what physicists use to do for saving Quantum Mechanics

[pedrone]

Consider a hydrogen atom.

There is attraction between the proton and the electron. So, suppose that (when the hydrogen atom will emit a photon) the electron moves from one level to another, by covering the space between the two levels.

Well, as there is a proton-electron Coulombic attraction, the electron is submitted to an acceleration (or deceleration), and according to Maxwell's theory the electron should have to emit a continuous espectrum (photons).

But this does not occur. It was not observed experimentally.

That's why the quantum theorists proposed the following: the electron does not move throughout the space that separates two levels

In other words: according to Quantum Mechanics, the electron disapears from its place in a level, and it appears instantaneously in another place of the other level, without to cross the space that separates the two levels.

Such Quantum Mechanics proposal is something like that called by Einstein to be "phantasmagoric", since only a ghost can do disapear from a place and to appear instantaneously in another place, without covering the space between the two places.


However, in 1989 Hans Dehmelt awarded the Nobel Prize with an experiment that disproves such Quantum Mechanics assumption.

In his experiment, Dehmelt showed that the electron covers the space between the two levels of energy in the atoms.

Therefore, Dehmelt experiment proves that Quantum Mechanics is wrong.

But as the quantum physicists cannot accept any theory which denies Quantum Mechanics, they discovered a way so that to save their theory again: they invented a theory in order to descredit Dehmelt experiment.
In this way, quantum theorists claimed that in Dehmelt experiment "the atom is dressed", and that was the reason why in his experiment it "seems" that the electron covers the space between levels, but acctually it does do it.
And so Quantum Mechanics was saved again.

This is the strategy used often by the quantum physicists, when a new experiment proves that Quantum Mechanics is wrong.


Do you remember other experiment which denies Quantum Mechanics, but the physicists rejected it by using such smart strategy ?

[dafydd]

Consider the lily.......

[MattusMaximus]

Originally Posted by pedrone

However, in 1989 Hans Dehmelt awarded the Nobel Prize with an experiment that disproves such Quantum Mechanics assumption.

In his experiment, Dehmelt showed that the electron covers the space between the two levels of energy in the atoms.

Therefore, Dehmelt experiment proves that Quantum Mechanics is wrong.

You know that we can actually look up why Dehmelt was awarded the Nobel prize...

Quote:

... In 1973 Dehmelt succeeded for the first time in observing a single electron in a trap, and two years later he introduced a method for "cooling" the electron - two inventions which improved accuracy considerably. The g-factor anomaly has now been determined by Dehmelt and his co-workers with an accuracy of a few parts in a billion, and this, together with corresponding theoretical calculations, constitutes one of the most critical tests we have of QED.

... A frequency stability of the same order might also be possible with the ion-trap technique. The method is based on an idea of Dehmelt in observing what is termed the quantum jump in a single ion in a trap. Laser radiation corresponding to two different transitions is used - one to a strong transition and one to a very weak one. The former is used for detecting the latter, which is very narrow and cannot be observed directly.

The realisation of methods of the extreme precision that now seems possible opens completely new opportunities for testing fundamental principles in quantum physics, gravitation theory and other branches of basic physics.

In other words, it was a spectacularly precise test which actually confirmed modern quantum theory - the exact opposite of what you stated.

You fail, pedrone.

[dafydd]

Why did he link to it? A six year old child could have spotted that it is in total contradiction to his claim. What is going on here?

[PixyMisa]

I think perhaps he's just not terribly bright.

[Ziggurat]

Originally Posted by pedrone

That's why the quantum theorists proposed the following: the electron does not move throughout the space that separates two levels

In other words: according to Quantum Mechanics, the electron disapears from its place in a level, and it appears instantaneously in another place of the other level, without to cross the space that separates the two levels.

Well, no. That isn't actually what quantum mechanics predicts. That's often given as a shorthand description for those who can't understand the math, or for those who don't want to deal with the full complexity of the problem, but in fact the time evolution of the wave function is NOT discontinuous. Quantum mechanics predicts NO discontinuities in the time evolution of a wave function. The Schrodinger equation explicitly prohibits such events. Your entire concept of quantum mechanics is wrong from the start, and all your conclusions about its invalidity therefore have no basis.

Quote:

Do you remember other experiment which denies Quantum Mechanics, but the physicists rejected it by using such smart strategy ?

As has been explained above, you haven't actually provided a first example.

[Dancing David]

Ziggy,
For us math low level people. Are you saying that 'quantum jumps' actually are not jumps?

ETA: there is a continuous transtion from one state to the next?

