The equation of everything
Following Cedric Villani, let you imagine a pond. Everything is calm and quiet, without a breath of wind, but at acertain point the pond surface is perturbed by a wave, without any external force. The next minute everything returns calm and quiet.
Villani used this poetical picture in order to describe some results about the Euler equation for an incompressible fluid: \[\frac{\partial v}{\partial t} + \nabla \cdot \left ( v \times v \right ) + \nabla p = f\] \[\nabla \cdot v = 0\] About this equation (or this sistem of wave equations), Scheffer (in 1993) found that the equation permit the spontaneous creation of energy form nothing, while Shnirelman (in 1997), found a new proof of this fact and proposed to enforce a criterion for physically prevent this kind of mathematical solutions. Sheffer and Shnirelman Theorem:
Villani used this poetical picture in order to describe some results about the Euler equation for an incompressible fluid: \[\frac{\partial v}{\partial t} + \nabla \cdot \left ( v \times v \right ) + \nabla p = f\] \[\nabla \cdot v = 0\] About this equation (or this sistem of wave equations), Scheffer (in 1993) found that the equation permit the spontaneous creation of energy form nothing, while Shnirelman (in 1997), found a new proof of this fact and proposed to enforce a criterion for physically prevent this kind of mathematical solutions. Sheffer and Shnirelman Theorem:
There is a weak solution of the Euler incompressible equation in 2-dimensions, without forcing ($f \equiv 0$) with compact support in space-time.Between 2007 and 2008 De Lellis and Szekelyhidi proofed a more general theorem that establishes, among other things, that the criterion of Shnirelman is not valid, or, in other world, that the solutions of the Euler incompressible equation without forcing are physically acceptable.
First evidence of photon polarisation in a quark transition
is considered a very important process to investigate possible manifestation of new physics. This decay process is forbidden in the first approximation in the Standard Model (SM) of particle physics and moreover in the second-order processes that govern the process in the SM the emitted photon is expected to be strongly polarised. Therefore it is very sensitive to new physics effects arising from the exchange of new heavy particles in electroweak penguin diagrams (see 14 June 2013 news). Indeed, several models of new physics predict that the emitted photon should be less polarised than in the SM. Up to now different experiments have measured the decay rate of this process, ruling out significant deviations of the rate from the SM prediction and strongly reducing the allowed parameter space of new physics models. The photon polarisation was, however, never previously observed.I think that this is a really intriguing news for a particle physics point of view.
A trip to the aquarium
Yesterday I gone to the Civic Aquarium of Milano. It was a very interesting tour, between aquariums and the reconstructed natural habitats. In particular I shotted a video of the tropical fishes (I used Giochi di luce - Game of light - by Andrea Carri like soundtrack):
Near to the acquarium there is a poster about the tropicalisation of the mediterranean sea: