Our Universe & Beyond: Truth Stranger than Fiction?
Have you ever been so engrossed in a science fiction novel that, once you put it down, you wondered: What if? Well, as we head into the 21st-century, modern science is beginning to reach the point where we might wonder if our universe is right out of a science fiction novel.
In the early 1900s, Albert Einstein provided a comprehensive view of gravity, called general relativity, which looked at gravity as a warping of the fabric of space-time. In fact, general relativity predicted that the universe was in a state of expansion. In the 1920s, Edwin Hubble's observations of the red-shift of galaxies provided the evidence for an expanding universe. And in the 1960s, yet more evidence confirming this fact was provided by the accidental discovery of the cosmic background radiation by Penzias & Wilson.
All three lines of evidence led to the inescapable scientific conclusion that the universe started out some time in the past, about 14 billion years ago, in a super-hot, super-dense state now commonly referred to as the big bang. But I, like many of you, cannot resist the obvious question: What happened before the big bang? Is there something beyond even our own universe - perhaps other universes?
Such questions, up until recently, seemed to be the stuff of philosophy at best or crackpot pseudoscience at worst. However, within the last few decades, there has been a respectable, though incomplete, scientific framework that has evolved for potentially addressing these questions.
For example, one view of quantum mechanics - the physics of the atomic and subatomic scale where all things are uncertain and ruled by chance - is commonly referred to as the "many worlds interpretation (MWI)". In this view, which has become more popular among scientists, the different outcomes for a particular measurement are seen as reflecting different world-lines. For example, suppose you make a measurement of quantum spin of a simple system, like an electron - a result of "spin up" leads to one world-line, whereas a result of "spin down" leads to another. MWI is often called a view of parallel universes, where the differing probabilities of chance measurements in quantum mechanics leads to different universes.
Could it be that our own universe is merely one among a multitude? If so, how much alike, or different, are those other universes from our own?
Another contemporary area of study in physics is so-called string theory. String theory, which would be more aptly named "string hypothesis" since is has yet to be tested, posits the notion that all forms of matter - protons, electrons, quarks, gluons, gravitons, etc - are merely expressions of ultra-tiny vibrating strings of energy. Vibrate a string in a different frequency or pattern, and you get a different fundamental particle. In string theory, our universe exists in not 4 dimensions, but a whopping 11!
An extension of string theory, also known as M-theory, postulates that our universe could very well exist on a membrane, or "brane", which floats within the higher-dimensional space of string theory. It has been proposed by some string theorists that the parallel universes of MWI could exist on similar branes floating within this higher-dimensional space. And, they say, if two branes collide, the amount of energy released would be truly immense - enough, say, to cause a big bang and get an entire universe started. Not only that, but this "brane-big-banging" process could take place multiple times between two or more branes as they drifted past one another.
Needless to say, these are heady topics, causing even the most seasoned scientist's head to spin. And none of these more controversial hypotheses have yet been tested, though they may someday. I find that these scientifically motivated speculations are more fascinating than any science-fiction novel. The truth could indeed be stranger than fiction.
Ad Astra - Matt Lowry