[EdipisReks]

Originally Posted by PixyMisa

I think perhaps he's just not terribly bright.

add in a bit of illusory superiority, and i think we might have a answer to dafydd's question.

[Ziggurat]

Originally Posted by Dancing David

Ziggy,
For us math low level people. Are you saying that 'quantum jumps' actually are not jumps?

ETA: there is a continuous transtion from one state to the next?

Yes, the transition from one state to another is continuous, though that answer deserves some clarification.

In quantum mechanics, we can describe the state of a particle as a linear combination of some basis set of states. Mathematically speaking, this is exactly equivalent to saying that a vector in 3D space can be written as a combination of x, y, and z components (our basis set). It's often convenient to use energy eigenstates (states with definite energies) as our basis states.

When the electron in an atom undergoes a transition from one state to another, that's mathematically equivalent to "rotating" in some phase space. The amplitudes of the component vectors change continuously as one rotates.

If one looks at the expectation value of energy during a transition from one energy eigenstate to another energy eigenstate, that value also changes continuously during transition. The tricky part, and probably the most relevant qualifier in regards to my response, is that this is the expectation value which is changing continuously. When we're in a superposition state with (for example) a 50/50 mixture of a high-energy state and a low-energy state, the expectation value is simply their average. If it's not an even mixture, then it's a weighted average. But if you perform a measurement, you will not get the (weighted) average. You will get either the high-energy value or the low-energy value, with the probability of each determined by the amplitudes of your superposition (the same factor that determines the weighting for the average).

So expectation values change continuously. But they change continuously as shifting probabilities between two discrete values, in the case of energy. There's quite a bit more to be said about what exactly a measurement is in quantum mechanics, but that's too broad a subject to adequately address in this response.

[pedrone]

Desconfiando da intuição semi-clássica de Dehmelt, alguns físicos teóricos usaram a mecânica ondulatória para mostrar que não ocorreriam períodos escuros. Logo em seguida, porém, em 1986, experimentos mostraram que Dehmelt estava certo! Observaram-se períodos escuros! Mas então... ocorreriam saltos quânticos de maneira objetiva nos átomos?
http://www.fis.ufba.br/dfg/pice/ff/ff-25.htm

TRANSLATION:
Distrusting of the half-classic intuition of Dehmelt, some theoretical physicists had used the wave mechanics to show that dark periods would not occur. Immediately afterwards, however, in 1986, experiments had shown that Dehmelt was certain! Dark periods had been observed! But then… would occur quantum jumps in objective way in atoms?

[MattusMaximus]

Originally Posted by Ziggurat

Yes, the transition from one state to another is continuous, though that answer deserves some clarification.

In quantum mechanics, we can describe the state of a particle as a linear combination of some basis set of states. Mathematically speaking, this is exactly equivalent to saying that a vector in 3D space can be written as a combination of x, y, and z components (our basis set). It's often convenient to use energy eigenstates (states with definite energies) as our basis states.

When the electron in an atom undergoes a transition from one state to another, that's mathematically equivalent to "rotating" in some phase space. The amplitudes of the component vectors change continuously as one rotates.

If one looks at the expectation value of energy during a transition from one energy eigenstate to another energy eigenstate, that value also changes continuously during transition. The tricky part, and probably the most relevant qualifier in regards to my response, is that this is the expectation value which is changing continuously. When we're in a superposition state with (for example) a 50/50 mixture of a high-energy state and a low-energy state, the expectation value is simply their average. If it's not an even mixture, then it's a weighted average. But if you perform a measurement, you will not get the (weighted) average. You will get either the high-energy value or the low-energy value, with the probability of each determined by the amplitudes of your superposition (the same factor that determines the weighting for the average).

So expectation values change continuously. But they change continuously as shifting probabilities between two discrete values, in the case of energy. There's quite a bit more to be said about what exactly a measurement is in quantum mechanics, but that's too broad a subject to adequately address in this response.

This is a great explanation, Zig. Thanks!

For those who don't necessarily have the background to fully understand what Zig wrote, I think that perhaps this link to Wikipedia (and more importantly, the associated animated gif image) might help you understand what he's saying. For purposed of this discussion, I would focus on parts G & H of the image at that link: notice that the solutions in G & H to the Schrodinger equation are smooth & continuous (i.e., there are no sudden gaps in the line).

I hope this helps to further clarify what Zig posted.

[dafydd]

Originally Posted by EdipisReks

add in a bit of illusory superiority, and i think we might have a answer to dafydd's question.

No might about it.

[Reality Check]

Originally Posted by pedrone

http://www.fis.ufba.br/dfg/pice/ff/ff-25.htm

What a big liar you are, pedrone !
Read the first sentence on the web page:

Quote:

Occur quantum jumps in atoms or not? The atomic model of Bohr (1913) left the impression that yes, despite the wave mechanics of Schrödinger (1926) indicate no.
...
We will examine these results, taken by Shimony as "among the most dramatic in the history of optics." We will see, however, that wave mechanics would eventually triumphing, making use of notions of "dressed atom" and "measuring null result", and transferring the discontinuity to the collapses accompanying comments.

This contradicts your OP since the Bohr model is not modern quantum mechanics which starts with the Schrödinger equation.
So

Originally Posted by pedrone

That's why the quantum theorists proposed the following: the electron does not move throughout the space that separates two levels

should read: That's why the quantum theorists proposed the following: the electron moves throughout the space that separates two levels.
and

In his experiment, Dehmelt showed that the electron covers the space between the two levels of energy in the atoms.

The author goes onto basically saying what Ziggurat has already stated. There is a discontinuity but it is not in the position or energy of the electron. It is in the wave function collapse. The concept of the dressed atom is applicable because the experiment uses laser beams.

[pedrone]

Originally Posted by pedrone

Desconfiando da intuição semi-clássica de Dehmelt, alguns físicos teóricos usaram a mecânica ondulatória para mostrar que não ocorreriam períodos escuros. Logo em seguida, porém, em 1986, experimentos mostraram que Dehmelt estava certo! Observaram-se períodos escuros! Mas então... ocorreriam saltos quânticos de maneira objetiva nos átomos?
http://www.fis.ufba.br/dfg/pice/ff/ff-25.htm

TRANSLATION:
Distrusting of the half-classic intuition of Dehmelt, some theoretical physicists had used the wave mechanics to show that dark periods would not occur. Immediately afterwards, however, in 1986, experiments had shown that Dehmelt was certain! Dark periods had been observed! But then… would occur quantum jumps in objective way in atoms?

In short:

In 1986 Dehmelt published his experiment.

In 1987 the theorists proposed a new theory:

Dressed-atom theory of stimulated pair transitions
Phys. Rev. A 35, 2164–2174 (1987)
http://pra.aps.org/abstract/PRA/v35/i5/p2164_1


Notice that earlier the Dehmelt experiment the theorists did not suppose the possibility that atom could be "dressed", in spite of they ought to expect it, by considering the foundations of Quantum Mechanics.

So, after Dehmelt experiments in 1986, the theorists at once had created the "Dressed-atom theory", so that to avoid that Quantum Mechanics should be contradicted by his experiment



I suppose the theorists will do the same regarding cold fusion.
And after the definitive cold fusion confirmation by experiments (probably the Rossi-Focardy experiment), the theorists will claim that the nucleus is "dressed", and that's why cold fusion occurs.

And at once the theorists will propose the "dressed-nucleus theory"

[Reality Check]

Originally Posted by pedrone

In short:

In 1986 Dehmelt published his experiment.

In 1987 the theorists proposed a new theory:

Dressed-atom theory of stimulated pair transitions
Phys. Rev. A 35, 2164–2174 (1987)
http://pra.aps.org/abstract/PRA/v35/i5/p2164_1

Notice that earlier the Dehmelt experiment the theorists did not suppose the possibility that atom could be "dressed", in spite of they ought to expect it, by considering the foundations of Quantum Mechanics.
...

In short: You are ignorant of the way science works !
Science is driven by empirical data. If the data says that a theory needs to be created to explain the data then the theory is created.

Even shorter: You are wrong !
In 1977: Dressed-atom description of resonance fluorescence and absorption spectra of a multi-level atom in an intense laser beam
Cohen-Tannoudji, C.; Reynaud, S.

[pedrone]

Originally Posted by Reality Check

In short: You are ignorant of the way science works !
Science is driven by empirical data. If the data says that a theory needs to be created to explain the data then the theory is created.

Even shorter: You are wrong !
In 1977: Dressed-atom description of resonance fluorescence and absorption spectra of a multi-level atom in an intense laser beam
Cohen-Tannoudji, C.; Reynaud, S.

wow!
so dressed-atom is used often when experiments disprove Quantum Mechanics...

[pedrone]

Originally Posted by Reality Check

In short: You are ignorant of the way science works !
Science is driven by empirical data. If the data says that a theory needs to be created to explain the data then the theory is created.

