What happened before the Big Bang?
Cosmologists don't know. Not only that--the conventional wisdom is that they can't know, that history before the Big Bang is fundamentally inaccessible to science.
But Martin Bojowald, a physicist at Penn State, says that the "past life" of our universe may not have been totally erased. In an article in Nature Physics, Bojowald argues that loop quantum gravity can be applied to a mathematical model of the universe to yield up some--but not all--of the universe's pre-Bang backstory.
I won't pretend to actually understand the argument, but the interesting thing is that we can say anything at all about what happened before the Big Bang--even if the substance of the discussion is just an accounting of answerable and unanswerable questions.
Nature, unfortunately, is tight-fisted with its articles; you can't read them online unless you have a subscription. But you can probably pick up the article online or in print at your friendly university library. Or, try the press release.