"Can photons in vacuum interact? The answer is not, since the vacuum is a linear medium where electromagnetic excitations and waves simply sum up, crossing themselves with no interaction. There exist a plenty of nonlinear media where the propagation features depend on the concentration of the waves or particles themselves. For example travelling photons in a nonlinear optical medium modify their structures during the propagation, attracting or repelling each other depending on the focusing or defocusing properties of the medium, and giving rise to self-sustained preserving profiles such as space and time solitons or rapidly rising fronts such as shock waves."
-- Lorenzo Dominici, Mikhail Petrov, Michal Matuszewski, Dario Ballarini, Milena De Giorgi, David Colas, Emiliano Cancellieri, Blanca Silva Fernández, Alberto Bramati, Giuseppe Gigli, Alexei Kavokin, Fabrice Laussy, Daniele Sanvitto. (Read Full Article:
"The Real-Space Collapse of a Two Dimensional Polariton Gas" )
We are taking a break
We regret that due to unavoidable reasons, we need to take a break. We'll not have our regular postings in next two weeks. Regular postings will resume on April 10th. In the mean-time, you may go through our past postings on various topics of interest. We suggest that you use the search box on top to search for past postings on topics of your interest (e.g. 'Einstein', 'Fusion', 'Nobel Prize', etc...)