Brian Greene explores the concept:
Imagine that when the apple fell on Newton’s head, he wasn’t inspired to develop the law of gravity, but instead reasoned that some apples fall down, others fall up, and we observe the downward variety simply because the upward ones have long since departed for outer space. The example is facetious but the point serious: used indiscriminately, the multiverse can be a cop-out that diverts scientists from seeking deeper explanations. On the other hand, failure to consider the multiverse can place scientists on a Keplerian treadmill in which they furiously chase answers to unanswerable questions.
Which is all just to say that the multiverse falls squarely in the domain of high-risk science.
There are numerous developments that could weaken the motivation for considering it, from scientists finally calculating the correct dark-energy value, or confirming a version of inflationary cosmology that only yields a single universe, or discovering that string theory no longer supports a cornucopia of possible universes. And so on.
But as with all rational bets, high risk comes with the potential for high reward. During the past five centuries we’ve used the power of observation and mathematical calculation to shatter misconceptions. From a quaint, small, earth-centered universe to one filled with billions of galaxies, the journey has been both thrilling and humbling. We’ve been compelled to relinquish sacred belief in our own centrality, but with such cosmic demotion we’ve demonstrated the capacity of the human intellect to reach far beyond the confines of ordinary experience to reveal extraordinary truth. The multiverse proposal might be wrong. But it might also be the next step in this journey, unveiling a breathtaking panorama of universes populating a vast cosmic landscape. For some scientists, including me, that possibility makes the risk well worth taking.
More on Greene's theories here.
The Dish 