Lorentz Institute

Sept. 21, 2022, 7:30 p.m.
Sitterzaal

Could Einstein Have Been Right After All?

Gilles Brassard

One of the most surprising aspects of quantum theory is that it tells us that we live in a nonlocal universe in which random correlations seem to appear instantaneously between arbitrarily distant locations. This idea was completely abhorrent to Einstein, who dismissed it as "spooky action at a distance". So-called loophole-free experiments have confirmed nonlocality beyond any reasonable doubt in 2015. But have they really? In this talk, I shall argue that no experiment whose purpose is to confirm the predictions of quantum theory can possibly be used as an argument in favour of nonlocality because any theory of physics that does not allow instantaneous signalling to occur and has reversible dynamics (such as unitary quantum theory) can be explained in a purely local and realistic universe. What if Einstein was right after all?... Once again!<br> No prior knowledge of quantum theory will be assumed. This talk is based on the original doctoral work of Paul Raymond-Robichaud while under my supervision. The proof of concept was published in the journal Entropy and is available open access at https://doi.org/10.3390/e21010087. More involved mathematics can be found in https://doi.org/10.1098/rspa.2020.0897 and culminates in https://arxiv.org/abs/1710.01380

Oct. 12, 2022, 7:30 p.m.
Sitterzaal

Cell deformation and mechanics of epithelial tissues

Jean François Joanny

The mechanical properties of tissues can be studied either at a macroscopic scale of the tissue or at the mesoscopic scale of the cell. The macroscopic description must include the non-conservation of the cell number due to cell division and cell death and leads to a non-conventional hydrodynamic theory. At the mesoscopic scale, we use a so-called vertex model which starts from a geometrical description of an individual cell. The aim of the lecture is to show on a simple example how one can derive the macroscopic properties of the tissue by a coarse-graining of the mesoscopic vertex model. Our main result is an explicit calculation of the cell pressure in the homeostatic state of a confined growing tissue. We show that the homeostatic pressure can be negative and depends on the existence of mechanical residual stresses

Oct. 12, 2022, 7:30 p.m. CE Jean François Joanny (Collège de France) Cell deformation and mechanics of epithelial tissues

Nov. 9, 2022, 7:30 p.m.
Sitterzaal

Are we living in the matrix?

David Tong

No. Obviously not. It's a daft question. But, buried underneath this daft question is an extremely interesting one: is it possible to simulate the known laws of physics on a computer? Remarkably, there is a mathematical theorem, due to Nielsen and Ninomiya, that says the answer is no. I'll explain this theorem, the underlying reasons for it, and some recent work attempting to circumvent it.

Nov. 9, 2022, 7:30 p.m. CE David Tong (University of Cambridge) Are we living in the matrix?

Nov. 30, 2022, 7:30 p.m. CE Eugene Demler (ETH) TBA

LS = Lorentz Seminar, Casimir room (276), Oort building
CE = Colloquium Ehrenfestii, De Sitter lecture room, Oort building
SBM = Soft & Biological Matter Seminar, Casimir room (276), Oort building
CS = Cosmology Seminar, Casimir room (276), Oort building
ST = String Theory Seminar, Casimir room (276), Oort building