### Monday, March 15, 2004

Interesting talk by Sean Carroll on eternal inflation and creating a low entropy situation at the big bang. Some inflationary models use a scalar field throughout space, then rolling down the potential hill of the field will deposit some of the potential energy into spacetime, causing it to expand. Then quantum fluctuations can take you back up the hill a bit, for even faster expansion, and even in a universe that has been spread out very flat by one inflationary period, one region of it can make another quantum jump and create another inflationary bubble. Any one finite region of space will thus get expanded into an infinite volume - going either direction in time no less! - and thus for every finite region entropy will increase indefinitely in both time directions. Thus our big bang with it's low entropy was not special - it was a perfectly typical and infinitely repeating situation.