Even shorter: You are wrong !
In 1977: Dressed-atom description of resonance fluorescence and absorption spectra of a multi-level atom in an intense laser beam
Cohen-Tannoudji, C.; Reynaud, S.

but I not sure the dressed-nucleus theory will succeed to expain cold fusion

[Reality Check]

Originally Posted by pedrone

wow!
so dressed-atom is used often when experiments disprove Quantum Mechanics...

wow! So you remain ignorant


The dressed atom theory existed before the experiment. It is a result of applying quantum mechanics to an atom in a laser beam.

[Reality Check]

Originally Posted by pedrone

but I not sure the dressed-nucleus theory will succeed to expain cold fusion

but I am sure that you have no idea what the dressed-nucleus theory is and that it has nothing to do with fusion.

[Dancing David]

Originally Posted by Ziggurat

Yes, the transition from one state to another is continuous, though that answer deserves some clarification.

In quantum mechanics, we can describe the state of a particle as a linear combination of some basis set of states. Mathematically speaking, this is exactly equivalent to saying that a vector in 3D space can be written as a combination of x, y, and z components (our basis set). It's often convenient to use energy eigenstates (states with definite energies) as our basis states.

When the electron in an atom undergoes a transition from one state to another, that's mathematically equivalent to "rotating" in some phase space. The amplitudes of the component vectors change continuously as one rotates.

If one looks at the expectation value of energy during a transition from one energy eigenstate to another energy eigenstate, that value also changes continuously during transition. The tricky part, and probably the most relevant qualifier in regards to my response, is that this is the expectation value which is changing continuously. When we're in a superposition state with (for example) a 50/50 mixture of a high-energy state and a low-energy state, the expectation value is simply their average. If it's not an even mixture, then it's a weighted average. But if you perform a measurement, you will not get the (weighted) average. You will get either the high-energy value or the low-energy value, with the probability of each determined by the amplitudes of your superposition (the same factor that determines the weighting for the average).

So expectation values change continuously. But they change continuously as shifting probabilities between two discrete values, in the case of energy. There's quite a bit more to be said about what exactly a measurement is in quantum mechanics, but that's too broad a subject to adequately address in this response.

Thanks, very cool and as always counter intuitive.

[Loss Leader]

Originally Posted by pedrone

But as the quantum physicists cannot accept any theory which denies Quantum Mechanics, they discovered a way so that to save their theory again: they invented a theory in order to descredit Dehmelt experiment.

Um ... the truth or falsity of your claim aside ... Isn't this the way science is supposed to work?

A theory is proposed that accounts for all observable phenomena. Its predictions about future phenomena are tested. If they are not observed, the test is scrutinized. If it is repeatable, the theory is changed. Scientific theories may change all at once in sudden revolutions, or gradually evolve.

So, isn't that what happened in your example?

Also, wouldn't young physicists looking to make a name for themselves be very happy if they could overturn orthodoxy? The most famous names in science did just that. Newton's calculus was an impossibly complicated mess that could barely be understood (almost none of his terminology even survives), but he gets the credit because he was the first.

Last, does this have to do with the fact that you are championing the work of a person whose experiments cannot be recreated, whose conclusions cannot find a peer-reviewed publisher, and whose patents are too vague even to be acceptable? If so, can you tell me how fusion was achieved without the production of gamma radiation?

[theprestige]

Originally Posted by pedrone

...ocorreriam saltos quânticos de maneira objetiva nos átomos?

[b]TRANSLATION:

...would occur quantum jumps in objective way in atoms?

Minor nitpick: presented as a question, the phrase should actually be translated "...would quantum jumps objectively occur in atoms?"

(Presented as a statement, the phrase would be translated "... quantum jumps would objectively occur in atoms.")

[dafydd]

Originally Posted by Reality Check

but I am sure that you have no idea what the dressed-nucleus theory is and that it has nothing to do with fusion.

Does he think that it is a nucleus spruced up for a night on the town?

[randman]

Originally Posted by Ziggurat

Well, no. That isn't actually what quantum mechanics predicts. That's often given as a shorthand description for those who can't understand the math, or for those who don't want to deal with the full complexity of the problem, but in fact the time evolution of the wave function is NOT discontinuous. Quantum mechanics predicts NO discontinuities in the time evolution of a wave function. The Schrodinger equation explicitly prohibits such events. Your entire concept of quantum mechanics is wrong from the start, and all your conclusions about its invalidity therefore have no basis.



As has been explained above, you haven't actually provided a first example.

I agree he's wrong but don't think your comment below is entirely correct.

Quote:

but in fact the time evolution of the wave function is NOT discontinuous. Quantum mechanics predicts NO discontinuities in the time evolution of a wave function.

