[HellsMascot (OP)]

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?

[lightarrow]

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.

[yor_on]

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.

[CPT ArkAngel]

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

[JP]

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.

[Pmb]

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

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.

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.

[Bill S]

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.

[Pmb]

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.

...but a distillation of the De Broglie-Bohm interpretation invites some comments.

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

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.

... 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.

It is not sufficient to say that everything that can happen happens, ...

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

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?

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.

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.

[Pmb]

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!

[lightarrow]

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.

[dlorde]

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.

[Pmb]

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.

[Bill S]

Pete, thanks for the thorough examination of my post.  I will try to do justice to a response.

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.   

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.

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? 

  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".

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.   

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?

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". 
 

[dlorde]

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.

[yor_on]

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..

[dlorde]

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...

[yor_on]

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.
=
Heh.
unreasoning reasoning huh

[yor_on]

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.

[Bill S]

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.

[Bill S]

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.