To illustrate this astonishing precision imagine that if the mass of the earth deviated from its actual mass by as much as the mass of a grain of sand the earth wouldn't exist. That's the sort of precision required in not just one cosmic parameter but in dozens of them.
Examples of this fine-tuning include the expansion rate of the universe (the cosmological constant) which must be calibrated to one part in 10^120. To grasp the magnitude of this number consider that there are only 10^80 atoms in the entire universe.
Another example is the strength of gravity. Imagine that the range of possible values for the strength of gravity is represented by a ruler stretched across the entire expanse of the universe. The actual strength of gravity is located at some point on the ruler. If it were stronger or weaker than what it is such that its value deviated by just one inch on the ruler, no stars or planets would exist.
A third example has to do with the initial conditions that existed at the origin of the universe. For instance the distribution of mass/energy in the earliest stage of the Big Bang could've had any value but the odds that it would be a value that produces a life-permitting universe was calculated by Roger Penrose to be one in 10^10^123. This is incomprehensible.
How is it that a universe such as ours exists with so many factors being just right for intelligent life? Some people, like philosopher Bertrand Russell, just shrug their shoulders and tell us that, "The universe is just there and that's all," but this is to display a strange lack of curiosity. It's a "science stopper."
Here's a list of some of the fine-tuned parameters in our universe and in our solar system and earth. You can find an explanation for most of them at the link:
Cosmic Constants
- Gravitational force constant
- Electromagnetic force constant
- Strong nuclear force constant
- Weak nuclear force constant
- Cosmological constant
- Initial distribution of mass energy
- Ratio of masses for protons and electrons
- Velocity of light
- Mass excess of neutron over proton
- Steady plate tectonics with right kind of geological interior
- Right amount of water in crust
- Large moon with right rotation period
- Proper concentration of sulfur
- Right planetary mass
- Near inner edge of circumstellar habitable zone
- Low-eccentricity orbit outside spin-orbit and giant planet resonances
- A few, large Jupiter-mass planetary neighbors in large circular orbits
- Outside spiral arm of galaxy
- Near co-rotation circle of galaxy, in circular orbit around galactic center
- Within the galactic habitable zone
- During the cosmic habitable age
- The polarity of the water molecule
When people say there is no evidence that a God exists what they mean is that they just haven't bothered to avail themselves of the evidence that's there.