The phenomenon of quantum entanglement is a situation in which information between two subatomic particles is transferred in a manner that seems to be instantaneous (faster than the speed of light). Einstein referred to it as "spooky action at a distance". Scientists from the Institute for Quantum Computing (IQC) at the University of Waterloo are saying they have demonstrated for the first time that three subatomic particles can be entangled.
Although interesting I don't consider this to be the most significant aspect of their work. What I consider to be the most significant aspect of their work is that it reinforces the results of many other quantum entanglement experiments that indicate faster than light travel of information (though not of matter) on the quantum level is possible. (The implication is that at least something can travel faster than light.) Of tremendous interest to me is that the question of how the information is transferred remains unanswered.
The articles below elaborate. The first is about the nature of quantum entanglement. The next two are about an experiment done only a year ago (March 2013) on whether quantum entanglement indicates faster than light travel. It was done by a team of researchers led by Professor Juan Yin at the University of Science and Technology of China in Shanghai. The results supposedly indicate that quantum entanglement involves travel of information on the quantum level at a speed of at least 10,000 times that of light. The last is about the recent demonstration that three subatomic particles can be entangled.
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That would lend credibility to all those alien sightings. I'm not a bit surprised that there is such thing as faster than the speed of light.
By the way, keep 'em coming, John. I almost never comment on these, because I don't have anything interesting to add, but I read every single article you post to the group, via discussion post.
Me too. I read the lot John, but I am usually too busy with a stream of deadline projects to get involved.
To both of you - I'm glad you appreciate it.
Quantum entanglement does NOT contradict the theory of relativity. Quantum mechanics has been fully integrated with special relativity (relativity without gravitation).
When the state of an entangled particle is "measured", the outcome is random.
Yes, "measuring" the state of an entangled particle also "measures" the state of the particle it's entangled with. But the outcome of that measurement is also random.
No information is transmitted, only randomness. Causality is limited in relativity by the speed of light. But because no information is transmitted, entangled particles don't violate this limit on causality.
This does not mean that people might be able to travel faster than light. People contain information, and information can't travel faster than light.
Per Wikipedia -
Measurements of physical properties such as position, momentum, spin, polarization, etc. performed on entangled particles are found to be appropriately correlated. For example, if a pair of particles is generated in such a way that their total spin is known to be zero, and one particle is found to have clockwise spin on a certain axis, then the spin of the other particle, measured on the same axis, will be found to be counterclockwise.
That certainly doesn't imply to me that two entangled particles are in random states relative to each other. It very much seems to imply that they are in an entangled state with each other.
if entanglement is consistent with relativity then why did Einstein refer to it as "spooky action at a distance"?
Because it's spooky :)
Here's a physics website addressing the entanglement + special relativity "paradox" - saying the same thing.
The information about what changes were made to the first particle reaches the second at a speed faster than that of light.
No - because changes aren't being made to the first particle. The state it ends up in is random.
Yes, the states of particle 1 and particle 2 are correlated - for example, they might be correlated such that they have opposite spins.
However, since particle 1 goes into a random state, particle 2 must be in the opposite random state. No information is transmitted.
The Star Trek transporter that sends people from one place to another faster than the speed of light, is impossible because there's information in people.
You are bringing up a "paradox" that was resolved a long time ago. I saw a discussion of it, about 15 years ago. Quantum mechanics has been fully integrated with special relativity.
And I don't disagree with what Wikipedia says (Wikipedia has a lot of errors but I didn't see anything wrong in your quotes).
It's a slightly subtle point, that's all, and you didn't understand it.
In fact, in special relativity, when two events are separated by a faster-than-light interval - their relative time depends on how the observer is moving!
You can find a velocity such that an observer moving with that velocity would see those two events happening simultaneously.
You can also find a velocity such that an observer moving with that velocity would see event A happening BEFORE event B.
You can also find a velocity such that an observer moving with that velocity would see event A happening AFTER event B.
Because of this, it doesn't MEAN anything in special relativity, to say "when particle A's state changes, particle B's state instantly changes".
It isn't correct to think of a signal being "transmitted" between the particles. If you think of it that way, maybe A "sends a signal" to B according to one observer. According to another observer, B "sends a signal" to A.
The speed of light is still the "speed limit" for the transfer of information.
the phenomenon of entanglement suggests that faster than light travel on the quantum level is suggested from John Doe's point of view and, if it exists from his point of view, it would represent a contradiction of relativity.
Could you show me an example of how you believe that quantum entanglement could result in information being transmitted faster than the speed of light?
Here is a precise setup:
Two particles are created, so that they have a total spin of zero, but the spin of each individual particle is unknown. Then the particles fly apart.
So if you measure the spin of particle A in the up-down direction, and particle A turns out to have spin up, then we know that particle B has spin down.
Please explain in what way this transmits information faster than the speed of light.
Please answer my question above.
I am trying to get you to think for yourself. You think in some vague way something is transmitted faster than light. Explain, exactly.
I have already tried to explain to you and it didn't work. All I've heard back has been derogatory comments from you.