We sometimes refer to the “fine-tuning” of the universe as a way to denote the necessity of various constants being exactly what they are, for the universe to exist as it does. This includes the forces identified as acting upon physical bodies, including gravity, the strong and weak nuclear forces, and electromagnetism. It also includes, however, the ratios of mass and velocity among various particles in the universe. It increasingly appears that the universe is “fine-tuned” in order to exist as it does, and to support life on earth. Theists view this as an argument from science for the existence of God, who does the fine-tuning.
The usual objection to the fine-tuning argument (discussed beginning here, here, here, and here) is that it is merely tautological. The argument is that though the odds may be a gazillion to one that a particular cosmological constant exists instead of all others, the odds are equal that one cosmological constant exists instead of one other. It’s not in the odds for and against, that the problem lies. Therefore, an atheist might argue, there is no reason to infer that some grand designer purposely stepped in to cause a universe to be.
The problem with the atheist position lies in the fact that the difference between the constant we have and all others is the difference between existence and non-existence of matter; and further, because matter is thought to be the total of reality for the atheist, that means that the one constant we have is the difference between all of existence and true nothing.
We have considered this in the context of one cosmological constant: the force of gravity. But the same issue is compounded because gravity is not the only constant in play. There are numerous big-picture measures that must align, for the universe to be. The measures of strong and weak nuclear forces, electromagnetism, and a host of mathematical relationships among particles and elements, all turn out to be critical to the very existence of the universe. Again, this means not merely the universe “as it is,” but the existence of the universe period.
Now the atheist point of view to explain the existence of the universe (and all universes if we are in a multiverse) is that each cosmological constant is as likely as each other cosmological constant, and the one we have happens to result in a universe. Never mind that existence (of anything) precedes the cosmological constant, and so the very existence of the cosmological feature (such as gravity) depends upon there being a universe in existence, so it is meaningless to speak of alternatives to the one cosmological constant that exists for that feature (gravity, in our example).
This problem with the atheist point of view is compounded when we begin to multiply the number of necessary measures of forces and mathematical relationships in the universe and the various ratios of forces within particles and elements. This means that even if it were possible to consider a probability of the universe existing, that probability diminishes by a factor of the number of other necessary constants, and those are innumerable. In other words, it appears mathematically impossible that there could exist a universe without precisely the forces we have, and again, if there were no universe, there would be no-thing. Not merely empty space in which the laws of physics would operate if there were physical things. But no physical thing, and no laws of physics to precede and govern, upon the advent of physical things.
Freeman Dyson, a noted physicist, wrote that “it almost seems as if the Universe must in some sense have known that we were coming.” This is actually gently put. Non-sentient stuff does not “know” anything. God does.