The information hidden in the shape of the CMB spectrum
ABSTRACT :
One of the first great predictions of the modern cosmology, that it would be an almost perfect blackbody with its temperature predicted to be around 5K by Alpher and Herman (1948), were verified with detection of CMB by Penzias and Wilson (1967) and measurement of its spectrum by COBE (1990). I will review the physics responsible for maintaining the Planck spectrum of the CMB at an incredibly high precision in the early Universe and how we can start to create tiny deviations from a blackbody, both with and without introducing physics beyond the standard model, once these equilibrium maintaining processes become inefficient. These (1 part in million to 10 billion) deviations promise to be an unprecedented rich source of cosmological infor mation if detected. Experiments which would be able to detect these spectral distortions are currently being proposed.