Room-temperature superconductivity?

[tomclarke]

on the note of maxwell's demon and entropy, there's actual a near equivalence to thermodynamic entropy and information entropy.

http://en.wikipedia.org/wiki/Entropy_in ... ion_theory

maxwell's demon can reverse entropy increase, but for that he would need an amount of information proportional to the amount of energy that would produce.

Yes, and so in a closed system there is no contradiction of second law.

[tomclarke]

Apologies if you or Johan think this is pedantic - mathematicians discovered in the late 19th and early 20th century that without extreme care they could build whole mathematical structures that seemed good but contained fatal flaws like Russell's paradox. I believe the situation is very similar here.

You have just now described your own approach incredibly well. You are defending a mathematical structure that seems good but contains fatal flaws. So let us rather argue plain physics as I am doing instead of "paths within Minkowski space". They are not required when discussing time-dilation, length contraction and the twin paradox. Even Einstein opposed the Minkowski construct for at least ten years after he had formulated his Special Theory of Relativity. He should have stuck to his guns!

Happy new year.

Plain physics is fine with me. But instantaneity his no plain physical meaning across space and reference frames, as you surely know.

So lets stick to physical arguments.

[johanfprins]

Plain physics is fine with me. But instantaneity his no plain physical meaning across space

So you are arguing that two events at separate positions within the same inertial reference frame can never occur instantaneously at the same instant in time?

and reference frames,

So when you synchronise two passing clocks this does not occur instantaneously at the same instant in time within both inertial reference frames?

as you surely know.

No I do not know: As I have just demonstrated, your statement that "instantaneity has no plain physical meaning" is patently false.

So lets stick to physical arguments.

That is what I just did!

[tomclarke]

Plain physics is fine with me. But instantaneity his no plain physical meaning across space

So you are arguing that two events at separate positions within the same inertial reference frame can never occur instantaneously at the same instant in time?

and reference frames,

So when you synchronise two passing clocks this does not occur instantaneously at the same instant in time within both inertial reference frames?

as you surely know.

No I do not know: As I have just demonstrated, your statement that "instantaneity has no plain physical meaning" is patently false.

So lets stick to physical arguments.

That is what I just did!

Johan. my position, stated above, is:

(1) instantaneity has meaning at single spatial location, even across frames.

(2) instantaneity has meaning within one frame over all space (you can accurately synchronise clocks at different locations using light-beams).


(3) instantaneity has no meaning at different spatial locations in different frames. (You can define any number of different measures of instantaneity - one for every possible frame - none is priviledged.)


Hence it is only partially defined. My quarrel with your demons was that your statement invoked instantaneity at different spatial locations and with relative velocity - the case where it is not meaningful.

Best wishes, Tom

[johanfprins]

Johan. my position, stated above, is:
(1) instantaneity has meaning at single spatial location, even across frames.

(2) instantaneity has meaning within one frame over all space.

Thank you. On this we agree.

(3) instantaneity has no meaning at different spatial locations in different frames.

Even though this is not the issue when I give my demons the extraordinary ability to communicate instantaneously; you are still wrong. It has now been experimentally proved that two entangled enitities moving relative to one another can communicate instantaneously with one another. So all I have to do is to "entangle" my demons. But, even so, I can have only one demon who has the power to instantaneously stop the relative motion. In addition, I can also reach the same conclusions I have reached above by not employing any demons at all. The arguments are then a little more tortuous.

Hence it is only partially defined.

Entanglement in quantum mechanics proves that you are wrong.

My quarrel with your demons was that your statement invoked instantaneity at doifferent spatial locations and with relative velocity - the case where it is noyt meaningful.

Thus, entanglement of two electrons moving relative to one another is "not meaningful"? Experiments during the past 40 years disagree with you; and I will rather accept experimental results than your opinion about what is "meaningful".

[tomclarke]

Johan. my position, stated above, is:
(1) instantaneity has meaning at single spatial location, even across frames.

(2) instantaneity has meaning within one frame over all space.

Thank you. On this we agree.

(3) instantaneity has no meaning at different spatial locations in different frames.

