What is your interpretation of quantum mechanics?

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Offline HellsMascot

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This could be a poll, but there would be too many options. What interpretation of quantum mechanics do you subscribe to (e.g. many-worlds, consistent history, deBroglie-Bohm)? The most commonly taught and widely accepted interpretation is that of the Copenhagen Interpretation. Do you feel this is a just treatment of our universe? Do you believe that the wave function describing a system, when observed, collapses into a discrete eigenstate? Perhaps wave function collapse is a human construct?

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Offline lightarrow

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Re: What is your interpretation of quantum mechanics?
« Reply #1 on: 14/05/2013 22:51:43 »
Copenhagen interpretation. Maybe (I really hope so) in the future an extension of it will be able to account even for the process of measurement.

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Offline yor_on

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Re: What is your interpretation of quantum mechanics?
« Reply #2 on: 14/05/2013 22:57:53 »
To me the Copenhagen defines us as parts of whatever experiment or system we observe, and that makes sense to me too. Many worlds theories exist in different versions as I've seen, but I don't see it excluding us as part of the experiment we do? What I don't subscribe too is the idea of a arrow as a illusion.
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Offline CPT ArkAngel

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Re: What is your interpretation of quantum mechanics?
« Reply #3 on: 15/05/2013 03:40:36 »
Quantum mechanics gives us a probability function. When an experiment measures a quantum state, you obtain a value among all the probable values given by the function.

Copenhagen interprets it as the reality. There is a superposition of all states until there is an observation, which fixes the state. There is no moon unless someone observes it. There is no causal explanation. Which is unsatisfactory.

Many worlds adds a simple causal explanation: each possible state exists in a different world. The act of observation generates a new path and a new world.

Both interpretations stop at looking for other causal interpretations. This is not a good scientific practice.

Gravity and electromagnetism have an infinite range, therefore everything is connected in our universe.  All the probable states are in this universe, there is no superposition for one particle taking alone, but there is a superposition of all states for all particles of the universe taking as a whole. The proof of that is the Pauli exclusion Principle.

The Bohm-De Broglie interpretation is the good one but it does not explains anything much further experimentally than other interpretions.

See my theory for an extension: http://www.thenakedscientists.com/forum/index.php?topic=34413.0

« Last Edit: 15/05/2013 03:43:11 by CPT ArkAngel »

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Offline JP

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Re: What is your interpretation of quantum mechanics?
« Reply #4 on: 15/05/2013 20:53:28 »
I'm partial to the many worlds interpretation because I find it philosophically fascinating.  But in practice, I'm very much an empiricist, so I stay out of fights over which interpretation is best: they all agree with observation.

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Offline Pmb

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Re: What is your interpretation of quantum mechanics?
« Reply #5 on: 15/05/2013 23:22:09 »
Quote from: HellsMascot
This could be a poll, but there would be too many options. What interpretation of quantum mechanics do you subscribe to (e.g. many-worlds, consistent history, deBroglie-Bohm)?
The Copenhagen Interpretation. There is an article online which will be of interest in this thread.

Quantum Mechanics and reality, Bryce S. Dewitt, Physics Today, September 1970  at http://www.projects.science.uu.nl/igg/jos/foundQM/qm_reality.pdf

It has a section the quantum theory of measurement.

Also Quantum Theory Needs No 'Interpretation', Christopher A. Fuchs and Asher Peres, Physics Today, March 2000 at http://www.google.com/url?sa=t&rct=j&q=Quantum+Theory+Needs+No+%27Interpretation%27+physics+today&source=web&cd=3&cad=rja&ved=0CD0QFjAC&url=http%3A%2F%2Fwww.phy.pku.edu.cn%2F~qhcao%2Fresources%2Fclass%2FQM%2FPTO000070.pdf&ei=gwmUUbrHGeHj4APshoGwCw&usg=AFQjCNHx2NQe38nPXbN6KXbU7Vo_3VlmMA&bvm=bv.46471029,d.dmg

Quote from: HellsMascot
The most commonly taught and widely accepted interpretation is that of the Copenhagen Interpretation. Do you feel this is a just treatment of our universe? Do you believe that the wave function describing a system, when observed, collapses into a discrete eigenstate?
Yes.

Quote from: HellsMascot
Perhaps wave function collapse is a human construct?
Of course it is. It's something created by humans to describe nature. Humans require descriptions. Nature doesn't give a hoot about what we wish to describe. :)
« Last Edit: 15/05/2013 23:50:32 by Pmb »

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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #6 on: 16/05/2013 00:08:21 »
All the interpretations tend to be a bit mystifying to non-scientists like me, but a distillation of the De Broglie-Bohm interpretation invites some comments.

The cosmos in which we live is infinite; not only is every part in contact with every other part, every part is the whole.  It is not sufficient to say that everything that can happen happens, as this implies progression.  In infinity there can be no change, no progression and no differentiation in time or space.

Change, movement and the passage of time that we observe is an illusion arising from our 3 + 1 dimensional perspective.

Quantum mechanics is a window into the infinite, through which we are just learning to look.  A measurement is simply the translation of quantum reality into our limited perception of reality.
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Offline Pmb

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Re: What is your interpretation of quantum mechanics?
« Reply #7 on: 16/05/2013 05:25:03 »
Quote from: Bill S
All the interpretations tend to be a bit mystifying to non-scientists like me, ...
Me too. It's difficult enough to study orthodox quantum mechanics, never mind studying all other interpretations. Especially those which cannot be tested by experiement such as the many worlds interpretation.

Quote from: Bill S
...but a distillation of the De Broglie-Bohm interpretation invites some comments.
I take it that you're familiar with it then?

Quote from: Bill S
The cosmos in which we live is infinite;...
That is not known to date. It's possible that the universe is spatially closed, which means that it's finite in extent.

Quote from: Bill S
... not only is every part in contact with every other part, every part is the whole.
That is incorrect. We are not in contact with most of the universe. E.g. there is no way to communicate with certain region of the universe, especially those galaxies which are moving away from us at speeds greater than the speed of light.

Quote from: Bill S
It is not sufficient to say that everything that can happen happens, ...
There is no way to prove such a think like that.

Quote from: Bill S
In infinity there can be no change, no progression and no differentiation in time or space.
What does In infinity there can be no change,.. mean? If taken literally then I quite disagree. Almost everything is chaning with time so how can you say that there can be no change at all? Is that what you really mean to say?

Quote from: Bill S
Change, movement and the passage of time that we observe is an illusion arising from our 3 + 1 dimensional perspective.
I don't know where you got that idea but it's quite wrong. There are very few physicists who would agree with such a statement. Except, of course, Julian Barbour who thinks that time is an illusion. Most, if not all, physicists don't accept that view.

Quote from: Bill S
Quantum mechanics is a window into the infinite, ...
Huh? Why? You're really confusing me. Please explain where you're getting these notions from or at least justify them for us.

