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Holo gravity/french physics blog


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not sure what to do with this information


there's a math and physics blog in french kept by somebody named Fabien Besnard. it seems nice. has some links to recreational mathematics and he is currently talking about the Einstein Centenary conference they had last week in Paris.


SFN has some posters who read French (maybe live in France or Quebec, not sure) so might like to check out this blog



Here is a specific article (the most recent)




where Fabien was talking about HOLOGRAPHIC GRAVITY and he referred to this paper (in English) by Thanu Padmanabhan



Holographic Gravity and the Surface term in the Einstein-Hilbert Action

T. Padmanabhan

Invited contribution to appear in the proceedings of: The Second International Workshop DICE2004 ...


"Certain peculiar features of Einstein-Hilbert (EH) action provide clues towards a holographic approach to gravity which is independent of the detailed microstructure of spacetime. These features of the EH action include: (a) the existence of second derivatives of dynamical variables; (b) a non trivial relation between the surface term and the bulk term; © the fact that surface term is non analytic in the coupling constant, when gravity is treated as a spin-2 perturbation around flat spacetime and (d) the form of the variation of the surface term under infinitesimal coordinate transformations. The surface term can be derived directly from very general considerations and using (d) one can obtain Einstein's equations just from the surface term of the action. Further one can relate the bulk term to the surface term and derive the full EH action based on purely thermodynamic considerations..."


Padmanabhan is a world-class cosmologist/relativist and was one of the featured speakers at the Paris Einstein 2005 conference.


I was reading Fabien's blog, since he was at the Paris conference (Carlo Rovelli, Brian Greene, Abhay Ashtekar, ....etc many famous speakers) and I wanted some news about what they said last week.


And Fabien chose to report on Padmanabhan's talk, he was impressed, used the english word "WOW"


he also referred to another Padmanabhan paper


and this John Baez "dark energy made easy" online essay



but the main thing that Besnard was blogging about was this Holographic Gravity idea and the paper I mentioned above.


so what to do with this link or bit of news? if I divide it up maybe neither piece is interesting, but if you are a french speaker and want to sample a french physics blog, and want a taste of last week's Paris conference AND think you might be interested in a holog. approach to gravity, then maybe you would like this



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Merci beaucoup martin. :D

pas de quoi auk


since your sig is about crows being black, here is an appropriate passage from the blog of Fabien Besnard:


Donnons deux exemples très simples. L’énoncé « tous les corbeaux sont noirs » est un énoncé scientifique puisqu’il suffit d’exhiber un corbeau d’une autre couleur pour invalider cet énoncé. Jusqu’à présent (à ma connaissance), on n’a jamais observé que des corbeaux noirs, c’est donc un énoncé très bien vérifié expérimentalement. Au contraire, supposons pour les besoins du raisonnement qu’il soit prouvé que Dieu existe. Alors même dans ce cas, l’énoncé « Dieu est bon » ne serait pas scientifique, car même la plus abominable des catastrophes ne suffirait pas à l’invalider...


That is from the previous entry about Karl Popper (friday, 22 July "Popper avait tort")

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