Observers

[exchemist]

You don't say?
Oh really? What evidence is there that entanglement binds energy? Binds it how?

None of course. This thing about "bound" energy is one of Dan's obsessions, along with the imagined crimes of Minkowski and his teacher at college, and entanglement. Given enough time, he will work at least one of these three into any given thread on any subject.

Dan's a sort of thinking man's Wellwisher, really, except that in his case it's not liberals, entropy and hydrogen bonding.

 

[origin]

Surely it is not that the state changes, but that determination of one also instantly determines the other?

Yes, I agree, very sloppy of me.

 

[danshawen]

Computer system in an aircraft is at rest but moving through the space. Computer systems in satellites are at rest, but moving through the space. So relax and acknowledge mix up rather than getting wild.

I suggested earlier that you should unlearn that will stabilize you and you will learn to use simple means like ....those qbits are stationary instead of writing that they are not moving through space.

The only difference between stationary and moving through space is the same as the difference between propagating at c ('moving through space') or having mass ('stationary').

Empty, inertialess 'space' ('light travel time') certainly does not distinguish between the two propagation states of energy, which is the whole motivation for relativity.

Entanglement works for both. If it did not, we would all instantly disintegrate in the instant we started to move relative to something else. But in a certain sense, we really do, don't we? When we move, we don't leave some "spooky ghost" of ourselves behind. Or don't we? Those Lorenz bouncing photon mirrors suggest that photons travel further if the spacecraft moves, so what if atomic structure did the same thing?

 

[danshawen]

None of course. This thing about "bound" energy is one of Dan's obsessions, along with the imagined crimes of Minkowski and his teacher at college, and entanglement. Given enough time, he will work at least one of these three into any given thread on any subject.

Dan's a sort of thinking man's Wellwisher, really, except that in his case it's not liberals, entropy and hydrogen bonding.

Thanks for reminding me; yes, that freshman physics instructor is the reason I rail against most of what he taught, and the failing grade (counterbalanced later by a real physics professor) was something I am proud of. In those days, repeating a course and getting an A+ the second time only averaged to passing with a c.

Damn relativistic (Mink rotation) Cadillac tail light problem really rankled me. Replace the tail lights with entangled ones. You only need to observe ONE to know what they both are doing. Not in Mink's schema of simultanaeity, of course.

The only good thing about that example was, if you know where the observer is, you know which way it rotated. But by placing the observer on the other side of the relativistic Cadillac, you can change a CCW Mink rotation into a CW Mink rotation Which way does it actually turn? From what point in its length does it pivot?

I paid for this instruction with scholarship award money, at least. Not everyone is so clever or fortunate.

 

[danshawen]

Anything you were taught that does not help you solve your current problems was very likely a waste of money spent on miseducation.

 

[The God]

Surely it is not that the state changes, but that determination of one also instantly determines the other?

The question is how to track the other guy?

We assume that every photon has its entangled brother, if we take measurement on the one the other photon gets affected, but how do we locate that in general.....we can't unless we create such pairs.

So I would feel that it's the state of entangled system as a whole which should matter rather than state of its constituents.

 

[danshawen]

The question is how to track the other guy?

We assume that every photon has its entangled brother, if we take measurement on the one the other photon gets affected, but how do we locate that in general.....we can't unless we create such pairs.

So I would feel that it's the state of entangled system as a whole which should matter rather than state of its constituents.

Exactly so.

 

[arfa brane]

Quantum theory has been accused of incompleteness because it cannot answer some questions that appear reasonable from the classical point of view. For example, there is no way to ascertain whether a single system is in a pure state or is part of an entangled composite system. Furthermore, there is no dynamical description for the “collapse” of the wavefunction.
In both cases the theory gives no answer because the wavefunction is not an objective entity. Collapse is something that happens in our description of the
system, not to the system itself. Likewise, the time dependence of the wavefunction does not represent the evolution of a physical system. It only gives the evolution of our probabilities for the outcomes of potential experiments on that system. This is the only meaning of the wavefunction.

On Physics being Statistical:

If we assume that information in our physical world is described by quantum mechanics, this leads us to conclude that information is actually a non commutative phenomenon. Perhaps this means that since information “lives” in spacetime (and possibly in some way defines spacetime structure. . .), spacetime itself is noncommutative, . . .
The general structure of classical mechanics . . . is linear, since it is nothing more than probability theory, even though it can be applied to physical systems where nonlinear aspects might be involved.
It is the statistical point of view that makes everything linear (this boils down to the use of averages, which are integrals and hence linear). The same goes for quantum mechanics. Its linear structure should not be viewed as an approximation to an underlying nonlinear world, but simply as a result of the fact that it is a mathematical framework for probability theory (i.e. statistics, averages), where the information involved happens to be noncommutative.
The appearance of a Hilbert space as the state space is simply a mathematical way of representing the noncommutative ∗-algebraic general structure . . .

I suggest that the common unease with taking quantum mechanics as a fundamental description of nature (the "measurement problem") could derive from the use of an incorrect notion, as the unease with the Lorentz transformations before Einstein derived from the notion of observer-independent time.
I suggest that this incorrect notion is the notion of observer-independent state of a system (or observer-independent values of physical quantities).
I reformulate the problem of the "interpretation of quantum mechanics" as the problem of deriving the formalism from a few simple physical postulates.
I consider a reformulation of quantum mechanics in terms of information theory. All systems are assumed to be equivalent, there is no observer-observed distinction, and the theory describes only the information that systems have about each other; nevertheless, the theory is complete.

