communication at 100000 times the speed of light

thephantom114 said:
So for example Photon 1 at point A changes from a sphere shape to a cube and Photon 2 at point B changes at the same time with no reasonable explanation?
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Yes. Although photons are points with no physical mass so they have no shape ;D
 
Greenlizard0 said:
^

Ok. Kind of interesting. I still have a copy of Steven Hawkins' "A brief history of time" to read through.
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I'd advise you not to read this, but to read some of Richard Feynman's books instead, particularly QED; they're vastly more readable and informative.

Amleto said:
This is either old, old news, or the reporter did a bad job explaining what the new thing was here.
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That's what I was thinking; entanglement's been known about for decades :confused:
 
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Even if there was any "communication" between the two photons, there is still no obvious way to use that to transmit information. Usually they measure the spin of particles in these experiments, in an entangled pair one will always be up the other down. The actual state of either is indeterminate until measured (not just unknown, think schrodingers cat, wave function collapse), once one has been measured, you will know the spin of the other.
But like someone else said above, they've known this for a long time, I'm missing what's new about this one, maybe the distance?
 
starfighter said:
Anyone know what they mean by "they found that the particles could instantly sense the other´s behavior"

So there was communication, but what kind exactly, the properties of one photon change in a particular way depending on the direction/speed of the other one? wouldnt you need to do lots of expermients and look for a pattern?

Also how do they "entangle" them as such, it isnt just 2 random photons I assume.
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In quantum mechanics, certain properties of tiny elementry 'particles' (like photons) are indeterminate until they are "collapsed" into a particular state. If two particles are simultaneously collapsed into a state where one depends on another (ie they are entangled), then what happens to one particle must in some sense happen to another - no matter how far apart they become after they are entangled.

For example, imagine a pair of electrons. Electrons have a property of spin; either 'up' or 'down'. If I entangle a pair of electrons one will of spin 'up' and the other 'down'. If I were to change the spin of one electron, the spin of the other electron would also change instantaneously - no matter how far away it is. In theory the particles could be light years apart, but in practice we've so far managed to recreate the phenomenon over a matter of miles.

You can see why Einstein had a problem with this - it seems like information is being transferred between the particles at faster than the speed of light, which violates relativity. However it's possible that it's more than that - the first and second particle are somehow "destined" to switch at the same time, when they become entangled (breaking the 'localism' and 'realism' assumptions).

Quantum mechanics describes, through its basic governing principles, the way in which entanglement occurs. But we still don't fully understand WHY such a thing should occur. We will need a deeper unifying theory to determine that - something like string theory which relies on more than just the 3+1 dimensions we see. To quote Richard Feynman: "Nobody really understands quantum mechanics"
 
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So erm..

They are taking a glass of lemonade, and a glass of limeade

They mix them together equally, but dont check them

They send them to 2 different tables for testing.

Table A says this is Lemon and lime

Table B says this is Lemon and lime..


OMG THEY ARE COMMUNICATING!!!

Or am i missing something here?
 
Imagine that when they get to the tables one is blue and one is red,

Lets say you can add a dye to the blue one to make it red, then right across the restaurant the red one suddenly turns blue at the same time you turn yous red.
 
Tefal said:
Imagine that when they get to the tables one is blue and one is red,

Lets say you can add a dye to the blue one to make it red, then right across the restaurant the red one suddenly turns blue at the same time you turn yous red.
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If that was the case, then that would be a perfect medium for communicating binary data.

yet, they haven't done that yet..

Odd.

Also to further my point, wasn't there something about, you cant do X because it will untangle said particles..
 
Actually they aren't binary, they are --- 0 or indeterminate/unmeasured/unknown or 1 iirc

3 possible positions, and its also takes quite a bit of kit to flip them iirc.
 
Angleboy said:
If that was the case, then that would be a perfect medium for communicating binary data.

yet, they haven't done that yet..

Odd.

Also to further my point, wasn't there something about, you cant do X because it will untangle said particles..
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Tefal's analogy is a good one :)

It's not 'odd' that this hasn't been utilised yet - read into quantum computing. Entanglement is at its very core. The most basic of quantum computers has already been produced, but it will likely be decades before the technology is ready for wide spread adaptation.

Knowing something in theory, and being able to prove its existence, is a long way away from being able to implement it in a useful manner.
 
yak.h'cir said:
I thought all photons had spin 1, it was just the direction that changed...
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sub-atomic particles can have positive or negative spin. and depending on the type of particle it can be integer spin or half integer spin, ie. -3, -2, -1, +1, +2, +3 or -2.5, -1.5, -0.5, +0.5, +1.5 etc.

The problem with using entanglement to communicate is because, as others have said, the process of measuring the spin collapses the wave function... which means, that before the spin of the particle is measured, we do not know what it is. So particle A has a property of spin, either +1, or -1 for simplicity, and particle B has the opposite spin to particle A. However we do not know which one is +ve and which one is -ve. When we measure particle A it then has a known spin, and we know what the spin of B is.... great - so you'd think we could now change the spin of A, and then that change would be seen in B? Well, not really, since whenever we are NOT measuring the spin, we don't know what the spin is. It doesn't matter if you measured it half a microsecond ago, it could be doing anything now - in fact, according to our best understanding of quantum mechanics, the particle may now be a house in the Yorkshire Dales since we cannot say anything at all about it while we are not measuring it. Measure it again and it's spin may be different just because... because why we don't understand yet.

So although action at a distance is indeed a real phenomena (which has been known about for decades as others have said), there is currently no real viable way of using it for communications...

Now, i'm gonna read that article and see if something new has cropped up to make me eat my words ;P

edit: For the record, anyone wondering how they can do the experiment if it's not yet useful for communications... They made the measurements 18km apart from each other, and then had to use standard methods of communication (whether that's intarwebz or the post office) to compare data and see that the two particles did indeed display this behaviour...
 
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dodgem said:
sub-atomic particles can have positive or negative spin. and depending on the type of particle it can be integer spin or half integer spin, ie. -3, -2, -1, +1, +2, +3 or -2.5, -1.5, -0.5, +0.5, +1.5 etc.
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I'm aware of this I just remembered something about photons being gauge bosons with spin 1. This was standard model but I don't believe this experiment has any results outside of this model.
 
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