One of astronomer's least favorite topics to talk about is time. Not time as in, "What time is coffee break?", but time as in "space and time." To the general public, the concepts of space and time as expressed by Einstein's General Relativity are very mysterious. "How can time be part of space itself?" "Does this mean time travel is possible?" and many similar questions are very popular for the public to ask. And then a few people think a little to hard and come up with ideas that are both amazing and amazingly wrong. The fact is that, except for very close to black holes, very close to the Big Bang, and across billions of light-years of space, time acts pretty normal on scales that matter to us. So when I talk about time below, remember that I'm talking about one of those three exceptions above, so things are going to get strange.
Astronomers often say that we cannot know what, if anything happened before the Big Bang, the cataclysmic explosion that marked the creation of the Universe 13.7 billion years ago. (In some exclusive circles, the Big Bang is also known as the "horrendous space kablooey," though most astronomers are too uptight to use that seemingly pedestrian terminology.) The Big Bang marked the beginning of time and space as we know it, so even asking the question, "what happened before the Big Bang?" is a little like asking, "why is a duck?" Just because we can ask the question doesn't mean it is a real question. If there was no time as we know it before the Big Bang, then asking what came before the Big Bang is a non-sensical question. If there was no time, there could be no before, no after, no present. Of course, there is still the pesky question of how the Big Bang came to be.
Yesterday, in a weekly segment on Space.com called "Mystery Mondays," the article introduced some scientists who claim that, maybe, we can tell what happened before the Big Bang. Yes, I said "before." In their hypothesis based on intriguing but unproven ideas of gravity, there were versions of time and space before the Big Bang, just with greatly different properties than what exists in our Universe. Not only that, but these properties may have left a faint imprint on the Big Bang, which we might be able to detect in our own Universe.
These properties would be very hard to detect -- the violence and space-time altering properties of the Big Bang would have erased most of these signatures. And, more to the point, as of yet the astrophysicists who are developing these ideas cannot even say what imprints these signatures might be, and how we could detect them and interpret them.
So, what (if anything) should you take away from this? The main thing that is interesting to me is that it may be possible for humans to someday get an idea of where the Big Bang came from, which might mean there is more out there than just our Universe. Or, maybe this is not possible. We are dealing with almost pure conjecture, here. So, if you go up to your friendly neighborhood astronomer and ask about those things that happened before the Big Bang, don't be surprised if you get a blank look followed by a mumbled discussion about time not existing before the Big Bang. We really have no idea, and it may be centuries before we do.