My preprint from January “Time-local unraveling of non-Markovian stochastic Schrödinger equations” has been accepted and published in Quantum. It is a new open-access journal managed by physicists (mine is just the 29th article!):
“Quantum is a non-profit and open access peer-reviewed journal that provides high visibility for quality research on quantum science and related fields. It is an effort by researchers and for researchers to make science more open and publishing more transparent and efficient.”
I have just posted on arXiv yet another preprint about Newtonian semi-classical gravity. It is not really an improvement from previous work but rather an easy introduction to the idea and the concepts, using a mathematically simpler basis.
Let me recall how I understand the problem of semi-classical gravity. If a semi-classical theory of gravity is to be fundamental, it has to specify two things:
How quantum matter moves in a given classical curved space-time.
How quantum matter curves this classical space-time.
The first point is I think pretty standard. In the general relativistic context it is answered by quantum field theory in curved space time but in the Newtonian limit, being so fancy is not even necessary. To specify the influence of space-time on quantum matter, one just puts the gravitational field as an external field in the Schrödinger equation. The tricky part is the second aspect: how quantum matter back-reacts on space-time. This problem is basically open. In the Newtonian limit, it means finding a good candidate for the gravitating mass density.
What if the reason the black hole (BH) information paradox has been discussed for so long is that there is actually no paradox to solve? What if people are just providing conjectural answers in “need for a question”? Tim makes a very convincing case that the paradox vanishes once things are properly defined and understood. This is an archetypal example of a situation where the clarity of mind of a serious philosopher of science should be stimulating for the physics community.
Ruwen Ogien, French philosopher, restless advocate of minimal ethics, died last week. Ogien was defending a conception of freedom, anchored in the harm principle of Mill, that seems today more needed than ever.
Ogien has highlighted a minimalist definition of ethics which one can (grossly) summarize this way: just do not harm others, the rest is (morally) irrelevant. In this conception, there are no crime without victims and individuals have no moral duties towards themselves. To illustrate this principle in its most extreme and perhaps shocking consequences, it implies that drug abuse, suicide, incest (between consenting adults) and even necrophilia, although not advisable, should not be forbidden or at least not on moral grounds. Such an extreme minimalist understanding of ethics is clearly not without flaws and sometimes arguably naive, but Ogien has finely harnessed it to propose a remarkably seductive and emancipating libertarianism. In my opinion, it gives the strongest case for gay marriage, the legalization of drugs and of prostitution, or against the headscarf ban.
I would like to start bringing to the attention of my (almost inexistant) readership some articles/preprints which I have particularly liked. The objective is to put forward works that may have been overlooked or that are original in some way. As I have never done such a thing in the past, I have a huge backlog of articles to consider and thus no lack of inspiration. To keep this post decently short, I chose to start with only 3 papers but in wildly different fields: stochastic thermodynamics, philosophy of physics and quantum optics.
The following entry is the translation of the appendix A of my thesis, initially written in french (French readers are thus invited to read it directly there). Surprisingly, one year after writing it, I still more or less agree with its content and thought it might be of interest to a broader audience, especially students and young physicists. I do not claim that it contains anything particularly new on foundations and is just aimed at taming the confusion that dominates the field, especially for beginners.
My preprint “Interacting quantum field theories as relativistic statistical field theories of local beables” has just appeared on arxiv. Fortunately, even with the few bold claims that I made, I have not been flagged so far by the algorithmic crackpot detector and my paper went through without difficulty. As I had emphasized in the previous post, for once it is a work I am very proud of. I do not know if every single detail will hold closer scrutiny, but at least I am confident that the main message is correct and should be of interest to people working in quantum foundations (on the pure theory and phenomenology sides).
I have been working on an ambitious project for quite some time and, although there are still questions to be settled, I think the main lessons are now robust enough that they can be profitably discussed. I have a draft (modified 09/02/2017) which I will put on the arxiv (update: it’s now on the arxiv) once I get some feedback (and likely tame some bold claims that may not be as firmly grounded as I first thought). Comments are of course very welcome. As I have also made a first presentation of the results at the seminar of the group of mathematical foundations of physics at LMU, I have some slides that give a short (and thus inevitably provocative) overview of my claims.
I have just posted on the arXiv a new preprint (a short letter) about a recent work of mine on non-Markovian stochastic Schrödinger equations. It is an unexpected technical byproduct of a more fundamental and long term research effort to construct tractable relativistic collapse models (but it will likely not seem related at all). Before explaining what I did in this preprint, it is probably worthwhile to recall a few things about stochastic Schrödinger equations and their history. This will be a rather technical entry but as the preprint itself is about something technical, there is no point in making a summary for a broad audience.
This entry is written in french as it deals principally with French idiosyncrasies.
Il y a quelques jours, l’Express a relevé un nombre assez alarmant de plagiats dans plusieurs ouvrages, chroniques et articles d’Étienne Klein, un vulgarisateur-philosophe populaire. Je tiens à préciser d’emblée que je n’ai pas d’antipathie particulière pour Klein. Même si sa tendance à se faire mousser, à se présenter comme un physicien professionnel qu’il n’est plus depuis longtemps, et à couvrir certains sujets simples de pédanterie verbeuse m’a toujours fortement agacé, il faut reconnaître que Klein est, ou était, un des meilleurs vulgarisateurs nationaux télégéniques (la concurrence étant, il est vrai, loin d’être rude). Mon objectif n’est donc pas de traîner Klein dans la boue : les faits sont suffisamment graves pour que d’autres s’en occupent et il tombera peut-être en disgrace médiatique pour un court instant. Je pense qu’il n’est pas utile d’ajouter à la charge. J’aimerais plutôt profiter de ce prétexte d’une possible recomposition du paysage de la “vulgarisation en physique française” pour tenter une réflexion personnelle sur le fond : qu’est ce que la bonne vulgarisation et comment faire pour en améliorer la diffusion en France ?
