd feel about you touching on topics other than planets outside of earth yet in our solar system. I'm happy to see you expanding your options for content
This was SUCH an incredible video. Really appreciate you explaining some of the basic principles around quantum physics and entanglement. Before watching this video, I didn't realize that I had the "classical" understanding of quantum physics, and you allowed me to understand things just a little more deeply. As a complete layperson who finds himself fascinated with trying to learn more about this field, that means everything to me. Thank you :)
I love that you have branched into incorporating theoretical physics and quantum topics. Huge fan of everything you put out, thanks for teaching me so much🤙
If time stops at the speed of light, it’s not really time travel. From the light’s perspective, it just goes backward and forward in time equally. It’s only us non-light-speed travelers who marvel at photons going back and forth in the timeline. For the photon, it’s just a day at the office.
Sabine Hossenfelder made a video sometime in the recent past where she explained why the delayed choice experiment is not sending information back in time.
I saw PBS Space Time's take on this subject, they also explain why it doesn't send information back in time, but that alone doesn't debunk a local causality breakdown! Same as entangled particles are effectively causally connected but it's impossible to send information via the connection.
Huygens Optics has a series about light. He explains his take on how it works (It takes hours of videos for him to fully explain though), and for my knowledge it holds up decently well.
In the delayed choice experiment, the first beam splitter creates two probable paths for the photon quanta to take with the second beam splitter allowing the two probabilistic photons to interfere with its probabilistic wave before being detected as an interference pattern. If you remove the second beam splitter the photon quanta still travels down both paths with oscillating probabilistic wave; whichever detector that is activated is the photon quanta that had the highest probabilistic wave at the time. So if you add the second beam splitter after the photon quanta passed the first beam splitter there is still two probabilistic paths that the photon quanta is taking allowing it to interfere with itself. This doesn't need backward time travel to explain it.
You talk about "probabilistic waves" as though they are physical entities that propagate through space and time. They aren't. You're really just using the wrong words to assert that light is a wave.
16:22 It is generally understood (perhaps erroneously, perhaps not) that a photon does not experience the passage of time. This implies that a photon must be everywhere at once. That is to say, in this quantum physics experiment, the photon exists on all points on the device at the same time, making up its properties on the spot whenever asked by an observer, and the only thing actually being measured is the "light" that the photon generates, not the actual photon. This is important. If the photon is asked about its specific properties as a "particle," then it behaves like a particle, until it is no longer being observed (for instance, the measurement has ended). So, if this is true, and the photon is actually in all points in some kind of quantum state across the entire device all at the same time, and you try to trick that photon by adding a new light splitter while the photon is already on both sides of that splitter (but before the photon's light is visible at that spot), then, yes, I would say the photon has adequate reason to behave strangely under these conditions. I would further go on to say, no, the photon does not send information to the past. The photon, if it actually IS already on every single point on the detector, would instantly know that a 2nd splitter has been inserted, and would change the properties of its "light" accordingly. We need to start asking bigger questions, like, are we actually measuring the photon, and do we actually even understand the photon, or are we just looking at the tip of the iceberg (the light of the photon)? Or I might be crazy.
I don't see why people think is it a sign a supreme intelligence to explain the most advanced & complicated topics to only a few other humans that end up understanding what was said.
@@MR-nl8xrWhat are you talking about...? The adage is that one fully understands something if they can break it down so much even the uneducated can understand -- not that said person has "supreme intelligence". Which still makes me question, what are you talking about? You don't understand the correlation or...?
The way you described information travelling back to the first splitter reminds me of the time travel premise in the Primer movie. The box has to be turned on in order to travel back to the moment it was turned on.
the thing that comes to my head is we need to keep in mind that the "time" that we observe works the way we feel only for us, there are relativistic effects happening, like in the twin paradox or lifespan of particles - generally we know that if we go very very fast, a long travel would feel for us like a short one, cause space looks like it shortens a lot (but only for us, not for a stationary observer) - so technically when something moves exactly at the speed of light, the path shortens to infinitely small (zero?) and time taken for the travel does too, so... what if for us the photon took for example 1 nanosecond to travel through the detectors etc, but for the photon everything happened at once, so there was no "time" to "know" that we add or remove detectors - for us it seems like we interact with the photon but from its pov it all happened in one plank's time length, so it "knew" how and if to split or not because it's like it saw the whole situation not like a movie as we observe it, but as A SINGLE FRAME ;o the life we know can't exist without time but if photons can, we have a new phenomenom to understand
Thumbs up. That is what I think is happening too. The scary thing about is a "time domain" to live in. A photon travelling milions of years (how come it does not attenuate to zero) still thinks it traveled no time. What if we pass that logic on us? We are here for some time, but in different time domain, it is just almost immeasurable blink of an eye... From the photons perspective, everything happens at once. All the universe history. Just BAM!
If time and distance doesn't really exist from the perspective of light, then from the perspective of light, everything would be infinitely densely packed. Similar to the early conditions of the big bang. Perhaps, for light, not much has changed since the big bang. If everything was infinitely close together from you're perspective, you'd never be able to notice inflation (the expansion). And it's not just light but anything that doesn't have mass. So when you don't have mass, time and space doesn't exist. And when something has mass, time and space exists. Perhaps the common denominator that produces the effect of time and space, is mass and the stuff resposible for it.
so you oversimplified the DCQE experiment (because it's too complicated to explain in a video that also covers Bell's Inequality/EPR) to the point that refuting acausal information is impossible. But the answer is no: information does not go backwards in time. What you showed is more like the Elitzur-Vaidman bomb-tester experiment, which is weird--the experiment that is.
it's not to overcomplicated to explain. it's pretty simple. if you're trying to measure how much water is in a cup and you're using a sponge with a ruler drawn on it you're going to ruin your measurement aren't you? same deal here. The double slit experiment is flawed because it relies on light detection. so if you draw a ruler on a sponge and dip it into a cup of water it's going to suck up some of the water and ruin your measurement isn't it? same deal here. everybody acts extremely impressed with the double slit experiment but they don't understand it well enough to realize why it's stupid and wrong. it's really simple. you cannot use a sponge as a ruler to take a measurement of water. you cannot use a photon detector to take a measurement of light. lol. because the detector absorbs some of the light you are trying to measure and ruins your measurement. it's that simple.
Re. the double 50-50 experiment: have scientists tried starting the experiment with two of those 50-50 mirrors, but remove the second mirror after the photon has entered / begun?
Yes, kind of. The physical device wasn't completely removed of the way, but they used a material which when exposed to electric current can change its property from reflective to transparent. So it can be seen as an ultra fast light valve to interrupt light or not. Then they also extended the length between the beginning and the end of the experiment by making the beam of light travel multiple back and forth in zigzag in order to be sure that the light would take more time to travel this lengthy path than the electric device to take to active itself.
14:52 - 15:04 so 1 photon was fired and both detectors detected a photon simultaneously. how is this possible? did the photon double itself? did we just create more energy? or is he saying that in both versions only 1 detector detects it at a time. but when the 2nd beam splitter is there the detectors end up making an interference pattern and when the 2nd beam splitter is not there, there is no interference pattern.
@@hoochygucci9432 Yeah, I'm pretty sure Einstein was correct. Bell presents a strong argument, but the test is so difficult to replicate and so prone to error it's a little hard to believe. It makes more since that the particles properties where predetermined on collision rather than undetermined until observed. But until more reseach is done, I certainly would not say Einstein was incorrect.
@@SirSithly I wouldn’t worry; there’s no benefit in understanding this nonsense. Whether these mathematicians are ‘correct’ about our cosmological beginnings or not; their concepts are obviously destructive; why the so-called ‘wise’ ones revert to trying to understand reality purely through numbers is a mystery that ends in disaster; but I suppose its profitable for nihilistic consumerism.
It’s all fantasy; concepts and interpretations of autistic minds; just look at your society; is it functional because its enlightened by modern physics elaborate philosophical enquiry or is it functioning because its zombified by an endless mindbending cosmology of everchanging non-comprehensible gibberish?
Thank you so much. Your presentations of Bell's inequality and of the delayed choice experiment are outstanding. I have just learned something fundamental about the strange world we live in.
That would mean the information still persists until it hits the detector, and interacting with that information will cause it to collapse. This makes more sense if the wave and particle are separate like pilot wave theory suggests. Then you have waves radiating away from the point particle in all directions, interacting with that wave anywhere along the path before it hits the detector would change the behavior of the particle. It would also allow a single particle to interfere with itself through a double slit.
When I first started studying QM my reaction was "what's going on? this doesn't make any sense" but now it's been 10 years and my reaction is "What's going on? this doesn't make any sense"
I'm really starting to like the idea that particles are activated and deactivated. Meaning that particles themselves don't actually travel but transfer their energy to an inactive particle in an assembly line like fashion, as one particle is activated the previous particle is deactivated and we can only detect the particles while they're active with energy. Using this logic could explain why light looks like a wave to us at certain times and a particle at other times, the wave is the energy activating the particles around it and the particle itself is what interacts with us.