 

[arfa brane]

So think about that. If physics is really about probabilities and if classical information is 'obliged' to have a quantum basis, then everything you do is because information exists.

It exists because, well, because we say it does, because we can identify information. This is somehow connected to our not being able to identify quantum information, to not being able to say it exists (??)

When you walk on a floor, say, it's because particles are interacting, so there is entanglement. But the entanglement is dissipative or must have low coherence limits, so all the information "appears" in a continuous way, not being "stored" for very long (or something like that).
Or maybe you can walk on a floor because the entanglement information is erased (?!)

 

[iceaura]

When you walk on a floor, say, it's because particles are interacting, so there is entanglement.

Entanglement is destroyed by interaction.

 

[arfa brane]

Entanglement is destroyed by interaction.

. . . between entangled particles and the environment.

 

[iceaura]

. . . between entangled particles and the environment.

Such as the rest of the particles in the atoms they are in, the rest of the atoms in a room temperature floor being walked on, all of the electromagnetic radiation impinging, and so forth.

 

[The God]

Fuchs and Peres extract......originally taken in quote by arfa.

. ...Collapse is something that happens in our description of the system, not to the system itself......

 

[danshawen]

On Physics being Statistical:

http://www.phy.pku.edu.cn/~qhcao/resources/class/QM/PTO000070.pdf

"All this said, we would be the last to claim that the foundations of quantum theory are not worth further scrutiny."

Statistical analysis is a powerful tool. I never meant to suggest that it should be discarded, but, there is a 100% probability that Cathy exists, as well as the box with the cake and the box with the fruit (from another part of the text). Also Schroedinger's cat and the canister of poison, a source of radioactive decay. Of these, the source of radioactive decay is statistical in nature. The rest are really not.

A dead cat cannot be said to be entangled with a live cat, even if they are identical twins. A piece of fruit cannot be said to be entangled with a piece of cake.

 

[James R]

Moderator note: danshawen is no longer permitted to contribute to this thread.

This is due to a series of off-topic posts, and due to his repeated posting of pseudoscience in this thread, which is in one of our Science subforums.

In addition, danshawen receives an official warning for potential exclusion from posting to our Science sections.

 

[Write4U]

How can values be measured with out an observer ?

setting up a fixed detector and come back in a week to see what it has recorded?

 

[exchemist]

So think about that. If physics is really about probabilities and if classical information is 'obliged' to have a quantum basis, then everything you do is because information exists.

It exists because, well, because we say it does, because we can identify information. This is somehow connected to our not being able to identify quantum information, to not being able to say it exists (??)

When you walk on a floor, say, it's because particles are interacting, so there is entanglement. But the entanglement is dissipative or must have low coherence limits, so all the information "appears" in a continuous way, not being "stored" for very long (or something like that).
Or maybe you can walk on a floor because the entanglement information is erased (?!)

I have great difficulty accepting that all interaction involves entanglement (as per the part of your post I have shown in bold). Can you explain to me what "entanglement" is occurring when the surface of a solid object (such as a foot) comes into contact with the surface of another solid object (such as a floor)?

Because it seems to me that physics accounts for this perfectly well without invoking entanglement at all. What happens when two surfaces press against one another can be explained by electrostatics and the Pauli Exclusion Principle, surely?

 

[arfa brane]

What happens when two surfaces press against one another can be explained by electrostatics and the Pauli Exclusion Principle, surely?

Yeah, I suppose those would go a long way towards explaining why you and your shoes don't merge together, and why you don't sink into the ground where it's solid enough.

Now you have "solid enough" to explain; you also haven't got much of an explanation for friction so far. The other point about these interactions: all the electrons involved are interacting strongly with nuclear charges, but as you know it's easy to charge yourself with extra electrons just by friction.

And since entanglement, say the production of maximally entangled photons, does involve interaction, then why is any interaction not the cause of some amount of entanglement, even a very weak kind? Can you say you know the answer?

 

[iceaura]

Now you have "solid enough" to explain; you also haven't got much of an explanation for friction so far.

Wait a minute - are you actually claiming that interactions between macroscopic solid objects involve quantum scale entanglement? I thought that was inadvertent.

 

[exchemist]

Yeah, I suppose those would go a long way towards explaining why you and your shoes don't merge together, and why you don't sink into the ground where it's solid enough.

Now you have "solid enough" to explain; you also haven't got much of an explanation for friction so far. The other point about interactions: all the electrons involved are interacting strongly with nuclear charges, but as you know it's easy to charge yourself with extra electrons just by friction.

Well let's take these things one at a time.

You use the term "solid enough". I would use the term "solid". A solid is a well defined phase of matter, in which atoms are held in fixed relation with one another (save for thermal vibration around a mean position) by ionic, metallic or covalent bonding, all of which forms of bonding are routinely explained with no reference to "entanglement". Where do you see the necessity to bring "entanglement" into this?

As for friction, that is explained by contact between microscopic asperities in the surfaces in contact. You do not even need to invoke quantum phenomena at all for this - except in the sense that asperities in solids are solid because of the way chemical bonding holds them rigid. What do you think "entanglement" has to do with it?

Certainly electrons interact with nuclear charges: the electrostatic attraction between one and the other is what binds electrons to atoms in atomic and molecular orbitals. But there is no "entanglement" involved in any of this. It is just standard 6th form atomic QM.

And finally, electrostatic charge separation by friction, i.e. the triboelectric effect, is explained here: https://en.wikipedia.org/wiki/Triboelectric_effect without any invocation of "entanglement", so far as I can see. Where do you think "entanglement comes into this?