Even though this is not the issue when I give my demons the extraordinary ability to communicate instantaneously; you are still wrong. It has now been experimentally proved that two entangled enitities moving relative to one another can communicate instantaneously with one another. So all I have to do is to "entangle" my demons. But, even so, I can have only one demon who has the power to instantaneously stop the relative motion. In addition, I can also reach the same conclusions I have reached above by not employing any demons at all. The arguments are then a little more tortuous.

Hence it is only partially defined.

Entanglement in quantum mechanics proves that you are wrong.

My quarrel with your demons was that your statement invoked instantaneity at doifferent spatial locations and with relative velocity - the case where it is noyt meaningful.

Thus, entanglement of two electrons moving relative to one another is "not meaningful"? Experiments during the past 40 years disagree with you; and I will rather accept experimental results than your opinion about what is "meaningful".

Johan,

You are here moving the goalposts.

Your contention is that instantaneity is meaningful because quantum entanglement defines it (uniquely).

Now, we can happily debate the precise mechanics of quantum entanglement. It was at one time one of my pet subjects, so I can probably keep up with you, and (perhaps) more.

But before we open a whole new field of debate, let me just ask:

If quantum entanglement uniquely defines simulataneity, what is the definition?

You might find it helpful to read the literature on Bell's theorem and causality. While Bell's theoreom is (generally though not universally) thought to be inescapable, and it implies either nonlocality or acausal signalling, E.T. Jaynes pointed out that the probabilities used in its formulation are logical not causal. In other words QE means that deduction can be made FTL, not that causation is FTL.

Specifically, Garrett (a friend of mine at Cambridge, we had a common interest in quantum measurement theory) showed that Bell's Theorem cannot be used to signal acausally.

In the light of this result I would think it impossible for QE to allow spacelike synchronisation of clocks, since this requires, typically, 2-way causal signalling.

But Johan, if you think otherwise formulate and post a precise thought experiment which will use QE to synchronise two clocks?

Of course, clocks in different frames can be synchronised: my point is that this is frame-dependent, there is no canonical way to do it (which would imply a global time).

[johanfprins]

You are here moving the goalposts.

I expected that you will try and hide behind this.

Your contention is that instantaneity is meaningful because quantum entanglement defines it (uniquely).

Yes, I do have two entangled "electrons" moving relative to one another: Since they are entangled their spins are not manifesting until you make a measurement on one of them: The opposite spin will then appear instantaneously on the other one where-ever it is and with whatever speed it is moving relative to the other part.

Now, we can happily debate the precise mechanics of quantum entanglement. It was at one time one of my pet subjects, so I can probably keep up with you, and (perhaps) more.

No please not. You are already making it impossible to talk real physics when it comes to relativity. It will just be a waste of time to even try to argue entanglement with you, if I cannot even disentangle your mind when it comes to Special Relativity

But before we open a whole new field of debate, let me just ask:

If quantum entanglement uniquely defines simulataneity, what is the definition?

You might find it helpful to read the literature on Bell's theorem and causality.

Oh I have read it

While Bell's theoreom is (generally though not universally) thought to be inescapable, and it implies either nonlocality or acausal signalling, E.T. Jaynes pointed out that the probabilities used in its formulation are logical not causal. In other words QE means that deduction can be made FTL, not that causation is FTL.

I know these arguments on Bell's theorem. Bell's theorem only served to define a condition that will indicate whether it is possible for two "entities" which are entangled, so that you do not know which entity represents which condition (say which one has spin up and which one has spin down), a measurement on one entangled entity (say causing it to have spin up) will result in the other part to instantaneously respond and thus show spin-down. The result is that it is possible. Thus, if one demon travels with one part of a bi-electron entangled electron and the other demon with the other part, a measurement of the spin by one demon on the part travelling with him, will immediately cause the opposite spin to manifest for the other part which is with the other demon.

Specifically, Garrett (a friend of mine at Cambridge, we had a common interest in quantum measurement theory) showed that Bell's Theorem cannot be used to signal acausally.

If one demon makes a measurement, he causes spin to appear at the other demon. It is not acausal at all.

