Stopping time

How does science work? And what's all this about quantum mechanics?

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Atla
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Re: Stopping time

Post by Atla »

uwot wrote: Sun Feb 25, 2018 9:39 pm
Atla wrote: Sun Feb 25, 2018 1:49 pmIn the quantum world there only seem to be correlations that ignore time and distances. Even apparent retrocausality, or breaking the speed of light, is perfectly normal in QM.
Really? Can you cite your source for this?
Apparent retrocausality - the delayed choice quantum eraser demonstrates this in my opinion. I think those who claim that it's "actual" classical retrocausality, are wrong though.

Speed of light - well entanglement is theorethically instantaneous. Experimentally, it's only been shown so far though that it's at least 10000 times faster than the speed of light.
uwot
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Re: Stopping time

Post by uwot »

Atla wrote: Sun Feb 25, 2018 9:47 pmApparent retrocausality - the delayed choice quantum eraser demonstrates this in my opinion. I think those who claim that it's "actual" classical retrocausality, are wrong though.
Fair enough. So do you have an alternative explanation?
Atla wrote: Sun Feb 25, 2018 9:47 pmSpeed of light - well entanglement is theorethically instantaneous. Experimentally, it's only been shown so far though that it's at least 10000 times faster than the speed of light.
Well the simplest interpretation involves matter and information. How do you explain that in your model?
Atla
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Re: Stopping time

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uwot wrote: Sun Feb 25, 2018 10:25 pm Fair enough. So do you have an alternative explanation?
Alternative explanation of what? I believe that there are only correlations in the quantum world, so it may look like we decide the past in the present, but actually past and present simply correlate. So we don't literally, actively "change", "rewrite" the past.
Well the simplest interpretation involves matter and information. How do you explain that in your model?
What do you mean by "simplest interpretation"? If by simplest we mean that it has the least amount of equations, then it's my interpretation, the Everettian.

What do you mean by matter and information here?

Well apparently the quantum world is nonlocal. It just is so, there doesn't seem to be any detectable mechanism to it, so maybe space is simply illusory.
uwot
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Re: Stopping time

Post by uwot »

Atla wrote: Sun Feb 25, 2018 10:45 pm
uwot wrote: Sun Feb 25, 2018 10:25 pmFair enough. So do you have an alternative explanation?
Alternative explanation of what?
This:
Atla wrote: Sun Feb 25, 2018 9:47 pmI think those who claim that it's "actual" classical retrocausality, are wrong though.
Atla wrote: Sun Feb 25, 2018 10:45 pmI believe that there are only correlations in the quantum world, so it may look like we decide the past in the present, but actually past and present simply correlate. So we don't literally, actively "change", "rewrite" the past.
But you believe in "the quantum world" and "correlations".
Atla wrote: Sun Feb 25, 2018 10:45 pm
uwot wrote: Sun Feb 25, 2018 10:25 pmWell the simplest interpretation involves matter and information. How do you explain that in your model?
What do you mean by "simplest interpretation"? If by simplest we mean that it has the least amount of equations, then it's my interpretation, the Everettian.
You mean Hugh Everett's many worlds?
Atla wrote: Sun Feb 25, 2018 10:45 pmWhat do you mean by matter and information here?
Entangled particles and the properties they communicate.
Atla wrote: Sun Feb 25, 2018 10:45 pmWell apparently the quantum world is nonlocal. It just is so, there doesn't seem to be any detectable mechanism to it, so maybe space is simply illusory.
Well yes, that's one possibility.
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Re: Stopping time

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uwot wrote: Sun Feb 25, 2018 11:09 pm But you believe in "the quantum world" and "correlations".
Well.. yeah, quantum behaviour seems to be happening, no prediction of QM was ever wrong and a third of the global economy is based on it.

Correlations.. well as far as I understand, that's what QM seems to describe. We get into New Age territory when we believe that it's more than correlations.

I believe that everything is the quantum world. Our classical everyday reality seems to be a very "special" part of the quantum world.
You mean Hugh Everett's many worlds?
Yes, I see it as the natural interpretation, with only one set of equations instead of two, and the collapse being only apparent. Now there aren't literally many worlds, the way I understand it, there is only the universal wavefunction.

That's my interpretation, and it may not be correct.
Entangled particles and the properties they communicate.
Hard to say. Depending on how we interpret it, this statement can already be misleading twice. Particles and their properties are the same thing. Entangled particles don't communicate in the classical sense, they just correlate (a property of theirs correlates).
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Noax
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Re: Stopping time

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Atla wrote: Mon Feb 26, 2018 8:18 am Yes, I see it as the natural interpretation, with only one set of equations instead of two, and the collapse being only apparent. Now there aren't literally many worlds, the way I understand it, there is only the universal wavefunction.