Well aren't all of reality and particles themselves just the interaction of feilds? If the feilds are everywhere then instantaneous communication doesn't seem so strange after all. Kind of like a Newton's cradle going in all directions. One ball smacks another but only the one at the other end moves. All of these seemingly distant particles were connected all along.
As usual, I still have no more understanding of Quantaum Physics, thanks to my tiny feeble brain. But, thank you for presenting another incredible video that was entertaining and fun to watch, regardless !
It's not your brain that's the problem. It's the sorry attempt to take physical observations with no formalized (mathematical) representation and hack them into a metaphysical postulate. We don't know what the hell particles do at the quantum level; we can't observe them in the same way we observe macroscopic objects. But even worse, a lot of these weirdo behaviors don't even have a formal mathematical model even in quantum physics, so interpretations are ridiculously ad hoc.
It's truly incredible that the wave pattern observed in the double slit experiment is due to the interference of the probability of which slit the particle will pass through. Probability interferes with itself creating a wave pattern.
Probability is not physical. It is a process that describes something physical. Nature makes patterns and we can assign numbers and probabilities to those patterns. That doesn't mean it is the probabilities that interfere.
@@wesjohnson6833 Perhaps technically true, but it's easy to snipe at "probability" as not accurate, a lot harder to say what is accurate. Let's hear it man, tell them what you think IS causing the interference so we can use the right terminology according to Wes
Point a to b. what happens is a probability wave trees to point b as a wave. When measured at b. The wave is broken and it becomes real. Absolutely mind blowing! Love the stuff!
After watching this a second time, I suspect that what's going on in the delayed choice experiment is that the photon is *_always_* going down both paths, but if the second beam splitter is not inserted to recombine the wave, then it can't hit both detectors and "pretends" that it took just one path by only being detected at one or the other!
This would be the Many Worlds Interpretation - branching worlds "decohere" when no longer in "superposition" and can no longer interact. The Copenhagen Interpretation says the wave "collapses" and the other possibilities disappear. And then there is the Relational Interpretation - past and future resonate to produce the present. I find talking about only one of those (and not by name) an incredibly strange choice.
They create the entangled particles rather than measuring if they are entangled. Once you make a measurement on them you break the entanglement. So you can't first determine if they are entangled and then go ahead an make a measurement. It sounds a bit chicken-and-egg, but you create the entangled pairs and perform measurements to make sure that the process you use does actually create entangled pairs. Then you use that same process in your other experiments and assume they are entangled.
According to our current understanding of physics, the transmission of information backward in time is not supported by any known physical laws. The concept of information traveling backward in time raises significant paradoxes and contradictions, such as the famous "grandfather paradox" where one could potentially alter the past in a way that prevents one's own existence. In classical physics and in our everyday experience, causality flows forward in time, meaning events in the past influence events in the future, not the other way around. While some theoretical physics concepts like closed time-like curves or wormholes have been proposed as potential mechanisms for time travel, they remain speculative and highly theoretical, lacking empirical evidence or practical application. Thus, as of our current understanding, information traveling backward in time remains purely hypothetical and is not supported by the principles of modern physics.
It doesn't have to choose between taking one path or both paths, right? The photon is always in a superposition of taking both paths no matter what you do before or after it passes the first beam splitter. However, once it arrives at the detectors, the superposition collapses (or expands to encompass the detectors and you as well) so that only one detector detects a photon I don't see the difference to the double slit experiment, there the photon also only hits one spot on the detection screen despite taking multiple paths beforehand
You are correct. The way the experiment is set up in this video, the delayed choice is just a red herring and irrelevant. It becomes more interesting when you use entangled pairs of photons, but even then it is just a mix of superposition and entanglement although these experiments (delayed choice quantum eraser, for instance) seem on the surface like something else is going on.
@I don't know... We’re not astrophysicists, so we don’t know quite how accurate these explanations for the layman are. I’m sure they are simplified so we can grasp them. One thing I notice is that theories are changing and developing quite often. Anyway, I’m very grateful for Alex for explaining the current theories in a way I can just about understand and in an entertaining and visually engaging way too, so if you think you know better and can produce an equally high-quality video, let’s see it.
Thank you kindly for having non-adsense at/near the very front/back/both of video, rather than interrupting like TV once the flow has set in. It suggests mutual consideration for the creator/viewership relationship :>
Very interesting. I cant say that I have a great grasp of quantum physics but from the small part I do know and from videos I have watched, its all fascinating. I really think that we are missing quite a lot here. The universe is such a beautiful crazy place.
Now when I first heard of the delayed choice experiment, it had a much more, "Spooky action at a distance" affect. I don't remember all of the details as to how the experiment was constructed, however the jist of it was that the "observer" would not get any information until after the photon had reached the screen at the end. If I remember correctly, they may have created an entangled pair of photons at the start. The result was that the implication of the photon going back in time to inform itself that, "IT'S A TRAP"!!, seemed much more apparent. Either way, excellent topic and video. Thank you for sharing.
How can you insert emove a beam splitter faster than the light traveling between? I accept the results but don't understand how exactly this experiment is conducted. Perhaps a video on that would be helpful?
I think there are other beam splitters and paths such that there's a 50% chance that the photon will go through the final beam splitter and a 50% chance that it won't But I'm not quite sure
@@Astromath They can use a crystal whose properties change with an electric current and then then use the current to make it a mirror/non-mirror or splitter/non-splitter. They have made it truly random though. This experiment has been done with a number of combinations of mirrors and splitters though and with entangled photons where they use more splitters.
I think the beam splitter is acting like a double-slit. Think of it. In splitting the beam, it makes the wavefunction go to both detectors, causing an interference pattern.
When I was first presented with your three detector positions for the two particles I thought they were arranged on a plane. But I think in order for the other two detectors to still have a 50% chance of each result, they would all have to be at 90 degree angles to each other, as in oriented along the X, Y, and Z axes, respectively. (Otherwise, if they were at something like 120 degrees or just any old random coplanar orientations, I would not expect a 50/50 chance for the other two detectors to get each result after the first particle was "measured".) I'm not sure if I missed you saying that this was the case, or if you did not say it (perhaps assuming it wasn't important or that we'd figure it out on our own), or if I'm simply wrong and *any* difference in detector orientation resets the probability to 50% (which does not seem like it fits with what I know about QM, especially considering how polarization works, etc, and also, how precisely aligned would the detectors then have to be in order to be "sufficiently aligned" to get the "spooky" entangled opposite result? Therefore I doubt I've got this wrong, at least).
But this shows why the mathematics is in error as the parallel postulate is false - the classical analyse with out the parallel postulate gives the same result as QM.
This makes me think we're going to find out that the universe exists in all moments at once, that everything we see sequentially in time is a perception we are bound by.
Biological life forms perceive time as linear to prevent them from going insane perceiving simultaneously the past, present, potential. From a higher perspective there is no time, only the infinite now of all potentials. It is only modern Scientists that are ignorant of the esoteric knowledge of us mystics.
It seems so. It would be interesting to know if the answers are not in the infinitely big but in the infinitely small. We already know that we can zoom in way more than we can zoom out. And what determine the other particles beside light to be entangled with each others? It's very interesting to imagine.
Either everything exists all at once, or time doesn't exist at all (outside of our brains' perception of reality anyway), there's only the present moment and motion
My guess is that light is indeed always a wave. When "light" is created, a connection between its two points is made instantly, in zero time. Light exists between the two points as a wave, but in the case where it acts like a particle, it's simply a concentration of that wave. It oscillates (probabilistically) from point A to point B that is already established, and acts like a tsunami in its concentration until it gets reflected back. Do that, and the tsunami stops, and dissipates along the return path. It is the observer that sees the concentration along the way, thus the "speed of light" is a constant no matter how fast you travel. I am guessing that light is actually using what we call "dark matter" as the quantum pathway to set a connection and then follow a two-dimensional path. And that's why it bends; its path is a straight line, even if it's shifted in spacetime. It doesn't go "back" in time, but the path is set instantly; it's the only way it could "turn around". It's like one good snap on a rope; that's the photon. But snap the rope from the reverse (reflection), and the tall wave ceases and it goes back to its more chaotic lower excitement.
I've had personal experience with "information" being passed back in time without any paradox on multiple occasions. Several times in my life I've experienced strong phantom pain in areas of my body that would months later have a reason to feel like that. The First Time it happened my wrist suddenly spasmed in pain for a few days then about 3 weeks later I broke that wrist in a BMX stunt gone wrong. The last time it happened was the scariest as it resulted in hospitalization and overnight observation with severe chest pain and sharp pains to my inner left groin. Was released clear of heart complications with doctors baffled as to the cause of my chest pain, something that was repeated later down the track. Cue Xmas day and an electric RC car cable of reaching 70km/hr with Broken front suspension and steering. Being unaware of the previously mentioned problems I attempted a manoeuvre that was meant to be driving from the middle of a park to the gravel road Infront of us that was meant to be a slide turn into a donut on the gravel. Instead it plowed into my left ankle tearing my groin in the process flipping me in the air landing on my left side breaking 4 ribs, my hip and crushed the bursa in my shoulder. 2 of the rib breaks were displaced fractures of the 4th & 5th ribs fraction of a millimetre from the bone cartilage join, to close for a normal see. Come to think of it most of the Temporally Referred Pain (TPR) I've suffered from seems to be self inflicted.
For that matter, premonitions and seeing things in dreams before they happen are real for me. I try not to think about it because it bothers me> I don't understand or like it. But it is what it is. There are more things in heaven and Earth than are dreamt of in our philosophies.
In other words, if you can control which way the particle spins, you can communicate faster than the speed of light, assuming the other particle is where you want to communicate to. Because it inherently knows what the other particle is doing, all you have to do is change to rotation back and forth in Morse code. I imagine in the future, submarines will use quantum Morse code to communicate. Furthermore, I can’t imagine that you could intercept a quantum message like that making it even more valuable.
I think binary would be a more efficient codification, but it does seem to suggest that. I believe quantum computers harness this entanglement from a different but similar property.
The problem is that you can't do that. When you setup you system and entangle the particles you don't yet know what message you want to send, so you make them in a superposed state where you don't know their spin yet. But then later you can't change that once the particules are separated without breaking the entanglement, the only thing you can do is measure that spin. You know that the other people at the end of your quantum phone will get the exact same result as you, but the message is still random (or what ever you defined at first when preparing the entanglement). This has other possible applications, but not communication.
Alex, you are GOLD. Such high quality voice, presentation, script, delivery and visuals. You should be on mainstream TV, your show would make you a very wealthy man indeed - or perhaps you already are?!.. You are a gift to us, and by far one of the best channels covering and explaining these complex subjects for people with basic to intermediate knowledge. Thank you man.
@@zack_120 No worries fella, I'm just pawing with you. I love Alex's channel, just think he should be doing really well and getting his content to more people. Money doesn't mean anything to me, I love to live simple, and spend time learning about life & the universe. Peace bro. X
My brain was fighting to keep up with all the information near the end of the video only to get thrown off by the burrito at 17:50. Something about time traveling, cool video 👍
what you're saying is... quantum entangled waves represent the function or method, showing possibilities, until the output is requested. So we're in a simulation.
Great video explaining those experiments. I have a question. How the heck did they add a beam splitter after the photon was sent? That's some faaast sleight of hand! :-)
Extremely fascinating! From another of my topics of great interest, I draw a parallel. Virtually all those who have experienced a near death experience (NDE) (and let's just take the hundreds that can be documented as having truly died and then verified information they could not possibly have sensed during their deaths - like detailed events outside the operating theatre) indicate that time and space are illusions and that this 3D world we "live in" is itself, an illusion. They all insist that this world serves as a sort of simplified stage on which we play a role for a short time in order to learn. When you think about it, learning can only happen when there are consequences, and these can only be experienced in a realm with time. If these NDE'ers are right, then our detection of sub-atomic particles is nothing more than us detecting bits whose real nature is beyond our own limited 3 dimensions and time. Much like a 2D person from flatland (in Abbott's great analogy), when encountering a 3D sphere passing through his world, see a dot becoming a circle, growing, then shrinking to a dot and then disappearing and thinking it utterly amazing. The only reason we think it strange when subatomic particles seem to be independent of time or space is that we are constrained to our 3 dimensions and time. We know only that world. But I have a hunch there is much more... If only science would borrow from other areas of study instead of focussing on their own siloed topics and methods. NDEs are now so well documented that they are the becoming the popular study material of numerous doctors and philosophers - something untouchable a mere 20-30 years ago.
"If only science would borrow from other areas of study instead of focussing on their own siloed topics and methods", Yeah, it took humanity thousands of years to develop objective scientific methods, lets now go back to mysticism, metaphysics and other unscientific garbage lol. What I am curious is, there are plenty of youtube channels, TVs and streaming services focusing on this gobbledygook, why not stay there ? Why bring these pseudo-scientific nonsense to channels which try to stay scientific ?
What explains this is measurement. With the first splitter you’re collapsing the wave function, with the second (if angle of impact is complementary) the light is returned to “close to its original (unaltered) state” which is “wave” A filter, or observer, is merely the elimination of redundant or meaningless and even sometimes contradictory information (like opposing waves that cancel each other out)
To answer your final question, I would think the second detector ends up being much much larger than it seems and the "small" movement to activate the second detector is in fact a much larger movement, so large in fact that it makes the particle appear to go back in time. The mis-perceptoin occurs due to our instinct regard "when" a choice was made to close the gap. This choice seems made by a random way or computer and is thus too small to perceive thus we think it is going backwards but the particle is still "inside" the detector. Or "outside" depending on how big you think it is. It is bigger.
In the past humans have often believed our sight was a sense that threw a mold over the world and allowed us to perceive it, like something invisible until you throw paint on it, revealing its location. It'd be interesting to know for certain that theres truly no offect in us looking at a particle
I can imagine how the world would appear differently if we had more than 5 senses. If we had a sense that can detect the radio waves? Or anything else that is invisible to us. It would appear very differently.
I think of it like flipping a coin into the air. While the coin is spinning, it’s kind of like heads and tails a the same time, until you catch it in your hand, then the wave function has collapsed and it’s heads or tails
"It'd be interesting to know for certain that theres truly no offect in us looking at a particle" On such small scales, any type of detection would be an interaction. Every observation has effect. Or, as Futurama put it: "No fair! You changed the outcome by measuring it!" This has nothing to do with the mystical influence of consciousness over the universe, though.
Particles are conscious on all frequencies Time is a spectrum, quite like light….it’s just that within our reality, certain spectra can’t be accessed/observed. Infrared or ultraviolet on the light spectrum and only the time spectra of the present can be accessed. Every program has its limits 🤷🏽♀️
if they are making it up on the spot then by rechecking the particles repeatedly you should get different results with each check. you can't ignore exceptions as they are still results.
@@squishy-tomato if they are only uncertain for just the first measurement then they are predetermined and aren't random at all. That would mean it was always the same before being observed. If it is uncertain when unobserved you would get different results with every observation. so say they were up up each time you observe them then they are always up up. if they are uncertain till observed then you will get results such as left right or down down. If they are locked in once observed then they aren't uncertain. you have no way to prove or disprove and there fore the theory can't be tested. At that point it is best to assume they are certain because you have no way to prove either way. how ever if the test comes up where they aren't fixed then you can say they are uncertain till viewed because they aren't locked.
@@squishy-tomato how can you test that they are uncertain? if you can't test a theory then it is best to assume the theory is incorrect until you can test it. I can say that it is uncertain the earth will rotate until I see the sun again and then it's locked in after that point. it was rotating prior to that but that could be tested. now to say something is one way without being able to test it and then saying that it is permanently that way only because you tested isn't science. science is being able to prove that it wasn't that was before testing it and then the testing backing up what you say. otherwise you are just making things up and saying prove me wrong.
What if observing a particle doesn't create it, but summons a predefined one that exists outside of time... or on the 4th dimension. Much like a circle will pop in and out of a 2d world when a 3d sphere passes through it, a certain version of the particle shows up when it's 'observed', making it seem like it was decided on the spot, when in fact it already existed outside the 3d plane, but it just had no reason to appear. Idk just guessing.
The backwards time aspect on the second experiment might be due to the photon traveling at the speed of light, maybe that one theory of photons existing for the entirety of their path is true, so something altering the previous section of their path could affect future travel across that path, since it's still within the timeframe of the photon's existence.
In the first experiment, I don't get where the 55% came from. That would be only expected if we hadn't omitted same-direction measurements. If we don't measure from the same detector, according to the table at 10:24, we get 2/3 chance for the same spin, and 1/3 chance for different spins. But even then, the table doesn't account for all combinations of spins -- if a particle has spin up/up/up or down/down/down, there's 100% chance that the second particle will have different spin in either direction. And such particles would make a total of 1/4 of measured particles (2 out of 8 possible spin combinations). When we add 1/3 of the remaining 75% of particles, where the table applies, we get a total of exactly 50% chance to measure different spins. Correct me if I'm wrong.
I don't get how omitting same-direction measurements would result in 55%. Regarding the tables, one gets 50% by not omitting, while getting 1/3 to 2/3 ratio with emitting. Also a single particle only has one angle of polarization, and can only be measured at one detector, while the other particle gets measured elsewhere. I do not know where he gets the 55% from either, he maybe just chose some random number as an example. I get 50% using classical physics. If detector 1 measures up (facing 90°), the particle measured could have had any polarization angle in beween 0° and 180°. intersecting that half circle with the half circle of another detector, they intersect in 1/3 of their arch, giving the particle a 1/3 chance to be measured the same and 2/3 of being measured the other way. Adding same-detector direction pairs, one arrives at 50% using classical physics.
