Home Discussion Forum Can anyone explain Quantum Entanglement?

Can anyone explain Quantum Entanglement?

Apparently Quantum Entanglement has been demonstrated again in Geneva. This would perhaps show that information travels faster than the speed of light.
And as aside: If one understood the atom, would one understand the universe?

5 COMMENTS

  1. It’s important to understand that so-called quantum entanglement — aka “spooky action at a distance” — only occurs in the quantum realm, which is at spatial dimensions smaller than 1.6^ minus 35 meters. It’s in this dimension that Einstein’s proscription against faster-than-light travel don’t *seem* to apply.
    In its simplest example, an identical pair of subatomic particles like electrons are separated by any distance, presumably even by light years. Whatever change is made to one particle will instantaneously happen to its twin particle. That, as you point out, suggests information is somehow moving through space faster than light.

  2. i read an article about this from Scientific American about a year ago
    (((and SWEET i just found a link so you can read it for free if youre interested)))
    the gist of it was that they took two photons (((at least im pretty sure it was photons))) and gave them the same quantum state and they did something to one of the photons and (((because they were the same because they occupied the same quantum state))) the same thing happened to the other photon and there was this instantaneous transfer of information (((instantaneous…obviously faster than the speed of light))) because the 2 photons are essentially the same, so anything that happens to the first would HAVE TO happen to the second….it still makes my head spin a bit too if that confused you 🙂
    If one understood the atom would one understand the universe? lol we’d like to think so, wouldnt we? probably not though, the universe is kind of sort of a complex place (((sense the mild, friendly sarcasm)))

  3. Q1: Yes. But not simply.
    >This would perhaps show that information travels faster
    >than the speed of light.
    Emphatically, “no”.
    Information cannot be sent through an entangled system, read up on the EPR paradox, Bell’s inequality, and the many experiments which have demonstrated the absence of hidden variables or non-local *information carrying* links.
    Entanglement is not as simple as ‘do something to one particle and the other one responds, no matter where it is’.
    >If one understood the atom, would one understand the universe?
    No.
    An atom is a very small and simple thing.
    The Universe has neither of those properties.

  4. Let me clear up a few things. First off, entanglement does not only happen on some tiny distance scale as others have suggested. It can happen on macroscopic distance scales as well. What is more important is the energy of the system and the isolation of the system. Most objects have far too much energy and are far too poorly isolated to exhibit entanglement. But some low energy, well isolated systems can be quite large.
    Entanglement can not be used to transfer information faster then the speed of light. jcrg is right about that. But, he is certainly wrong to say that entanglement can not be used to transfer information, it just does it as fast or slower than the speed of light. Quantum teleportation is an example of using entanglement to transfer information and this idea is used in Quantum Key Distribution and other quantum cryptography applications.
    So, to answer your question, entanglement does, in a way, convey some part of the information instantaneously. But to be of any value, this MUST be accompanied by a corresponding piece of information that takes a classical route between the entangled particles. That classical route can not be traveled any faster than the speed of light. In a general way, the idea is that you can get the information instantaneously, but you wont know what it means and will have no way of using that information until that classical information makes it to you. And many would argue that information that can not be used is not information at all. This gets around Einstein’s relativistic arguments because it this entanglement can not be used to TRANSFER information between two points without a corresponding, much slower, accompanying piece of information.
    And, to answer your question about what exactly is entanglement, it is when you have two objects, each of which have quantum states, and the total quantum state of the 2-particle system can not be separated into out into the 2 independent particles. This means the states of each particle is linked to the state of the other particle. If you want to know more, I suggest a book or a class on the subject. It is not really something that can be explained in a paragraph.

  5. This forum consists of only a handful of real physicists and astronomers, so from now on you would be better suited asking real physics forums.
    Study Bell’s theorem and how Dirac aether may be a solution.

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