[Ziggurat]

Originally Posted by randman

I agree he's wrong but don't think your comment below is entirely correct.

How so?

The Schrodinger equation describes the time evolution of the wave function. Solutions to that equation do not permit temporal discontinuities. People frequently discuss the measurement process as if it were discontinuous, but 1) that's not the only way to handle it (for example, Everett's Many Worlds interpretation), and 2) even when you do treat the measurement process as a discrete, discontinuous collapse, you're not using the Schrodinger equation. Collapse is basically what happens when you STOP using quantum mechanics, and brush everything about the measurement process itself under the rug.

So I'll stand by what I said about quantum mechanics not having discontinuous time evolution.

[WhatRoughBeast]

Originally Posted by Loss Leader

If so, can you tell me how fusion was achieved without the production of gamma radiation?

Loss Leader, I hate to even seem to even partly support Pedrone, but you've missed something. The patent application by He Who Must Not Be Named (not Voldemort) specifically calls for gamma radiation subsequent to beta+ decay as the primary energy transfer mechanism.

And the Swedish Professor report makes no mention of radiation measurement during the Demonstration Which Must Not Be Named, only before and after.

[Loss Leader]

Originally Posted by WhatRoughBeast

Loss Leader, I hate to even seem to even partly support Pedrone, but you've missed something. The patent application by He Who Must Not Be Named (not Voldemort) specifically calls for gamma radiation subsequent to beta+ decay as the primary energy transfer mechanism.

And the Swedish Professor report makes no mention of radiation measurement during the Demonstration Which Must Not Be Named, only before and after.

Thanks for the correction. Was there any shielding for gamma radiation at all during the Demonstration Of Doom? Did anybody turn into Lou Ferrigno?

[randman]

Originally Posted by Ziggurat

How so?

The Schrodinger equation describes the time evolution of the wave function. Solutions to that equation do not permit temporal discontinuities. People frequently discuss the measurement process as if it were discontinuous, but 1) that's not the only way to handle it (for example, Everett's Many Worlds interpretation), and 2) even when you do treat the measurement process as a discrete, discontinuous collapse, you're not using the Schrodinger equation. Collapse is basically what happens when you STOP using quantum mechanics, and brush everything about the measurement process itself under the rug.

So I'll stand by what I said about quantum mechanics not having discontinuous time evolution.

Basically, you are arguing MWI which was obvious from the terminology. Keep in mind that math showing the probability of something happening is not the same as being physically continuous.

Say I write an equation where "A" has a 20% probability to show up at points 1-5. That doesn't mean "A"'s path there is necessarily continuous.

[randman]

JUst add a little more on the wave function collapse or decoherence, etc,......I don't see how there isn't some sort of discontinuity involved. In MWI, there would be a continuous linear progression from what I've been told about the idea, but there is a lateral discontinuity within the universe (the Multiverse). There are universes that are no longer continuous in this scenario with each other. I know you may be technically talking of continuity in time, but there is a fairly major spatial discontinuity here being proposed as the solution.

If you think the particle as existing more in a wave-like trajectory, then collapsing into a single path, that's a form of discontinuity it seems to me. It doesn't just narrow down for example.

If you think of it as not really in a wave-like trajectory or a single path but as a mere potential for discrete form, then you really are talking about even it's past "becoming" due to "measurement" or sufficient interaction. That's not really continuous in one sense because the measurement/observation/interaction event causes it to exist not just as potential but in discrete form even from the trajectory it would have had to have taken in the past (if it were discrete).

I also question the whole concept of continuous in time. What evidence do we have there is such a thing as a unit of time. If there were one fundamental unit of time, nothing would be moving as time is just a measurement of changes. If nothing was moving, then the universe would be frozen (Lynd's argument). Moreover, since things experience different rates of what we call time, which just means the changes around them occur faster or slower from their vantage point based on their relative velocity, you should expect some fuzziness, jumping and quantization. That's because from any one vantage point, something else is always not in an exact, precise position. This inherent imprecision is more evident with particles because they are so small.

[Ziggurat]

Originally Posted by randman

Basically, you are arguing MWI which was obvious from the terminology.

I don't actually like MWI. I find it deeply unsatisfying, though I recognize that's not exactly a rigorous objection. But more to the point, I'm not actually arguing in favor of it. Rather, I'm arguing against a naive Copenhagen interpretation.

Quote:

Keep in mind that math showing the probability of something happening is not the same as being physically continuous.

The evolution of the wave function is the only time evolution that quantum mechanics actually describes. And that's always continuous. So on what basis can one claim that anything in quantum mechanics is not continuous with respect to time?

