Photon's age? consider two interacting photons in the EPR effect

  • Thread starter GearsofWar
  • Start date
26
0

Main Question or Discussion Point

consider two interacting photons in the EPR effect.

the photons separate and move towards different detectors 1 km in each direction.

measuring the first photon instantaneously affects the other photon.

how much has teh first photon aged?

how much has the second photon aged?
 

Answers and Replies

Doc Al
Mentor
44,828
1,084
measuring the first photon instantaneously affects the other photon.
Are you sure about that? How would you know?

how much has teh first photon aged?

how much has the second photon aged?
How would you define the "age" of a photon? According to whom?
 
26
0
Are you sure about that? How would you know?


How would you define the "age" of a photon? According to whom?

Aspect et al and several experiments have demonstrated Bell's inequalites and action-at-a-distance.

Good question!

Does a photon age?

Suppose a battery-operated clock flew at 99.999999999999999999999999999999999999% the speed of light.

When we decelerated the clock to rest relative to the lab frame, and took the batteries out so the hands woudl stop, would we all agree on the time read on the clock?
 
JesseM
Science Advisor
8,492
12
Aspect et al and several experiments have demonstrated Bell's inequalites and action-at-a-distance.
The violation of Bell's inequalities only shows the failure of local realism with unique outcomes, that's not the same as showing action-at-a-distance. For example, advocates of the many-worlds-interpretation argue that they can explain these results without violating locality, at the cost of disputing that any given measurement has a unique outcome.
 
26
0
The violation of Bell's inequalities only shows the failure of local realism with unique outcomes, that's not the same as showing action-at-a-distance. For example, advocates of the many-worlds-interpretation argue that they can explain these results without violating locality, at the cost of disputing that any given measurement has a unique outcome.
Hello Jesse,

Do photons age?

Also, if you're right, that would be great if you could add that information to the wikipedia page:
http://en.wikipedia.org/wiki/Bell's_theorem
http://en.wikipedia.org/wiki/Action_at_a_distance_(physics [Broken])

Also, I think you could publish some papers updating this one:
http://www.drchinese.com/David/Bell_Compact.pdf

Rock on!
 
Last edited by a moderator:
26
0
The violation of Bell's inequalities only shows the failure of local realism with unique outcomes, that's not the same as showing action-at-a-distance. For example, advocates of the many-worlds-interpretation argue that they can explain these results without violating locality, at the cost of disputing that any given measurement has a unique outcome.
P.S. What are some of the famous experiments that have demonstrated the many-worlds that refute Aspect et al's experiments?
 
26
0
The violation of Bell's inequalities only shows the failure of local realism with unique outcomes, that's not the same as showing action-at-a-distance. For example, advocates of the many-worlds-interpretation argue that they can explain these results without violating locality, at the cost of disputing that any given measurement has a unique outcome.
Hello Jesse,

You may also want to contact amazon.com and various publishers/authors and tell them that their books are wrong:
https://www.amazon.com/dp/0452284570/?tag=pfamazon01-20
https://www.amazon.com/dp/0312343418/?tag=pfamazon01-20
https://www.amazon.com/dp/0631232214/?tag=pfamazon01-20

I have those books sitting here and none of them say what you say.

Thanks!
 