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Offline Pmb

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Re: What is your interpretation of quantum mechanics?
« Reply #8 on: 16/05/2013 05:26:21 »
I'm partial to the many worlds interpretation because I find it philosophically fascinating.  But in practice, I'm very much an empiricist, so I stay out of fights over which interpretation is best: they all agree with observation.
Beautifully said my good man!

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Offline lightarrow

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Re: What is your interpretation of quantum mechanics?
« Reply #9 on: 16/05/2013 12:47:46 »
Perhaps wave function collapse is a human construct?
Don't know exactly what you mean but if you mean that the collapse is *caused* by the human act of observation (the man who opens the box to see if the cat is dead or alive), then it's not. The collapse is caused by the act of measurement.

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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #10 on: 16/05/2013 23:45:43 »
Don't know exactly what you mean but if you mean that the collapse is *caused* by the human act of observation (the man who opens the box to see if the cat is dead or alive), then it's not. The collapse is caused by the act of measurement.
Quite. And an 'act of measurement' occurs for any interaction with the system (e.g. any particle interaction). Observers not necessary. The idea that an 'observation' or 'measurement' must involve a conscious observer seems as popular an error as the idea that the Uncertainty Principle is a consequence of the Observer Effect.

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Offline Pmb

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Re: What is your interpretation of quantum mechanics?
« Reply #11 on: 17/05/2013 01:58:24 »
Quote from: dlorde
Quite. And an 'act of measurement' occurs for any interaction with the system (e.g. any particle interaction). Observers not necessary. The idea that an 'observation' or 'measurement' must involve a conscious observer seems as popular an error as the idea that the Uncertainty Principle is a consequence of the Observer Effect.
M'man! You're awesome! That is precisely the way I see it. In fact the paper by Bryce de Witt that I posted a link to above addreses that exact thing. You should give it a read. I think that you'd like it.

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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #12 on: 17/05/2013 02:08:19 »
Pete, thanks for the thorough examination of my post.  I will try to do justice to a response.

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I take it that you're familiar with it then?

I struggled with "Wholeness and the Implicate Order" and have dipped into a few other things, eg "The Undivided Universe".  I am quite willing to accept that my interpretations may have been wide of the mark, but surely testing one's understanding is a part of learning.   

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That is not known to date. It's possible that the universe is spatially closed, which means that it's finite in extent.

Of course it is not known, but the concept of an undivided universe in which: "The velocity of any one particle depends on the value of the guiding equation, which depends on the whole configuration of the universe" lends itself to speculations along those lines.

I generally follow John Gribbin in distinguishing between the Universe and the cosmos.  I do so in an attempt to avoid confusion, but, unfortunately, terminology is by no means standardised, so it doesn't always help.

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That is incorrect. We are not in contact with most of the universe.

This is absolutely true, but can we be sure that just because we lack the ability to achieve this contact, contact is impossible? 

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  There is no way to prove such a think like that.

I suspect that some confusion has crept in here because you quoted only part of my sentence.  "Saying that everything that can happen happens"  implies progression.  Hopefully, we can agree on that without digressing into a definition of "happen".

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Almost everything is chaning with time so how can you say that there can be no change at all? Is that what you really mean to say?

Precisely!  "With time" everything is changing.  Only if you regard infinity/eternity as a very long time can you draw a comparison between what happens in time and what is in eternity.  That is a concept with which I would certainly take issue.   

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I don't know where you got that idea but it's quite wrong. There are very few physicists who would agree with such a statement. Except, of course, Julian Barbour who thinks that time is an illusion. Most, if not all, physicists don't accept that view.

I didn't get the idea from Barbour's "The End of Time", but to my surprise I found much in that book that provided a scientific route to ideas I had formulated from a more philosophical approach.

I take your point that most physicists don't agree with Barbour, but then, scientific veracity is not a matter for a democratic vote, is it?

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Huh? Why? You're really confusing me. Please explain where you're getting these notions from or at least justify them for us

I will gladly try to explain how "these notions" come about, but it may take a while, so, it being 2am, I shall save that for another post.

Bohm and Barbour will, hopefully save me from having to take the ideas into "New Theories".  :)
 
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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #13 on: 17/05/2013 17:10:08 »
M'man! You're awesome! That is precisely the way I see it. In fact the paper by Bryce de Witt that I posted a link to above addreses that exact thing. You should give it a read. I think that you'd like it.
To be fair, 'measurement as interaction' isn't an original idea ;-)  When I first heard about Schrodinger's Cat and Wigner's anthropocentric ('the buck stops here') recourse to consciousness for the wavefunction collapse, I couldn't see where, in the process of reaching conscious awareness (whatever that means), collapse might occur, or why. In the limit, Wigner view seemed no different to the EWG (Many Worlds) universe before consciousness evolved, and substituting the mystery of consciousness for the mystery of wavefunction collapse seemed a lazy trick. The claim that consciousness (undefined) is somehow privileged is also Special Pleading on a par with the deist claim that, everything must have a cause - er, except God (also effectively undefined, except as the arbitrary 'first-cause-by-definition' and philosophical back-stop).

Naively, I also couldn't see why an observer must necessarily physically affect the observed system so as to collapse the wavefunction. IOW, surely the Observer Effect applies only to a subset of observations? For example, imagine that Schrodinger's cat is one of those genetically engineered glow-in-the-dark cats. In this situation, the observer doesn't require any external interaction with the observed system, photons or otherwise; he/she can observe the light emitted directly by the cat to determine whether it is alive or dead. This makes observation a passive activity - so how can it physically affect the system? I later found the observer could be considered part of the system as soon as information from the system reached him/her, but this again seemed to mirror the EWG interpretation, as the observer would then become part of the system superposition, and as the superposed states were independent and non-interacting, each observer superposition would be aware of only a single history.

I don't have the maths, but I used to wonder whether one could use Feynman's 'Sum Over Histories' path-integral approach, where the contributions of histories to the probability amplitude are summed over all possible histories, and cancel each other by interference, leaving only the classical outcome. It would tidy up a lot of loose ends...  ;)

The paper you linked to is interesting, with some elegant statistical arguments, and makes the point that, if nothing else, 'Many Worlds' has the advantages of being entirely causal, and raising interesting questions about measurement theory.
« Last Edit: 17/05/2013 17:52:42 by dlorde »

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Offline yor_on

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Re: What is your interpretation of quantum mechanics?
« Reply #14 on: 17/05/2013 17:44:08 »
The way I think of the Copenhagen definition is that you are part of a experiment. The experiment per se are not actively involved in setting parameters and limitations. You do that, before, also defining a outcome by it. And that's the 'part' I'm referring to there. The cat is a beautiful example on that you don't know a outcome, but your choice of parameters and limits will still make a difference. And where they end you still should, practically seen, find relations defining a outcome doing some forensic work on any 'real experiment'. You can't assume consciousness to define the 'mechanics' of a universe unless you define the universe itself to have that consciousness. Although it will still be correct to define it such as 'relations' defining a outcome, including you making your choice of experiment, as well as observation..
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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #15 on: 17/05/2013 17:51:30 »
The way I think of the Copenhagen definition is that you are part of a experiment. The experiment per se are not actively involved in setting parameters and limitations. You do that, before, also defining a outcome by it. And that's the 'part' I'm referring to there. The cat is a beautiful example on that you don't know a outcome, but your choice of parameters and limits will still make a difference. And where they end you still should, practically seen, find relations defining a outcome doing some forensic work on any 'real experiment'. You can't assume consciousness to define the 'mechanics' of a universe unless you define the universe itself to have that consciousness. Although it will still be correct to define it such as 'relations' defining a outcome, including you making your choice of experiment, as well as observation..

