Spooky action at a distance is faster than light

Re: seriously good research

"Does this indicate Heim theory might not be crackpot ?"

Since the only person who understands Heim theory - Heim himself - is dead, the answer is "No one knows."

Re: seriously good research

One ponders tunneling and its apparent superluminal tunneling.

Now, this.

Why can't information travel at FTL velocity? It isn't matter nor energy, only quantum state.

An examination of this, should it be verified, could yield interesting information about the very nature of space, for there are models that showed superluminal expansion of the universe itself after the big bang.

Well, we'll see. It'll all come out in the wash, as others attempt to replicate this experiment.

Re: Some context ...

Physicists choose (b) because there's no experimental evidence for (a), and plenty of reason (e.g. Bell's inequality) for believing that hidden variable theories don't make sense. (The Bohm-ists have never been able to produce a complete theory that can be tested.)

In (b), there are no 'particles' in any classical sense - there are only probability distributions. Ultimately QM isn't about little bits slapping into other bits, it's about event probabilities.

In fact I suspect there's nothing but probability going on, and reality is just a fog of probability densities which look as solid as clouds do when you fly over them, but have no more substance.

If stop expecting QM to talk about physical things and start thinking about event possibilities, it stops being quite so weird.

Re: It's impossible to send data this way ...

Its impossible to send information FASTER THAN LIGHT, because in order to know whether your measurement ("here") is an encoded 1 or 0, you need to compare it against the other distant measurement ("there"). E.g. if they both are the same, it's "1", if they differ, its "0". So to understand your result, you have to wait for the results from over there to be sent to you here, and that waiting time depends on the speed of light.

Re: I find this stuff fascinating but I'm a total idiot who knows absolutely nothing...

#1 no, the have entangled properties, but the properties are created in the entangled common source. There is no communication ('information transfer') between the particles.

#2 no, think about the two particles as a single two-particle state of matter. The matter wave is as large as the distance of the two particles -- and once you measure a property of the wave at one point, you also know about some properties of the wave at another point.

#3 yes, the world is composed of entangle particles. But for an object of macroscopic size , the complex entangled (quantum mechanical) properties average out to classical properties, hence we cannot predict them. So even though the answer is a yes, you might pretend that the answer is no and you wont miss anything.

#4 this point is related to #3: we cannot predict observations on the level of the universe, so you can hypothesize all you want about local or non-local properties and nobody can prove you wrong.

Hope this helps.

Re: Spooky action != Information

I think I'd like to add one small rider to this; whilst finding a red in one bag means there must be a blue in the other, and vice-versa, the analogy presented in your post implies that the redness/blueness has already been decided and it's just that the people haven't looked in the bags yet.

With the particle-based experiment, the redness/blueness has not been decided yet and won't be decided until someone looks in the bag, at which point the decision will also have been made for the other bag all the way over there, so somehow it "knows" that we just looked in our bag, which is the apparent weirdness.

Just thought it was worth spelling out.

Feynman said in a lecture, NO-ONE understands quantum mechanics. We have a theory that shows what happens, but not why it happens, hence we don't understand it.

I _know_ that I don't understand quantum mechanics, so what does this imply for my entangled identical twin? (Everyone in our family says that we are spooky.)

Re: you don't understand quantum mechanics.

Hmm. If this forum were full of physicists working in the relevant subfields of quantum mechanics or quantum information, then you might well be able to prove something. But not necessarily the "don't understand quantum mechanics" part.

Isn't the atomic clock difference on probes down to their speed, not the gravity?

And I cannot accept that information cannot be transfered between two points faster than light would travel between two points... there must be a way

Sure. All you have to do is give up on causality.

If you can transmit information beyond the bounds of your light-cone, it's possible - even easy - to arrange for temporal paradoxes. These can include, for example, receiving information about your own future. Well, that's awkward, isn't it?

Consider a fairly simple case, adapted from Milton Rothman's classic 1980 article "On Faster-than-Light Paradoxes":

- A spaceship leaves Earth and travels away from it at a normal, subluminal speed, say 0.5c.

- The Earth and the spaceship have relative motion with a significant velocity, which means their reference frames are significantly shifted from one another.