JesseM
Science Advisor
8,492
12
P.S. What are some of the famous experiments that have demonstrated the many-worlds that refute Aspect et al's experiments?
It doesn't refute the experiment, it simply interprets the results in a way that doesn't conflict with locality (which is fine, because one of the necessary assumptions of a proof of Bell's theorem is that measurements have a single definite outcome, which isn't true in the many-worlds interpretation). If you're interested in references for the claim that many-worlds advocates think it can explain the results of these experiments without violating locality, this paper lists a number of them:
In the Everett interpretation the nonlocal notion of reduction of the wavefunction is eliminated, suggesting that questions of the locality of quantum mechanics might indeed be more easily addressed. On the other hand, while wavefunctions do not suffer reduction in the Everett interpretation, nonlocality nevertheless remains present in many accounts of this formulation. In DeWitt’s (1970) often-quoted description, for example, “every quantum transition taking place on every star, in every galaxy, in every remote corner of the universe is splitting our local world on earth into myriads of copies of itself.” Contrary to this viewpoint, others argue (Page, 1982; Tipler, 1986, 2000; Albert and Loewer, 1988; Albert, 1992; Vaidman, 1994, 1998, 1999; Price, 1995; Lockwood, 1996; Deutsch, 1996; Deutsch and Hayden, 2000) that the Everett interpretation can in fact resolve the apparent contradiction between locality and quantum mechanics. In particular, Deutsch and Hayden (2000) apply the Everett interpretation to quantum mechanics in the Heisenberg picture, and show that in EPRB experiments,1 information regarding the correlations between systems is encoded in the Heisenberg-picture operators corresponding to the observables of the systems, and is carried from system to system and from place to place in a local manner. The picture which emerges is not one of measurement-type interactions “splitting the universe” but, rather, producing copies of the observers and observed physical systems which have interacted during the (local) measurement process (Tipler, 1986).
And in this subsequent paper by the same author, I think he's arguing that the Everett interpretation of quantum field theory can also be understood in terms of information encoded in purely local operators.

For a simple "toy" model of how we can violate one of the Bell inequalities without violating locality if we allow experimenters to split into multiple copies on each measurement, see my post #11 on this thread.
 
26
0
Which experiments prove the many-worlds theories?

How many worlds/flying spaghetti monsters would Everret suppose?

What I like about Aspect's experiment is that it is real.
 
JesseM
Science Advisor
8,492
12
Also, I think you could publish some papers updating this one:
http://www.drchinese.com/David/Bell_Compact.pdf
Pretty sure DrChinese would agree with my statements, although you can ask him, he posts here regularly. In post #36 in the thread I linked to above he says:
Bell's Theorem compares local realistic theories with Quantum Mechanics. Bell tests such as the one you reference (under strict locality conditions) are just tests of local realistic theories. The "strict locality" part does NOT mean it is testing locality alone. This is a common misconception. It may be that the "true" theory is local and non-realistic. Many folks believe this to be the case, and it is a popular (even if not the majority) interpretation of QM. If you are in this camp, you do not believe that there are causes which propagate faster than c. You also believe that the QM is "complete".
I think, though I'm not sure, that when he says "it may be the case that the 'true' theory is local and non-realistic", and that "it is a popular (even if not the majority) interpretation of QM" in which QM is seen as "complete", that he's referring to the MWI.
 
JesseM
Science Advisor
8,492
12
Which experiments prove the many-worlds theories?

How many worlds/flying spaghetti monsters would Everret suppose?

What I like about Aspect's experiment is that it is real.
I don't think you understand what an "interpretation" of QM means--they all are constructed to agree on predictions, so there's no experimental way to test any of them. See wikipedia's article on interpretation of quantum mechanics which lists a number of them. Any claim that QM involves FTL effects is itself dependent on your choice of interpretation (for example, it would be true in Bohm's interpretation).
 
26
0
Alain Aspect's experiments have demonstrated a FTL correlation.

Have you ever read his paper in:
https://www.amazon.com/dp/0691083150/?tag=pfamazon01-20

Quantum entnaglement and faster-than-light correlations have been shown in multiple experiments.

Many worlds have never been seen.

I'm not sure what your problem with reality is...
 
JesseM
Science Advisor
8,492
12
Alain Aspect's experiments have demonstrated a FTL correlation.

