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Quantum Entanglement Drives the Arrow of Time

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Re: Quantum Entanglement Drives the Arrow of Time

#51

Post by cgio »

softatlas wrote: post #13

The rate of information increases. Hence why Information wants to be free. Parasitic on Only information explains its own existence. Which all, I think, intuitively follows from Spinozist/Cartesian "Conatus" principle. That is to say: The order and connection of ideas is the same as the order and connection of things. Some of us rave about this or that: "well, how many folk use X today" or "qualify as X" or "subscrib…

I have the sense there is something you are trying to say, but I cannot know what the dimensions of proportionality can be. I can see why you assign frozen temporal localities to property assignment but I think there is some confusion in your argument between information as perceived and information as signaled.

Re: Quantum Entanglement Drives the Arrow of Time

#52

Post by sinesha »

yati wrote: post #43
sinesha wrote: post #37

Earlier quoted context omitted.

1. When you tell me the result 6296, my brain becomes only classically correlated with it, not entangled. The source of randomness (whether you got it through a quantum experiment or not) does not matter here, as I am only receiving the classical information. 2. After I forget it completely, all I can say is that I (my current body) am not correlated with the event --- but there is no reason to think of the event as…

When you say you receive classical information as the outcome of that experiment, what's an example situation in real life when you receive quantum information and do indeed get entangled with it (I mean if at all such a situation ever arises)?

"real life" as in "they can do it for real in a lab": Alice has two photons, applies a quantum operation to them so that they become entangled, and gives one to Bob. Bob received "quantum information" from Alice. They can use this resource (entanglement between the photons they own) to perform several tasks now, like "teleportation" of the state of a particle, or secure key distribution.

Re: Quantum Entanglement Drives the Arrow of Time

#53

Post by throwaway7548 »

aaren wrote: post #47
throwaway7548 wrote: post #44

Earlier quoted context omitted.

Can't I? What if the state of these poor remaining neurons and the body is scanned, encoded as polarization of a bunch of photons and sent to a receiver far far away? In that case good old environment would definitely end up behind the cosmic horizon.

Then you have implemented teleportation and we have new problems to think about!

Oh. Common. No need for any new inventions.

Just replace a person [that gets entangled with a particular outcome of a random event (have measured it)] with a simpler organism, say a dog. Or a hamster. Or with a roomba vacuum cleaner ;). Or even with a computer. And we definitely know that a state of a computer can be represented as a bit string encoded on any media. Including polarization of a bunch of photons.

Re: Quantum Entanglement Drives the Arrow of Time

#54

Post by oofabz »

salimmadjd wrote: post #16

Seeing this article is rather bittersweet. I came to a similar conclusion in my college years but I never pursuit it further. Taking Quantum Physics in college was a life changing experience and it reshaped how I viewed the world. I was always obsessed by time and one afternoon it became clear. I explained my variation not as a cup of coffee but a handful of dice. Essentially every tick of time is rolling these dice.…

> variation of dice from one combination to the next is the arrow of time

How can a sequence of random numbers introduce a preferred direction? Randomness has the same properties backwards and forwards, and random numbers are not dependent on one another.

You are presupposing the arrow of time to explain the arrow of time. You say you roll the dice every tick of time, but what makes the tick? Why does it tick in the direction it does? The dice do not explain such things.

Re: Quantum Entanglement Drives the Arrow of Time

#55

Post by joe_the_user »

dalek_cannes wrote: post #15

Do we need entanglement to explain the Arrow of Time? Even though in classical mechanics, the past and the future are both equally observable, we remember the past and not the future because the future does not contain certain information yet -- the information to be introduced into the universe in the form of quantum fluctuations. One could even argue that all information in the universe was created at some point in…

Well,

Information is produced in the course of a system evolving and information is destroyed (the past is forgotten).

The tendency of a system to move towards greater entropy could be said to give an explanation for the difference between past and future. But how does that work in an open system like the planet earth, where entropy hasn't increased, where the system has self-organized over time.

The ability of a system to store information in only one direction of movement could be the explanation - if we could define that more exactly. But since information is constantly being "created", destroyed and transformed, defining this is a difficult task.

Which is to say the problem as a whole is hard.

Re: Quantum Entanglement Drives the Arrow of Time

#56

Post by jostylr »

millstone wrote: post #31

> After some time, most of the particles in the coffee are correlated with air particles; the coffee has reached thermal equilibrium. No doubt this is some way oversimplified explanation, but it still makes no sense. Say I have hot coffee and lukewarm coffee. The lukewarm coffee will equilibrate faster. Does it interact with the air faster? What if I bring in coffee that's the same temperature as the air, so that it'…

There's also the question of heating up the coffee. Are you disentangling it from the air and entangling it with the hot particles below? It does not make sense to equate equilibrium with entanglement.

