During the last fifty years, scientists have discovered that the existence of life and especially intelligent life, anywhere in the universe, depends on a very precise balance of initial conditions. The fundamental constants of physics and chemistry are just right to allow for life. Things like the strength of gravity; the relative masses of subatomic particles; the precise strength of the nuclear weak force, the nuclear strong force, and electromagnetism; and so forth. From what I understand, there are something like 30 separate parameters that must be finely tuned in order to produce a life-sustaining universe.
After discovering one of the first purported cases of fine-tuning, Sir Fred Hoyle (the British astrophysicist, who was an atheist) admitted: “A common sense interpretation of the facts suggests that a superintellect has monkeyed with physics...” (The Universe: Past and Present Reflections).
We know a lot more now. As Dr. Robin Collins (who has degrees in physics and philosophy) said, “Almost everything about the basic structure of the universe—for example, the fundamental laws and parameters of physics and the initial distribution of matter and energy—is balanced on a razor’s edge for life to occur” (Reason for the Hope Within).
The objection often given at this point is: “If the universe was not so finely tuned, we would not be here to observe it.” They say we shouldn’t be surprised to find it finely tuned, because if it wasn’t finely tuned, we wouldn’t be here to be surprised about it.
But, there is a simple illustration sometimes used that easily refutes this. Imagine being dragged in front of a firing squad of 30 trained marksmen to be executed. You hear the command given, and then you hear the roar of the guns. And then, you observe that you are still alive—that all 30 of the marksmen missed. Are you going to say, “Well, I guess I shouldn’t be surprised that they all missed. After all, if they hadn’t all missed, I wouldn’t be here to be surprised about it”? No, you would be extremely surprised that you do observe that you are alive, due to the enormous improbability of 30 trained marksmen all missing. You would surely think it must be a conspiracy (they all missed on purpose)—that it was setup by someone for some reason. If you were asked, “How did you survive?”—it would be very inadequate to answer, “Well, if I didn’t survive, I wouldn’t be here to answer you.”
This is the same with respect to the universe. As philosopher Dr. William Lane Craig said, “Similarly, we should not be surprised that we do not observe features of the universe incompatible with our existence. (We cannot observe that we do not exist.) Yet we should be surprised that we do observe features of the universe compatible with our existence—in view of the enormous improbability that the universe should possess such features” (Cosmos and Creator).
At the end of "Collision," atheist Christopher Hitchens admitted that he found the fine-tuning argument as the most intriguing argument from the design side. And he said, “...even though it doesn’t prove a design, doesn’t prove a designer, could all that have happened without—you have to spend time thinking about it, working on it. It’s not trivial. We all say that.”
Personally, I have to agree with Dr. Werner Von Braun (the rocket scientist) who said this in his letter to the California State Board of Education, “One cannot be exposed to the law and order of the universe without concluding that there must be design and purpose behind it all.”