The universe we live in has certain fixed values, as well called the Planck constants. Without those seven constants life on our planet, and anywhere else in the universe, would be impossible.
In other words, if only one of those constants would be only slightly different, I wouldn't be sitting here at my computer writing this blog post. In fact, I wouldn't exist, and neither would you. Earth would probably be just a barren planet, with no flora and fauna at all.
So logical thinking would reason that there must be a design behind it all. The probability of these constants coming into effect exactly as they are by chance is so minute that it can be practically ignored.
That was a tough nut for science to crack. The constants can be proven, but scientists couldn't just live with the idea of a creator/designer behind it all - it's just not scientific.
So they racked their brains, did a couple of brainstorms, wrote papers, discussed the issue. There had to be a way out of it, there had to be an explanation how this universe came to pass without God being behind it.
And bingo - born was the new theory of parallel universes. Because if you accept the idea that there are simultaneously millions of universes, what's happening then in our universe is simply a random configuration of values.
We were just lucky!