# Parameters of Cosmology: Overview

The Big Bang theory of the universe allows plenty of room for variations in the details (parameters) of the actual structure and behavior of our universe. These "free parameters" are important, but must be determined by observations, not theory. The parameters effect very basic aspects of our universe:

- Will the universe expand forever, or will it collapse?
- Is the universe dominated by exotic dark matter?
- What is the shape of the universe?
- How and when did the first galaxies form?
- Is the expansion of the universe accelerating rather than decelerating?
- And more...

Since the CMB radiation was emitted so long ago (and far away), it carries a great deal of information about the properties of our universe which can be measured in no other way. This early radiation was effected everywhere by the physics of matter within the bounds set by the parameters. So we have a large statistical sample of microwave radiation (across the whole sky) to help us determine these parameters.Because WMAP can measure the CMB patterns of radiation with tremendous accuracy, it accurately determines most of the basic parameters of cosmology.

In order to understand how WMAP determines cosmological parameters, we need to give a little background on the physical evolution of the early universe and understand how cosmologists describe the statistical properties of the microwave background radiation.