Scientifically speaking, why the universe exists and why it looks like what it looks like is still a mystery. We don’t know why anything exists rather than nothing, or why energy-matter works as it does. Furthermore, there is still no explanation to why the universe’s force constants are as they are.
Christian apologist William Lane Craig, among others, talk about the universe being fine tuned for life, planets, stars and even atoms to exist, as you can see in the video above. The cosmological constant, Λ, has a value of approximately 10−122, and if this would change by less than a trillion’s trillionth of a percent, the universe would either be sucked back into a black hole right after big bang or disparse so quickly that stars would never form.
Leonard Susskind, professor of theoretical physics at Stanford, explain the fine tuning of the universe in more detail above. Now, if the universe was caused either by nothingness or from something unintelligent and non-designing, as atheists would argue, the fine tuning becomes really hard to explain. Our universe where the cosmological constant and other constants like the gravitational constant are suitible for stars, planets and life to exist, is ridiculously unlikely. Susskind is not a theist due to his lack of faith in miracles, but he isn’t an atheist either because of his inability to refute the idea that a divine entity caused this complex universe, and so he remains agnostic.
However, Hemant Mehta, the Friendly Atheist, disagrees with the idea of fine tuning. He rebutes the argument saying that we’re not the centre of the universe, no matter what religious people believe, and if things were different we would simply have this conversation on another planet, maybe with an extra eye or two, or nobody would have any conversation whatsoever.
Now, I get the impression that Mehta doesn’t really get the argument. Maybe he’s simply heard a very bad version of it, but the fact that he mixes the fine tuning of the gravitational constant with “If Earth were slightly out of orbit, we’d be screwed” makes me think that he has heard two different arguments and mixed them up. I agree that it’s not an argument for God’s existence to say that the earth is in the perfect spot to breed humans, because if it wasn’t we may have just been in another solar system.
However, you cannot simply say the same about the universe, which is nothing less than all of time and space, that is, everything that exists. While we have billions of hospitable planets in the universe, we have just one universe – that could have been totally inhospitable if certain constants were different. Some try to explain this with the theory of multiverses, where there are numerous universes where constants may be different (which probably would make most of them inhospitable for life). And Susskind explains in his video above that he even believes that these constants may vary in different parts of our universe.
We have to remember though that when we speculate about these things, we are entering the arena of faith. Which isn’t a bad thing – I as a Christian like faith very much – but then atheists cannot blame theists for believing in things that cannot be empirically measured. Multiverses or different cosmic laws in other parts of our universe cannot be empirically measured either.
And if countless universes exist – what caused them to exist? If their constants vary, why do they do that? This is the constant question that constantly brings us back to God’s existence. And I think that He is a very good explanation to the fine tuning of the universe, not the least because I have come in contact with Him and seen miracles, prophetic visions and have heard His voice. When I hear that it is extremely unlikely that the universe came into being by chance, my faith in Him is strengthened even more.