Spooky Physics: Signals Seem to Travel Faster Than Light

[Michaelangelica]

Strange News

Spooky Physics: Signals Seem to Travel Faster Than Light

 

By Charles Q. Choi, Special to LiveScience

 

posted: 13 August 2008 01:01 pm ET

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Strange events that Einstein himself called "spooky" might happen at least 10,000 times the speed of light, according to the latest attempt to understand them.

 

Atoms, electrons, and the rest of the infinitesimally tiny building blocks of the universe can behave rather bizarrely, going completely against the way life as we normally experience it. For example, objects can sometimes be said to exist in two or more places at the same time, or spin in opposite directions simultaneously.

 

One consequence of this murky realm of quantum physics is that objects can get linked together, such that what happens to one instantaneously has an effect on the other, a phenomenon dubbed "quantum entanglement." This holds true no matter how far apart these objects are from each other.

 

Einstein rebelled against the notion of quantum entanglement, derisively calling it "spooky action at a distance." One could instead argue that an entangled object releases an unknown particle or some other signal at high speeds to influence its partner, giving the illusion of a simultaneous reaction.

 

In the past, experiments have ruled out any suspects for such hidden signals from the realm of classical physics. Still, one exotic possibility remains — that such x-factors instead travel faster than the speed of light.

 

To investigate this possibility,

 

Spooky Physics: Signals Seem to Travel Faster Than Light | LiveScience

[Moontanman]

Strange News

 

 

Spooky Physics: Signals Seem to Travel Faster Than Light | LiveScience

 

Isn't this really just a case of the particles being synchronized together at the start and when they are measured apart you know what each is because you knew what they were at the start? kinda like two watches being set to the same time and then when they are miles apart you know what one watch is due to it's already known relationship with the other watch. No real communication between them?

[Boerseun]

I don't think there's anything inherently "spooky" about quantum entanglement.

 

I also don't think there's any sort of "magic particle" that is beamed from the one to the other at 10,000 the speed of light. Imagine an entangled pair, one in Europe and the other in the US, say New York. If something were to change to the European particle, and it had to send off its "magical beyond-light speed message" to the other particle, how can it know where to beam the info? Or does the superluminal information radiate in a sphere from the originating particle? Which means the entire universe would be filled with these magical particles?

 

No - rather, entanglement to me points to a higher dimension.

 

Imagine, we know that travel faster than light is impossible. But only in any given dimension. Say, for instance, we have two entangled particles. We can increase the distance between them in the three dimensions we're used to, and they are still right next to each other in the fourth dimension, literally touching. Then, if something happens to the one, the change which is propagated at what appears to be a superluminal speed in the comfy 3 dimensions we are used to, is actually propagated through the fourth dimension, at a speed lower than the speed of light - although it will appear faster in 3D.

 

Imagine a square. Imagine two points on that square, A and B. Imagine the square is 10cm by 10cm, and A and B are 1cm apart. Imagine travelling from A to B at the speed limit as imposed by this square universe, 1cm/second. Now, imagine lifting that square up to find out that its actually a cube, and that A and B is on different sides of the cube, more than 10cm apart. You have travelled that distance in 1 second. Yet, it's ten times faster than what your universe allows!

 

The issue lies with dimensions. And if two entangled particles are light years away from each other, they might still be lying right next to each other in a higher dimension. And the speed, in any given dimension, cannot exceed c, but what dimensions are we talking about, here? Flat squares as in my example, or a higher dimension which isn't immediately visible, as per my example where a square is raised to form a cube?

[dkv]

There is a common notion that particles can not untangle on its own.But I think it is not true.

The particle entanglement can be short lived also.

Short-lived proton entanglement in yttrium hydrides

[Overdog]

Isn't this really just a case of the particles being synchronized together at the start and when they are measured apart you know what each is because you knew what they were at the start? kinda like two watches being set to the same time and then when they are miles apart you know what one watch is due to it's already known relationship with the other watch. No real communication between them?

 

Not exactly...it is more like having two coins in a box, you take one coin out of the box without looking at either of them. Now lay your coin on the table, if it's showng heads, you know the coin in the box is showing tails.

 

The spooky thing is you don't know what they were at the start, or whether you will lay your coin on the table with heads or tails.

 

At least that's the way I understand it...

 

Entanglement is a strange feature of quantum physics, the science of the very small. It’s possible to link together two quantum particles – photons of light or atoms, for example – in a special way that makes them effectively two parts of the same entity. You can then separate them as far as you like, and a change in one is instantly reflected in the other. This odd, faster than light link, is a fundamental aspect of quantum science – Erwin Schrödinger, who came up with the name “entanglement” called it “the characteristic trait of quantum mechanics.” Entanglement is fascinating in its own right, but what makes it really special are dramatic practical applications that have become apparent in the last few years.