Sorry, I can't make head or tail of any of that...

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Offline yor_on

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Re: What is your interpretation of quantum mechanics?
« Reply #16 on: 17/05/2013 17:55:38 »
All of this reasoning though, builds on existent arrow. But so do statistics, and motion, relative or not. Show what does not build on a arrow and I will point out to you where it comes from historically, and that should involve a arrow somewhere in its buildup. To me it's the exact same as when I refer to 'c' as a 'clock', I need that 'speed' first, to be able to define it as a clock. Without that definition I don't have one.
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Heh.
unreasoning reasoning huh :)
« Last Edit: 17/05/2013 18:01:33 by yor_on »
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Offline yor_on

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Re: What is your interpretation of quantum mechanics?
« Reply #17 on: 17/05/2013 17:58:47 »
Relations define outcomes. Relations being all parameters, what we know and what we might infer from earlier experiments. Making that experiment we define and limit the relations as good as we can, to get a clear and consistent 'repeatable experiment'. And your choice of observation must also play part of what you see.
=

This is not a definition set in stone, defining 'relations'. What we think cause a outcome may change with more knowledge and experimenting, but it will still be relations. And I don't expect consciousness to be excluded from those relations. It, as much as a arrow, define a experiment, testing some idea. But the universe should be able to exist without it, or else we have to assume that the universe is a consciousness. In the end that might be a question of personal taste, but experimentally seen I expect the one where a universe exist, even though no 'life' existing at all.

But you can't ignore it, after all, it's consciousness that defined what we think we know, so far.

And by 'personal taste' I refer to quantum logic and super-positions, defining something without a linear arrow microscopically. But the universe we exist in is defined by outcomes, and linear time.
« Last Edit: 17/05/2013 18:20:34 by yor_on »
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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #18 on: 18/05/2013 00:51:57 »
I have been wrestling with the concepts of time and eternity/infinity for several decades.  It seems that the more I try to think about either, the more they seem to be entwined, scientifically and philosophically, with everything else, and the more complex they become.  To some extent, QM and its possible interpretations do seem to provide opportunities to tie up a few loose ends.  To offer the explanation which Pete asked for, and to make it meaningful, would involve going back over quite a long process of thought.  I would not attempt to do that in a single post.  Whilst I would welcome comments at any stage, and would point out that a conclusion might be some way off, I would also invite anyone to shout "stop!" at any point.
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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #19 on: 18/05/2013 00:59:41 »
The Infinite Cosmos  Part 1.

Theories as to the origin of the cosmos should not be confused with theories about the origin of the Universe.  The two things might be the same, or they might not.  The evidence we will be considering suggests that they are not the same in our frame of reference, but the same evidence may also indicate that there could be other frames of reference in which the situation might be different.  The best current theory of the origin of the Universe is the Big Bang theory.  This indicates, quite plainly that our Universe is finite; at least it had a beginning.  Of course, it is often argued that although our Universe had a beginning, it might not have an end, therefore it could be said to be infinite.  However, this is really a case of confusing “infinite” with “unbounded”.  Scientists and philosophers may speculate about its future, but the “moment of creation” is clearly pinpointed.  This invites the question, “what came before the Big Bang”.  The frequently offered answer, “nothing”, turns out to be quite unsatisfactory.  In fact, the more closely one looks at this "nothing" the more "somethingy" it becomes. The bouncing universe theory, which postulates that the universe expands from a big bang, then contracts to a big crunch, followed by another big bang, over and over again, seems to provide a possible way out, but this runs into the problem of infinite regression, and with it, the equally problematic “infinite series”.

On closer inspection, the bouncing universe turns out to be just one of a multitude of multiverse theories, all of which, in some way or another, involve the idea that our Universe is not all that there is.  A convenient term for this greater concept is the “cosmos”.  We then have to ask if the cosmos might be finite or infinite.  At first sight, we may seem only to have transferred this question, and all the difficulties that accompany it, from the Universe to the cosmos.  However, such may not necessarily be the case.  For a start, we have almost certainly parted with the Big Bang as the start of it all.  I suppose we could suggest a big bang as the origin of the cosmos, but as far as I am aware there is no evidence to indicate that this might be the situation, so we would simply be plucking a theory out of the air, which is not the best foundation for anything resembling serious enquiry.

What about an infinite cosmos in which our Universe is temporarily embedded?  This feels as though it could have quite a lot going for it; but does it stand up to closer scrutiny?  As we have seen, cosmological evidence points to the probability that we live in a finite Universe; this accords with our perception, and may lead to the further “perception” that we live in a finite cosmos; one which, like the observable Universe, has three dimensions of space and one of time; a cosmos that, somewhere, had a beginning.  If this were the case, it would mean that the cosmos must have had a precursor.  This seems to leave us once again with the problem of infinite regression.  The only way to avoid infinite regression is to postulate an infinite precursor.  We have now exchanged one question for another:  “How can a finite cosmos arise out of an infinite precursor without dividing that eternal precursor, and in so doing, dividing infinity? 

At this point we have to ask ourselves what we mean by dividing infinity.  In mathematics we can have more than one infinity, but in reality, infinity must be everything; if it does not include everything, it is not infinite.  If we postulate more than one infinity, then neither is infinite, because the contents of one infinity must always be excluded from the other; which is nonsense.

Before we can make any real progress we have to answer one very pertinent question: Can there ever have been a time when there was absolutely nothing?  Some scientists talk of the Universe having been created from nothing by a quantum fluctuation.  Unfortunately, this does not solve the problem, because a fluctuation must, by definition, be a fluctuation of something.  In some scientific descriptions the apparent creation from nothing of virtual particles in the vacuum requires that there be particles already there; presumably, these are necessary catalysts.  Even if we accept that virtual particles simply appear as a result of quantum fluctuations in the vacuum, then we must regard the vacuum as something in which fluctuations can occur.  All we have done is push the problem further into the past.  It seems impossible to escape the conclusion that there can never have been a time when there was absolutely nothing; otherwise there would be nothing now, but this leads us to ask the question: If we live in a finite Universe, how can the change from infinite to finite have been accomplished without changing the infinite?  We might reason that the nature of infinity is such that whatever we do to it, it remains unchanged.  Like zero, which can be multiplied or divided by any number, but remain unchanged, infinity might be unchanged by any action to which it might be subjected.  I suspect that this might be the most promising line of enquiry, but I also suspect that it will lead to more complications than might at first be evident.

