The universe began in a hot big bang 13.7 billion years ago. It is remarkably homogeneous on the large scale, and at the time period we're observe the cosmic microwave background, segments of the cosmos that are out of causal contact with each other are similar at the level of about ten parts per million. How did this remarkable synchronization come about?
In the early 1980s then-SLAC postdoc Alan Guth, current KIPAC member Andrei Linde, and others developed a bold answer to this question. They proposed that during the very first instants after the Big Bang, the Universe underwent a period of ultra-rapid expansion—known as inflation—which paradoxically smoothed out all the structure and blemishes that were around at this time. Although we still do not have a good understanding of the reason why this expansion might have happened or how it may have come to an end, the theory leads to some quite general observable consequences. More specifically, the Universe has been shown to be flat as expected and variation of the level of initial fluctuations with size was as predicted by quantum mechanics. The idea of inflation has contributed to an even more exciting possibility that our Universe is just one of the large number of universes called the Multiverse.
The next steps include: exploring the physics of inflation by studying the polarization of the cosmic microwave background radiation and looking for the "B-mode" pattern, which is a window on the epoch of inflation; measuring fine details of the distribution of galaxies in space; and performing theoretical computations that mimic the physical process that drove the inflationary expansion. KIPAC members are involved with each of these research activities.