Nishant Agarwal
I am a second year graduate student in Astronomy at Cornell University and am working with Prof. Rachel Bean. My chief interest is in theoretical cosmology.
I have recently been working on the problem of dark energy. The problem of dark energy is that of the acceleration of the universe. We know that the universe is expanding and that its expansion is accelerated. However because of the simple reason that gravity is attractive we would expect the expansion of the universe to slow down with time. The acceleration can be attributed to some strange form of matter (energy) which has negative pressure. It can also be explained by modifying the way that gravity behaves on large scales. I have been looking at modified gravity theories in which we try to modify the equations of General Relativity in order to explain dark energy as being an effect of a modification of gravity itself rather than being due to some undiscovered particles.
Another theory that has fascinated me for some
time is that of inflation. The inflationary model proposes that the universe had
a very rapid exponential expansion in its early history just after the big bang.
This rapid expansion is needed in order to explain some standard problems in
cosmology like the horizon problem and the flatness problem. Inflation is
accepted as a part of the standard model of cosmology but lacks a firm physical
explanation to its origin. String theory opens up interesting avenues of
explaining inflation. I am currently working on Brane Inflation which is the
string theory motivated way of understanding inflation.