Whatever it might be that has always existed must exist in eternity.  This statement might seem so self-evident as to be tautologous, but it is a point that is worth making, and keeping in mind.  Another point, one that is perhaps less obvious, that is worth stressing, is that an object that is finite can never become infinite.  Although, in theory, it can increase “for ever”, it can never reach a point where it is infinite; it would always be moving towards infinity, but would require “infinite time” in order to arrive at infinity; which, quite obviously, it could never do.  It is said of an “open universe” that it would go on expanding for ever.  Scientists seem to have no problem with that idea, and, perhaps chalk it up as yet another type of infinity, along the lines of Georg Cantor’s “infinity of infinities”.  However, we must not forget that Cantor’s infinities were mathematical infinities.  In the “real” world, even the assertion that a finite object could “increase for ever” is misleading, because it assumes the possibility of an infinite progression.  Although this is a mathematical possibility, it involves some serious complications in the physical world.  Mathematical “truths” do not always equate to physical realities.  It seems that there must be a distinction between “endless” and “eternal”.  In our finite frame of reference we cannot see an end for something that apparently goes on for ever; yet we still have to distinguish between that and something that is eternal.  The seemingly endless may have an end somewhere.  We may not be able to see it, or even imagine it, but there is no way we can be sure it is not there.  On the other hand, that which is eternal has, by definition, no end.  We may not be able to imagine this, either, but the definition is there, and if we change it in any way it is no longer eternal. 
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Offline lightarrow

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Re: What is your interpretation of quantum mechanics?
« Reply #20 on: 18/05/2013 11:48:46 »
Don't know exactly what you mean but if you mean that the collapse is *caused* by the human act of observation (the man who opens the box to see if the cat is dead or alive), then it's not. The collapse is caused by the act of measurement.
Quite. And an 'act of measurement' occurs for any interaction with the system (e.g. any particle interaction).
Yes, but you have only changed the name of the process.
What's an "interaction"?
For example, when a beam of light is bent, without absorption, by a glass prism, does the beam "interact" with the glass or not? Explain why yes or why not.
« Last Edit: 18/05/2013 11:52:46 by lightarrow »

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Offline yor_on

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Re: What is your interpretation of quantum mechanics?
« Reply #21 on: 18/05/2013 14:42:44 »
What do you say about this Lightarrow? :)

to get a interaction you need a 'system'. Even when you define it as being something interacting with itself. That makes it one of two possible definitions, either something 'unitary' can interact with itself, or it can't be 'unitary'. If it isn't unitary, then you either have a hidden parameter, or what you call unitary can't be. If it can interact with itself then it must consist of more parts than one.

All from my own way of thinking of it, that everything 'observes' and adapts to everything (aka relations) :)
And welcome to the philosophy forum :)
=

Btw, maybe the arrow could be seen as a 'hidden parameter' here, as we have probability?
« Last Edit: 18/05/2013 14:45:40 by yor_on »
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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #22 on: 18/05/2013 15:23:03 »
... you have only changed the name of the process.
Just emphasising the semantic difference between the term in physics and the term in common usage.

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What's an "interaction"?
It is the mutual effect of two objects on each other, involving the transfer of energy between objects and/or fields.

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For example, when a beam of light is bent, without absorption, by a glass prism, does the beam "interact" with the glass or not? Explain why yes or why not.
Yes, it interacts. Considered as a wave, the frequency remains constant but the phase velocity is changed entering the glass; the refractive index of glass varies with frequency, so the change in phase velocity of the different light frequencies varies, resulting in the frequency dependent refraction & splitting of the beam. Considered as particles, the photons interact with the electrons in the glass, by scattering, absorption, and re-emission (see Feynman's 'QED', ch.3, p.107).

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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #23 on: 18/05/2013 15:53:18 »
Some minor quibbles:
...
I suppose we could suggest a big bang as the origin of the cosmos, but as far as I am aware there is no evidence to indicate that this might be the situation, so we would simply be plucking a theory out of the air, which is not the best foundation for anything resembling serious enquiry.
There may be no evidence for the big bang as origin of the cosmos, but neither is there any evidence for the greater cosmos itself, so the idea of a greater cosmos is open to the same objection. If you accept the possibility of the greater cosmos without evidence, is it reasonable to reject ideas concerning that cosmos for lack of evidence? The big bang as origin of the cosmos must surely remain a possibility unless there is contrary evidence. An analogy that comes to mind is a death that might be murder, but there is no evidence of it. You would not then exclude the possibility that the murderer was a woman because of the lack of evidence that a woman did it - there is no evidence that anyone did it.

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In mathematics we can have more than one infinity, but in reality, infinity must be everything; if it does not include everything, it is not infinite.  If we postulate more than one infinity, then neither is infinite, because the contents of one infinity must always be excluded from the other; which is nonsense.
It's not clear to me that this is the case, because it is not clear to what you are referring with 'infinity'; spatial extent? temporal extent? Some explanation/clarification required.

With regard to your later musings on temporal infinity, it's worth bearing in mind temporally closed models of the universe, such as Hawking's model, which describes time itself starting at the big bang. His model had the universe and time ending at a big crunch, which we now believe to be unlikely, but as he put it, if time starts at the big bang, it makes no more sense to ask what was before the big bang than it does to ask what's north of the North Pole.

Of course, there is now a variety of hypotheses about pre-big bang physics, so Hawkings model has lost its original appeal, but it seems to me that the concept of an origin of time (and possibly an end of time) could be applied to the greater cosmos (metaverse?) just as to our universe.

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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #24 on: 18/05/2013 19:14:48 »
Dlorde,  your quibbles are certainly not trivial.  Gratifying as it might be when someone agrees with you; in terms of the development of ideas, it is much more valuable when they disagree.

I take your point about there being no direct evidence for the "greater cosmos".  One of the ideas that is central to my thinking is that if there had ever been a time when there was nothing, there would still be nothing now.  There will probably be plenty of people who will disagree with that, and I look forward to reading their arguments, however, "given that there can never have been a time when there was nothing, it follows that there must be more to our Universe than meets the eye", because our Universe seems to be finite.

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..... it is not clear to what you are referring with 'infinity'; spatial extent? temporal extent? Some explanation/clarification required.

A large part of the thrust of my reasoning is that infinity is not a very large space, and eternity is not a very long time.  In fact, making any distinction between infinity and eternity has relevance only in our limited understanding.  Time and space may have no part in the definition of infinity, but we lack the vocabulary to define it in any other way.