I did not say Bell's theorem itself can be used in this manner: Bell only formulated a condition which must manifest if instantaneous contact is not possible (as Einstein has claimed when he and his students formulated the EPR paradox). It was subsequently found that this conditions does not manifest.

In the light of this result I would think it impossible for QE to allow spacelike synchronisation of clocks, since this requires, typically, 2-way causal signalling.

Why 2-way? One demon measures spin when he zeroes his clock, and the other demon zeroes his clock when spin manifests on his part of the entangled wave. The clocks must then be synchronised instantaneously.

But Johan, if you think otherwise formulate and post a precise thought experiment which will use QE to synchronise two clocks?

I have just done it.

Of course, clocks in different frames can be synchronised: my point is that this is frame-dependent, there is no canonical way to do it (which would imply a global time).

This is where you are wrong: The time rate within any and all inertial reference frames are exactly the same when measured within each inertial reference frame. After all: Einstein's first postulate for SR states "All inertial observers are equivalent". How can two inertial observers within two different inertial refrence frames be equivalent if their clocks do not tick at the exact same time rate?

Ignoring the effect on time that gravity has, it means that if the instant of the Big Bang is used for synchronising clocks, then there must be a global time. After all such a time is used to conclude that when we reverse time our universe will finally become a point in space-time?

The fact is that according to SR, if you suddenly stop all relative motion you will find that all clocks in the universe, no matter in which inertial reference frame they were when motion stopped, will show exactly the same time.

But as I said, I do not require demons to prove what I derived above with demons. Neither do I require them to prove that the time rates of all clocks within all inertial reference frames are identically the same since this is mandated by Einstein's first postulate of SR that it must be so.

[tomclarke]

Yes, I do have two entangled "electrons" moving relative to one another: Since they are entangled their spins are not manifesting until you make a measurement on one of them: The opposite spin will then appear instantaneously on the other one where-ever it is and with whatever speed it is moving relative to the other part.

Glad we've nailed this. What you write here is not true because spin cannot "manifest instantaneously". You can only determine spin by measuring it at some point in time, the measurement itself then changes the spin.

Now, it is true that two measurements of entangled electrons at points A,B far separated will result in correlated statistics. However the times at which these two measurements are made do not matter, and do not affect the correlation.

Try again, and this time answer the question: how can you synchronise two clocks by measuring spin?

I agree, if spin "manifested instantaneously" you could do it. But it does not, and a sequence of repeated observations will not help because the entangled correlation will apply only to the first one. Furthermore, it will be the same correlation whenever that first measurement is made.

[Axil]

I agree, if spin "manifested instantaneously" you could do it.

Usually when physicists talk about nonlocality in quantum mechanics, they’re referring to the fact that two particles can have immediate effects on each other, even when separated by large distances. Einstein famously called the phenomena “spooky interaction at a distance” because information about a particle seems to be traveling instantaneously; faster than the speed of light, violating the laws of causality.

Recent experiments in quantum physics revivify nonlocality in quantum mechanics.

These experiments indicate that quantum mechanics in violation of common sense does not conform to a principle of Leibniz’s metaphysics, the identity of indiscernibles. According to the principle, a pair of entangled quantum particles must be indiscernible from a single particle, since both objects have in common all the same properties—this is the only stipulation of the principle, number being irrelevant.

On the other hand, the single-state nonlocality demonstrated by nonlocality of a Single Particle reinforces the equivalence of a single state and an entangled state—giving more credence to the position that quantum field theory, where fields are given primacy, that fields are fundamental, and particles secondary, is the best representation of reality.

[happyjack27]

....

On the other hand, the single-state nonlocality demonstrated by nonlocality of a Single Particle reinforces the equivalence of a single state and an entangled state—giving more credence to the position that quantum field theory, where fields are given primacy, that fields are fundamental, and particles secondary, is the best representation of reality.

odd, we've spent so much time getting used to the idea that everything's made up of "particles". and now we have to dispense with that hard-won notion and replace it with the notion that everything's made up of "quantum fields", and the "particles" that were once king are merely arbitrary and ephemeral singular manifestations of the "quantum fields".

i don't know which is better/worse, being a walking talking Georges Seurat ( http://en.wikipedia.org/wiki/Georges_Seurat ) painting, or being an amalgamation of complex-valued probability fields.