[randman]

Originally Posted by Ziggurat

I don't actually like MWI. I find it deeply unsatisfying, though I recognize that's not exactly a rigorous objection. But more to the point, I'm not actually arguing in favor of it. Rather, I'm arguing against a naive Copenhagen interpretation.



The evolution of the wave function is the only time evolution that quantum mechanics actually describes. And that's always continuous. So on what basis can one claim that anything in quantum mechanics is not continuous with respect to time?

See my second response above.

[Ziggurat]

Originally Posted by randman

JUst add a little more on the wave function collapse or decoherence, etc,......I don't see how there isn't some sort of discontinuity involved.

Your measurement process isn't instantaneous. It always takes time to do a measurement. So there is time for the system to evolve, continuously, from whatever superposition state it stated in to whatever state your measurement yields. There's not necessarily any need for a discontinuity even during "collapse". In fact, quantum mechanics doesn't allow for such a discontinuity. To get a discontinuity, something other than quantum mechanics has to happen. That's a possibility, of course. But as a practical matter, "collapse" of the wave function always happens when you stop using quantum mechanics because it simply becomes too difficult.

Quote:

In MWI, there would be a continuous linear progression from what I've been told about the idea, but there is a lateral discontinuity within the universe (the Multiverse). There are universes that are no longer continuous in this scenario with each other.

That is, I think, an misunderstanding of MWI.

Let's take the simplest example, a particle in a superposition state of spin up and spin down. We measure this particle. MWI would say that since the particle was in a superpositions state, the detector (which is now entangled with the particle because of the measurement process) is now ALSO in a superposition state. And when we look at the detector, we become entangled, and also become a superposition state.

Of course, we never "observe" ourselves or our detectors as being superpositions. According to MWI, that's just the result of the two parts of our superposition not interacting with each other. The part of the wave function of ourselves which observed a spin up doesn't interact with the part of the wave function of ourselves which observed a spin down. So each part of our linear combination will behave as if the wave function has collapsed, even though no actual collapse happened. There is no spatial discontinuity either. The two parts of our spin superposition occupied the same space, so do we.

Quote:

I also question the whole concept of continuous in time.

If time isn't continuous, then standard quantum mechanics is wrong anyways. If the real world has discrete time, that still can't make a theory based on continuous time predict a discontinuity. It just means the theory is wrong, but we're talking about the predictions of the theory.

Quote:

What evidence do we have there is such a thing as a unit of time. If there were one fundamental unit of time, nothing would be moving as time is just a measurement of changes. If nothing was moving, then the universe would be frozen (Lynd's argument).

Um... you seem to be arguing in favor of continuous (not discrete) time.

[randman]

Originally Posted by Ziggurat

Your measurement process isn't instantaneous. It always takes time to do a measurement. So there is time for the system to evolve, continuously, from whatever superposition state it stated in to whatever state your measurement yields. There's not necessarily any need for a discontinuity even during "collapse". In fact, quantum mechanics doesn't allow for such a discontinuity. To get a discontinuity, something other than quantum mechanics has to happen. That's a possibility, of course. But as a practical matter, "collapse" of the wave function always happens when you stop using quantum mechanics because it simply becomes too difficult.



That is, I think, an misunderstanding of MWI.

Let's take the simplest example, a particle in a superposition state of spin up and spin down. We measure this particle. MWI would say that since the particle was in a superpositions state, the detector (which is now entangled with the particle because of the measurement process) is now ALSO in a superposition state. And when we look at the detector, we become entangled, and also become a superposition state.

Of course, we never "observe" ourselves or our detectors as being superpositions. According to MWI, that's just the result of the two parts of our superposition not interacting with each other. The part of the wave function of ourselves which observed a spin up doesn't interact with the part of the wave function of ourselves which observed a spin down. So each part of our linear combination will behave as if the wave function has collapsed, even though no actual collapse happened. There is no spatial discontinuity either. The two parts of our spin superposition occupied the same space, so do we.



If time isn't continuous, then standard quantum mechanics is wrong anyways. If the real world has discrete time, that still can't make a theory based on continuous time predict a discontinuity. It just means the theory is wrong, but we're talking about the predictions of the theory.



Um... you seem to be arguing in favor of continuous (not discrete) time.

I think you are stretching things. For example:

Quote:

Your measurement process isn't instantaneous. It always takes time to do a measurement. So there is time for the system to evolve, continuously, from whatever superposition state it stated in to whatever state your measurement yields. There's not necessarily any need for a discontinuity even during "collapse". In fact, quantum mechanics doesn't allow for such a discontinuity.