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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #25 on: 18/05/2013 19:42:11 »
The Infinite Cosmos  Part 2

Assuming, as, apparently, most scientists do, that the Big Bang theory is correct, our Universe must be finite; in so far as it had a beginning, but even if it could continue to expand “for ever” it could never become infinite.  Even claiming that it is expanding towards infinity is misleading.  If it can never reach infinity, in what sense can it be said to be approaching infinity; in fact it never gets any nearer.  It cannot even be likened to a hyperbolic curve which, although it never becomes a straight line, at least in theory, does, quite obviously, become increasingly straight, and therefore more like a straight line.  On the other hand a finite object that seems to go on for ever must always be an infinite distance away from infinity.

Consider the following.  Those intrepid adventurers Alice and Bob, in their respective space craft, are the only occupants of an infinite void.  Each perceives her/him self to be at the centre of the void.  There is an infinity of void extending in every direction.  This sounds like being at the centre of a sphere, but it makes no sense to describe infinity as spherical.  A sphere has, by the very fact of being a sphere, a boundary surface; infinity does not.  However far you travel in infinity, you will never reach a boundary.  A sphere has one fixed centre, but as the perceptions of Alice and Bob have already shown, there is no fixed centre to infinity, nor would it matter how far apart they were, they would still have infinity in every direction. 

What changes when Alice or Bob moves?  Any movement that either, or both, may make is movement relative to the other, not movement relative to the infinite void.  Inevitably this leads to the conclusion that whatever movement you make in infinity makes no actual difference to your position in infinity.  Before you move you are at the central point; after you move you are at the central point, but you were already there, so have you moved? 

Before we leave Alice and Bob in the void, consider one more strange thing.  Suppose that Alice and Bob are an infinite distance apart; if each moves, say, a billion light years towards the other, are they still an infinite distance apart?  Intuitively, it might feel as though they should be two billion light years closer to each other, but that would mean that the distance between them was less than infinite.  If the distance between them is less than infinite, it must be finite.  This means that something that was infinite has become finite.  Reverse their journey and something finite suddenly becomes infinite.  This is impossible.  It seems that if they are an infinite distance apart, however they may move, the distance between them will always remain infinite.  Perhaps the logical conclusion to draw from this is that in infinity, distance has no relevance at all.  This must lead us to ask if, in fact, Alice and Bob in infinity can actually move relative to each other, or if the concept of movement is simply transferred from our dimensions.

Whatever relevance distance might or might not have in infinity, it does seem that the occupants of infinity may be able to move relative to one another, but not relative to the infinite background.  There is a ring of familiarity here; this scenario has a distinctly Einstienian feel.  In 4-dimensional spacetime we can move relative to one another, but can identify no static background against which we can establish absolute motion or rest.  Given that relative movement is, at least in theory, possible in infinity, we must look at the question of time, because movement is change and change requires time in which to happen.  However, we should not lose sight of the fact that there is a major difference between spacetime, as we experience it, and infinity.  In spacetime we can identify no static background against which we can measure motion, but having said that, there is no way we can know with certainty that it is not actually possible to move relative to spacetime.  In infinity, it is infinity itself that seems to provide that background, but here we can establish that movement relative to that background is not possible.   

It seems that all we are doing is asking ever more questions, without answering any.  To attempt to answer at least some of these questions, we must look even more closely at the idea of infinity.  For the sake of simplicity the term “infinity” will be used to cover “eternity” as well; in fact, the terms are interchangeable.  In general usage eternity is simply “infinite” time, but there is a serious caveat here that must not be overlooked.  Eternity is not an infinite expanse of time; in fact, it does not involve time, the two concepts are, incompatible.  The concept of eternity as being in any way “temporal” arises from our limited ability to comprehend the nature of infinity.  Like “Flatlanders” who cannot even imagine a third spatial dimension, we try to examine infinity using only our four dimensions of spacetime.  Thus we find ourselves constantly falling back on temporal analogies and terminology, which are, at best, only of limited value, and, at worst, are downright unhelpful.   

We might wonder if we could devise some sort of thought experiment to probe eternity and time as we have just done with infinity and space.  Here, the task becomes much more difficult because as far as time is concerned we have only one observable dimension.  What is worse, we seem constrained to move in that dimension only in one direction, and, for all practical purposes, at one speed.  Of course, in a thought experiment, we can use perfect instruments and ideal conditions, so there is no bar to our travelling at sufficiently close to the speed of light for relativistic effects to become important.  In other words, we can construct our experiment in such a way as to make time dilation significant. 

If Alice could travel along the time dimension at close to the speed of light, relative to Bob, and then return, she would find she had aged less than Bob.  Unfortunately, even in our idealised experimental conditions, there seems to be no way of reversing Alice’s travel along the time dimension.  We might invoke closed time-like loops, but these come with problems of their own that might only serve to distract us from our consideration of infinity/eternity.
   
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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #26 on: 18/05/2013 19:47:33 »
One of the ideas that is central to my thinking is that if there had ever been a time when there was nothing, there would still be nothing now.
This is where closed or one-ended temporal systems can be considered. If time itself 'begins' when the universe or cosmos initiates (our language is inadequate for this kind of thing!), then there is never a time when there is nothing, yet it's debatable whether time is infinite in the past direction...

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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #27 on: 19/05/2013 02:39:54 »
Accepted! If time began with the Universe, then there was no time (unbounded or otherwise) before that.  However, that is little more than a semantic device.  It is no more a scientific proposition than saying  "God created the Universe", so we can ask no more questions about its origin.

In spite of such eye-catching book titles as "A Universe From Nothing"; the "nothing" always seems to turn out to be something.

If there was nothing before the Universe; was there an infinity of nothing?
If not: what came before the nothing?
Why might it be preferable to imagine that there was nothing, rather than that there was a timeless cosmos?
Which of those is, logically, more likely to give rise to a universe with space and time?
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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #28 on: 19/05/2013 12:02:13 »
It is no more a scientific proposition than saying  "God created the Universe", so we can ask no more questions about its origin.
True enough, although it has advantages over the God proposition, not least Occam's Razor.

But the same objection applies to your subsequent questions, none of which are scientific, yet you still ask them:
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If there was nothing before the Universe; was there an infinity of nothing?
If not: what came before the nothing?
Why might it be preferable to imagine that there was nothing, rather than that there was a timeless cosmos?
Which of those is, logically, more likely to give rise to a universe with space and time?

Incidentally, I'm not sure the idea of a 'timeless cosmos' has any useful meaning, but maybe there's a place for it in the maths...