We have two systems that have been isolated from each other. Then they get together and get entangled. The number of states in which they have come to thermal equilibrium while entangled is far greater than the number in which they do not.

They are being entangled, but that is just the process of putting the systems together, a necessary step in removing their isolationist tendencies, I would imagine. So entanglement is part of the process, but the classical notion of the evolution going to "more states" is still there.

But going towards equilibrium is more general than isolationist --> entangled. Whatever your state psi is of the system, it is likely to evolve, if it can, into a state that belongs to a more numerous class.

Re: Quantum Entanglement Drives the Arrow of Time

#57

Post by loup-vaillant »

cromwellian wrote: post #3

This Google Talk https://www.youtube.com/watch?v=dEaecUuEqfc uses entanglement and quantum information theory in a clear and understandable way to explain 'spooky' quantum phenomena, like the quantum eraser, de-coherence, the aspect experiment, and the measurement problem. Even if you don't know any QM, just basic algebra and calculus, it's really approachable. I used to be a fan of the Many Worlds interpretation, bu…

I must say, I'm not sure what he even means by this "zero universe" business. Sure, the classical illusion is bust, but the wave function itself, as far as we know, is real, is it not?

While we're at throwing quantum explanation links, here is the Quantum Physics Sequence on Lesswrong: http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ I'd say the math is even simpler there, yet the explanation go deeper. It's a long read however.

Re: Quantum Entanglement Drives the Arrow of Time

#58

Post by trhway »

elzr wrote: post #5

This was surprisingly beautiful. As a geek in programming/computers/information/mathematics, but only a physics admirer from afar, it is very suggestive, even natural, to explain the deepest physical reality in terms of information: "It was as though particles gradually lost their individual autonomy and became pawns of the collective state. Eventually, the correlations contained all the information, and the individu…

>"It was as though particles gradually lost their individual autonomy and became pawns of the collective state.

this and all other reformulations of it can be said simply - increasing entropy.

Re: Quantum Entanglement Drives the Arrow of Time

#59

Post by jostylr »

From a Bohmian perspective, quantum mechanics consists of a wave function psi(q) that guides all the particles Q. The wave function is distinct from the particles. The particles are in equilibrium, relative to the wave function. It is the wave function that is not in equilibrium in its realm of states.

As it turns out, the usual psi^2 probability distribution of the particles is a reflection that the particles are in quantum equilibrium, that is, psi^2 is the natural measure in quantum mechanics for what equilibrium ought to be since it is the only measure preserved by the dynamics. And so if the particles start that way, they stay that way. And they are likely to start that way using psi^2 as the distribution.

There is actually a lot of subtlety involved in accepting that argument; I recommend http://plato.stanford.edu/entries/qm-bohm/#qr and an actual paper: http://www.ge.infn.it/~zanghi/BMQE.pdf

But what it implies is that the wave function is responsible for the arrow of time. It is a special state that evolves into a less special state. Presumably this is what their research is pointing at.

I would also comment that their description is exactly the classical explanation transferred to the quantum world (which it needs to be since our world is quantum). That is, we start in a special state and it evolves into a less special state because the less special states are more numerous and so more likely to be, all things being equal. And by more likely, we are talking 10^100 kind of more likely.

They still have the problem that the fundamental evolution of the wave function is time reversible. So if that bothered someone (it shouldn't), then their argument does not actually resolve that problem.

So I take from their work that what they are doing is getting the classical thermodynamic explanation (which is about volumes in phase space, not human ignorance) and translating it to the quantum theory. Neither wrong nor revolutionary.

Re: Quantum Entanglement Drives the Arrow of Time

#60

Post by neolefty »

From the article

  One aspect of time’s arrow remains unsolved. 
  “There is nothing in these works to say why you
  started at the gate,” Popescu said, referring to
  the park analogy. “In other words, they don’t
  explain why the initial state of the universe was
  far from equilibrium.” He said this is a question
  about the nature of the Big Bang.
Could it be that expansion, which proceeded much faster than light, therefore didn't allow entanglement to take place, delaying the heat death of the universe until everything is fully entangled?

If expansion had been slower, would entropy maybe have kept up with it, leaving us as just a single black hole instead of a dispersed, interesting, unentangled, things-are-still-happening universe 13 billion years later?

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