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Hey I'm the scheduled guest for the june 14th Physics AMA and I was told to maybe make a little presentation and asks for any questions for the AMA people might have, so here it is.

About me

So I am Samuel Lereah, got a Master degree in particle physics from the university of Nantes. My master thesis was on the topic of non-relativistic path integrals in Riemannian spaces, focused on the problem of operator ordering (with stochastic integrals, phase space quantization and those kind of things). Currently not working in the field of physics (due to job market troubles), but in softwares, but I am still very much so into doing physics as a hobby (I am also still looking to do a PhD, if anyone has some to offer!).

My interests are mainly in general relativity and quantum field theory. I quite like odd topics in those fields and the AMA will be about causality in physics, mostly on the topic of spacetimes with closed timelike curves (ie time machines, for a more casual term). Probably something along the lines of a general outline of the history of the topic, some important theorems, the behaviour of matter in such spacetimes and the many limitations preventing them from occuring.

So if you have any questions on that topic you'd like me to answer during this AMA feel free to ask in this thread and I'll do my best to try to answer it.

Time and date

The AMA will be on tuesday june 14 at 16:00 UTC, in the Physics Stack Exchange chatroom, the h-bar.

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    $\begingroup$ I would suggest giving details about the event. Where is it? How do people participate? $\endgroup$
    – DanielSank
    Commented May 30, 2016 at 17:48

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The topic of stochastic processes is very valuable in real physics research, yet it is barely mentioned much less taught in the typical physics curriculum (at least in the USA). How did you, personally, acquire your knowledge of stochastic integrals etc? What was your trajectory through books/papers/courses in coming to a useful understanding of stochastic processes?

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    $\begingroup$ Bump this, and add on what the prerequisite knowledge one should have to really understand the topic $\endgroup$
    – Skyler
    Commented Jun 9, 2016 at 11:10
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thanks very much for accepting the invited speaker invitation as the 1st guest! here are some miscellaneous mostly not-so-formal questions that may be of interest to others, partly based on your own (extensive!) prior dialog in the physics chat room H Bar (which btw for anyone interested and isnt aware, is in a searchable transcript). note some of these can be considered somewhat general & applicable to other guests also who might choose to answer from it. (as reflected here, interestingly the sessions may give us all a chance to focus on more subjective/ personal areas than are typically addressed in the normally tight/ objective-leaning SE format.)

  • can you talk about testability or falsifiability of CTCs (closed timelike curves)? is anyone working in this area? do any modern experiments/ measurements have any connection to CTCs? do you think its relevant to the field or do you consider yourself more a mathematical physicist not so concerned about physical plausibility?

  • youve mentioned you saw the movie interstellar (you maybe seem to like other scifi movies also) which features some advanced science ideas on CTCs and utilized expert advisors in the area like Kip Thorne to some degree. what are your thoughts on the movie, whats it like to watch, was there anything glaring about it? should hollywood try to avoid serious science, or does it fit in somehow? what other hollywood/ scifi movies do you like, and do any of them also have physics angles?

  • youve mentioned the challenges of moving forward to a physics Phd. what do you think of the Phd system wrt physics or more generally? does it work or have flaws? what could be changed about it to make it better?

  • you have very strong grasp of US/ American (pop) culture and say youve visited on occasion, however your nationality is (apparently) French, and you pepper chat with funny memes etc. can you say anything about the occasional rivalry between these countries, have you noticed it? does it ever come up in chat? where did you get so much enthusiasm for US culture? or is it maybe partly internet culture also?

  • can you talk about your experience in school getting your undergraduate/ graduate degree? how did your school compare to neighboring schools? what was your thinking in choosing it in particular? was there anything particularly memorable about the experience? did you "hang out/ socialize" with other physics students or were you more the type to focus on the education?

  • you work in software engineering as a day job and have written about it as a necessity. what elements of this appeal to you? do you see some connection with physics? did you do any algorithmic work relating to physics in school or otherwise? do you have some languages/ areas you like?

  • what do you think are some of the leading areas of physics to do research in? besides CTCs, what areas do you focus on? is this a good age for physics? where is it all going/ leading, what does the future hold for the field and you in particular?

  • whats your opinion on top physics schools or your favorite journals? if you could choose any school in the world to do a Phd or postdoc at, which would it be and why?

  • what do you think of the physics stackexchange site? do you recall how you 1st heard about it? what does it mean to you? what kind of direction is it going in? whats there to like/ dislike?

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    $\begingroup$ +1 It would be interesting and helpful to have a conversation on subjects as the current system in the field of physics, to have opinions expressed so that made already physicists could express their views and younger(master and below) could gain an idea of how the system works from personal experiences. I will up vote. $\endgroup$
    – Constantine Black
    Commented Jun 8, 2016 at 8:47
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    $\begingroup$ some other ideas/ questions that occurred to me: (1) CTCs are informally called "wormholes". is the latter term nearly slang, or is it used in any papers? can you say anything about the etymology/ history of "wormhole"? was it first used in scifi before science analyzed CTCs? (2) did einstein have anything to say about CTCs or was it all built up post-einstein? (3) CTCs are often referred to as possible "time machines". can you elaborate on this? deserved, or undeserved? what about time paradoxes? (4) are there "any other" possible/ plausible applications of CTCs that have been proposed? $\endgroup$
    – vzn
    Commented Jun 8, 2016 at 15:02
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    $\begingroup$ Dude, break these up into separate posts :) $\endgroup$
    – DanielSank
    Commented Jun 8, 2016 at 21:04
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Since you mentioned closed timelike curves aka "time machines": Are they likely to exist in our universe? And how could they be observationally confirmed in a universe where they exist?

If you could maybe give a layman's explanation as well as mathematical detail?

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Since your interests are GR and Quantum Field Theory, with maybe some insight into Quantum Gravity (QG), could you summarize with some technical reasonings, what is known and what key findings are still needed for Hawking et al's conjecture that the BMS super translation symmetries and conserved charges are the basis for doing away with the information paradox?

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Maybe a discussion on geometries explaining the expansion of the universe, it's acceleration and some connections with quantum mechanics or QFT. On this basis, some thoughts on the arbitrariness of theoretical models for the expansion, how can we limit them down and what's the potential role of QM or QFT on this subject and on observations that may be based on the last.

Thanks.

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  1. What is the necessary mathematical/physical background for general relativity and quantum field theory?

  2. If you had to pick one book as an introduction to GR and one as an introduction to QFT, what would they be?

  3. What are the standard "advanced" references for GR and QFT (books, seminal papers)?

  4. What is the standard introduction to time travel research? How about advanced material?

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