A couple of nice cosmo/quantic papers with philosophy angles

Discussions ranging from space technology, near-earth and solar system missions, to efforts to understand the large-scale structure of the cosmos.

A couple of nice cosmo/quantic papers with philosophy angles

Postby Marshall on August 28th, 2015, 1:32 pm 

http://arxiv.org/abs/1508.05543
Relational Quantum Cosmology
Francesca Vidotto
(Submitted on 22 Aug 2015)
The application of quantum theory to cosmology raises a number of conceptual questions, such as the role of the quantum-mechanical notion of "observer" or the absence of a time variable in the Wheeler-DeWitt equation. I point out that a relational formulation of quantum mechanics, and more in general the observation that evolution is always relational, provides a coherent solution to this tangle of problems.
20 pages, 4 figures. Contribution to the forthcoming book on Philosophy of Cosmology edited by K. Chamcham, J. Barrow, J. Silk and S. Saunders for Cambridge University Press

http://arxiv.org/abs/1508.05533
An argument against the realistic interpretation of the wave function
Carlo Rovelli
(Submitted on 22 Aug 2015)
Testable predictions of quantum mechanics are invariant under time reversal. But the change of the quantum state in time is not so, neither in the collapse nor in the no-collapse interpretations of the theory. This fact challenges the realistic interpretation of the quantum state. On the other hand, this fact follows easily if we interpret the quantum state as a mere calculation device, bookkeeping past real quantum events. The same conclusion follows from the analysis of the meaning of the wave function in the semiclassical regime.
4 pages, 3 figures

The latter was claimed to be refuted by Dieter Zeh, but the "refutation" http://arxiv.org/abs/1508.06895
didn't seem to me to make much sense.

Both papers address (may actually solve) some problems at a philosophical level.
The role of the observer, and time, are long-standing puzzles in cosmology. John Barrow, Joe Silk, and Simon Saunders are major figures in cosmology and in foundations/interpretation of quantum theory. It is interesting that they are assembling and editing a book on Phil. of Cosmology and have included this paper by Vidotto.

Some of us watched parts of the Oxford 2013 conference on Cosmology and Quantum Foundations. As I recall it was Dandelion who found and passed along to us the link to those videos. Some were pretty remarkable.
We have a thread about them. I guess I could get the Oxford philosophy of science YouTubes by googling [rovelli oxford cosmology]
or something like that. Yes! that gets one of the talks:
https://www.youtube.com/watch?v=TzmykSv6OBY
User avatar
Marshall
Honored Member
 
Posts: 7915
Joined: 17 Oct 2006
dandelion liked this post


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby Marshall on August 28th, 2015, 4:42 pm 

Final paragraph:
God did not over-fill the world with moving waves on infinite dimensional configuration spaces. She didn’t even draw it with heavy continuous lines. She just dotted it with sparse quantum events.

At the end there is a 19th century French pointillist painting of a sailboat made with dots of light (photon events if you like) I wish I could find an online copy somewhere.

I think it is a section of this painting by Georges Seurat called "La Seine a la Grande Jatte" painted around 1888
Image
There is also a more famous painting of the shore at La Grande Jatte, with many people in various attitudes enjoying the space and the weather. But this painting is mainly just of the river, as the title indicates.
User avatar
Marshall
Honored Member
 
Posts: 7915
Joined: 17 Oct 2006


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby Marshall on August 28th, 2015, 5:32 pm 

"She just dotted it with sparse quantum events."

this is the core idea of event-based interactive ontology, or interactive quantum Realism. I don't know what else to call it. We had some related threads. It's not good (and it leads to contradictions and paradoxes) to fill heavy continuous "reality" in between interactions/events. that is overloading, making an excessive ontology.

People who believe in the quantum wave function often overlook that the Schroedinger wave function of a several particle system can't live in ordinary 3D space. The wave function for an N particle system lives on 3N dimensional space. To handle arbitrarily many particles you need a world of a huge number of dimensions (essentially infinite as Rovelli points out..)

