Quantum Entanglement, Bell Inequality, EPR paradox

Quantum Entanglement, EPR paradox, Bell Inequality, and the implication for Einstein's Theory of Relativity.

[EugeneKhutoryansky]

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[Tasermaxx]

I still don't understand it. And now I'm craving watermelon.

[ronaldderooij]

Well done again! My compliments. It still leaves that unpleasant feeling that, although we can see and describe what is happening, we do not really understand anything about it.

[vette]

If the message is instant, is it really traveling?

[ceceliapassarella]

I'm not a scientist or a mathematician but I enjoy these videos because they require imagination to visualize a theory that is abstract this is eminently attractive to my curiosity's about how things work and why

[alepel]

I love what you create Eugene. Keep it up and I'm sure you'll earn the audience you deserve.

[zeycus]

I find the presentation of the paradox too slow (but clear!), and the claimed "logical resolution" too fast and vague.

[thomassouthern]

Another explanation could be that the two measurements happen at the same moment from the perspective of the entangled system. Remember, to even notice this, we have to being the measurements together "no faster than causality allows". In other words, we are not looking at messages nor are we looking at time travel of messages. Rather this is about how time is formed from entanglement of mass particle systems. We have six entangled photon experiments that basically tell us all we can currently know about how this works.

1. Delayed choice quantum eraser experiment
2. Photons entangled in time experiment
3. No definite causal order of a photon in a quantum gate experiment
4. Toy universe time experiment
5. Time is continuous toy universe experiment
6. No objective quantum reality experiment

But that is not all. See, it is all about the fact that even decohered entanglement information can always be recovered if the information is relevant between two subsystems. That is the main point of the delayed choice quantum eraser experiment. This information being recoverable means that the idea of entanglement history or entanglement entropy or entanglement bulk has reality.


Now, if you remember maxwell's demon from this same series, then you know the solution is in the brain of the demon which holds the missing entropy. Well, guess what? That entanglement bulk might as well be the demons brain.

Anyways, I love these videos dearly even though I very much disagree with the solution to the paradox in this case.

[guillaumemartin]

You explain so good ! I hope you are a teacher now, and I hope your students will be one of those who will unify Quantum Mechanics and relativity !

[MrKmanthie]

I think it's nice how you have a kitty-cat as the "observer" in the animation, as opposed to some animated person, etc. Is that a nod to Schrodinger?

[M.athematech]

Instantaneous messaging is not the majority view of what is occurring. What Bell failed to mention (or which he and other physicists are unaware of) is that his inequalities are just George Boole's inequalities for checking if data is being modeled correctly by random variables - if the data violates the inequalities it means your variables are chosen inconsistently. The obvious flaw in this case is the ignoring of the fact that the X, Y and D are not properties solely of the particles in the pair but of the combination of particles and detector configuration. The particles are not little balls but a phenomenon spread over space as represented by the wave function, including the region of space connecting the detectors and the wave function is altered by alteration of detector configuration. Even in delayed choice experiments alteration of the wave function occurs within relativistic constraints.

[QuicksilverSG]

The point at which the spin of the entangled particles is determined is when the wave-function of the measurement device becomes entangled with the wave-function of the particles. It doesn't matter which particle is measured because both entangled particles share the same wave-function. The crucial point to understand is that these wave-functions don't manifest in physical space-time, they propagate instantaneously throughout Configuration Space, a complex-valued domain of potentially limitless numbers of dimensions where the wave-function is defined. No information is transmitted between particles in physical space-time, all entangled particle properties derive from their entanglement with the measurement device. What we observe in relativistic space-time is the quantum mechanical projection of events that evolve deterministically in Configuration Space.

[BarryKort]

In the derivation of Bell's Inequality, he posits a presumptive hidden variable, λ(x, t). One member of the twin particles has a position +x at time t, while the twin has a position -x at time t. But note that Bell blithely adopts a common master clock, t, so that λ(x, t) can be algebraically canceled out by λ(-x, t), regardless of the function λ(•).

If you appreciate that a gravitational gradient perturbs timekeeping so that the particles speeding off in opposite directions age at their own idiosyncratic rates, then one can no longer algebraically cancel out λ. The derivation of Bell's Inequality breaks down; the presumptive hidden variable λ(x, t) remains present. Indeed one can say the hidden variable is time itself. That is, in reality, each particle ages according to its own local clock, rather than being governed by a common master clock.

In Aspect's experiment, λ(x, t) could be Maxwell's Equation for the photon, or (equivalently) Feynman's rotating vectors. But recall that photons traversing a gravitational gradient gain or lose energy and thus change their wavelength (or color) accordingly. The two photons are thus represented by sinusoids which are not perfect mirrors of each other and thus cannot be algebraically canceled out. They will have a residual nonzero "beat frequency" which remains present, thus spoiling Bell's convenient cancellation of λ(x, t) midway through his derivation.

That's why Bell's Inequality doesn't hold in the real cosmos where there is no universal master clock that keeps identical time everywhere and everywhen.

The not-so-hidden variable is time, itself.

[marveloussoftware]

Its not "something is wrong with the rules of logic as we understand them." Its simply because some of our assumptions are wrong. Its amazing how humans seldom think they could be wrong. When most of the time when we find things to be illogical or weird its because our beliefs, interpretations or assumptions are wrong.

[ahmadfodeh]

now i understand and dont understand both at the sametime, so without observers i cant make up my mind, but when someone asks me i instantaneously make up my mind that i don't understand it :)

[BarryKort]

In the opening animation, the spin axis is depicted as a fixed direction in space. But suppose the spin axis is precessing around that mean direction. Then, the instantaneous spin direction is time-varying, with a mean direction that is fixed. Now, when the particle passes through the detector, the outcome will depend randomly on how much the orientation of the detector varies from the mean spin direction. Sometimes, the particle's instantaneous spin direction will lean beyond the 90° mark, thereby giving an otherwise unexpected measurement.

Moreover, this notion of a time-varying hidden variable throws a monkey wrench into Bell's derivation. Where Bell comes to the point where his presumptive hidden variables perfectly cancel out, we now end up with a non-vanishing "beat frequency" due to the fact that time-keeping is not uniform for all locations in space. The violation of Bell's Inequality is to be expected for time-varying hidden variables, given that each particle is governed by its own idiosyncratic clock, rather than by a common universal clock that keeps the same time everywhere and everywhen in the cosmos.

[addyad_yt]

I feel so sleepy because of the pace of the video and the soothing background piano music

[BR-hiyt]

The reason you get a sine wave is that you cannot DETECT the particles spin without error. Its the inherent DETECTION error that makes it a sine wave.

[PremVijayVelMani]

Double likes. Now I can understand EPR paradox without understanding the hidden variable of bell inequality.
Actually I watched this when it was released but now again I watched to understand more deeply.
I request for videos explaining different interpretations of quantum in more detail. Thank you.

[Daniel-fvff]

Once again this channel seems to be the only one that can actually explain what's going on from first principles.