For the physicists out there - QM interpretations?

[michaeld]

Copenhagen?

Many worlds?

DeBroglie-Bohm?

Consciousness causes wavefunction collapse? (Note this is often confused with Copenhagen.)

"Shut up and calculate" - and don't bother me with irrelevant philosophical questions?

 

I will admit to having spent an inordinate amount of time over the years worrying about how to interpret quantum mechanics. I won't summarise the issue here unless someone requests it, but if you're not familiar and want to find out, try

https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics .

 

I lean many worlds but I hate it. I want to disprove it or at least knock a huge hole in it. Unfortunately the case for many worlds seems pretty compelling to me, as things stand. I might say more later but I thought I'd get all your thoughts first! (And even though I labelled this as for physicists, really I'd like to hear from anyone who is interested in the subject. That being said I'll tag the physicists I know of here - @Heart @Kelly @Siggy @A name is required. Sorry to anyone I missed out.)

[goldendaaysss]

50 minutes ago, michaeld said:

I lean many worlds but I hate it. I want to disprove it or at least knock a huge hole in it. Unfortunately the case for many worlds seems pretty compelling to me, as things stand.

I'm nowhere near this level of physics understanding, but I really relate to this sentiment. There are quite a few things I've come across so far in physics that make me feel like things shouldn't work that way in the world, even if I know with quite a high degree of certainty that they do.

 

Despite my almost complete lack of the necessary background to back up my thoughts on this however, from reading the wikipedia you linked the DeBroglie-Bohm interpretation makes most sense to me. This is probably because when I've previously thought about quantum mechanics it all seemed very hypothetical and "timey-wimey" if you like, but if I think about it in terms of the physical world, particles having definite positions at all times gives me a greater sense of comfort than many of the other interpretations, most likely because I haven't thought about it for nearly long enough and it's closer to the ideas of reality I've been exposed to.

[Tercy]

35 minutes ago, michaeld said:

Consciousness causes wavefunction collapse? (Note this is often confused with Copenhagen.)

*headdesk*

 

I knew ideas like this exist in the media, pop science, the Deepak Chopras of the world and such, but I didn't realise they were taken this seriously in 'academia'.

My thought on QM (amongst other things) is that experiments and equations that have some established basis in reality should be given appropriate respect, but care should be taken not to get mislead building elaborate theories on what might be nothing more than quirks in the maths, holes in our understanding, limitations of our equipment, etc.

[michaeld]

10 hours ago, goldendaaysss said:

Despite my almost complete lack of the necessary background to back up my thoughts on this however, from reading the wikipedia you linked the DeBroglie-Bohm interpretation makes most sense to me. This is probably because when I've previously thought about quantum mechanics it all seemed very hypothetical and "timey-wimey" if you like, but if I think about it in terms of the physical world, particles having definite positions at all times gives me a greater sense of comfort than many of the other interpretations, most likely because I haven't thought about it for nearly long enough and it's closer to the ideas of reality I've been exposed to.

Bohmian theory is something I plan to delve more deeply into at some point. The main issues are (a) it looks quite contrived - the distinguished role of position over other observable variables is arguably quite arbitrary, (b) it is awkward generalising the theory to include other physical phenomena such as atomic spin.

 

The non-locality - the fact the theory involves faster than light signals - is also awkward when combined with Einstein's theory of special relativity.

 

I still think Bohmian mechanics can teach us something important.

 

Re "consciousness causes collapse":

 

9 hours ago, Tercy said:

*headdesk*

 

I knew ideas like this exist in the media, pop science, the Deepak Chopras of the world and such, but I didn't realise they were taken this seriously in 'academia'.

It isn't really - consciousness causes collapse has always been a fringe idea among physicists. The name it's associated with is Eugene Wigner. Unfortunately some of the pop science you mention wrongly attributes it to some of the QM founding fathers (Bohr, Heisenberg etc).

[uhtred]

It is possible that human intuition, which is formed from experience, is not equipped to understand some of these things.  We calculate the results, but our brains may be unable to decide what they *mean*.   Or, maybe humans are simply not smart enough to understand the universe - no reason we should be, clearly no other animal is. 

 

That said, I do not see any reason to believe that the wave-function every collapses. and that we are not just all vast probability densities distributed over a vast number of states -some of those states very disjointed (imagine a quantum-triggered nuclear bomb: the two resulting states have a fantastically low probability of overlapping with each other.  OTOH, they are so different that interference from  the other state can be completely ignored.