Have you ever read his paper in:
https://www.amazon.com/dp/0691083150/?tag=pfamazon01-20
No, does he address the possibility that measurements may have non-unique outcomes?
GearsofWar said:
Quantum entnaglement and faster-than-light correlations have been shown in multiple experiments.
Quantum entanglement has been seen, and the correlations predicted in entanglement have been seen (and the MWI would not dispute either prediction). But to call these correlations "FTL" requires certain assumptions about the interpretation of QM which are just as untestable as the assumptions made by the the MWI.
GearsofWar said:
I'm not sure what your problem with reality is...
It's you who has a problem with understanding the logic of Bell's proof if you think the entanglement experiments definitively prove FTL. It only proves that given certain assumptions, one of which must be the assumption of unique outcomes to measurements; the proof only tells you that all the assumptions cannot simultaneously be correct, it doesn't prove that some of them can't be correct (such as the assumption of locality) if others are incorrect (the assumption of unique outcomes, i.e. 'realism'). You don't have to accept that there's any real likelihood that realism is violated, but you do have to accept that the results of the entanglement experiments can't prove that it isn't, in which case the results could still be compatible with locality.
 
26
0
No, does he address the possibility that measurements may have non-unique outcomes?

Quantum entanglement has been seen, and the correlations predicted in entanglement have been seen (and the MWI would not dispute either prediction). But to call these correlations "FTL" requires certain assumptions about the interpretation of QM which are just as untestable as the assumptions made by the the MWI.

It's you who has a problem with understanding the logic of Bell's proof if you think the entanglement experiments definitively prove FTL. It only proves that given certain assumptions, one of which must be the assumption of unique outcomes to measurements; the proof only tells you that all the assumptions cannot simultaneously be correct, it doesn't prove that some of them can't be correct (such as the assumption of locality) if others are incorrect (the assumption of unique outcomes, i.e. 'realism'). You don't have to accept that there's any real likelihood that realism is violated, but you do have to accept that the results of the entanglement experiments can't prove that it isn't, in which case the results could still be compatible with locality.
You say, "Quantum entanglement has been seen, and the correlations predicted in entanglement have been seen (and the MWI would not dispute either prediction). But to call these correlations "FTL" requires certain assumptions about the interpretation of QM which are just as untestable as the assumptions made by the the MWI."

What would I have to assume to call the correlations FTL?

Numerous experiments have shown FTL correlations. What special assumptions are you assuming that they are assuming?
 
JesseM
Science Advisor
8,492
12
What would I have to assume to call the correlations FTL?
You'd have to assume that "realism" is correct, i.e. that each measurement has a unique outcome, instead of causing the experimenter to split into multiple versions which observe different outcomes. There's at least one other assumption you'd have to make too even if you accepted realism, namely the assumption that "superdeterminism" is false (see the discussion following ThomasT's post #57 on this thread). You'd also have to assume no backwards-in-time influences where the experimenter's choices can influence the state the two particles are created in, which would be violated in the transactional interpretation of QM (though depending on your point of view this may be a violation of locality, but I think the time-symmetry of the laws of physics makes it ambiguous whether locality is violated by a future event influencing an event in its own past light cone).
 
26
0
Hello!

Yes--I assume that realism is real and that backwards-in-time effects aren't.

I think this is how Newton/Einstein/Bohr/Fermi/Dirac/Feynman/Heisenberg approached physics and relativity.

Perhaps you don't take realism to be real. Now I understand your general dismissal of experiment in relativity and qauntum mechanics.
 
Last edited:
ZapperZ
Staff Emeritus
Science Advisor
Education Advisor
Insights Author
2018 Award
35,225
4,043
Hello!

Yes--I assume that realism is real and that backwards-in-time effects aren't.

I think this is how Newton/Einstein/Bohr/Fermi/Dirac/Feynman/Heisenberg approached physics and relativity.

Perhaps you don't take realism to be real. Now I understand your general dismissal of experiment in relativity and qauntum mechanics.
JesseM did no such thing. You have a problem with comprehension. Therefore, prolonging this thread is useless.

Zz.
 

Related Threads for: Photon's age? consider two interacting photons in the EPR effect

Replies
3
Views
567
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
23
Views
12K
Replies
4
Views
1K
  • Last Post
2
Replies
34
Views
6K
  • Last Post
Replies
3
Views
604
  • Last Post
Replies
1
Views
2K
Top