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What kind of universe do we need to live in for induction to work?
Posted: 26 November 2011 04:47 PM   [ Ignore ]   [ # 46 ]
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Write4U - 26 November 2011 04:40 PM

Does that make the probability wave a metaphysical phenomena, i.e. pure potential? Bohm referred to that as the “implicate and explicate order”.

As I understand it (which isn’t much) that makes the probability wave real, as real as the tree that fell in the forest unheard. But again I’m not expert enough to be sure about the proper interpretation.

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Posted: 26 November 2011 04:50 PM   [ Ignore ]   [ # 47 ]
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That is my point. Obviously the probability wave exists, however it is not physical (instantiated reality).

It’s fascinating!

[ Edited: 26 November 2011 04:57 PM by Write4U ]
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Posted: 26 November 2011 04:54 PM   [ Ignore ]   [ # 48 ]
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Write4U - 26 November 2011 04:50 PM

That is my point. Obviously the probability wave is real, however it is not physical (instantiated).

Well ... it is physical, as physical as anything in a physical law. It’s as physical as quarks, which are never seen singly. And it’s instantiated everywhere.

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Posted: 26 November 2011 05:27 PM   [ Ignore ]   [ # 49 ]
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dougsmith - 26 November 2011 04:54 PM
Write4U - 26 November 2011 04:50 PM

That is my point. Obviously the probability wave is real, however it is not physical (instantiated).

Well ... it is physical, as physical as anything in a physical law. It’s as physical as quarks, which are never seen singly. And it’s instantiated everywhere.

I am not sure if I agree with that. 
Why can there not be natural laws which govern metaphysics?
How do we know that everything is instantiated (manifest reality) everywhere.?
Suppose we have a double slit, but no receptor. Can the probability wave become instantiated or does it just fizzle out as all waves do eventually?

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Posted: 26 November 2011 05:34 PM   [ Ignore ]   [ # 50 ]
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Does anyone know if the double slit experiment destroys (cancels) a number of photons, or is it even possible to count and compare the number of photons fired with the number of particles recorded on the receptor behind the double slit?

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Posted: 26 November 2011 06:30 PM   [ Ignore ]   [ # 51 ]
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Write4U - 26 November 2011 05:27 PM
dougsmith - 26 November 2011 04:54 PM

Well ... it is physical, as physical as anything in a physical law. It’s as physical as quarks, which are never seen singly. And it’s instantiated everywhere.

I am not sure if I agree with that. 
Why can there not be natural laws which govern metaphysics?
How do we know that everything is instantiated (manifest reality) everywhere.?
Suppose we have a double slit, but no receptor. Can the probability wave become instantiated or does it just fizzle out as all waves do eventually?

Metaphysics is the study of the bases of natural laws. There may be metaphysical laws but they cannot be arrived at experimentally. If they could, they would be physical laws.

I’m not sure about your last question but I don’t think that waves ‘fizzle out’ in the way you claim. For example, electromagnetic waves (light) propagate for billions of light years.

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Posted: 26 November 2011 06:31 PM   [ Ignore ]   [ # 52 ]
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Write4U - 26 November 2011 05:34 PM

Does anyone know if the double slit experiment destroys (cancels) a number of photons, or is it even possible to count and compare the number of photons fired with the number of particles recorded on the receptor behind the double slit?

If you count the particles before they interact with the slit, that changes the experiment and you no longer get the wave interaction at the far end. (IIRC).

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Posted: 26 November 2011 06:49 PM   [ Ignore ]   [ # 53 ]
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dougsmith - 26 November 2011 06:30 PM
Write4U - 26 November 2011 05:27 PM
dougsmith - 26 November 2011 04:54 PM

Well ... it is physical, as physical as anything in a physical law. It’s as physical as quarks, which are never seen singly. And it’s instantiated everywhere.

I am not sure if I agree with that. 
Why can there not be natural laws which govern metaphysics?
How do we know that everything is instantiated (manifest reality) everywhere.?
Suppose we have a double slit, but no receptor. Can the probability wave become instantiated or does it just fizzle out as all waves do eventually?