There was a young lady named Bright, Whose speed was much faster than light. She set out one day, In a relative way, And arrived on the previous night.
Bell's work has additional underlying assumptions, like statistical independence of certain aspects of the events. Those assumptions could be violated instead of locality.
I'm not well versed on this science, but to me it seam that being the detectors are arranged in this way would cause them to not function properly because the triangulation attempts to detect to the position being it is able to be 360degrees infinite it would be detected randomly in the opposite direction at 50 percent split to the other aposing detectors, which leans me on believing that there is a flow of force attracted to the detectors in a attractive way and rather perfect detection how does the detector make its voltage?
5 years ago I was working at Caterpillar in NC. I looked at the "accidents since" board: It said 122, but I saw: "288" then it was only 122. I told my manager; he wrote it down. We all forgot about it. Then months later I saw "accidents since" board report ZERO. Caterpillar was entirely focused on how this accident happened and took everyone on a tour of how an employee broke her arm in the parking lot on that day: Day 288. My boss was scared of me and everyone else after that. I get lots of these premonition. The woman was walking in the back lot - there was a 1mm crack on the road: Her shoe grabbed the leveled crack and throw her on the parking lot. They then trained us all on how to avoid us from falling down if you foot hits a 1mm crack in the floor! Gulf War Vet: 1990-1991.
Yes, time travels in both directions at same time. Take a key ring with key on it. Put another key in, but before continue put key already on ring in also. Then complete. One goes on and one comes off, yet both traveled exact same path in the exact same way. Phone signals internet, electric power lines, tire pushes against road, road pushes back. Energy flows both ways.
When I first heard of this family of delayed choice experiments, and the apparent implications for time, I was quite worried it appeared obvious to me that particles aren't travelling backwards in time and only something like super-determinism would make sense of this apparent time travel. Fortunately it turns out that there *are* quantum physicists who "clearly do understand what is happening here", and I would strongly recommend @SabineHossenfelder 's video "The Delayed Choice Quantum Eraser, Debunked" for anyone who wants to get their head around the subtlety of what's going on.
I remember hearing that photons don't experience time. Not in the sense of having the ability to perceive, but in the sense that emission and absorption of the photon happen simultaneously when you look at them in the photon's frame of reference. So, for it, there is no future or past, only the instant present. If you look at this experiment from this perspective, the results don't seem strange at all.
Could you make one of the two paths longer than the other? On the shorter path a detector is placed that modifies the longer path if it detects the photon but NOT modified if both paths detect a photon. Then if the longer path is modified would you see the photon jump to both paths after the modification occured?
I remember a slomo guys video where they filmed light travelling through a medium. Could you do this same experiment and film it in the same way? To see the light go back in time?
Quantum entanglement CANNOT transmit information at all. You can choose to measure something at point X which tells you what the corresponding value at point Y, BUT that does NOT constitution transmission of information. "Delayed Choice" is a fallacy.
Warframe as a sponsor? Thats really cool! Played that games years ago and it was great but having not played for so long its pretty much impossible to understand what is new or what im doing at all. That said..its awesome that the game inspired you, it certainly made me interested in space aswell.
Following Einstein's EPR paradox, the system also includes the experimental set up, the particles are not only entangled within themselves but also with the experiment apparatus, so loncality principle applies, meaning time and distance are irrelevant within the experiment boundaries and no need to use the " backwards" term to explain it...
11:15 With the example setup here I would expect the classical prediction to be 66% and the quantum to be 75%. Where are your numbers coming from? You don't get to handwave away the math with "once you crunch the numbers", and then come up with the wrong numbers.
Quantum Theory sounds a lot like time and perception. "So long as it is being perceived, it is moving forward." but that leads to the question, "what is needed to perceive time?" And this theory might just be telling us that WE are not the answer but a byproduct. We perceive time as only moving forward because we are "attached" to this universe at this time. Or the second experiment is just acting similarly to what lightning is doing: Every bolt has branching paths but the only path that matters is the one that hits first, which causes all other paths to go backwards to strike with the bolt, all happening faster than the eye can see.
2:52 but how can you know the 'original' momentum or whatever of the particles and in what way do you mean? In what time and space? Bc you could theoretically pick any time and space making your base number anything.
omg one of the best videos on the topic iv seen. congrats man, really good analogies and really good explanation when there simple shouldnt be an analogy!
It's almost as if there's some kind of conspiracy, some kind of intelligence that's keeping us from discovering or accurately measuring things at the quantum level. But that would be crazy.
It has been explained by a paper 2008: "Explanation "Causality as an emergent macroscopic phenomenon": The Lee-Wick O(N) model 2008". The explanation is more mindbogglingly strange that first imagined, both spacetime and causality are emergent properties of quantum fields.
But information is not really travelling backwards through time at all - isn’t it simply that superpositioned states don’t resolve until they are forced to, and when they do, they always do so in a way that maintains the self-consistency of the universe I.e. entangled states.
it helps to look at the photon from einsteins perspective. for the photon itself there is no time passing. the entire path was taken in one moment. the photons moment is projected into the world we experience as a line. but from the perspective of the photon there is no before or after in relation to points on the photons way. the entire way is one single moment for the photon. so the 2nd beam spliter is either present in the moment or not.
what we experience as paradox can be simply explained by the relativity of simultaneity
I suppose that makes sense, but it hardly makes it an easier concept to grasp xD
Came here to say this, but you beat me to it, (and quite eloquently, I might add).
No, the photon is just data. It doesn't go two ways, things can't be in two places at once. It's not measured, why waste resources computing it when noone needs the data to render their reality.
For "delayed" experiments the same applies.. it was never physically there, only potentially hence the "wave" behaviour. If the data is available in a double slit type detector storage, you get particle behaviour. The behaviour is determined at the measurement stage, there is nothing going back in time.
Also, particles don't communicate anything. The underlying system manages them, and they can be in pairs "entangled" as a single thing.. super simple, nothing needs to be communicated. When we measure one thing, the other bit is automatically set.. because we entangled them😉
I suspect when a photon changes direction, it is actually absorbed and re-emitted, it is not the same photon any more
but that's not true. These experiments are performed in air, where the speed of light is 0.9997c
The second experiment (the "Delayed Choice"), does not necessarily show communication backwards in time either. It shows the same as the first experiment: there is some form of coordination that happens instantaneously.
In the Delayed Choice experiment, the photon always takes both paths, also when there is no beam splitter in place. It is just that all the other possible paths disappear instantaneously when the photon is detected. That is the "normal" QM quirk, called the measurement problem. Measuring a photons collapses all possible outcomes into a single one.
Ya
Hey Big-Brain - Why you gotta ruin time-travel for everyone?
@@moistmike4150 Sorry, I was instructed by someone from the future to make sure time travel never gets discovered. It wrecks havoc in the future.
But what if those entangled entities are far away enough that the influence dark energy has leaves them traveling at relativistic speeds away from each other?
Would that imply time travel?
That entanglement would ignore time and space to reach that instant communication.
What is considered time travel anyways?
@@markopecinovic4475 entanglement is not communication.
I remember when you questioned how we'd feel about you touching on topics other than planets outside of earth yet in our solar system. I'm happy to see you expanding your options for content
Who wrong?!
I think he was touching more than just topics with this video.
Planets 🤣 Outside Of Earth 🤣 Gtfooh!
@@noelalexisshaw-nas-noz5142 Think about the children.
This was SUCH an incredible video. Really appreciate you explaining some of the basic principles around quantum physics and entanglement. Before watching this video, I didn't realize that I had the "classical" understanding of quantum physics, and you allowed me to understand things just a little more deeply. As a complete layperson who finds himself fascinated with trying to learn more about this field, that means everything to me. Thank you :)
Thank you! And I'm glad!
It's not Einstein's Quantum Theory!
I love that you have branched into incorporating theoretical physics and quantum topics. Huge fan of everything you put out, thanks for teaching me so much🤙
too bad quantum eraser was debunked years ago but still dudes clickbait with it
Sounds like you're describing the Grand Old Duke of York. _"When he was only half way up, he was neither up nor down."_
Loved the slightly longer video, and the topic was very interesting as well. Keep up the good work!
I saw this video and immediately decided to subscribe to your channel a couple of years ago.
Interesting stuff, as always. Thankyou Alex.
If time stops at the speed of light, it’s not really time travel. From the light’s perspective, it just goes backward and forward in time equally. It’s only us non-light-speed travelers who marvel at photons going back and forth in the timeline. For the photon, it’s just a day at the office.
Thank you so much for this my entire life I thought spin meant the partical was actually spinning this makes so much more sense now, thank you so much
Sabine Hossenfelder made a video sometime in the recent past where she explained why the delayed choice experiment is not sending information back in time.
Ah, but did she only make that video because _this_ video was made in the future, hmmm?
@@Xune2000 🤔
I saw PBS Space Time's take on this subject, they also explain why it doesn't send information back in time, but that alone doesn't debunk a local causality breakdown! Same as entangled particles are effectively causally connected but it's impossible to send information via the connection.
