Quantum Foundations: outlook on this research field?

[askingquestionst]

TL;DR Summary

Interested in Quantum Foundations, but having trouble understanding what the field really is. Theoretical? Part of Quantum Information? Job market?

Recently, it has come to my attention a field called Quantum Foundations. This is exactly what brought me into Physics, even though back then I didn't know it was a research area.

In my Physics classes, I got disappointed and unmotivated at the "Shut up and calculate!" attitude of my Physics professors. To them, truly understanding the nature of Quantum Mechanics was a "philosophical endeavor" and that what matters is reliably predicting the final state considering the initial state (Copenhagen Interpretation, anyone?).

I have been having trouble finding information about Quantum Foundations, however. Is it considered a theoretical field? (I have heard really bad things about job market for Theoretical work).
I have found some researchers but they seem to be connected to Theoretical Quantum Information, and I can't quite understand why. Is Quantum Foundations a sub field of Quantum Information? I though QI was concerned with cryptography, memory, computing and other things, and it sounds like it is "applied" quantum. Meanwhile, Foundations would be more about fundamentally understanding quantum mechanics instead of using it as a means to and end. I don't see much similarity between both.

Also, how bleak are its job opportunities? I know that it probably doesn't have as many opportunities as Condensed Matter or AMO, but is it as bad as String Theory for job outlooks?

Someone more acquainted with this field, please shine a light on me.

 

[PeterDonis]

Moderator's note: Moved thread to QM foundations forum.

 

[Demystifier]

Summary:: Interested in Quantum Foundations, but having trouble understanding what the field really is.

You can start with my "Quantum Foundations I: What is it all about & (why) should mathematical physicists care?"
http://thphys.irb.hr/wiki/main/images/d/d5/QFound1.pdf

 

[askingquestionst]

You can start with my "Quantum Foundations I: What is it all about & (why) should mathematical physicists care?"
http://thphys.irb.hr/wiki/main/images/d/d5/QFound1.pdf

This was great and really interesting. Exactly what I was thinking.
Is there any experimental work in this field?

It seems like it is really niche. I tried contacting some profs near me but they won't reply.

 

[Demystifier]

Is there any experimental work in this field?

I'm not an expert in experimental work, but there is a lot. See e.g.
https://arxiv.org/abs/quant-ph/0701071

 

[RUTA]

There are many experiments in foundations of physics. I have two explained in these Insights: https://www.physicsforums.com/insights/weak-values-part-1-asking-photons/
https://www.physicsforums.com/insights/weak-values-part-2-quantum-cheshire-cat-experiment/
This Insight references one by Zeilinger: https://www.physicsforums.com/insig...elayed-choice-no-counterfactual-definiteness/
Just go to his website and read his papers, he has published dozens.
Here is another recent one: https://arxiv.org/pdf/1907.05607.pdf
This is an old one, but famous: https://arxiv.org/pdf/quant-ph/9903047.pdf

 

[askingquestionst]

There are many experiments in foundations of physics. I have two explained in these Insights: https://www.physicsforums.com/insights/weak-values-part-1-asking-photons/
https://www.physicsforums.com/insights/weak-values-part-2-quantum-cheshire-cat-experiment/
This Insight references one by Zeilinger: https://www.physicsforums.com/insig...elayed-choice-no-counterfactual-definiteness/
Just go to his website and read his papers, he has published dozens.
Here is another recent one: https://arxiv.org/pdf/1907.05607.pdf
This is an old one, but famous: https://arxiv.org/pdf/quant-ph/9903047.pdf

This is fascinating, and exactly what I wanted to learn when I joined Physics! It's the actual investigation of the "why" of quantum.

Do you know how hard it is as a field? Not in terms of difficulty, but in terms of positions and competition(postdocs, etc). Foundations almost passed me by unnoticed, whereas Cosmology, Strings and Particle seem so much bigger even if they are also saturated. Some people convinced me that Strings is so ridiculously competitive and there are so few positions in it that I might as well discount tenure in it as a possible career outcome. I am worried Foundations has a similar negativy.

This makes me confused on whether or not I should actually pursue it, or leave it as a side hobby.

 

[RUTA]

This is fascinating, and exactly what I wanted to learn when I joined Physics! It's the actual investigation of the "why" of quantum.

Do you know how hard it is as a field? Not in terms of difficulty, but in terms of positions and competition(postdocs, etc). Foundations almost passed me by unnoticed, whereas Cosmology, Strings and Particle seem so much bigger even if they are also saturated. Some people convinced me that Strings is so ridiculously competitive and there are so few positions in it that I might as well discount tenure in it as a possible career outcome. I am worried Foundations has a similar negativy.

This makes me confused on whether or not I should actually pursue it, or leave it as a side hobby.

Foundations is not viewed favorably within the physics community as a whole. Quantum computing/information (QI) was only granted its own section heading for the APS March Meeting three years ago. Foundations of physics is included in QI for presentations at the APS Meeting. The plenary talks for foundations at the March Meeting are well attended, though. Sean Carroll, Aharonov, Spekkens, Leifer, and Zeh have given talks, but we haven't gotten Zeilinger yet.