That's my interpretation, and it may not be correct.
Fair enough, but under this interpretation, quantum effects are completely local, there is no retrocausality, and no nonlocal effects at 10000x light speed. And BTW, the number is easily far greater than 10000x.
Atla
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Re: Stopping time

Post by Atla »

Noax wrote: Mon Feb 26, 2018 12:37 pm Fair enough, but under this interpretation, quantum effects are completely local, there is no retrocausality, and no nonlocal effects at 10000x light speed.
Have to disagree, how do you make it local? That sounds completely impossible to me.
And BTW, the number is easily far greater than 10000x.
Yes as I said, theorethically it's instantaneous (infinite "speed").
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Re: Stopping time

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The way I see it, the main "problem" with the MWI is that it doesn't derive the Born-rule, it doesn't really address measurements. What the MWI does however, is give a sensible framework in which to interpret measurements. (Those who claim that decoherence solves everything, are just plain wrong.)

And the other mainstream interpretations are basically the other way around: they address the measurements, however they do not give a sensible framework in which to interpret them.

And at the heart of all this, is the still unsolved measurement problem, which is in my opinion the single greatest mistery in the history of science and philosophy. What is the nature of the quantum observer? What is a measurement? (I've been thinking about this question on and off for years now, and this is where things get really, really mindblowing, even compared to the rest of QM.)

(edit: I use the terms "observation" and "measurement" interchangeibly)
Atla
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Re: Stopping time

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Noax wrote: Mon Feb 26, 2018 12:37 pm Fair enough, but under this interpretation, quantum effects are completely local
Mmmm thanks for pointing out the MWI locality vs nonlocality issue. I did some reading and found several online discussions where physicists argue passionately with other physicists about it, turns out they themselves use the term "nonlocality" in like 2-3 different ways, confusing the hell out of each other. I don't know how many different versions of MWI there are, must be like a dozen or so.

The version I subscribe to is this: there is only the universal wavefunction, and it is automatically nonlocal because of entanglement. However, there are only spooky correlations at a distance, not spooky actions at a distance. And the universal wavefunction isn't chopped up, things aren't literally "branching" or "splitting", new universes aren't "created" and all that funny stuff.
uwot
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Re: Stopping time

Post by uwot »

Atla wrote: Mon Feb 26, 2018 8:18 am
uwot wrote: Sun Feb 25, 2018 11:09 pmEntangled particles and the properties they communicate.
Hard to say. Depending on how we interpret it, this statement can already be misleading twice. Particles and their properties are the same thing.
For practical purposes, you can add "property" to "observation" and "measurement" and use all three interchangeably. You can take this instrumentalist approach, bolt on a positivist angle and insist that is all there is, and frankly it's impossible to prove otherwise. In Kantian language they are all interchangeable with phenomenon. On the other hand, you can have a realist outlook and while it serves no scientific purpose, it is just as impossible to prove that there is no noumenon in which 'properties' inhere and are responsible for the observable and measurable phenomena.
Atla wrote: Mon Feb 26, 2018 8:18 amEntangled particles don't communicate in the classical sense, they just correlate (a property of theirs correlates).
Well 'they' have to be treated as a single quantum system, but point taken, 'communicate' is misleading.
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Noax
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Re: Stopping time

Post by Noax »

Atla wrote: Mon Feb 26, 2018 5:44 pm Mmmm thanks for pointing out the MWI locality vs nonlocality issue. I did some reading and found several online discussions where physicists argue passionately with other physicists about it, turns out they themselves use the term "nonlocality" in like 2-3 different ways, confusing the hell out of each other. I don't know how many different versions of MWI there are, must be like a dozen or so.
I was unaware of different versions, but I suppose there are.
By nonlocality, I mean taking a measurement of one entangled particle has no causal effect on other particles that are not present. This means the wave function of the unmeasured entangled pair particle is not effected while outside the light cone of the measurement of the first particle. Other interpretations state otherwise, but without demonstration of transfer of information, it remains interpretation. Nobody has devised a faster than light messaging device.
The version I subscribe to is this: there is only the universal wavefunction, and it is automatically nonlocal because of entanglement.
The whole point was to eliminate necessity of spooky action at a distance. Sure, there is entanglement, but that is not an action. Each particle of the pair is still in superposition until measured, with the original probabilities holding.
Atla
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Re: Stopping time

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Noax wrote: Tue Feb 27, 2018 12:29 am
Atla wrote: Mon Feb 26, 2018 5:44 pm Mmmm thanks for pointing out the MWI locality vs nonlocality issue. I did some reading and found several online discussions where physicists argue passionately with other physicists about it, turns out they themselves use the term "nonlocality" in like 2-3 different ways, confusing the hell out of each other. I don't know how many different versions of MWI there are, must be like a dozen or so.
I was unaware of different versions, but I suppose there are.
By nonlocality, I mean taking a measurement of one entangled particle has no causal effect on other particles that are not present. This means the wave function of the unmeasured entangled pair particle is not effected while outside the light cone of the measurement of the first particle. Other interpretations state otherwise, but without demonstration of transfer of information, it remains interpretation. Nobody has devised a faster than light messaging device.
The version I subscribe to is this: there is only the universal wavefunction, and it is automatically nonlocal because of entanglement.
The whole point was to eliminate necessity of spooky action at a distance. Sure, there is entanglement, but that is not an action. Each particle of the pair is still in superposition until measured, with the original probabilities holding.
I think we agree then, we just meant something else by or some other aspect of nonlocality.
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Re: Stopping time