Huygens Optics has a series about light. He explains his take on how it works (It takes hours of videos for him to fully explain though), and for my knowledge it holds up decently well.
Lol
In the delayed choice experiment, the first beam splitter creates two probable paths for the photon quanta to take with the second beam splitter allowing the two probabilistic photons to interfere with its probabilistic wave before being detected as an interference pattern. If you remove the second beam splitter the photon quanta still travels down both paths with oscillating probabilistic wave; whichever detector that is activated is the photon quanta that had the highest probabilistic wave at the time. So if you add the second beam splitter after the photon quanta passed the first beam splitter there is still two probabilistic paths that the photon quanta is taking allowing it to interfere with itself. This doesn't need backward time travel to explain it.
I like this explanation, it makes sense
What you wrote is logical.
You talk about "probabilistic waves" as though they are physical entities that propagate through space and time. They aren't. You're really just using the wrong words to assert that light is a wave.
@@BladeOfLight16 What are the right words?
Exactly what I thought
16:22 It is generally understood (perhaps erroneously, perhaps not) that a photon does not experience the passage of time. This implies that a photon must be everywhere at once. That is to say, in this quantum physics experiment, the photon exists on all points on the device at the same time, making up its properties on the spot whenever asked by an observer, and the only thing actually being measured is the "light" that the photon generates, not the actual photon. This is important. If the photon is asked about its specific properties as a "particle," then it behaves like a particle, until it is no longer being observed (for instance, the measurement has ended). So, if this is true, and the photon is actually in all points in some kind of quantum state across the entire device all at the same time, and you try to trick that photon by adding a new light splitter while the photon is already on both sides of that splitter (but before the photon's light is visible at that spot), then, yes, I would say the photon has adequate reason to behave strangely under these conditions. I would further go on to say, no, the photon does not send information to the past. The photon, if it actually IS already on every single point on the detector, would instantly know that a 2nd splitter has been inserted, and would change the properties of its "light" accordingly. We need to start asking bigger questions, like, are we actually measuring the photon, and do we actually even understand the photon, or are we just looking at the tip of the iceberg (the light of the photon)?
Or I might be crazy.
Thank you for breaking things down in an easy to understand way.
I don't see why people think is it a sign a supreme intelligence to explain the most advanced & complicated topics to only a few other humans that end up understanding what was said.
@@MR-nl8xrWhat are you talking about...? The adage is that one fully understands something if they can break it down so much even the uneducated can understand -- not that said person has "supreme intelligence". Which still makes me question, what are you talking about? You don't understand the correlation or...?
Ευχαριστούμε!
Thank you!
Good video! Also, the Duviri Paradox is going to be incredible!
Some of my ex girlfriends seem to possess this ability.
Bruh💀
Super positioning?
😂😂
🤣🤣🤣👍
Keyword: ex!
Just listened to Einsteins biography audiobook. The one sentence stuck with me:" even Einstein's mistakes are better than today's newest findings."
Read his own book out of my later years" Citadel press Nj.
Albert Einstein.
He stated he is a proud Jew and Zionist not an atheist.
dude you a real g for that one
The way you described information travelling back to the first splitter reminds me of the time travel premise in the Primer movie. The box has to be turned on in order to travel back to the moment it was turned on.
You never know how much boxes were created anywhere in Universe from its localstart (aka Big bang) 😅
the thing that comes to my head is we need to keep in mind that the "time" that we observe works the way we feel only for us, there are relativistic effects happening, like in the twin paradox or lifespan of particles - generally we know that if we go very very fast, a long travel would feel for us like a short one, cause space looks like it shortens a lot (but only for us, not for a stationary observer) - so technically when something moves exactly at the speed of light, the path shortens to infinitely small (zero?) and time taken for the travel does too, so... what if for us the photon took for example 1 nanosecond to travel through the detectors etc, but for the photon everything happened at once, so there was no "time" to "know" that we add or remove detectors - for us it seems like we interact with the photon but from its pov it all happened in one plank's time length, so it "knew" how and if to split or not because it's like it saw the whole situation not like a movie as we observe it, but as A SINGLE FRAME ;o
the life we know can't exist without time but if photons can, we have a new phenomenom to understand
Thumbs up. That is what I think is happening too. The scary thing about is a "time domain" to live in. A photon travelling milions of years (how come it does not attenuate to zero) still thinks it traveled no time. What if we pass that logic on us? We are here for some time, but in different time domain, it is just almost immeasurable blink of an eye... From the photons perspective, everything happens at once. All the universe history. Just BAM!
If time and distance doesn't really exist from the perspective of light, then from the perspective of light, everything would be infinitely densely packed.
Similar to the early conditions of the big bang.
Perhaps, for light, not much has changed since the big bang.
If everything was infinitely close together from you're perspective, you'd never be able to notice inflation (the expansion).
And it's not just light but anything that doesn't have mass.
So when you don't have mass, time and space doesn't exist.
And when something has mass, time and space exists.
Perhaps the common denominator that produces the effect of time and space, is mass and the stuff resposible for it.
so you oversimplified the DCQE experiment (because it's too complicated to explain in a video that also covers Bell's Inequality/EPR) to the point that refuting acausal information is impossible. But the answer is no: information does not go backwards in time. What you showed is more like the Elitzur-Vaidman bomb-tester experiment, which is weird--the experiment that is.
it's not to overcomplicated to explain. it's pretty simple. if you're trying to measure how much water is in a cup and you're using a sponge with a ruler drawn on it you're going to ruin your measurement aren't you? same deal here.
The double slit experiment is flawed because it relies on light detection.
so if you draw a ruler
on a sponge
and dip it into a cup of water
it's going to suck up some of the water and ruin your measurement isn't it?
same deal here.
everybody acts extremely impressed with the double slit experiment but they don't understand it well enough to realize why it's stupid and wrong.
it's really simple.
you cannot use a sponge as a ruler to take a measurement of water.
you cannot use a photon detector to take a measurement of light. lol.
because the detector absorbs some of the light you are trying to measure and ruins your measurement.
it's that simple.
Another fascinating and thought-provoking video. Thank you for using your platform to spread knowledge!
Re. the double 50-50 experiment: have scientists tried starting the experiment with two of those 50-50 mirrors, but remove the second mirror after the photon has entered / begun?
This is a wonderful question. I’m just commenting to be in the loop in case it gets answered. Because I can’t find anything on it
You would have to remove the mirror faster than the speed of light. So no probably not.
@@un.defined than they should try to slow down the light as much as we are possible to, and try to make the change after the photon begun?
@@Byk37 I guess it depends on if altering the speed of light (in a non-vacuum setting) will have repercussions?
Yes, kind of.
The physical device wasn't completely removed of the way, but they used a material which when exposed to electric current can change its property from reflective to transparent. So it can be seen as an ultra fast light valve to interrupt light or not.
Then they also extended the length between the beginning and the end of the experiment by making the beam of light travel multiple back and forth in zigzag in order to be sure that the light would take more time to travel this lengthy path than the electric device to take to active itself.
14:52 - 15:04 so 1 photon was fired and both detectors detected a photon simultaneously. how is this possible? did the photon double itself? did we just create more energy?
or is he saying that in both versions only 1 detector detects it at a time. but when the 2nd beam splitter is there the detectors end up making an interference pattern and when the 2nd beam splitter is not there, there is no interference pattern.
Way too hard for me to grasp, but loved your explanations anyway!
No one understands it. To say Einstein is wrong is a stretch. Roger Penrose doesn't think so.
don't beat yourself up, no one gets it yet boss
@@hoochygucci9432 Yeah, I'm pretty sure Einstein was correct. Bell presents a strong argument, but the test is so difficult to replicate and so prone to error it's a little hard to believe. It makes more since that the particles properties where predetermined on collision rather than undetermined until observed. But until more reseach is done, I certainly would not say Einstein was incorrect.
@@SirSithly I wouldn’t worry; there’s no benefit in understanding this nonsense. Whether these mathematicians are ‘correct’ about our cosmological beginnings or not; their concepts are obviously destructive; why the so-called ‘wise’ ones revert to trying to understand reality purely through numbers is a mystery that ends in disaster; but I suppose its profitable for nihilistic consumerism.
It’s all fantasy; concepts and interpretations of autistic minds; just look at your society; is it functional because its enlightened by modern physics elaborate philosophical enquiry or is it functioning because its zombified by an endless mindbending cosmology of everchanging non-comprehensible gibberish?
Thank you so much. Your presentations of Bell's inequality and of the delayed choice experiment are outstanding. I have just learned something fundamental about the strange world we live in.
That would mean the information still persists until it hits the detector, and interacting with that information will cause it to collapse. This makes more sense if the wave and particle are separate like pilot wave theory suggests. Then you have waves radiating away from the point particle in all directions, interacting with that wave anywhere along the path before it hits the detector would change the behavior of the particle. It would also allow a single particle to interfere with itself through a double slit.
👍
Thank you for breaking things down in an easy to understand way.. Thank you for breaking things down in an easy to understand way..
