If you've ever had a phenomenally bad day and wished that maybe there were a version of reality where all of your wrong turns, missteps and poor judgment calls righted themselves, congratulations! You've joined a community of scientists, philosophers and theologians who have long speculated that the universe we know isn't the only game in town.
To most people, the concept of multiple universes - or the "multiverse," as it has come to be known - conjures images of better places where prettier versions of themselves amass the wealth, power and fame that eludes them in this world. And who can blame them? Some of the most entertaining science fiction is built on this idea. But fans may be disappointed to learn that the idea that proved such an effective device in television series like Star Trek and Sliders is actually a misrepresented oversimplification of an issue scientists have been wrestling with for decades.
But take heart, stalwart Trekkers. The real thinking behind the concept of multiple universes is boldly taking physics, cosmology, religion and philosophy where no one has gone before.
The big bang's bigger meaning
British author Michael Moorcock introduced the general public to the term "multiverse" in a short story called "The Sundered Worlds," printed in a 1962 issue of Science Fiction Adventures. But the idea of multiple universes had been bandied about, in one form or another, as early as the 16th century.
It was 1576 when British astronomer Thomas Digges modified Copernicus' idea of the universe. What Copernicus thought was a clearly defined "outer rim," said Digges, was really unbounded space filled with stars stretching infinitely in every direction. Though Digges couldn't have known it at the time, a big-bang explosion started our universe in motion and, in doing so, produced cosmic microwaves. As Digges peered into the sky, these rays were traveling through that unbounded space; their detection confirmed the big-bang theory and earned Arno Penzias and Robert Wilson the 1978 Nobel Prize in Physics.
The radiation led physicists to believe that space is expanding and that matter is spread more or less randomly through it. In the 1980s, Alan Guth at the Massachusetts Institute of Technology and Andrei Linde at Lebedev Physical Institute in Moscow came up with the idea that the universe ballooned in a rapid burst soon after the big bang, and that burst exponentially increased the size of the universe. This new theory of "inflation" set the stage for modern multiverse theory.
Inflation creates what physicists call a "false vacuum," a fancy name for "bubble." If inflation created the bubble we know as our universe, who's to say it didn't create others in the same way? There may be an infinite number of universes co-existing with the bubble that is our universe.
It's easy to get tripped up by the terminology; most dictionaries simply define "universe" as "all matter and energy, including Earth, galaxies and intergalactic space." So even if there is more out there than we previously thought, it makes sense that "universe" would cover it all. But when we say "universe," we really mean "the universe as we understand it" - our concept of the unchanging laws of nature, the pull of gravity, the dimensions in which we move. The places beyond our realm, where these constants may not be so constant, are all parts of the multiverse.
We can't see these places, even with the best lenses on the biggest telescopes. These other universes, if they exist at all, are inaccessible. Events that happen there won't affect us. As it turns out, the possibility that these other worlds might be hovering somewhere in the great beyond may provide an explanation of how we came to be in the first place.
That explanation, though, is taking awhile. Until recently, some physicists had lost hope that it would come during their lifetimes.
"What happened during the last two years is quite amazing," said Linde, who now teaches at Stanford University. During that time, Linde and other researchers at Stanford were able to reconcile our universe's continued expansion with a popular, still-evolving theory that may eventually explain our universe, the multiverse and all that lies in between. Physicists refer to this still elusive, all-encompassing crystal ball of an idea as, aptly, the Theory of Everything.
"We see right now that even if we confine ourselves with one particular theory [of how the universe began], it may have 10 to the degree of 1,000 different versions of it," he said. "This idea of the multiverse became much more mathematically developed."
Here's where science-fiction scribes' imaginations go into warp drive. With that many possible combinations of matter, there's also that many possible ways a universe similar to ours could develop. The mundane view is that there's also that many possible ways a universe exactly like ours could develop, but it's much more fun to think of your interstellar alter ego basking in the adoration of a crowd of cheering fans than it is to imagine him or her making your monthly mortgage payment.