February 27, 2015: Shri Kulkarni, Russell Frank Lecture Series

Professor Shri Kulkarni Director of the Caltech Optical Observatories will present a lecture entitled "The Restless Universe and the Palomar Transient Factory”

7:30pm Friday February 27 Bigelow Physics Building

Cosmic explosions were first noted nearly two thousand years ago Together, supernovae and variable stars have contributed richly to key problems in modern astrophysics: distances to galaxies, cosmography and the build up of elements in the Universe.

The Palomar Transient Factory (PTF), an innovative 2-telescope system, was designed to explicitly to chart the transient sky with a particular focus on events which lie in the nova-supernova gap. The PTF is now finding an extragalactic transient every 20 minutes and a Galactic (strong) variable every 10 minutes. The results so far: ultra-luminous supernovae as the end of the most massive stars in the Universe, progress in understanding the origin of Ia supernovae (which were used by astronomers to discover dark energy), and the identification of curious events of value to future gravitational wave observatories in space.

Admission is free. This talk is intended for a general audience including enthusiasts of all backgrounds and ages.

best regards
George Rhee

Jan 30, 2015 Forum: Fulvio Melia, The Zero Active Mass Condition in FRW Cosmologies

Abstract: The standard model of cosmology is based on the Friedmann-Robertson-Walker (FRW) metric. Often written in terms of co-moving coordinates, this elegant and highly practical solution to Einstein's equations is based on the Cosmological principal and Weyl's postulate. But not all of the physics behind such symmetries has yet been recognized. We invoke the fact that the co-moving frame also happens to be in free fall to demonstrate that the FRW metric is valid only for a medium with zero active mass. In other words, the application of FRW appears to require an equation-of-state rho+3p = 0, in terms of the total energy density rho and total pressure p. Though the standard model is not framed in these terms, the optimization of its parameters brings it ever closer to this constraint as the precision of the observations continues to improve.

UNLV Physics & Astronomy Forum is held in the conference room of the Bigelow Physics Building, BPB-217 at 3:45PM.  Refreshments at 3:30.