As for making a living, it looks to be the case that QI is now receiving funding. Two of my undergrad classmates are now working under grants for QI. They both earned their PhDs in quantum optics many years ago and recently followed the money to QI. Who knows how much longer that funding will last. If QI becomes a dead end like string theory, the money will dry up of course. Prospects in foundations per se are grim and will likely never be good -- it's really philosophy of physics and philosophy has never been robustly funded. The vast majority of those working in foundations make their money otherwise, e.g., I make my money teaching undergrad physics, not doing foundations research.

Everyone has to decide for themselves what they want to do with their life, so I won't advise you one way or another :-)

 

[askingquestionst]

Foundations is not viewed favorably within the physics community as a whole. Quantum computing/information (QI) was only granted its own section heading for the APS March Meeting three years ago. Foundations of physics is included in QI for presentations at the APS Meeting. The plenary talks for foundations at the March Meeting are well attended, though. Sean Carroll, Aharonov, Spekkens, Leifer, and Zeh have given talks, but we haven't gotten Zeilinger yet.

As for making a living, it looks to be the case that QI is now receiving funding. Two of my undergrad classmates are now working under grants for QI. They both earned their PhDs in quantum optics many years ago and recently followed the money to QI. Who knows how much longer that funding will last. If QI becomes a dead end like string theory, the money will dry up of course. Prospects in foundations per se are grim and will likely never be good -- it's really philosophy of physics and philosophy has never been robustly funded. The vast majority of those working in foundations make their money otherwise, e.g., I make my money teaching undergrad physics, not doing foundations research.

Everyone has to decide for themselves what they want to do with their life, so I won't advise you one way or another :-)

Wonderful. You told me everything I wanted to know. I had contacted some professors whose names I found online that are involved with this field, and while they were really informative about the field of Quantum Foundations itself, they couldn't tell me about the job market in regards to it.

I have been looking for all this information you provided me for quite some time! Thank you a lot.

Indeed, I will have to think a lot if I want to pursue this or to remain as an 'outsider', just reading the papers. The good part is that the literature in this field seems to be quite digestible. The bad part is that I unfortunately can't ignore the statistics pertaining the academic job market, and I think that if I focused in Foundations in a PhD program, I would be left with very poor options if I had to go to industry afterwards. It does not seem like the skills involved here are useful in Data Science nor Finance, which are the typical absorbers of Physics PhDs.

 

[bhobba]

Is there any experimental work in this field?

Yes: https://arxiv.org/abs/quant-ph/0206196

Trouble is there was a mistake. I forget what it was, but demystifyer may know off hand.

It seems like it is really niche. I tried contacting some profs near me but they won't reply.

That is hopeless. They might have no interest but can easily point you to some freely available literature eg:
https://quantum.phys.cmu.edu/CHS/histories.html

My only suggestion is to first understand QM well. I would recommend - Ballentine - QM - A Modern Development. Plus he explains the minimal statistical interpretation - it's called the Ensemble Interpretation. Interestingly there is a misconception Einstein did not think QM correct - that is wrong - he thought it correct but incomplete. He held to the Ensemble Interpretation. He even really had no trouble with its statistical nature - after all he did foundational work on statistical mechanics. He simply believed that like classical mechanics is the foundation of statistical mechanics, there is some other theory behind QM. We know QM in its more advanced variant Quantum Field Theory is incomplete because we really have no idea what is going on beyond the Planck Scale. Sometimes you hear it is because we can't mesh QM and Gravity. The situation is more subtle than that - we have a perfectly good quantum theory of gravity up to about the Planck Scale:
https://blogs.umass.edu/donoghue/research/quantum-gravity-and-effective-field-theory/

But you need to build up to Ballentine - my suggestion is first Susskind:
https://www.amazon.com/dp/0465062903/?tag=pfamazon01-20
Then Sakurai:
https://www.amazon.com/dp/1108473229/?tag=pfamazon01-20

That way you know what is understood well and is no problem eg Schrodinger's Equation, what some think is an pseudo issue, and what is an an actual issue, plus various views in between. It varies from interpretation to interpretation.

Also I found a little piece written by John Baez helpful:
https://math.ucr.edu/home/baez/bayes.html

I could say more about my views, but figuring it out for yourself leads to better understanding. If you have any difficulties ask here.

Thanks
Bill

 

[bhobba]

It does not seem like the skills involved here are useful in Data Science nor Finance, which are the typical absorbers of Physics PhDs.

Data science is a goldmine for job opportunities these days. Many involved in math and/or physics are getting qualified in the area as a way to actually earn money while doing what they enjoy on the side. If you have a strong math background or a PhD in a math related area there are courses available to quickly get you up to speed in the field eg:
https://www.kaplanprofessional.edu.au/data-science-bootcamp/

Thanks
Bill

 

[Demystifier]

Yes: https://arxiv.org/abs/quant-ph/0206196

Trouble is there was a mistake. I forget what it was, but demystifyer may know off hand.

I noticed this only now. The experiment ruled out a straw man version of Bohmian mechanics (BM), that is, a version of BM that does not take into account the quantum equilibrium.

 

[A. Neumaier]

There is also a journal called 'Foundations of Physics'.