It does not work to imagine the world as a lot of little wave functions slithering and wiggling around. Logical troubles abound. Collapse, branching, you have to attribute a direction to time to imagine what the thing is doing IN BETWEEN interactions (but the actual process from one event to the other is time reversible)

I can't do an adequate job of paraphrasing. the paper is only 4 pages and it's written to be clear and accessible. Better just read it.
User avatar
Marshall
Honored Member
 
Posts: 7915
Joined: 17 Oct 2006
Braininvat liked this post


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby Marshall on August 28th, 2015, 7:17 pm 

Maybe what's emerging in this and similar papers could be called the pointillist interpretation of quantum mechanics.
User avatar
Marshall
Honored Member
 
Posts: 7915
Joined: 17 Oct 2006
Dave_Oblad liked this post


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby Braininvat on August 29th, 2015, 1:05 am 

Excellent paper. But something about the discussion of T- invariance bothered me. Regarding the beta decay example. Will read further and get back this weekend when I'm fresher. But really, QM is at its core about discreteness. If it's not Seurat, it's not real QM. The whole continuous evolution of the state vector thng, always gives me indigestion.
User avatar
Braininvat
Forum Administrator
 
Posts: 6850
Joined: 21 Jan 2014
Location: Black Hills


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby Marshall on August 29th, 2015, 3:05 am 

Midnight here, I'm looking forward to hearing more of your thoughts about this in morning. turning in now.
I agree about the continuous evolution of the state. useful book-keeping device for us but maybe not the real way she operates. Sleepy. must turn in. Glad you dumped that rude so-and-so.
User avatar
Marshall
Honored Member
 
Posts: 7915
Joined: 17 Oct 2006


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby Braininvat on August 29th, 2015, 9:59 am 

I guess the beta decay example works....the electron only manifests, is only "real" when there is an interaction. In relational QM, there really is no quantum state...and in cosmology, by extension of this concept, there is no universal quantum state. In the beta decay example, there is no concern about an imagined time-reversal where an electron wave evenly contracts around a nucleus, because you don't really have an interaction for that. So no need to fret that there's no way to codify a T-negative electron wave collapsing into a nucleus. The only interaction is the electron and the atom in the Geiger counter....that is where the electron is manifest and real, in a relational view. Forget the radioisotope emitter, forget the larger universe. So we get back to a 3D space with sparse quantum events, a pointilist ontology. I think this makes some sense, even if I can't wrap my head around where gravity fits into the cosmological picture.
User avatar
Braininvat
Forum Administrator
 
Posts: 6850
Joined: 21 Jan 2014
Location: Black Hills


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby Braininvat on August 29th, 2015, 10:22 am 

https://en.m.wikipedia.org/wiki/Trojan_wave_packet

I was reading about these and thinking about how some observer interactions can be extended and controlled for a long time, where a massive quantity of events is handled with a continuity function that allows the best "bookkeeping" for the probability of where the electron field is strongest. We need the continuity of fields, in a pointillist universe, or there is chaos. We need to know what observer expectations should be.
User avatar
Braininvat
Forum Administrator
 
Posts: 6850
Joined: 21 Jan 2014
Location: Black Hills


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby Braininvat on November 4th, 2018, 11:56 am 

Had forgotten this thread. Thanks for reminder, Dandelion.
User avatar
Braininvat
Forum Administrator
 
Posts: 6850
Joined: 21 Jan 2014
Location: Black Hills
dandelion liked this post


Re: A couple of nice cosmo/quantic papers with philosophy an

Postby hyksos on November 4th, 2018, 4:50 pm 

Hear ye, hear ye
User avatar
hyksos
Active Member
 
Posts: 1480
Joined: 28 Nov 2014
dandelion liked this post



Return to Astronomy & Cosmology

Who is online

Users browsing this forum: No registered users and 9 guests