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2Physics Quote:
"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" )

Thursday, October 20, 2005

One Decade of Top Quark

A decade ago in this week, experimental physicists representing seventy-four institutions in Brazil, Canada, Colombia, France, India, Italy, Japan, Korea, Mexico, Russia, Taiwan, and the United States announced the discovery at Fermilab of the top quark, a fundamental building block of matter and the universe.

The name "quark" was taken by Murray Gell-Mann from the book "Finnegan's Wake" by James Joyce. The line "Three quarks for Muster Mark..." appears in the fanciful book. Gell-Mann received the 1969 Nobel Prize for his work in classifying elementary particles. There are 6 different kinds of quark: Up, Down, Charm, Strange, Top and Bottom. Being in a confined state, they act as constituents of fundamental particles like Proton and Neutron but not, for instance, electron. The confinement of quarks implies that we cannot isolate them to measure their masses in a direct way. The masses and their existence must be implied indirectly from scattering experiments. To know more about quarks at your own pace, visit
these pages of hyperphysics.

Fermilab will celebrate 10 years of discovery of Top quark and the new possibilities it opened for science in a half-day symposium entitled "Top Turns Ten" on Friday afternoon, October 21, at Fermilab. The agenda is here.



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