When I first started studying QM my reaction was "what's going on? this doesn't make any sense" but now it's been 10 years and my reaction is "What's going on? this doesn't make any sense"
I'm really starting to like the idea that particles are activated and deactivated. Meaning that particles themselves don't actually travel but transfer their energy to an inactive particle in an assembly line like fashion, as one particle is activated the previous particle is deactivated and we can only detect the particles while they're active with energy. Using this logic could explain why light looks like a wave to us at certain times and a particle at other times, the wave is the energy activating the particles around it and the particle itself is what interacts with us.
That sounds a lot like a field.
Well aren't all of reality and particles themselves just the interaction of feilds? If the feilds are everywhere then instantaneous communication doesn't seem so strange after all. Kind of like a Newton's cradle going in all directions. One ball smacks another but only the one at the other end moves. All of these seemingly distant particles were connected all along.
It's all waves. Particles are static pieces of information that seem also to update the wave function (localize).
As usual, I still have no more understanding of Quantaum Physics, thanks to my tiny feeble brain.
But, thank you for presenting another incredible video that was entertaining and fun to watch, regardless !
Yeah, welcome to being intelligent where the only thing you know for certain is that you don't.
You are not alone
Richard Feynman said, "Nobody understand quantum mechanics"
It's not your brain that's the problem. It's the sorry attempt to take physical observations with no formalized (mathematical) representation and hack them into a metaphysical postulate. We don't know what the hell particles do at the quantum level; we can't observe them in the same way we observe macroscopic objects. But even worse, a lot of these weirdo behaviors don't even have a formal mathematical model even in quantum physics, so interpretations are ridiculously ad hoc.
It's truly incredible that the wave pattern observed in the double slit experiment is due to the interference of the probability of which slit the particle will pass through. Probability interferes with itself creating a wave pattern.
Probability is not physical. It is a process that describes something physical. Nature makes patterns and we can assign numbers and probabilities to those patterns. That doesn't mean it is the probabilities that interfere.
@@wesjohnson6833 Perhaps technically true, but it's easy to snipe at "probability" as not accurate, a lot harder to say what is accurate. Let's hear it man, tell them what you think IS causing the interference so we can use the right terminology according to Wes
Point a to b. what happens is a probability wave trees to point b as a wave. When measured at b. The wave is broken and it becomes real. Absolutely mind blowing! Love the stuff!
After watching this a second time, I suspect that what's going on in the delayed choice experiment is that the photon is *_always_* going down both paths, but if the second beam splitter is not inserted to recombine the wave, then it can't hit both detectors and "pretends" that it took just one path by only being detected at one or the other!
I thought this was incredibly obvious lol
This would be the Many Worlds Interpretation - branching worlds "decohere" when no longer in "superposition" and can no longer interact.
The Copenhagen Interpretation says the wave "collapses" and the other possibilities disappear.
And then there is the Relational Interpretation - past and future resonate to produce the present.
I find talking about only one of those (and not by name) an incredibly strange choice.
and how does this explain the double slit experiment?
What if the particles spin in these directions:
↑↑↓↓←→←→ for B and then A starts?
Then the particles get 30 lives... 😂
Ahh.. the Konami particle.
I'm curious how they measure if a particle is entangled or not to know if they are when calculating the Spin of different directions.
They create the entangled particles rather than measuring if they are entangled. Once you make a measurement on them you break the entanglement. So you can't first determine if they are entangled and then go ahead an make a measurement.
It sounds a bit chicken-and-egg, but you create the entangled pairs and perform measurements to make sure that the process you use does actually create entangled pairs. Then you use that same process in your other experiments and assume they are entangled.
Thanks Alex. That went some way in improving my understanding about this. Excellent explanation
Didn’t expect a Warframe sponsor. Not a bad choice of a channel to sponsor
According to our current understanding of physics, the transmission of information backward in time is not supported by any known physical laws. The concept of information traveling backward in time raises significant paradoxes and contradictions, such as the famous "grandfather paradox" where one could potentially alter the past in a way that prevents one's own existence.
In classical physics and in our everyday experience, causality flows forward in time, meaning events in the past influence events in the future, not the other way around. While some theoretical physics concepts like closed time-like curves or wormholes have been proposed as potential mechanisms for time travel, they remain speculative and highly theoretical, lacking empirical evidence or practical application.
Thus, as of our current understanding, information traveling backward in time remains purely hypothetical and is not supported by the principles of modern physics.
It doesn't have to choose between taking one path or both paths, right? The photon is always in a superposition of taking both paths no matter what you do before or after it passes the first beam splitter. However, once it arrives at the detectors, the superposition collapses (or expands to encompass the detectors and you as well) so that only one detector detects a photon
I don't see the difference to the double slit experiment, there the photon also only hits one spot on the detection screen despite taking multiple paths beforehand
You are correct. The way the experiment is set up in this video, the delayed choice is just a red herring and irrelevant. It becomes more interesting when you use entangled pairs of photons, but even then it is just a mix of superposition and entanglement although these experiments (delayed choice quantum eraser, for instance) seem on the surface like something else is going on.
Freaking fascinating. Nicely done.
L
@@alphaone2834a month later and nobody cared about your L buddy.. how does it feels to be cringe incarnate?
I love these educational videos!💚💚💚
@I don't know... We’re not astrophysicists, so we don’t know quite how accurate these explanations for the layman are. I’m sure they are simplified so we can grasp them. One thing I notice is that theories are changing and developing quite often. Anyway, I’m very grateful for Alex for explaining the current theories in a way I can just about understand and in an entertaining and visually engaging way too, so if you think you know better and can produce an equally high-quality video, let’s see it.
My brain shorted out a little from that ad at the beginning. I actually watch a lot more Warframe content than astronomy/science. :)
Thank you kindly for having non-adsense at/near the very front/back/both of video, rather than interrupting like TV once the flow has set in. It suggests mutual consideration for the creator/viewership relationship :>
Very interesting. I cant say that I have a great grasp of quantum physics but from the small part I do know and from videos I have watched, its all fascinating. I really think that we are missing quite a lot here. The universe is such a beautiful crazy place.
but we're not. QM always describes experiment.
Now when I first heard of the delayed choice experiment, it had a much more, "Spooky action at a distance" affect. I don't remember all of the details as to how the experiment was constructed, however the jist of it was that the "observer" would not get any information until after the photon had reached the screen at the end. If I remember correctly, they may have created an entangled pair of photons at the start. The result was that the implication of the photon going back in time to inform itself that, "IT'S A TRAP"!!, seemed much more apparent. Either way, excellent topic and video. Thank you for sharing.
Awesome video & topic. Thank you for sharing this that was very interesting. I loved it. ❤
How can you insert
emove a beam splitter faster than the light traveling between? I accept the results but don't understand how exactly this experiment is conducted. Perhaps a video on that would be helpful?
Probably two really long rolls of fibre optic cable to buy the time for the switch. Just a guess though.
I think there are other beam splitters and paths such that there's a 50% chance that the photon will go through the final beam splitter and a 50% chance that it won't
But I'm not quite sure
That's why they built CERN I think. They made light travel a very long path to measure the delay
Theres the long path option, or the electronic beam splitter option. Both work.
@@Astromath They can use a crystal whose properties change with an electric current and then then use the current to make it a mirror/non-mirror or splitter/non-splitter. They have made it truly random though. This experiment has been done with a number of combinations of mirrors and splitters though and with entangled photons where they use more splitters.
Gotta love youtube recomendations, one second you're chilling, the next you're learning about quantum theory.
I think the beam splitter is acting like a double-slit. Think of it. In splitting the beam, it makes the wavefunction go to both detectors, causing an interference pattern.
When I was first presented with your three detector positions for the two particles I thought they were arranged on a plane. But I think in order for the other two detectors to still have a 50% chance of each result, they would all have to be at 90 degree angles to each other, as in oriented along the X, Y, and Z axes, respectively. (Otherwise, if they were at something like 120 degrees or just any old random coplanar orientations, I would not expect a 50/50 chance for the other two detectors to get each result after the first particle was "measured".)
I'm not sure if I missed you saying that this was the case, or if you did not say it (perhaps assuming it wasn't important or that we'd figure it out on our own), or if I'm simply wrong and *any* difference in detector orientation resets the probability to 50% (which does not seem like it fits with what I know about QM, especially considering how polarization works, etc, and also, how precisely aligned would the detectors then have to be in order to be "sufficiently aligned" to get the "spooky" entangled opposite result? Therefore I doubt I've got this wrong, at least).
But this shows why the mathematics is in error as the parallel postulate is false - the classical analyse with out the parallel postulate gives the same result as QM.
This makes me think we're going to find out that the universe exists in all moments at once, that everything we see sequentially in time is a perception we are bound by.
Biological life forms perceive time as linear to prevent them from going insane perceiving simultaneously the past, present, potential.
From a higher perspective there is no time, only the infinite now of all potentials.
