## Dark Matter Problem

Alex Cahill '11 | June 22, 2009As you may or may not know, there is a problem in the field of cosmology which is that the mass in the universe that we can observe does not add up to what we would expect based on other observations. To explain how galaxies clump and stars move around in their galaxies, additional mass, called ‘dark matter’ is required. It is called ‘dark’ because it doesn’t give off light. The only problem is that because we can only observe it indirectly, no one really knows what this stuff is. Consequently, we don’t know how to write down the necessary equations that explain it’s gravity.

Well, there is a possible solution to this problem that Martin and I have been looking at for the last couple weeks. There is a newly proposed theory of gravity by Petr Horava, which includes non-relativistic properties, such as faster than light travel for incredibly short distances. In this theory, time and space, are treated unequally, which leads to an extra term that appears in our solutions. This term acts like cold dark matter (cold because it’s not self-interacting). Here is the paper that explains the theory if you would like to read it: arxiv.org/abs/0905.3563. The whole situation is very exciting and we hope to find out more about it.