Metaphysics is the study of the bases of natural laws. There may be metaphysical laws but they cannot be arrived at experimentally. If they could, they would be physical laws.

I’m not sure about your last question but I don’t think that waves ‘fizzle out’ in the way you claim. For example, electromagnetic waves (light) propagate for billions of light years.

That is true, but when they arrive here they are mere ripples, not a wave of unimaginable amplitude. But then again, considering the stuff they have to travel through to reach us, their staying power is remarkable.

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Posted: 26 November 2011 09:05 PM   [ Ignore ]   [ # 54 ]
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dougsmith - 26 November 2011 06:31 PM
Write4U - 26 November 2011 05:34 PM

Does anyone know if the double slit experiment destroys (cancels) a number of photons, or is it even possible to count and compare the number of photons fired with the number of particles recorded on the receptor behind the double slit?

If you count the particles before they interact with the slit, that changes the experiment and you no longer get the wave interaction at the far end. (IIRC).

Can they not be counted before they are fired, i.e. a premeasured quantity of photons? I understand once they are released no interference is allowed.

[ Edited: 26 November 2011 09:12 PM by Write4U ]
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Posted: 26 November 2011 09:14 PM   [ Ignore ]   [ # 55 ]
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I am sorry, perhaps all this belongs in another thread. I don’t mean to hijack the topic.

My enthusiasm knows no bounds…. red face

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Posted: 27 November 2011 01:27 AM   [ Ignore ]   [ # 56 ]
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dougsmith - 26 November 2011 04:47 PM

As I understand it (which isn’t much) that makes the probability wave real, as real as the tree that fell in the forest unheard. But again I’m not expert enough to be sure about the proper interpretation.

I wholeheartedly disagree. Real objects can be detected because they have causal effects (even if there is nobody there to notice them). But the probability wave does not cause anything. In the two slit experiment the measuring of the photons is caused by the light source with its surroundings, especially the 2 slits. The probability wave is nothing more than an algorithm to determine the probability where photons will arrive, given the initial conditions of the experiment.

Do not forget that the real concept is not probability wave but wave function. And it is totally unclear what it is that ‘waves’. With sound it is the simple moving of molecules, sea waves it is molecules at density borders (water is more dense than air. See here for another astonishing example of ‘density waves’), light is distorting of the electromagnetic field, etc. But there is nothing known to ‘wave’ in the wave function: no hidden variables. The only thing we know: taking the ‘size’ of the wave function, then take the square of it, and integrate it over the universe in such a way that the outcome is 1 (the photon’s chance to be somewhere in the universe is 1), then you know the probability to measure it at a certain place. (This also explains the rather peculiar dimension of the wave function: m⁻⁽³/²⁾. Square it, you get m⁻³, integrate it over a volume (m³) and it has no dimension anymore. As is the case with probabilities. But of course this argumentation is a wagging of the dog…)

Quarks are also real, because they play causal roles, even if their kind of existence is rather strange compared to our everyday notions.

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Posted: 27 November 2011 01:34 AM   [ Ignore ]   [ # 57 ]
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dougsmith - 26 November 2011 06:31 PM
Write4U - 26 November 2011 05:34 PM

Does anyone know if the double slit experiment destroys (cancels) a number of photons, or is it even possible to count and compare the number of photons fired with the number of particles recorded on the receptor behind the double slit?

If you count the particles before they interact with the slit, that changes the experiment and you no longer get the wave interaction at the far end. (IIRC).

There are ways around it. Take e.g. a process that sends 2 photons in opposite directions. If you just count the photons in one direction, and do your two slit experiment with the others, you can compare them.

And in a ideal experiment, Write4U, they would be exactly the same. It is even easy to see that it must be the case: photons are energy, and energy cannot be destroyed.

In the experiment above, when you try to predict where a photon arrives, based on where you measured the other photon, you get entanglement. But just counting is harmless in this respect.