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uwot wrote: Mon Feb 26, 2018 11:37 pm For practical purposes, you can add "property" to "observation" and "measurement" and use all three interchangeably. You can take this instrumentalist approach, bolt on a positivist angle and insist that is all there is, and frankly it's impossible to prove otherwise. In Kantian language they are all interchangeable with phenomenon. On the other hand, you can have a realist outlook and while it serves no scientific purpose, it is just as impossible to prove that there is no noumenon in which 'properties' inhere and are responsible for the observable and measurable phenomena.
Again, I'm not really sure what this Kantian noumenon-phenomenon delusion system is all about, but all such dualities seem to break down in QM. It is inherent in the laws of QM.
Such properties exist regardless of measurement, they are apparently in superposition, what measurement does is, bring them into an apparently collapsed state.

I also wouldn't state that science is only about developing instrumentalist approaches for practical purposes, it used to be more than that. Which is why most founders of QM were locked in almost religious debates. But they encountered a philosophical brick wall that still stands 80+ years later.
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Re: Stopping time

Post by uwot »

Atla wrote: Tue Feb 27, 2018 8:37 amAgain, I'm not really sure what this Kantian noumenon-phenomenon delusion system is all about...
Well, as long as you insist it is a delusion, you are going to struggle. It is true that many people believe that there is something independent of mind which 'causes' phenomena; you yourself allude to as much here:
Atla wrote: Tue Feb 27, 2018 9:24 am Sunlight is reflected from the Moon, that light travels for a little more than a second, and then hits the eye. What happens after that is up to debate, no one really knows yet, but those signals get processed in various ways in the brain and then an imagine of the Moon is constructed from them.
Strictly speaking though, it is an hypothesis. Simply put it is something like: The cause of all the phenomena that suggest there is a universe made of some stuff, is a universe made of some stuff. However, as Descartes pointed out, and Hume hammered home, you cannot prove that any interpretation of phenomena is true.
Atla wrote: Tue Feb 27, 2018 8:37 amSuch properties exist regardless of measurement...
If you say this, then you are claiming that there exists something independent of measurement, which is precisely what noumenon means.
Atla wrote: Tue Feb 27, 2018 8:37 amI also wouldn't state that science is only about developing instrumentalist approaches for practical purposes, it used to be more than that.
Yup. Pretty much up to the publication of the second edition of Newton's Principia. Responding largely to Cartesians, Newton added the General Scholium, which included a passage known as hypotheses non fingo:
"But hitherto I have not been able to discover the cause of those properties of gravity from phaenomena, and I frame no hypotheses. For whatever is not deduc’d from the phaenomena, is to be called an hypothesis; and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferr’d from the phaenomena, and afterwards render’d general by induction." https://isaac-newton.org/general-scholium/
Atla wrote: Tue Feb 27, 2018 8:37 amWhich is why most founders of QM were locked in almost religious debates. But they encountered a philosophical brick wall that still stands 80+ years later.
Which is why physicists generally ignore philosophy and concentrate on the maths: "Shut up and calculate".
Atla
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Re: Stopping time

Post by Atla »

uwot wrote: Tue Feb 27, 2018 10:17 am Well, as long as you insist it is a delusion, you are going to struggle. It is true that many people believe that there is something independent of mind which 'causes' phenomena; you yourself allude to as much here:
Strictly speaking though, it is an hypothesis. Simply put it is something like: The cause of all the phenomena that suggest there is a universe made of some stuff, is a universe made of some stuff. However, as Descartes pointed out, and Hume hammered home, you cannot prove that any interpretation of phenomena is true.
If you say this, then you are claiming that there exists something independent of measurement, which is precisely what noumenon means.
I can't make sense of any of this, sounds like thinking from 1900. QM has pretty much shown that things can't be divided into noumena and phenomena. I don't really know what mind or interpretation of phenomena or independent is supposed to mean here.
Yup. Pretty much up to the publication of the second edition of Newton's Principia. Responding largely to Cartesians, Newton added the General Scholium, which included a passage known as hypotheses non fingo:
"But hitherto I have not been able to discover the cause of those properties of gravity from phaenomena, and I frame no hypotheses. For whatever is not deduc’d from the phaenomena, is to be called an hypothesis; and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferr’d from the phaenomena, and afterwards render’d general by induction." https://isaac-newton.org/general-scholium/
Which is why physicists generally ignore philosophy and concentrate on the maths: "Shut up and calculate".
Yes, but we are on a philosophy site. And btw there were many great scientists since Newton who would have been insulted if you told them that science shouldn't also at least try to make sense of the world, just because Newton said so.

Not everyone wants to just shut up and calculate, for example to quote a Nobel laureate, "Niels Bohr brainwashed a whole generation of theorists into thinking that the job of interpreting quantum theory was done 50 years ago".
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