SuperCosmologists Think Out of the Box

Well, it is the end of the first day here for me at the Supercosmology workshop at Aspen's Center for Physics. It was great. Physics discussion was rich and plentiful right from the word go. Ok, at least from 11:15am, when Liam McAllister gave a presentation entitled "Progress and Problems in String Inflation". He gave an excellent talk, and there was great discussion all the way through. Later, Richard Easther gave a talk entitled "Trans-Planckian Physics and Cosmology", but I had another meeting to go to and so could not attend. So what's with the title? Well, it riffs on a joke I inadvertently made in an earlier post. The kind of cosmology being discussed here focuses on models that try to build our universe by starting outside of it, in some sense. The thing we usually think of as the universe is embedded within the larger dynamics of string theory or M-theory that is "outside the box" that is the universe we normally think about. So are we just sitting around dreaming? What do we do? Well, lets start with your "normal" cosmologist - even more normal than CosmicVariance's own Mark or Sean. Being physicists, they write equations for the various quantities that we wish to study, such as the scale size and curvature of the universe, and the densities of various components such as matter, radiation, dark energy, etc. They might even make up various auxiliary dynamical quantities, such as a scalar field called the "inflaton" which has a particular dynamics -controlled by a "potential" function- which provides energy to drive an accelerated expansion phase in the very early universe, making it the really extremely flat universe we see today. The point is that these good people are working "within the box" in that they write equations in the 3+1 dimensional spacetime which we observe. They study the consequences of these equations on our observations in our 3+1 dimensional universe.