[Axil]

....

On the other hand, the single-state nonlocality demonstrated by nonlocality of a Single Particle reinforces the equivalence of a single state and an entangled state—giving more credence to the position that quantum field theory, where fields are given primacy, that fields are fundamental, and particles secondary, is the best representation of reality.

odd, we've spent so much time getting used to the idea that everything's made up of "particles". and now we have to dispense with that hard-won notion and replace it with the notion that everything's made up of "quantum fields", and the "particles" that were once king are merely arbitrary and ephemeral singular manifestations of the "quantum fields".

i don't know which is better/worse, being a walking talking Georges Seurat ( http://en.wikipedia.org/wiki/Georges_Seurat ) painting, or being an amalgamation of complex-valued probability fields.

See:

http://arxiv.org/PS_cache/arxiv/pdf/070 ... 0322v1.pdf

[happyjack27]

i don't know which is better/worse, being a walking talking Georges Seurat ( http://en.wikipedia.org/wiki/Georges_Seurat ) painting, or being an amalgamation of complex-valued probability fields.

See:

http://arxiv.org/PS_cache/arxiv/pdf/070 ... 0322v1.pdf

i still don't know which i'd rather be.

[happyjack27]

i think the later would feel more like a Duchamp painting:

http://en.wikipedia.org/wiki/Nude_Desce ... ase,_No._2

[johanfprins]

Glad we've nailed this. What you write here is not true because spin cannot "manifest instantaneously". You can only determine spin by measuring it at some point in time, the measurement itself then changes the spin.

Correct and when you have two entangled entities and you measure spin on one of them, then the opposite spin must appear instantaneously on the other entity no matter how far it is away and no matter with which speed it is moving relative to the entity which is being measured.

Now, it is true that two measurements of entangled electrons at points A,B far separated will result in correlated statistics. However the times at which these two measurements are made do not matter, and do not affect the correlation.

Obviously, after spin has manifested on the part not being measured, you can measure it at any time later than it manifested on the part you first measured. But this does not remove the fact that once you measure spin on one part the opposite spin must appear simultaneously on the other part.

Try again, and this time answer the question: how can you synchronise two clocks by measuring spin?

I have just told you!

I agree, if spin "manifested instantaneously" you could do it.

Good, so we agree.

But it does not, and a sequence of repeated observations will not help because the entangled correlation will apply only to the first one.

No it applies to both: One cannot have spin on one part and no spin on the other part.

Furthermore, it will be the same correlation whenever that first measurement is made.

Correct! So it only requires one demon to make a measurement and the other demon will know istantaeously that such a measurement has been made! So what is your problem?

[johanfprins]

Usually when physicists talk about nonlocality in quantum mechanics, they’re referring to the fact that two particles can have immediate effects on each other, even when separated by large distances.,

Exactly here physicists are making the mistake! Two separate entities can obviously not have immediate effects on each other "when separated by large distances".

Einstein famously called the phenomena “spooky interaction at a distance” because information about a particle seems to be traveling instantaneously; faster than the speed of light, violating the laws of causality.

When two "particles" entangle, two waves merge to form a single holistic wave which is in immediate contcat with itself within the volume it occupies within three-dimensional space, even when this volume consists of two or more fragments. These fragments are NOT independent entities!

Recent experiments in quantum physics revivify nonlocality in quantum mechanics.

Correct, since fractions of a holistic wave are in immediate contact.

According to the principle, a pair of entangled quantum particles must be indiscernible from a single particle, since both objects have in common all the same properties—this is the only stipulation of the principle, number being irrelevant.

Except for using the confusing term "particles" an entangled wave is a single holistic enrity since all the entangled sub-waves have lost their separate identities, even when the holistic wave manifests as fragments of the holistic entity.

On the other hand, the single-state nonlocality demonstrated by nonlocality of a Single Particle reinforces the equivalence of a single state and an entangled state—giving more credence to the position that quantum field theory, where fields are given primacy, that fields are fundamental, and particles secondary, is the best representation of reality.

It is simpler than that: "Particles" just do not exist at all.