Eric D. Carlson
Particle Physics and Particle Astrophysics
Particle physics has made some major discoveries in the past few decades. In particular, we have developed a picture of the universe called the Standard Model of Particle Physics, which describes the Universe we see with uncanny accuracy. Every particle (with the possible exception of the Higgs Boson) has been seen in current high energy particles, and with the exception of neutrino masses, no properties or parameters outside of the standard model has been clearly seen in particle colliders.
Unfortunately, building bigger colliders is very expensive and takes time. The only collider currently under construction that is likely to yield evidence for new particles is the Large Hadron Collider which will collide protons at 7 TeV center of mass energy. It will be completed around 2005, but for those of us who are impatient, or who are interested in energies or cross-sections not obtainable in particle colliders, we would like to find an alternative.
In contrast to conventional particle physics, particle astrophysics is replete both with unsolved mysteries and virtual experiments that cannot be replicated on Earth. Perhaps the greatest mystery is the fact that at least 90% of all matter in the Universe is dark, having a nature unknown to us. Some of my research has involved with seeking new or unusual dark matter particles.
The Universe also contains numerous natural particle colliders. At right is one picture of the supernova SN1987A, the nearest supernova in over 400 years. The collapsing core of the progenitor star generated densities and temperatures that are only exceeded by our particle colliders, but on a scale of both time and space that we cannot hope to duplicate in the laboratory. Under such circumstances, even weakly interacting particles like neutrinos can be produced in copious amounts, and neutrinos were indeed detected from the supernova. But even particles with interactions considerably weaker than neutrinos could be produced as well. Such events provide some of the best opportunities for detection of new particles.
But supernovae and other contemporary cosmic disasters pale in comparison with the Big Bang. During the first picosecond of the Universe's violent beginning, particles collided with energies which we cannot now recreate, and probably never will be able to recreate. Only particle astrophysics can hope to provide us with experimental evidence under these extereme conditions.
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