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Posted: 27 November 2011 05:56 AM   [ Ignore ]   [ # 58 ]
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GdB - 27 November 2011 01:27 AM

I wholeheartedly disagree. Real objects can be detected because they have causal effects (even if there is nobody there to notice them). But the probability wave does not cause anything. In the two slit experiment the measuring of the photons is caused by the light source with its surroundings, especially the 2 slits. The probability wave is nothing more than an algorithm to determine the probability where photons will arrive, given the initial conditions of the experiment.

Do not forget that the real concept is not probability wave but wave function. And it is totally unclear what it is that ‘waves’. With sound it is the simple moving of molecules, sea waves it is molecules at density borders (water is more dense than air. See here for another astonishing example of ‘density waves’), light is distorting of the electromagnetic field, etc. But there is nothing known to ‘wave’ in the wave function: no hidden variables. The only thing we know: taking the ‘size’ of the wave function, then take the square of it, and integrate it over the universe in such a way that the outcome is 1 (the photon’s chance to be somewhere in the universe is 1), then you know the probability to measure it at a certain place. (This also explains the rather peculiar dimension of the wave function: m⁻⁽³/²⁾. Square it, you get m⁻³, integrate it over a volume (m³) and it has no dimension anymore. As is the case with probabilities. But of course this argumentation is a wagging of the dog…)

Quarks are also real, because they play causal roles, even if their kind of existence is rather strange compared to our everyday notions.

I dunno. Isn’t it these waves that have causal effects on detectors? If not the waves, then what?

IIRC Feynman in one of his lectures says that all there ever are are particles, and they follow the wave functions. If that’s the proper interpretation, I’m OK with it too, and then yes, the waves only describe how the particles interact over a given distance.

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Posted: 27 November 2011 09:18 AM   [ Ignore ]   [ # 59 ]
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dougsmith - 27 November 2011 05:56 AM

I dunno. Isn’t it these waves that have causal effects on detectors? If not the waves, then what?

No. the waves themselves do not interact with the detectors. I think this becomes clear when you see that it’s only the square of the absolute value of the wave function that has an observable meaning. But it predicts only a probability of an event, not an event itself.

Another way is to see that Heisenberg developed quantum mechanics, based on observables only. There is no wave function in matrix mechanics. But the observable predictions of wave mechanics and matrix mechanics are equivalent:

When it was introduced by Werner Heisenberg, Max Born and Pascual Jordan in 1925, matrix mechanics was not immediately accepted and was a source of great controversy. Schrödinger’s later introduction of wave mechanics was favored.

Part of the reason was that Heisenberg’s formulation was in a strange new mathematical language, while Schrödinger’s formulation was based on familiar wave equations. But there was also a deeper sociological reason. Quantum mechanics had been developing by two paths, one under the direction of Einstein and the other under the direction of Bohr. Einstein emphasized wave-particle duality, while Bohr emphasized the discrete energy states and quantum jumps. DeBroglie had shown how to reproduce the discrete energy states in Einstein’s framework—- the quantum condition is the standing wave condition, and this gave hope to those in the Einstein school that all the discrete aspects of quantum mechanics would be subsumed into a continuous wave mechanics.

Matrix mechanics, on the other hand, came from the Bohr school, which was concerned with discrete energy states and quantum jumps. Bohr’s followers did not appreciate physical models which pictured electrons as waves, or as anything at all. They preferred to focus on the quantities which were directly connected to experiments.

From Wikipedia.

dougsmith - 27 November 2011 05:56 AM

IIRC Feynman in one of his lectures says that all there ever are are particles, and they follow the wave functions. If that’s the proper interpretation, I’m OK with it too, and then yes, the waves only describe how the particles interact over a given distance.

My ‘easy way’ to see this is the following: if we talk about the path of quantum particles, we can see them as waves; if we talk about the interaction of quantum systems, it’s particles.

The last resort of thinking about the wave function as a cause of a quantum event must be given up as soon as entanglement is involved.

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Posted: 27 November 2011 02:11 PM   [ Ignore ]   [ # 60 ]
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I’ll take your word for it, GdB. I can’t say I really understand it; I expect I’d need to understand the equations to do that.

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