First, who says it's not instantaneous. Doesn't matter how long it would you or I to measure something, it's the interaction at some stage. Moreover, the amount of time isn't relevant. It's the discontinuous change in spatial occupancy from one state to another without intermediate states.

Quote:

Let's take the simplest example, a particle in a superposition state of spin up and spin down. We measure this particle. MWI would say that since the particle was in a superpositions state, the detector (which is now entangled with the particle because of the measurement process) is now ALSO in a superposition state. And when we look at the detector, we become entangled, and also become a superposition state.

That's not how I have heard it explained but there appear to be different MWI versions so maybe I heard a different one.

Quote:

Of course, we never "observe" ourselves or our detectors as being superpositions. According to MWI, that's just the result of the two parts of our superposition not interacting with each other. The part of the wave function of ourselves which observed a spin up doesn't interact with the part of the wave function of ourselves which observed a spin down. So each part of our linear combination will behave as if the wave function has collapsed, even though no actual collapse happened. There is no spatial discontinuity either. The two parts of our spin superposition occupied the same space, so do we.

Ok, let's just push this out a little further. A particle somewhere interacts with something, must be gazillions of instances of this throughout the universe, the way I have heard it is the particle's seeming collapse is just that it takes on path in one universe and another in a different one, and so there are really a whole lot of alternate universes including very many we don't even exist in at all. So there is definitely a separation and difference between those universes and this one. We are not in super-positional states in the overwhelming majority of these universes within the multiverse's evolution.

What you explain as MWI seems more like the idea that all we have is the quantum state of possibilities and would seem to open the door to even universes or places within this universe where if there were people there, they might experience very different things, maybe as someone posted on another thread, gravity working the opposite way, but when we look in that direction, we only see the potential based on where we are at....but that's a different topic.

Quote:

If time isn't continuous, then standard quantum mechanics is wrong anyways.

Not really and no more than anything else. Math generally assumes units of time. It is an idealization that works because of the statistical likelihood, but if there is no unit of time, and I don't see how there could be, everything in the physical world is discontinuous to some degree.

Think of it like the surface of a very smooth ball. It seems continuously smooth, and is sufficiently so for us to calculate things, but in reality, it's surface is fractal and changing.

There is no absolute continuity in all likelihood of time because there is no unit of time. If you imagine one, you could imagine dividing it further.

Plus and getting back to relativity, everything is always experiencing some difference in time, however slight, based on speed, right? So if you pick any interval of so-called time from one vantage point, something else is moving during that same interval because it's experience of time is different even if only very slightly so.

Therefore, there is no precise definite position of anything, just within a certain approximation even if that approximation is relatively very precise from a human perspective.

[W.D.Clinger]

Originally Posted by randman

Originally Posted by Ziggurat

How so?

The Schrodinger equation describes the time evolution of the wave function. Solutions to that equation do not permit temporal discontinuities. People frequently discuss the measurement process as if it were discontinuous, but 1) that's not the only way to handle it (for example, Everett's Many Worlds interpretation), and 2) even when you do treat the measurement process as a discrete, discontinuous collapse, you're not using the Schrodinger equation. Collapse is basically what happens when you STOP using quantum mechanics, and brush everything about the measurement process itself under the rug.

So I'll stand by what I said about quantum mechanics not having discontinuous time evolution.

Basically, you are arguing MWI which was obvious from the terminology. Keep in mind that math showing the probability of something happening is not the same as being physically continuous.

Say I write an equation where "A" has a 20% probability to show up at points 1-5. That doesn't mean "A"'s path there is necessarily continuous.

Schrödinger's equation says nothing about probabilities.

Had randman possessed even the dimmest understanding of Schrödinger's equation, he would not have written such nonsense.

Originally Posted by randman

JUst add a little more on the wave function collapse or decoherence, etc,......I don't see how there isn't some sort of discontinuity involved. In MWI, there would be a continuous linear progression from what I've been told about the idea, but there is a lateral discontinuity within the universe (the Multiverse). There are universes that are no longer continuous in this scenario with each other. I know you may be technically talking of continuity in time, but there is a fairly major spatial discontinuity here being proposed as the solution.

The conclusion I draw from the above is that randman doesn't understand the mathematical concepts of continuity and discontinuity.

Schrödinger's equation doesn't even make sense unless the wave function is continuous and differentiable with respect to time. With respect to other variables in phase space, the only possible source of discontinuity is the Hamiltonian itself.

Originally Posted by randman

If you think the particle as existing more in a wave-like trajectory, then collapsing into a single path, that's a form of discontinuity it seems to me. It doesn't just narrow down for example.