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Offline lightarrow

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Re: What is your interpretation of quantum mechanics?
« Reply #29 on: 19/05/2013 14:20:04 »
Quote
What's an "interaction"?
It is the mutual effect of two objects on each other, involving the transfer of energy between objects and/or fields.
It's not enough, if you want the term "interaction" to be synonimous of the term "measure" I have used in this context. See down.
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For example, when a beam of light is bent, without absorption, by a glass prism, does the beam "interact" with the glass or not? Explain why yes or why not.
Yes, it interacts. Considered as a wave, the frequency remains constant but the phase velocity is changed entering the glass; the refractive index of glass varies with frequency, so the change in phase velocity of the different light frequencies varies, resulting in the frequency dependent refraction & splitting of the beam. Considered as particles, the photons interact with the electrons in the glass, by scattering, absorption, and re-emission (see Feynman's 'QED', ch.3, p.107).
But if the light beam is made of single photons, a photon's wavefunction doesn't collapse after having passed through the glass prism, so that "interaction" is not a "measure" of the quantum state of the photon (in particular, of its frequency).
« Last Edit: 19/05/2013 14:21:50 by lightarrow »

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Offline lightarrow

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Re: What is your interpretation of quantum mechanics?
« Reply #30 on: 19/05/2013 14:24:13 »
What do you say about this Lightarrow? :)
See my answer to dlorde. What do you think about it?

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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #31 on: 19/05/2013 16:13:22 »
Quote from: dlorde
Incidentally, I'm not sure the idea of a 'timeless cosmos' has any useful meaning, but maybe there's a place for it in the maths...

Before addressing the question of any useful meaning for a timeless cosmos, or any place for it in the maths, consider Cantor's mathematical infinities.  His countable and uncountable infinities found their places in the maths of the time, and have remained there.  What is rarely considered is that he discovered that there existed an infinity of these infinities.  Where does that fit into "the maths"?
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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #32 on: 19/05/2013 23:19:31 »
The Infinite Cosmos  Part 3

We should return to the question as to how a finite cosmos might arise out of an infinite precursor without dividing that eternal precursor, and in so doing, dividing infinity.  Three possible answers come readily to mind: (i) there is an infinite, intelligent, entity that can create a cosmos without undergoing any change in itself; (ii) the infinite precursor, although not an intelligent entity, was able to spawn a finite cosmos without undergoing change.  One must then assume that this finite cosmos gave rise to our finite Universe; and, (iii) we live in an infinite cosmos, which somehow was unchanged by the “creation” of our finite Universe.  Any of the above possible answers appears to involve a leap of faith, but we have to ask if any answer might be more logically likely than either of the others.

Theologians would undoubtedly opt for the first choice.  An entity such as this lends itself to the concept of God, the creator, whose eternal realm is outside our cosmos, but who, with a little imaginative thought, could be woven into our world view.  It is still tempting to argue that the act of creation would divide eternity into two “halves”, but this temptation may arise from our restricted view of the proposed spiritual realm. Because our only experience is of linear time, it is very difficult for us to achieve any real feeling for the nature of eternity.  There may be some mystics who can do this; Fred Alan Wolfe would have us believe there are yogis who can; and he justifies this call to belief on the basis of quantum mechanics.  Michael Talbot cites numerous examples of mystics and psychics who can experience a timeless, spaceless realm.  Julian Barbour’s “Platonia”, without resorting to mystics and psychics, paints a picture of a timeless “world” in which all movement and change are illusions, establishing that scientists as well as mystics can have profound thoughts about eternity.  In addition, as we reasoned above, movement and change seem to be possible in infinity, provided they are restricted to the frames of reference of individual occupants.   

If one were formulating an argument regarding the possible existence and nature of any causal entity that might have been responsible for the “creation” of the cosmos, it could be tempting to start the argument from a consideration of the nature of the observable Universe.  Indeed, many theist arguments have this starting point.  It is easy to think that, because progressively fewer scientists seem to believe in God, any argument that relied on observations of the Universe would become progressively less powerful as time passed.  Such a position would, undoubtedly, spring from a belief that arguments from the nature of the Universe would necessarily be based on the apparent order of the Universe, which many interpret as indicating intelligent design.  However, order and apparent design are not the only arguments that might be made from observations of the Universe, and some of the other lines of reasoning could actually become stronger with time.  For example; if one argued that there is life in the Universe, therefore its creative force must also include life; this could, a few decades ago, have been countered be the assertion that the Universe contained matter; therefore the creative entity must also have included matter.  This would necessarily have cast considerable doubt on any spiritual or supernatural claims made about the “creator”, who, at least from the theist perspective, needed to be spiritual.  To some extent, Einstein wrecked this counter argument by pointing out that matter and energy were interchangeable, and it seems easier to equate a spiritual being with pure energy than with any kind of matter.  However, things have progressed even further since Einstein, and the counter argument is by no means as secure as it would have seemed before quantum physics raised serious questions about the reality of what we perceive as matter.  Even more doubt is cast on the concrete nature of matter by the theory of the “holographic” Universe, a concept which, although it is still very much a minority view, cannot necessarily be ruled out.

If one acknowledges that the material world is not necessarily as solid as it seems to us, and if one accepts that an effect is unlikely to be greater than its cause, then it seems reasonable to argue that whatever is responsible for the existence of our Universe must contain the essential elements of our Universe in order to be able to “create” them.  For example; the Universe contains life and intelligence, therefore the “cause” of the Universe must also contain life and intelligence.  Naturally, there are many who would disagree with this line of reasoning and maintain that it is unscientific.  However, that pillar of scientific reason, Richard Dawkins, appears to support this view.     

  One of the arguments that Dawkins uses to refute the belief that the Universe had a creator is that any being who could create something as complex as the Universe would, itself, have to be very complex, and would therefore have had to evolve.  Apart from the fact that he seems to be ignoring the scientific concept of the “Boltzmann Brain”, he is, at worst, sidestepping the whole idea of eternity, and, at best, trying to apply Darwinian evolution to eternity.  It is worth repeating that eternity is not an endless succession of time, it must be something quite different, and if there is one thing that evolution needs it is time.

  Evolution provides us with the best, possibly the only, scientific explanation, not only for life on Earth, but for the existence of our Universe, as we perceive it.  Unless and until science can provide us with a better explanation than the Big Bang for the origin of our Universe, then, within this Universe, evolution rules – OK.   I am not suggesting that the evolution of the Universe from the initial singularity, or whatever the starting point might have been, was Darwinian “survival of the fittest”, but an evolutionary process can, nevertheless, be traced from the Big Bang to the present day.  The important thing to remember about evolution is that it involves change, and change, as noted above, requires time.

Asserting that there is a creator who created the cosmos might seem to lead to an infinite regression situation in which the next question must be: Who created the creator? – and so on, ad infinitum.  However, this regression can be brought to a halt at any point by invoking an eternal creator.  In the spirit of William of Ockham, we would have to concede that nothing was achieved by protracting the list of creators beyond one. 

Theists choose to call the ultimate cause of the Universe “God”, and God is interpreted in a multitude of ways by various religions, sects and philosophical schools.  Atheists, on the other hand, look for explanations that do not involve God, or any intelligent “designer”, and tend to produce their own array of explanations.  In spite of claims and counter-claims by both sides, it seems that either position is ultimately a question of “faith”.  Perhaps this is why everyone hates an agnostic.  The agnostic has seen through both sides, and, like the true scientist, is keeping all options open in case some hard evidence should be produced in favour of one side or the other.   