The Strange World of Quantum Entanglement

[Boerseun]

Yes. I know. Every devil needs an advocate, so I'll be it.

 

Please bear me out for a second:

 

The essence of the quantum mechanical "spookiness" boils down to Schroedinger's Cat. You chuck a cat in a box with poison, and you won't know if the cat is dead or alive until you open the box and look. Quantum mechanics hold that the cat is both dead and alive until you measure the poor pussy's fate.

 

Same with entangled pairs.

 

Let's say I have two bricks. We don't know what colour the bricks have been painted, but we do know that they are painted the same colour. The fact that they are painted identical is one thing we know for sure. We just don't know which colour. Quantum mechanics, in this case, will have you believe that the bricks are all the colours of the rainbow until we inspect it, in which case the "probability wave" collapses and the bricks take on a specific colour.

 

So now we separate the bricks. Lets say we launch the one to Jupiter, and keep the other one under a black cloth in our laboratory on Earth. Remember, nobody has ever seen either of the bricks, but we do know that they are the same colour. They are, in the QM vernacular, "entangled". So our lonely space-brick arrives at Jupiter. And back home on Earth, in front of hundreds of inquisitive eyes we yank the cloth of our brick. It turns out the brick is painted a bright green. According to QM, the brick in orbit around Jupiter immediately, *magically*, turns green. The "information" about it's earth-bound partner's greenness travelled from Earth to Jupiter instantaneously.

 

Which is bullshit, of course.

 

And its bullshit because we knew for a fact that they were both the same colour, we just didn't know what colour. We could have checked either one of them for that particular property, and then knew for a fact, instantaneously, what the other brick's colour would be. Fact is, no "signal" magically travelled between the bricks which determined this particular property. We, the observers, simply deduced the property of the other brick by applying what we know of the one to the other, because we know they are the same colour.

 

And our deductions in this regard have nowhere, anywhere, broke the speed of light.

 

If you have two particles, and they both have an identical property, whatever it might be, then of course you'll instantly know the property of the one by measuring the other - regardless of the distance between them.

 

What am I missing here?

[Thunderbird]

What about paired positive negative effect at a distance. Changing the charge of one and having it effect the other instantly at a distance. It does not appear to me that any thing "traveled" the distance it appears that on the quantum level things are connected, or balanced, or are essentially one. This ties in with super position, particles being in two places at once. If you really take Boehm's theory of wholeness to hart this so called phenomenon are not spooky at all. What you are left with is that how then are we observing this complexity of things in time in space. This to me becomes the real mystery.

[Overdog]

Here is how Schrödinger put the puzzle in the first part of his two-part article (Schrödinger, 1935; p. 559):

 

Yet since I can predict either x1 or p1 without interfering with the system No. 1 and since system No. 1, like a scholar in an examination, cannot possibly know which of the two questions I am going to ask first: it so seems that our scholar is prepared to give the right answer to the first question he is asked, anyhow. Therefore he must know both answers; which is an amazing knowledge; quite irrespective of the fact that after having given his first answer our scholar is invariably so disconcerted or tired out, that all the following answers are ‘wrong.’

What Schrödinger showed was that if two particles are prepared in a quantum state such that there is a matching correlation between two ‘canonically conjugate’ dynamical quantities — quantities like position and momentum whose values suffice to specify all the properties of a classical system — then there are infinitely many dynamical quantities of the two particles for which there exist similar matching correlations: every function of the canonically conjugate pair of the first particle matches with the same function of the canonically conjugate pair of the second particle. Thus (Schrödinger, p. 559) system No. 1 ‘does not only know these two answers but a vast number of others, and that with no mnemotechnical help whatsoever, at least with none that we know of.’

 

Schrödinger coined the term ‘entanglement’ to describe this peculiar connection between quantum systems (Schrödinger, 1935; p. 555):

 

When two systems, of which we know the states by their respective representatives, enter into temporary physical interaction due to known forces between them, and when after a time of mutual influence the systems separate again, then they can no longer be described in the same way as before, viz. by endowing each of them with a representative of its own. I would not call that one but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought. By the interaction the two representatives [the quantum states] have become entangled.

He added (Schrödinger, 1935; p. 555)...

 

...Attention has recently been called to the obvious but very disconcerting fact that even though we restrict the disentangling measurements to one system, the representative obtained for the other system is by no means independent of the particular choice of observations which we select for that purpose and which by the way are entirely arbitrary. It is rather discomforting that the theory should allow a system to be steered or piloted into one or the other type of state at the experimenter's mercy in spite of his having no access to it.