It is only modern Scientists that are ignorant of the esoteric knowledge of us mystics.
It seems so. It would be interesting to know if the answers are not in the infinitely big but in the infinitely small. We already know that we can zoom in way more than we can zoom out. And what determine the other particles beside light to be entangled with each others? It's very interesting to imagine.
Either everything exists all at once, or time doesn't exist at all (outside of our brains' perception of reality anyway), there's only the present moment and motion
@@Aura.ad.Infinitum Almost! Think of the speed of light as the minimum distance between events in space and try to work it out from there!
Would you consider doing a video on the Milky Way and the Andromeda Galaxies colliding? That would be an Awesome Video, Thank You!
My guess is that light is indeed always a wave. When "light" is created, a connection between its two points is made instantly, in zero time. Light exists between the two points as a wave, but in the case where it acts like a particle, it's simply a concentration of that wave. It oscillates (probabilistically) from point A to point B that is already established, and acts like a tsunami in its concentration until it gets reflected back. Do that, and the tsunami stops, and dissipates along the return path. It is the observer that sees the concentration along the way, thus the "speed of light" is a constant no matter how fast you travel. I am guessing that light is actually using what we call "dark matter" as the quantum pathway to set a connection and then follow a two-dimensional path. And that's why it bends; its path is a straight line, even if it's shifted in spacetime. It doesn't go "back" in time, but the path is set instantly; it's the only way it could "turn around". It's like one good snap on a rope; that's the photon. But snap the rope from the reverse (reflection), and the tall wave ceases and it goes back to its more chaotic lower excitement.
One of your best vids so far, wonderful job!
I've had personal experience with "information" being passed back in time without any paradox on multiple occasions.
Several times in my life I've experienced strong phantom pain in areas of my body that would months later have a reason to feel like that. The First Time it happened my wrist suddenly spasmed in pain for a few days then about 3 weeks later I broke that wrist in a BMX stunt gone wrong. The last time it happened was the scariest as it resulted in hospitalization and overnight observation with severe chest pain and sharp pains to my inner left groin. Was released clear of heart complications with doctors baffled as to the cause of my chest pain, something that was repeated later down the track. Cue Xmas day and an electric RC car cable of reaching 70km/hr with Broken front suspension and steering. Being unaware of the previously mentioned problems I attempted a manoeuvre that was meant to be driving from the middle of a park to the gravel road Infront of us that was meant to be a slide turn into a donut on the gravel. Instead it plowed into my left ankle tearing my groin in the process flipping me in the air landing on my left side breaking 4 ribs, my hip and crushed the bursa in my shoulder. 2 of the rib breaks were displaced fractures of the 4th & 5th ribs fraction of a millimetre from the bone cartilage join, to close for a normal see.
Come to think of it most of the Temporally Referred Pain (TPR) I've suffered from seems to be self inflicted.
For that matter, premonitions and seeing things in dreams before they happen are real for me. I try not to think about it because it bothers me> I don't understand or like it. But it is what it is. There are more things in heaven and Earth than are dreamt of in our philosophies.
@@tyharris9994 I've had one premonition only, but it was absolutely real. It doesn't bother me that it can happen.
In other words, if you can control which way the particle spins, you can communicate faster than the speed of light, assuming the other particle is where you want to communicate to. Because it inherently knows what the other particle is doing, all you have to do is change to rotation back and forth in Morse code. I imagine in the future, submarines will use quantum Morse code to communicate. Furthermore, I can’t imagine that you could intercept a quantum message like that making it even more valuable.
I think binary would be a more efficient codification, but it does seem to suggest that. I believe quantum computers harness this entanglement from a different but similar property.
So it seems we may already be there in some sort. Quantum navigation through entanglement.
The problem is that you can't do that.
When you setup you system and entangle the particles you don't yet know what message you want to send, so you make them in a superposed state where you don't know their spin yet.
But then later you can't change that once the particules are separated without breaking the entanglement, the only thing you can do is measure that spin.
You know that the other people at the end of your quantum phone will get the exact same result as you, but the message is still random (or what ever you defined at first when preparing the entanglement).
This has other possible applications, but not communication.
Alex, you are GOLD. Such high quality voice, presentation, script, delivery and visuals. You should be on mainstream TV, your show would make you a very wealthy man indeed - or perhaps you already are?!.. You are a gift to us, and by far one of the best channels covering and explaining these complex subjects for people with basic to intermediate knowledge. Thank you man.
He may not be looking for $$ in a greedy way like you may
@@zack_120 No worries fella, I'm just pawing with you. I love Alex's channel, just think he should be doing really well and getting his content to more people. Money doesn't mean anything to me, I love to live simple, and spend time learning about life & the universe. Peace bro. X
@@TheHexCube Sounds like you are on the right track, but either way it's your freedom :D
@@zack_120 Thnx for reply. We're ok. Alex is the best!
My brain was fighting to keep up with all the information near the end of the video only to get thrown off by the burrito at 17:50. Something about time traveling, cool video 👍
what you're saying is... quantum entangled waves represent the function or method, showing possibilities, until the output is requested. So we're in a simulation.
Einstein: God does not play dice
God: 🎲🎲🎲🎰
With quantum physics, it seems more as if God plays Calvinball with the Universe...;-)
God does play dice, but they are loaded.
god does play dice but the dice is stack already
Great video explaining those experiments. I have a question. How the heck did they add a beam splitter after the photon was sent? That's some faaast sleight of hand! :-)
Extremely fascinating! From another of my topics of great interest, I draw a parallel.
Virtually all those who have experienced a near death experience (NDE) (and let's just take the hundreds that can be documented as having truly died and then verified information they could not possibly have sensed during their deaths - like detailed events outside the operating theatre) indicate that time and space are illusions and that this 3D world we "live in" is itself, an illusion. They all insist that this world serves as a sort of simplified stage on which we play a role for a short time in order to learn. When you think about it, learning can only happen when there are consequences, and these can only be experienced in a realm with time. If these NDE'ers are right, then our detection of sub-atomic particles is nothing more than us detecting bits whose real nature is beyond our own limited 3 dimensions and time. Much like a 2D person from flatland (in Abbott's great analogy), when encountering a 3D sphere passing through his world, see a dot becoming a circle, growing, then shrinking to a dot and then disappearing and thinking it utterly amazing. The only reason we think it strange when subatomic particles seem to be independent of time or space is that we are constrained to our 3 dimensions and time. We know only that world. But I have a hunch there is much more...
If only science would borrow from other areas of study instead of focussing on their own siloed topics and methods. NDEs are now so well documented that they are the becoming the popular study material of numerous doctors and philosophers - something untouchable a mere 20-30 years ago.
"If only science would borrow from other areas of study instead of focussing on their own siloed topics and methods", Yeah, it took humanity thousands of years to develop objective scientific methods, lets now go back to mysticism, metaphysics and other unscientific garbage lol. What I am curious is, there are plenty of youtube channels, TVs and streaming services focusing on this gobbledygook, why not stay there ? Why bring these pseudo-scientific nonsense to channels which try to stay scientific ?
What explains this is measurement.
With the first splitter you’re collapsing the wave function, with the second (if angle of impact is complementary) the light is returned to “close to its original (unaltered) state” which is “wave”
A filter, or observer, is merely the elimination of redundant or meaningless and even sometimes contradictory information (like opposing waves that cancel each other out)
To answer your final question, I would think the second detector ends up being much much larger than it seems and the "small" movement to activate the second detector is in fact a much larger movement, so large in fact that it makes the particle appear to go back in time. The mis-perceptoin occurs due to our instinct regard "when" a choice was made to close the gap. This choice seems made by a random way or computer and is thus too small to perceive thus we think it is going backwards but the particle is still "inside" the detector. Or "outside" depending on how big you think it is. It is bigger.
In the past humans have often believed our sight was a sense that threw a mold over the world and allowed us to perceive it, like something invisible until you throw paint on it, revealing its location. It'd be interesting to know for certain that theres truly no offect in us looking at a particle
I can imagine how the world would appear differently if we had more than 5 senses. If we had a sense that can detect the radio waves? Or anything else that is invisible to us. It would appear very differently.
I think of it like flipping a coin into the air. While the coin is spinning, it’s kind of like heads and tails a the same time, until you catch it in your hand, then the wave function has collapsed and it’s heads or tails
"It'd be interesting to know for certain that theres truly no offect in us looking at a particle" On such small scales, any type of detection would be an interaction. Every observation has effect.
Or, as Futurama put it: "No fair! You changed the outcome by measuring it!"
This has nothing to do with the mystical influence of consciousness over the universe, though.
I liked this tomorrow.
😂
Wow this is crazy. Imagine what we could do with this.
Ironically, next to nothing lol.
on that small scale? Probably nothing
reality can be ruined if it goes wrong
Pretty much "just" FTL internet so far.
@@64fanatic FTL internet? Bro whatcha talking about nothing like that exist and its impossible using this tech. Impossible.
