I have an opinion which is slightly heterodox, about the standard ideas in cosmology. The inflationary universe scenario, that Alan Guth really pioneered, people like Andre Linde and Paul Steinhardt really pushed very hard. This is a wonderful idea, which I suspect is right. I suspect that some part of the history of the universe is correctly explained by the idea of inflation, the idea that we start in this little tiny region that expanded and accelerated at this super-fast rate. However, I think that the way most people, including the people who invented the idea, think about inflation is wrong. They are too sanguine about the idea that inflation gets rid of all the problems that the early universe might have had. There is this feeling that inflation is like confession — that is wipes away all prior sins. I don't think that is right. We haven't explained what needs to be explained until we take seriously the question of why inflation ever started in the first place. It's actually a mistake and something wrong on the part of many of the people who buy into inflation that inflation doesn't need to answer that question because once it starts it answers all the questions that you have.