 

That all of curse leads to the Anthropic principle in its worst form.   I HATE the anthropic principal, so I just ignore it all, and let my monkey-brain happily do science without worrying about what it *means*.  Now I want a banana. 

[michaeld]

I think there's also an interesting "meta question" - does the interpretation of quantum mechanics actually matter? Are they just different ways of looking at the same thing? Or is there an actual scientific question worth investigating here, which can be settled by logic and observation? This, I guess, was why I included a "shut up and calculate" option too in my OP.

 

I am not a physicist so I'd be interested in other views, but my impression is that the "it's a real question, worth investigating" camp has been growing in the last few decades, along with a general dissatisfaction with the "orthodox" Copenhagen interpretation. I used to be very much in the other camp myself - it works experimentally so there's nothing more to say! For a long time I even identified as a logical positivist (https://en.wikipedia.org/wiki/Logical_positivism). I am still pretty instrumentalist but I've gained more and more sympathy for the realist way of thinking in recent years. One of these days I might wake up and find myself identifying as a scientific realist....

 

There are various actual physicists who also seem to have followed this path - such as Steven Weinberg, who has become unhappy with any of the interpretations of QM in recent years, even (maybe surprisingly, at least to me) the many worlds interpretation. Myself, I can't really find anything wrong with many worlds - and in fact I think the other interpretations also imply Many Worlds in disguise - but I don't regard it as a settled question. I still hold out hope some killer argument or experimental result will emerge that changes things.

[uhtred]

On 9/25/2018 at 3:50 AM, michaeld said:

I think there's also an interesting "meta question" - does the interpretation of quantum mechanics actually matter? Are they just different ways of looking at the same thing? Or is there an actual scientific question worth investigating here, which can be settled by logic and observation? This, I guess, was why I included a "shut up and calculate" option too in my OP.

 

I am not a physicist so I'd be interested in other views, but my impression is that the "it's a real question, worth investigating" camp has been growing in the last few decades, along with a general dissatisfaction with the "orthodox" Copenhagen interpretation. I used to be very much in the other camp myself - it works experimentally so there's nothing more to say! For a long time I even identified as a logical positivist (https://en.wikipedia.org/wiki/Logical_positivism). I am still pretty instrumentalist but I've gained more and more sympathy for the realist way of thinking in recent years. One of these days I might wake up and find myself identifying as a scientific realist....

 

There are various actual physicists who also seem to have followed this path - such as Steven Weinberg, who has become unhappy with any of the interpretations of QM in recent years, even (maybe surprisingly, at least to me) the many worlds interpretation. Myself, I can't really find anything wrong with many worlds - and in fact I think the other interpretations also imply Many Worlds in disguise - but I don't regard it as a settled question. I still hold out hope some killer argument or experimental result will emerge that changes things.

I think "interpretations" are by definition things that are not measurable, and so are sort of outside of the realm of hard physics. (though perfectly valid as philosophical discussions by physicists).  

[Pentachromacy]

On 9/25/2018 at 6:50 AM, michaeld said:

I think there's also an interesting "meta question" - does the interpretation of quantum mechanics actually matter? Are they just different ways of looking at the same thing? Or is there an actual scientific question worth investigating here, which can be settled by logic and observation? This, I guess, was why I included a "shut up and calculate" option too in my OP.

 

I am not a physicist so I'd be interested in other views, but my impression is that the "it's a real question, worth investigating" camp has been growing in the last few decades, along with a general dissatisfaction with the "orthodox" Copenhagen interpretation. I used to be very much in the other camp myself - it works experimentally so there's nothing more to say! For a long time I even identified as a logical positivist (https://en.wikipedia.org/wiki/Logical_positivism). I am still pretty instrumentalist but I've gained more and more sympathy for the realist way of thinking in recent years. One of these days I might wake up and find myself identifying as a scientific realist....

 

There are various actual physicists who also seem to have followed this path - such as Steven Weinberg, who has become unhappy with any of the interpretations of QM in recent years, even (maybe surprisingly, at least to me) the many worlds interpretation. Myself, I can't really find anything wrong with many worlds - and in fact I think the other interpretations also imply Many Worlds in disguise - but I don't regard it as a settled question. I still hold out hope some killer argument or experimental result will emerge that changes things.

If you want a Unified Field Theory. It absolutely does.