MAP and Planck vs the Real Universe

The Microwave Anisotropy Probe (MAP) and Planck Surveyor satellites promise to provide accurate maps of the sky at a range of frequencies and angular scales, from which it will be possible to extract estimates for cosmological parameters. But the real Universe is a nasty, messy place, full of non-linear astrophysics. It is certainly clear that MAP and Planck will fix the background cosmology at an unprecedented level. However, they will have to contend with everything that the Universe throws at them: multiple foregrounds; structure formation effects; and other complications we haven't even thought of yet. Some examples of such effects will be presented. Only an ideal, theorist's universe can be described by a number of free parameters in the single digits, while in reality it is likely that a greater wealth of information waits to be discovered. These `higher-order' processes should be considered as potentially measurable signals, rather than contaminants. The capabilities of Planck seem ideally suited to fully understanding the physics encoded in the microwave sky.