First, the LAWS OF THE UNIVERSE. Two such finely tuned laws are:
- The law of gravity that acts on all matter. Without gravity, stars would break apart and we would have no long-term energy to sustain life.
- The strong nuclear force. Without this, the protons in the nucleus of an atom would repel each other and our universe would be made up of nothing more than hydrogen.
- We know that the gravitational constant, which is the value of how much masses will be attracted to one another could sit in a range anywhere within 1x 1040 power, or 1 followed by 40 zeros. But if the force of gravity was increased by one part in a billion, billion, billion, billion, advanced life would be crushed according to Cambridge Royal Society Research professor Martin Rees.
- Barrow & Tipler, in their landmark book The Anthropic Cosmological Principle, note that if Einstein's cosmological constant varied in either direction by as little as 1 x 10120, (which is a fraction so small that it would take more zeros to write than there are atoms in the universe) If this were to be changed by even that amount, the universe would expand too fast for galaxies & stars to form.
Taking all this into account, John Leslie remarks, "Clues heaped upon clues can constitute weighty evidence, despite doubts about each element in the pile."
Does the Multiverse Solve this Problem?Carrier claims that the multiverse hypothesis solves the problem of an exquisitely fine-tuned universe poised just right for advanced life to develop. He claims by simply having an infinite number of universes being created, there is bound to be one that would have the conditions we see, and naturally we are here because we happen to live in that universe. But I see at least three problems with this assumption:
The Many Worlds Hypothesis is SpeculatoryThe idea of an infinite number of universes having every conceivable construction of laws is sheer speculation. There simply is no observable data to back this up. In fact, there cannot be any observable data since we would never be able to observe anything outside our own universe. If we can see it, measure it, or in some other way capture data, we know it's in this universe.
The Many-Universe Making Machine Would Then Need to be Designed.If an infinite number of universes that are all divergent are somehow being generated continually, we've simply pushed the problem back a notch. What is this thing, this mechanism that is a universe-generating machine? How come it functions so well at generating universes that it never stops? How does it get all the right components to make a self-sustaining universe together and spit out a finished product? If it is a mind, then it s still evidence for God. If it is material, then the machine must itself have been created somehow, which means we're back to the same question.
Even with Multiple Universes, Our Universe is SpecialEVEN IF multiple universe creation in chaotic/eternal inflation is true, it coupled with our observation that the cosmological constant is non-zero would seem to suggest that our universe would appear to be the first one ever to appear. In their paper "Disturbing Implications of a Cosmological Constant" physicists at MIT and Stanford (Lisa Dyson, Matthew Kleban, Leonard Susskind) show that given the factors necessary for life and the low initial entropy conditions, either there is no real cosmological constant or "an unknown agent intervened in the evolution, and for reasons of its own restarted the universe in the state of low entropy characterizing inflation." 
References Rees, Martin. Just Six Numbers: The Deep Forces that Shape the Universe (New York: Basic Books, 2000) 30.
 Collins, Robin. "A Recent Fine-Tuning Argument." The Philosophy of Religion Reader. Ed. Meister Chad. New York: Routledge, 2008.
 L. Dysona,b, M. Klebana, L. Susskinda, "Disturbing Implications of a Cosmological Constant" Journal of High Energy Physics 0210:011,2002. Revised 14 Nov 2002
Available online at http://arxiv.org/pdf/hep-th/0208013.pdf