"What was there before the Big Bang?"
That's a question that both kids and adults love to pose to anyone who seems sympathetic. After all, if the universe has only been around for roughly 14 billion years, isn't it legitimate to ask what was in existence before the mother-of-all-events cranked up the cosmos?
For a long time, the usual response of scientists to this metaphysical query was "no, it's not legitimate to ask."
Why? Because time -- which after all is at the root of concepts like "before" -- is part and parcel of our universe. In fact, in relativity theory time and space are fungible, and under the right circumstances, time is as much like space as length is like width.
But the point is, the time and space we experience every day were products of the Big Bang. In other words, the naïve view of Mr. and Mrs. Front Porch -- that the Big Bang was a massive explosion that occurred in a large, empty room when the calendar read 14 billion BC -- is not quite right. There was no "empty room" and no calendar. Both were created with the Big Bang.
That explanation might mollify your eight-year-old niece, but it's somewhat unsatisfying to physicists, because it claims that the universe just "happened" -- there was no predecessor. The cosmos is a miracle: end of story.
But now scientists in the U.K. are claiming something remarkable. They may have found fossilized footprints of events that took place before the Big Bang.
This would be somewhat of a relief, because there are problems with a view of the Big Bang as a one-off, transcendent event. On the one hand, there's been discussion for years about the fact that the architecture of our universe seems remarkably well suited for life. If gravity were somewhat stronger or weaker, stars wouldn't exist, and neither would you. And the same can be said of other constants of physics. Several have to be "just right."
Again, that sounds like a miracle happened: There's been one Big Bang, and holy moly, Batman, it produced a cosmos that's amenable to our presence.
This has motivated scientists -- who are not always down with the idea of miracles -- to suspect that our universe is not alone; that there might be others. After all, if there are myriad universes, each with somewhat different properties, then having a few (like ours) that are dandy for life is to be expected. That's like throwing a million darts at a target: some will hit the bullseye just by chance.
This trendy idea, positing a "multiverse" in which our cosmos is merely a local bubble in a far larger sea of cosmic bubbles, not only solves the problem of why our universe is so amenable to our existence, but it seems to be an inevitable consequence of new work in theoretical physics. "Eternal inflation," as it's called -- the endless generation of new universes -- may be a hyper-cosmic imperative. It seems that it must happen. The new book by Stephen Hawking and Leonard Mlodinow, The Grand Design, elaborates this idea.
Well, speculation about multiple universes might look good on blackboards, and it surely makes for scintillating lunch-time conversation if your dining companions are hooked on cosmology. But now two teams of scientists in the U.K. claim to have uncovered actual evidence that our universe has interacted with others. They report finding ring-like features in the background radio glow that is the faint echo of the Big Bang -- features that could be "bruises" from encounters with other universes.
Admittedly, the features are neither obvious nor certain, and it's likely that only new results from the Planck telescope, launched into space a year ago, will tell us whether the claims of the Big Bang bruises are true.
But if so -- if it turns out that a multiverse is more than a nice idea, but a fact -- then we will be humbled yet again. Five centuries ago, Copernicus upset humanity's applecart with the news that the Earth is not the center of the cosmos. It could be that before you've paid off your house, we'll learn that the universe is not the center of the universe either!