Physicists spooked by faster-than-light information transfer

[FordPrefect]

...interesting! No wait ...confusing!


http://www.nature.com/news/2008/080813/full/news.2008.1038.html

 

[ar81]

What if it was the same proton in two different places?
There would not be FTL then. You would have a wormhole or an Alcubierre field phenomena.

 

[Artlav]

Hm.
Who said they got cause and effect right?

 

[Urwumpe]

Even more important: HOW did they measure this?

 

[ar81]

Even more important: HOW did they measure this?

They observed quantum walkie-talkies... :rofl::rofl:

 

[willy88]

That's just messed up. :blink:

That's one small step for a photon, one gigantic leap for photonkind?

 

[MajorTom]

The photons must have been the bearers of Bad News, which may well travel FTL.

 

[movieman]

...interesting! No wait ...confusing!

Not really; there's nothing 'spooky' about any of this, people just use non-relativistic quantum mechanics and then act surprised when it allows things to travel faster than light. If you want to eliminate faster than light information transfer then, oddly enough, you need to use relativistic quantum mechanics.

Google 'Transactional Interpretation' sometime and you shouldn't be confused anymore. The only 'spooky' thing is that any scientists still think there's anything odd going on here.

 

[bujin]

What if it was the same proton in two different places?
There would not be FTL then. You would have a wormhole or an Alcubierre field phenomena.

Or the same photon viewed from two different angles? The photons could be connected through higher dimensional space, but because we can only "see" in three dimensions, it looks like two different photons.

This is the description of quantum entanglement given in Michael Talbot's "The Holographic Universe" book, which analogises* it as two video cameras looking at a fish in a tank, one from the front and one from the side. The feeds of both cameras go to separate locations and appear to be of two different fish, but when the fish on one video moves, the fish on the other video moves at exactly the same time.

That's not to say I believe this interpretation, but it is a nice way of thinking about it.



* did I just make up that word, or does it really exist? :huh:

 

[Jarvitä]

Summary:

Einstein: A particle with mass may not travel faster than the speed of light. A particle without mass may only travel with the speed of light in its current environment.

Quantum physicists: ...maybe.

On the other hand, maybe in a few decades people who still swear by Newtonian dynamics and the laws of general and special relativity will be seen as the new flat-earthers.

 

[Kyle]

Now we know we can go faster than light, if theirs a will theres a way.

 

[spcefrk]

So why not keep one photon running in a loop and send the second down the fiber?

 

[Messierhunter]

Why wouldn't it be possible to use this effect for instantaneous communication between two distant points in space? Or would it?

 

[Urwumpe]

Why wouldn't it be possible to use this effect for instantaneous communication between two distant points in space? Or would it?

Well, the energy would still have to transfer limited by the speed of light. Maybe you can first establish a relativistic communication line and then use such FTL transfer of information. But still, I have doubts that the experiment showed a real FTL transfer of information. Some more tests of the experiment would be needed to be sure and find a practical use.

 

[movieman]

Why wouldn't it be possible to use this effect for instantaneous communication between two distant points in space?

Because there's no control over the 'information transfer'. Typically you send out two particles with correlated states (e.g. one has spin up and one spin down); you don't know which one is spin up until you measure the state, but once you measure that state you immediately know that the other is spin down.

You can't control the state of the particle you measure, and the only 'information transfer' occurring is inside your head. The whole thing is massively overblown.

 

[Messierhunter]

Because there's no control over the 'information transfer'. Typically you send out two particles with correlated states (e.g. one has spin up and one spin down); you don't know which one is spin up until you measure the state, but once you measure that state you immediately know that the other is spin down.

You can't control the state of the particle you measure, and the only 'information transfer' occurring is inside your head. The whole thing is massively overblown.

So because you can't force the wave function to collapse in a desired way you can't send any information with it? Now to expose my complete lack of quantum mechanical understanding, I know I read somewhere that you can force light to act as either a wave or a particle given certain setups - if you force an entangled particle to act a certain way can't you force the antiparticle to act a certain way simultaneously as well?

 

[movieman]

So because you can't force the wave function to collapse in a desired way you can't send any information with it?

Yes. A wave function is just a complex means of saying 'you can't tell what state a particle is in until you look at it' in mathematics; and the Transactional Interpretation is just an even more complex means of saying 'you can't tell what state a particle is in until you look at it, but it's always been in that state since the last interaction' in mathematics.

You can't change the state of the particle, you can only see what state it was in. The 'information transfer' occurs inside your head when you imply the state of one particle from the state of the other.

 

[spcefrk]

So because you can't force the wave function to collapse in a desired way you can't send any information with it? Now to expose my complete lack of quantum mechanical understanding, I know I read somewhere that you can force light to act as either a wave or a particle given certain setups - if you force an entangled particle to act a certain way can't you force the antiparticle to act a certain way simultaneously as well?

I don't know that you can consciously change the spin of a particle. Now if you could separate two "entangled" particles and predictably manipulate the spin then (assuming the other particle changes spin direction instantaneously -- read:FTL) you could at least work out 1's and 0's FTL speed.

But I'm with Movieman on this. They didn't appear to show that the spin is itself dependent on some FTL relationship which is crucial to it being used at all for FTL communication.

Disclaimer: Aero Engineer with No Quantum Mech. or Relativity Background other than Thermo 1 and Gen. Chem. ...

 

[Sherrif of Nottingham]

Um... sorry, I know absolutely nothing about FTL stuff, but i'm with Urwumpe, how would you know if it actually traveled faster than light, we can only communicate as fast as light, so I don't see how they got it.

Secondly, could this solve the lagg time with communicating with a mars rover? Or something of that nature?

Imagine, cell phones that worked on the moon... FRIGGEN SWEET!

 

[Imagineer]

It is important to remember that the model is not the thing.

Newton's laws are a mathematical model of ordinary objects traveling at ordinary speeds. His model does not accurately predict the behavior of extreme masses at extreme speeds.

Einstein's general relativity is a more complex mathematical model which more accurately predicts the behavior of extreme masses at extreme speeds.

Quantum Mechanics is a collection of mathematical models developed to predict the behavior of subatomic particles and was originally developed independently of relativity. It is not surprising that some of it's predictions are at odds with relativity.

Putting Quantum Mechanics and Relativity together as a single, unified theory is an ongoing research project.

Newton's laws, Relativity and Quantum Mechanics are all mathematical models used to predict or infer behavior and are not the behavior itself. All of these mathematical models are subject to revision if data comes in that the models do not predict.