Schrödinger's equation says absolutely nothing about "collapsing".

Originally Posted by randman

If you think of it as not really in a wave-like trajectory or a single path but as a mere potential for discrete form, then you really are talking about even it's past "becoming" due to "measurement" or sufficient interaction. That's not really continuous in one sense because the measurement/observation/interaction event causes it to exist not just as potential but in discrete form even from the trajectory it would have had to have taken in the past (if it were discrete).

Even if that made any sense, it would have nothing to do with Schrödinger's equation.

Originally Posted by randman

I also question the whole concept of continuous in time. What evidence do we have there is such a thing as a unit of time. If there were one fundamental unit of time, nothing would be moving as time is just a measurement of changes. If nothing was moving, then the universe would be frozen (Lynd's argument). Moreover, since things experience different rates of what we call time, which just means the changes around them occur faster or slower from their vantage point based on their relative velocity, you should expect some fuzziness, jumping and quantization. That's because from any one vantage point, something else is always not in an exact, precise position. This inherent imprecision is more evident with particles because they are so small.

The conclusion I draw from the above is that randman doesn't understand the mathematical concept of "continuous in time."

The concept of continuity with respect to time does not depend upon randman's notion of "a unit of time." randman's notion of "a unit of time" must differ from the Newtonian and Einsteinian notions, because the Newtonian and Einsteinian notions do not preclude motion.

The rest of randman's paragraph consists of even more unsupported assertions that, because they don't even follow from randman's mistakes, are fairly characterized as non-sequiturs.

[randman]

Forgot to respond to this:

Quote:

Um... you seem to be arguing in favor of continuous (not discrete) time.

I am saying there is neither continuous, nor discrete, time. Time is just spatial relationship in one sense (sequence of spatial changes), but I'd go further and define space a little differently. It's because there is no discrete unit of time that what seems to be time is not so smooth and discontinuous to some degree.

[randman]

WD jumps in with his usual nonsense, having no clue what's being discussed and believing he understands it, quotes some math, but hasn't even grasped, nor considered what he is responding to.

Hey wd, how do you know a mathematical point in time exists in the universe?

[W.D.Clinger]

Originally Posted by randman

WD jumps in with his usual nonsense, having no clue what's being discussed and believing he understands it, quotes some math, but hasn't even grasped, nor considered what he is responding to.

Hey wd, how do you know a mathematical point in time exists in the universe?

Your question is naive, both philosophically and physically.

People who haven't yet understood the basics of freshman calculus shouldn't be lecturing physicists and mathematicians on quantum mechanics and continuity.

[WhatRoughBeast]

Originally Posted by Loss Leader

Thanks for the correction. Was there any shielding for gamma radiation at all during the Demonstration Of Doom? Did anybody turn into Lou Ferrigno?

The article describing the test claimed 2 cm lead thickness on the demo unit, and that the unit was operated "in a shielded room" (no further detail). Since the patent application claims a reasonable energy of 10 MeV per nucleus, and beta+ decay gives 2 gammas, the nominal gamma radiation from the process is 5 MeV. I have no idea what the half-value thickness for lead / 5 MeV is, but for 100 keV it's .012 cm, and for 500 keV it's .42 cm, so I have real doubts about the utitlity of a piddling 2 cm. A rough linear extrapolation give a half value of something like 70 cm.

Oooh. You don't think they might be (gasp) faking it, do you?

If the Hulk made an appearance, nobody made a fuss about it.

[Reality Check]

Originally Posted by randman

WD jumps in with his usual nonsense, having no clue what's being discussed and believing he understands it, quotes some math, but hasn't even grasped, nor considered what he is responding to.

Hey wd, how do you know a mathematical point in time exists in the universe?

Hey randman, why are you displaying so much ignorance of QM by posting this. What W.D.Clinger stated is standard QM that you can verify just by looking at Schrödinger's equation.

1. Schrödinger's equation says nothing about probabilities.
2. Schrödinger's equation has to be continuous in time because it is differentiated by time.
3. Schrödinger's equation does not describe any collapse of the wave funciton. It describes the continuous evolution of the wave function.

Hey randman, do you know that a mathematical point in time is defined to exist in the universe? This was first stated by this guy Euclid 2300 years ago in terms of a general geometry.

[randman]

Originally Posted by W.D.Clinger

Your question is naive, both philosophically and physically.

People who haven't yet understood the basics of freshman calculus shouldn't be lecturing physicists and mathematicians on quantum mechanics and continuity.

So you cannot answer but choose not to admit it.

Ok.