Returning to our list of “possible answers”; Ockham’s razor might usefully be invoked in order to dispose of the second option, which contains an “entity” for which there is no apparent “necessity”.  In reality, the second answer differs from the third only in form, and in the fact that it lets in the possibility of infinite regression.

Scientists might be more inclined to go for the third choice, particularly if they happen to be atheists.  On the face of it, the third choice seems to involve less “faith” than does the first.  However, an exploration of the concept of infinity, and how our apparently finite cosmos might be dovetailed into it, raises some interesting physical and philosophical questions. 

   The alternative to a created cosmos seems to be an infinite cosmos.  Understanding this may require some thought.  An infinite cosmos must contain everything that exists, or ever can exist.  There can be nothing that is outside an infinite cosmos: no matter, energy, space or time; no potential and no uncertainty.  Outside an infinite cosmos there can be no creation, because there can be no creator.  Nothing can be added to an infinite cosmos, because all that is, or can be, is already included in it.  Nothing can be taken away, because there is nowhere for it to go.

I guess this is a good place to make a break as there will probably be quite a few objections to this latest installment, so I'll need time to consider some possible answers. :)
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Offline zbhfw

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Re: What is your interpretation of quantum mechanics?
« Reply #33 on: 20/05/2013 00:11:15 »
I go by the interpretation put forth by Feynman... there is a way to calculate the probability of something happening, (the path integral), but all else is asking questions that have no meaning, and any imagined answers will probably look as silly to future generations as the flat earth theory. By the way, 'QED, the Strange Theory of Light and Matter' is available as an ebook, with a new introduction that is relative to this discussion.

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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #34 on: 20/05/2013 01:23:39 »
But if the light beam is made of single photons, a photon's wavefunction doesn't collapse after having passed through the glass prism, so that "interaction" is not a "measure" of the quantum state of the photon (in particular, of its frequency).
If you read Feynman (QED pp.101 & 107), you'll see he explicitly describes the scattering interaction as the photon being absorbed by an electron and a new photon being emitted. If you prefer the wavefunction collapse interpretations, the absorbed photon's wavefunction clearly must collapse. There is a probability amplitude for photons to pass through the glass without interacting, but for the observed refraction, the scattered photons are also required.

As already mentioned, the frequency of the light doesn't change, but its phase velocity does (depending on frequency). The use of 'measure' in physics generally refers to an observation (collapsing the wavefunction if you like), but in QM, any interaction has this effect, so 'measure' is the subset of interaction that involves observation. That's all I was saying.
« Last Edit: 20/05/2013 01:37:29 by dlorde »

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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #35 on: 20/05/2013 01:29:28 »
... consider Cantor's mathematical infinities.  His countable and uncountable infinities found their places in the maths of the time, and have remained there.  What is rarely considered is that he discovered that there existed an infinity of these infinities.  Where does that fit into "the maths"?
Cantor's transfinite numbers are esoteric and interesting, but I'm not sure what you mean by "Where does that fit into 'the maths'?" - the maths is the maths of transfinite numbers (wikipedia has a reasonable stab at it). When I said there may be a place in the maths for a timeless cosmos, I was referring to the maths used in the physics of cosmology; it was just a rhetorical statement.

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Offline yor_on

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Re: What is your interpretation of quantum mechanics?
« Reply #36 on: 20/05/2013 08:51:55 »
Yes Lightarrow :) To me it's a question of what 'reality' should be seen as. The first thing I would like to measure is if the photon would differ for passing that glass. If it won't, then that need a explanation, as I would from my first definition expect anything meeting another object to interact, especially if passing through it.

You can argue it a lot of ways, naively lift up the issue about a 'size' and ask yourself what the probability is for something without size to interact at all? That one you can use neutrons for too. But light is presumed to interact with matter. If it didn't we wouldn't be here.

And it will change angle passing that glass, depending on incoming direction. So it must interact to me unless I assume that light not to interact depending on angles, meaning a light beam 'hitting' a perfect transparent glass straight on then gets excluded from interaction. So, the question to me would be if it really can be proven that this photon in no way change momentum energy frequency passing that glass?

And that is in a way the exact same question as the one about a 'ideal elastic collision', aka light reflected from a perfect mirror.

You could also argue this way, presuming no measurable change, assuming all light quanta to be identical, then there was no glass represented from the definition of a photon interacting with matter. And that one might fit a idea of 'relations' and light non propagating. Because in such a definition we just look for a logic, we do not discuss what the logic implies when when it comes to questions about if the universe is closed or not. Neither do we ask ourselves what 'energy' really, really, is :) We just look at causality, experimenting on it, to then define relations.
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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #37 on: 20/05/2013 09:48:39 »
... I would from my first definition expect anything meeting another object to interact, especially if passing through it.
As already mentioned, there is an amplitude for photons to pass through the glass without interacting.

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Re: What is your interpretation of quantum mechanics?
« Reply #38 on: 20/05/2013 12:23:46 »
Want to expand on that one dlorde?
Using my definition it either interact, meaning that it will differ, or it doesn't. If there is a measurable change then that should be a result from a interaction, and that includes everything that differ from how we define it to have behaved before, including its propagation.
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Re: What is your interpretation of quantum mechanics?
« Reply #39 on: 20/05/2013 12:31:20 »
Using Feynman's many paths then I would say that that is a result from statistics, defining probabilities. That to me is the same concept as I described when discussing light as non propagating. We use logic to define it, and if that logic won't fit a macroscopic definition then it doesn't matter, as long as the logic makes sense and give us a prediction. From it you can, or you can't, 'prove' how it really should be, also depending on what experiments you can imagine up to define your hypothesis. And to me the most important things there should be the experiments and the logic, if that works then the theory can wait a little :) Because a theory is just as good as our preconceptions, and we all have such.
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Offline lightarrow

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Re: What is your interpretation of quantum mechanics?
« Reply #40 on: 20/05/2013 12:55:51 »
But if the light beam is made of single photons, a photon's wavefunction doesn't collapse after having passed through the glass prism, so that "interaction" is not a "measure" of the quantum state of the photon (in particular, of its frequency).
If you read Feynman (QED pp.101 & 107), you'll see he explicitly describes the scattering interaction as the photon being absorbed by an electron and a new photon being emitted. If you prefer the wavefunction collapse interpretations, the absorbed photon's wavefunction clearly must collapse. There is a probability amplitude for photons to pass through the glass without interacting, but for the observed refraction, the scattered photons are also required.

