Paul Steinhardt had credentials as a leading cosmologist. He has come up with a new cosmology which does not seem to require inflation. Those interested can read about it at the following URL http://www.edge.org/3rd_culture/steinhardt02/steinhardt02_index.html This is a cyclic cosmology, while the Big Bang is essentially a one time cosmology with a beginning, and an end.
As I understand it, the Big Bang does not require an end...unless you are talking about the heat death of the universe. BTW, the WMAP satellite appears to have discovered evidence of inflation.
Steinhardt is definitely a big name. I most recently heard him speak last spring at Harvard at a conference honoring Sidney Coleman. I found it amusing that his talk recalled Coleman's work on the nucleation of bubbles of true vacuum, an idea central to inflationary cosmology. I had the chance to hear Steinhardt describe his cosmology in detail while I was spending some time out in Seattle at the Institute for Nuclear Theory. One thing you can definitely say is that it's interesting. It's quite a feat to design a completely working cosmology in this era of "precision cosmology" that has come to be dominated by the hot Big Bang model. It's also encouraging that one can distinguish his model from the inflationary cosmology by looking at the spectrum of primordial gravitational waves. I can't say I find the inclusion of string theory to be truly satisfactory, although it would be wonderful if Steinhardt was found to be on the right track. Such a discovery might finally be some real, if circumstantial, experimental evidence that string theory is headed in the right direction. It is sort of interesting that both Alan Guth, who is just down the hall, and Steinhardt both see the discovery of dark energy as lending support to their respective models. Fortunately, time will tell.