- We assume some means of instantaneous communication. (This experiment works with any FTL communication; instantaneous is just a convenience.)

- At 12:00 on a particular day, Earth sends a message to the spaceship.

- Due to the difference in reference frames, when the spaceship receives that message, its onboard clock says that it's 10:00, not 12:00. If we had a universal frame of reference, we'd have to say that the message "went into the past".

- Now the spaceship echoes the message back to Earth. When does this reply arrive?

- Does the instantaneous communication channel work asymmetrically, so the spaceship's message arrives two hours later, Earth time, ie at 14:00?

- Does it work symmetrically, so the reply arrives two hours earlier, at 8:00?

Neither is acceptable. If the channel is asymmetric, then Earth is in a special frame of reference. The messages it sends "go into the past". Earth can put a timestamp on its messages to detect this special status. Now relativity is out the window, and we have to explain why Earth is in a special reference frame. (In any case, relativity is theoretically necessary - there are all sorts of problems if you try to assume a universal reference frame - and has been experimentally confirmed up the wazoo.)

If the channel is symmetric, then at 8:00 Earth receives a copy of the message it won't send for another four hours. Determining why that's bad is left as an exercise for the reader.

Of course, there are those SF authors (eg Charles Stross) who run with the latter idea, and write novels around the concept of causality-violation technology. Next to false vacuum collapse, though, that's about as bad-ass an apocalypse scenario as you can invent.

Re: One for the physicists

Sorry, you can't do that.

Any real wire is made of atoms. When you pull on a wire, you're jiggling the atoms about. The individual atoms can't jiggle about faster than the speed of light. So you can't propagate any kind of force through the wire at that kind of speed, either.

Re: "it's so strong that there's no give or elasticity in it"

No, it isn't that strong.

More specifically, the atoms/molecules in the wire are held together with electromagnetic fields, whose (maximum) speed is that of light. Therefore, the effect of your pull can also only be transmitted at the same speed; the wire therefore can never have "no give" and be as strong as you would like..

And as long as you insist that your wire is made of stuff subject to a relativistic universe and its maximum speed, that same holds.

Re: One for the physicists

> let's say that it's so strong that there's no give or elasticity in it

None at all?

OK. you pull on it. You manage to move the bit at your end. But the force you use causes the whole of the wire to accelerate *incredibly* slowly - far more slowly than your end of it does.

The result is a broken wire.

Vic.

Re: One word...

That's not a word.

Re: Is this an actual physical effect or a mathematical one?

"The intersection of a pair of scissors can travel faster than light, but seeing as it's just a geometric point along two lines, it's not an actual thing, and therefore can travel as fast as it likes.

Is this "information transfer" something similar? As nothing physical is actually being transmitted between Alice and Bob."

Your scissors analogy is an example of a thought experiment that's often used to postulate that FTL is possible. As you have said, no information is actually transferred, so it's not a demonstration of FTL at all, but an illusion. No part of the scissors can receive a message from another part of the scissors sent at a speed greater than that of light.

It's problematic to think of entangled particles as having 'parts' that might send each other signals. I don't know that that analogy works at all well. As I mentioned earlier, it might be better to think about the system as a single large particle. Although I wait to stand corrected by anyone with greater knowledge of this kind of thing.

Re: So...

Any measurement that you do of an entangled photon on Earth will affect the state of its counterpart on Mars. But if you do any measurement of its counterpart on Mars, you have affected the state of its counterpart on Earth. So, no matter what you do, it's not possible to set/know the state on Earth and have someone on Mars also measure the state over there. Roughly speaking. That's the basis of quantum cryptography: that any such attempt is doomed to failure due to the devious nature of quantum mechanics.

Re: A teeny problem folk- we don't actually know c

Your "true vacuum" does not allow any measurement, because your measurement relies on propagating some particle, e.g., a photon, through the vacuum -- but then the vacuum is no longer a true vacuum (there is a probability for particle pair creation).

This does not really matter, because we understand the pair creation process and can account for it in our physics models (I think this is part of quantum chromodynamics, but don't nail me down on this). So we do know c quite well.