 

In the second part of the paper, Schrödinger showed that, in general, a sophisticated experimenter can, by a suitable choice of operations carried out on one system, ‘steer’ the second system into any chosen ‘mixture’ of quantum states. That is, the second system cannot be steered into any particular state at the whim of the experimenter, but the experimenter can constrain the state into which the second system evolves to lie in any chosen set of states, with a probability distribution fixed by the entangled state. He found this conclusion sufficiently unsettling to suggest that the entanglement between two separating systems would persist only for distances small enough that the time taken by light to travel from one system to the other could be neglected, compared with the characteristic time periods associated with other changes in the composite system. He speculated that for longer distances each of the two systems might in fact be in a state associated with a certain mixture, determined by the precise form of the entangled state...

 

...Bell looked at entanglement in simpler systems than the EPR case: matching correlations between two-valued dynamical quantities, such as polarization or spin, of two separated systems in an entangled state. What Bell showed was that the statistical correlations between the measurement outcomes of suitably chosen different quantities on the two systems are inconsistent with an inequality derivable from Einstein's separability and locality assumptions — in effect from the assumption that the correlations have a common cause.

 

Bell's investigation generated an ongoing debate on the foundations of quantum mechanics. One important feature of this debate was confirmation that entanglement can persist over long distances(see Aspect et al.), thus falsifying Schrödinger's supposition of the spontaneous decay of entanglement as two entangled particles separate. But it was not until the 1980s that physicists, computer scientists, and cryptographers began to regard the non-local correlations of entangled quantum states as a new kind of non-classical resource that could be exploited, rather than an embarrassment to be explained away...

Quantum Entanglement and Information (Stanford Encyclopedia of Philosophy)

[freeztar]

I found this link on quantum nonlocality interesting.

 

I also found the following article which talks about quantum entaglement in time. :hyper:

http://arxiv.org/PS_cache/quant-ph/pdf/0402/0402127v1.pdf

[Moontanman]

So far I am not impressed with the whole spooky action at a distance thing. The idea about the colored bricks seems to explain the whole thing quite well. What am I missing here?

[Overdog]

So far I am not impressed with the whole spooky action at a distance thing. The idea about the colored bricks seems to explain the whole thing quite well. What am I missing here?

 

Maybe the fact that you actually get to determine what color the remote brick will be, from a distance, apparently instantaneously?

[Moontanman]

Maybe the fact that you actually get to determine what color the remote brick will be, from a distance, apparently instantaneously?

 

I don't follow you, isn't that exactly what you are doing with ther particles? At the beggining you don't know what the spins are but you know if one has a certain spin then you know what the other one is!?

[Overdog]

I don't follow you, isn't that exactly what you are doing with ther particles? At the beggining you don't know what the spins are but you know if one has a certain spin then you know what the other one is!?

 

It's more complicated than that. Quantum state is transferred. Check out this article...

 

Quantum teleportation - Wikipedia, the free encyclopedia

 

Edit:

 

Here's another article...

 

In the October 23 1998 issue of Science, the physicists described how they used squeezed-state entanglement to teleport light. In previous teleportation experiments (announced over the last year by separate research groups in Austria and Rome), only two-dimensional discrete variables (e.g. the polarization states of a photon, or the discrete levels of a two-level atom) were teleported. In this recent experiment, however, every state, or the entire quadrature phase amplitude, of the light beam was teleported. In the Science article, the researchers explain that teleporting optical fields may someday be appropriate for the use in communication technology.

 

First quantum teleportation between light and matter

 

If it were just spin, the brick analogy might hold up...

[Moontanman]

It's more complicated than that. Quantum state is transferred. Check out this article...

 

Quantum teleportation - Wikipedia, the free encyclopedia

 

I hate to appear dense but this just seems to be a fancy obfuscation of knowing the possible states before hand and knowing what they are after because you already know the possibilities. IE the bricks are the same color but you don't know what color until you look at one of them. No matter how far apart they are looking at one allows you to know the other.

[freeztar]

It's not just about starting states. If you colored the Earth-brick yellow, the Jupiter-brick would instantly turn yellow.

[Moontanman]

It's not just about starting states. If you colored the Earth-brick yellow, the Jupiter-brick would instantly turn yellow.

 

Then you would have communication of information faster than light:naughty:

[Overdog]

Maybe this one will explain it better...

 

Beam Me Up Scotty? A Q&A about Quantum Teleportation with H. Jeff Kimble: Scientific American