The image of the burrito at the end without acknowledging it was hilarious
Particles are conscious on all frequencies
Time is a spectrum, quite like light….it’s just that within our reality, certain spectra can’t be accessed/observed. Infrared or ultraviolet on the light spectrum and only the time spectra of the present can be accessed. Every program has its limits 🤷🏽♀️
if they are making it up on the spot then by rechecking the particles repeatedly you should get different results with each check. you can't ignore exceptions as they are still results.
@@squishy-tomato if they are only uncertain for just the first measurement then they are predetermined and aren't random at all. That would mean it was always the same before being observed. If it is uncertain when unobserved you would get different results with every observation. so say they were up up each time you observe them then they are always up up. if they are uncertain till observed then you will get results such as left right or down down. If they are locked in once observed then they aren't uncertain. you have no way to prove or disprove and there fore the theory can't be tested. At that point it is best to assume they are certain because you have no way to prove either way. how ever if the test comes up where they aren't fixed then you can say they are uncertain till viewed because they aren't locked.
@@squishy-tomato how can you test that they are uncertain? if you can't test a theory then it is best to assume the theory is incorrect until you can test it. I can say that it is uncertain the earth will rotate until I see the sun again and then it's locked in after that point. it was rotating prior to that but that could be tested. now to say something is one way without being able to test it and then saying that it is permanently that way only because you tested isn't science. science is being able to prove that it wasn't that was before testing it and then the testing backing up what you say. otherwise you are just making things up and saying prove me wrong.
It happens. He started all of this. Give him credit. We learn new things all the time
I mean, I already liked and subscribed to Astrum's video, how much more credit can I give the guy?
What if observing a particle doesn't create it, but summons a predefined one that exists outside of time... or on the 4th dimension. Much like a circle will pop in and out of a 2d world when a 3d sphere passes through it, a certain version of the particle shows up when it's 'observed', making it seem like it was decided on the spot, when in fact it already existed outside the 3d plane, but it just had no reason to appear. Idk just guessing.
The backwards time aspect on the second experiment might be due to the photon traveling at the speed of light, maybe that one theory of photons existing for the entirety of their path is true, so something altering the previous section of their path could affect future travel across that path, since it's still within the timeframe of the photon's existence.
In the first experiment, I don't get where the 55% came from. That would be only expected if we hadn't omitted same-direction measurements.
If we don't measure from the same detector, according to the table at 10:24, we get 2/3 chance for the same spin, and 1/3 chance for different spins.
But even then, the table doesn't account for all combinations of spins -- if a particle has spin up/up/up or down/down/down, there's 100% chance that the second particle will have different spin in either direction. And such particles would make a total of 1/4 of measured particles (2 out of 8 possible spin combinations).
When we add 1/3 of the remaining 75% of particles, where the table applies, we get a total of exactly 50% chance to measure different spins.
Correct me if I'm wrong.
I don't get how omitting same-direction measurements would result in 55%. Regarding the tables, one gets 50% by not omitting, while getting 1/3 to 2/3 ratio with emitting.
Also a single particle only has one angle of polarization, and can only be measured at one detector, while the other particle gets measured elsewhere.
I do not know where he gets the 55% from either, he maybe just chose some random number as an example.
I get 50% using classical physics. If detector 1 measures up (facing 90°), the particle measured could have had any polarization angle in beween 0° and 180°.
intersecting that half circle with the half circle of another detector, they intersect in 1/3 of their arch, giving the particle a 1/3 chance to be measured the same and 2/3 of being measured the other way. Adding same-detector direction pairs, one arrives at 50% using classical physics.
not sure you understand quantum mechanics, just another video completely reading things wrong
There was a young lady named Bright,
Whose speed was much faster than light.
She set out one day,
In a relative way,
And arrived on the previous night.
This comment really deserves to be seen!
Bell's work has additional underlying assumptions, like statistical independence of certain aspects of the events. Those assumptions could be violated instead of locality.
I'm not well versed on this science, but to me it seam that being the detectors are arranged in this way would cause them to not function properly because the triangulation attempts to detect to the position being it is able to be 360degrees infinite it would be detected randomly in the opposite direction at 50 percent split to the other aposing detectors, which leans me on believing that there is a flow of force attracted to the detectors in a attractive way and rather perfect detection how does the detector make its voltage?
5 years ago I was working at Caterpillar in NC. I looked at the "accidents since" board: It said 122, but I saw: "288" then it was only 122.
I told my manager; he wrote it down.
We all forgot about it. Then months later I saw "accidents since" board report ZERO.
Caterpillar was entirely focused on how this accident happened and took everyone on a tour of how an employee broke her arm in the parking lot on that day: Day 288.
My boss was scared of me and everyone else after that. I get lots of these premonition. The woman was walking in the back lot - there was a 1mm crack on the road: Her shoe grabbed the leveled crack and throw her on the parking lot. They then trained us all on how to avoid us from falling down if you foot hits a 1mm crack in the floor!
Gulf War Vet: 1990-1991.
Yes, time travels in both directions at same time. Take a key ring with key on it. Put another key in, but before continue put key already on ring in also. Then complete. One goes on and one comes off, yet both traveled exact same path in the exact same way.
Phone signals internet, electric power lines, tire pushes against road, road pushes back. Energy flows both ways.
When I first heard of this family of delayed choice experiments, and the apparent implications for time, I was quite worried it appeared obvious to me that particles aren't travelling backwards in time and only something like super-determinism would make sense of this apparent time travel. Fortunately it turns out that there *are* quantum physicists who "clearly do understand what is happening here", and I would strongly recommend @SabineHossenfelder 's video "The Delayed Choice Quantum Eraser, Debunked" for anyone who wants to get their head around the subtlety of what's going on.
I remember hearing that photons don't experience time. Not in the sense of having the ability to perceive, but in the sense that emission and absorption of the photon happen simultaneously when you look at them in the photon's frame of reference. So, for it, there is no future or past, only the instant present. If you look at this experiment from this perspective, the results don't seem strange at all.
You are absolutely correct!!! I fully explain this in my book, "Infinity, Time, Death and Thought" - 2017.
Could you make one of the two paths longer than the other?
On the shorter path a detector is placed that modifies the longer path if it detects the photon but NOT modified if both paths detect a photon. Then if the longer path is modified would you see the photon jump to both paths after the modification occured?
This!!
I remember a slomo guys video where they filmed light travelling through a medium.
Could you do this same experiment and film it in the same way? To see the light go back in time?
Well, capturing light on video would be like measuring/observing it, thus breaking the entanglement and superposition.
I tried googling what a 'detector' was in quantum mechanics, and it broke my mind
This is my favorite experiment: Delayed-Choice Quantum Eraser! It proves that reality is virtual.
Quantum entanglement CANNOT transmit information at all.
You can choose to measure something at point X which tells you what the corresponding value at point Y, BUT that does NOT constitution transmission of information.
"Delayed Choice" is a fallacy.
Warframe as a sponsor? Thats really cool! Played that games years ago and it was great but having not played for so long its pretty much impossible to understand what is new or what im doing at all. That said..its awesome that the game inspired you, it certainly made me interested in space aswell.
Following Einstein's EPR paradox, the system also includes the experimental set up, the particles are not only entangled within themselves but also with the experiment apparatus, so loncality principle applies, meaning time and distance are irrelevant within the experiment boundaries and no need to use the " backwards" term to explain it...
11:15 With the example setup here I would expect the classical prediction to be 66% and the quantum to be 75%. Where are your numbers coming from? You don't get to handwave away the math with "once you crunch the numbers", and then come up with the wrong numbers.
Quantum Theory sounds a lot like time and perception. "So long as it is being perceived, it is moving forward." but that leads to the question, "what is needed to perceive time?"
And this theory might just be telling us that WE are not the answer but a byproduct. We perceive time as only moving forward because we are "attached" to this universe at this time.
Or the second experiment is just acting similarly to what lightning is doing: Every bolt has branching paths but the only path that matters is the one that hits first, which causes all other paths to go backwards to strike with the bolt, all happening faster than the eye can see.
I totally love the video you will release in three weeks.
Thank you for explaining how infinite improbability drive works. Remember don't panic.
2:52 but how can you know the 'original' momentum or whatever of the particles and in what way do you mean? In what time and space? Bc you could theoretically pick any time and space making your base number anything.
Fantastic video as usual in this channel.
omg one of the best videos on the topic iv seen. congrats man, really good analogies and really good explanation when there simple shouldnt be an analogy!
It's almost as if there's some kind of conspiracy, some kind of intelligence that's keeping us from discovering or accurately measuring things at the quantum level. But that would be crazy.
It has been explained by a paper 2008: "Explanation "Causality as an emergent macroscopic phenomenon": The Lee-Wick O(N) model 2008". The explanation is more mindbogglingly strange that first imagined, both spacetime and causality are emergent properties of quantum fields.
But information is not really travelling backwards through time at all - isn’t it simply that superpositioned states don’t resolve until they are forced to, and when they do, they always do so in a way that maintains the self-consistency of the universe I.e. entangled states.