Looking up at the stars, as our long-ago ancestors did, one can only get a small idea as to the size of the universe. A telescope allowed us to see further and expanded our understanding. Today's research goes even further, and greatly augments our knowledge of the universe. In fact, the universe is so big that no one knows exactly how big it is, because light simply cannot travel fast enough to illuminate it. Now, take that, our one infinitely big universe, and multiply it by infinity. Now, you have the idea of the multiverse, a theory which states that there are a seemingly infinite amount of universes. Life, on the other hand, does not come so infinitely. The multiverse, a theory consisting of several contested explanations, and the anthropic principle, which universes must follow in order to sustain life, are necessary in order to greater understand our own existence, by showing its extreme rarity.
The multiverse is, in the simplest terms, multiple universes. It is a “proposal that there could also be other Big Bangs that might be completely disconnected from ours” (Bernard, and Ellis 2.29). If a Big Bang was possible in our own universe, then it should be possible for them to occur elsewhere under similar, or even perhaps differing, conditions. This idea seems rather simple, however, it encompasses an enormous amount theory and explanation, around a theory that is not yet well confirmed.
While the multiverse would seem to be a hard theory to prove, cosmologists actually have some evidence pointing to its existence. According to cosmologists, specifically Tegmark, the question is “not whether there is a multiverse . . . but rather how many levels it has” (1), suggesting there is enough evidence present to, at least somewhat, confirm the theory. The four levels outlined by Tegmark make the attempt to explain the multiverse in terms of “parallel universes”, which are falsifiable and, therefore, more scientifically credible (1).
The first level, Level I, suggests that there are an infinite amount of regions “the size of our observable universe” which are past our cosmological horizon, with the same physical constants and only differing in initial conditions (Tegmark 3). Because the universe is accelerating faster than the speed of light, light has only been able to travel so far since the Big Bang, which creates a cosmological horizon known as the observable universe – the part of our universe that we can actually see. As Level I suggests, there are an infinite number of regions past our horizon, all being the same size as our observable universe. The next scenario takes the explanations given in Level I slightly farther. The Level II multiverse consists of an “infinite set of distinct [Level I multiverses] . . . some perhaps with different dimensionality and different physical constants” (Tegmark 5). These universes are described as a chain reaction – one inflating universe produces another – which is explained by “chaotic inflation”, a...