As already mentioned, the frequency of the light doesn't change, but its phase velocity does (depending on frequency). The use of 'measure' in physics generally refers to an observation (collapsing the wavefunction if you like), but in QM, any interaction has this effect, so 'measure' is the subset of interaction that involves observation. That's all I was saying.
I don't have Feynmann's QED available in this moment, so don't know what he means, but let me contest your interpretation. If that were a qm measure, why you can't say which is the photon's energy after coming out of the prism?
(As you know, infact, the photon's wavefunction is still in the same superposition of frequencies which had the photon before entering the prism).

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Offline lightarrow

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Re: What is your interpretation of quantum mechanics?
« Reply #41 on: 20/05/2013 13:03:28 »
Yes Lightarrow :) To me it's a question of what 'reality' should be seen as. The first thing I would like to measure is if the photon would differ for passing that glass. If it won't, then that need a explanation, as I would from my first definition expect anything meeting another object to interact, especially if passing through it.
The photons which enters the prism is not the same as the one who comes out, but in a very subtle way; the photon which comes out has now frequency entangled with its direction: if the detector detects the photon at a specific angle, then its energy is specific (larger angles = larger frequencies) but *you can't say the photon's energy before detecting the angle of arrival of the photon*, so its wavefunction hasn't collapsed after coming out of the prism.

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Offline CD13

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Re: What is your interpretation of quantum mechanics?
« Reply #42 on: 20/05/2013 13:26:38 »
Bill S,

Thanks for the arguments. It seems that until we can understand infinity (and I mean understand, not describe), we'll always be like ants thinking that our bit of the nest is everything,

As a scientist myself, I can understand the frustration this may bring. At the age of eight, the annoyance of being told by schoolmates that the highest number in the world can be beaten by the highest number plus one is still a vivid memory. Cantor's work was impressive but it reminds me of the school playground again.

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Offline CD13

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Re: What is your interpretation of quantum mechanics?
« Reply #43 on: 20/05/2013 13:34:47 »
Bill S,

Oh, and another thing.

If the cosmos or multiverses are infinite, surely there must be a infinite amount of information/knowledge. So our partial knowledge will always be zero. Yes, I know you can't divide by infinity but you know what I mean. So I know as much now as I did when I was eight.

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Offline Bill S

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Re: What is your interpretation of quantum mechanics?
« Reply #44 on: 20/05/2013 16:28:37 »
Quote from: CD13
So our partial knowledge will always be zero.

Mathematically our partial knowledge would be zero, but there must be another way to look at it, because if you apply the same reasoning to matter in an infinite cosmos, then our "share" of that matter must be zero - yet we are here.

My protracted ramblings should - I hope - reach that alternative, I just hope others have the patience to stay with the animadversions of an old codger long enough.  :)
There never was nothing.

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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #45 on: 20/05/2013 22:32:47 »
Want to expand on that one dlorde?

Sure, you can read it in Feynman's own words HERE (page 107). If you need to get up to speed on his summing of probability amplitude arrows approach, start from the beginning of Chapter 3, 'Electrons and their Interactions' (p.87). He explains it more clearly and precisely than I ever could.

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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #46 on: 21/05/2013 00:02:58 »
If that were a qm measure, why you can't say which is the photon's energy after coming out of the prism?
If it was a measurement, you could know. Like I said, measurements are the subset of interactions where an observer is involved. All measurements are interactions, but not vice-versa. If an interaction occurs unobserved, you're not going to know the energy. If you arranged things so that you captured the scattered photons, you could measure their energy.

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As you know, infact, the photon's wavefunction is still in the same superposition of frequencies which had the photon before entering the prism).
The way I read it, the wavefunction describes the quantum state of a particle. Feynman explicitly says (with italicised emphasis) that the scattered photon is  a new photon, which means a new particle wavefunction (with the same frequency probability amplitudes as the incoming photon, but different in some other respects). From the point of view of the system of including incoming photon, electron and scattered photon, it's all part of the same evolving complex wavefunction that describes that system. Whether the wavefunction of a particle that persists through the interaction, e.g. the electron, collapses at the interaction would depend on your interpretation - go with Wigner and it doesn't collapse until a conscious observer (e.g. 'Wigner's Friend') 'observes' it; go with Objective Collapse interpretations, and it collapses when the system superpositions reach a certain complexity or size, etc.; go with Many Worlds and it never collapses, it just looks that way to an observer.

It's worth noting that Feynman doesn't mention the collapse of the wavefunction in his discussion of refraction, he deals only with the probability amplitudes of various actions. He'd probably say the interpretation doesn't matter if you can work out what happens without it (and you can).

I'm happy to take corrections and adjustments to my description if they correspond to my understanding of Feynman's description, or explain where my understanding of Feynman's description falls short.



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Offline Pmb

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Re: What is your interpretation of quantum mechanics?
« Reply #47 on: 21/05/2013 01:07:05 »
Quote from: dlorde
If it was a measurement, you could know. Like I said, measurements are the subset of interactions where an observer is involved.
I have some problems with the notion of an observer being involved. One has to define "observer" and I'm sure that we can all agree that the universe existed before observers where here and that life existed before it knew how to make an observation.

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Re: What is your interpretation of quantum mechanics?
« Reply #48 on: 21/05/2013 14:32:34 »
I had the same problems Pete, in the end I found the best way to be to think of it as relations, and define them as 'observing' each other. That way you can add whatever you like to it, as long as it introduce something new, be it a measurable change or just something changing the relations I thought I knew before finding it. And a consciousness it just one more relation as I think, slightly differing in that it discuss 'free will', so becoming 'indeterministic' to me. Although that one is discuss-able :) depending on how you define chaos, probabilities, and randomness.

As well as what we find to be statistics naturally. Without statistics existing, and provable, to give us the logic, binding a past to a present, enabling us to predict a future, I wouldn't expect us to find a logic order (causality) to anything. Although maybe there is some other way to define it? But I still expect statistics to be the ground for defining it otherwise. What I mean is that we might not have thought about it this way in Newtonian society, as that was a 'clock work' universe presumed to be 'finite', but behind that we now find statistics, as I think :)

But everything is parameters, and it will be you that define them, depending on what you find yourself knowing at that time.
« Last Edit: 21/05/2013 14:42:05 by yor_on »
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Offline dlorde

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Re: What is your interpretation of quantum mechanics?
« Reply #49 on: 21/05/2013 18:02:22 »
I have some problems with the notion of an observer being involved. One has to define "observer" and I'm sure that we can all agree that the universe existed before observers where here and that life existed before it knew how to make an observation.
That's my point; interactions happen regardless of the existence of observers (which usually refers to consciousness, even if there is an intermediary device). There's no reason for special pleading for consciousness. So a measurement is just an interaction that has meaning for an observer. If interactions collapse the wavefunction, then a measurement will do so; if interactions don't collapse the wavefunction, then neither will a measurement. Or so it seems to me.

All assuming 'measurement' doesn't have some other meaning I'm unaware of.
« Last Edit: 21/05/2013 18:04:16 by dlorde »