Though the Big Bang began 13.7 billion years ago, the universe is still expanding. We are living inside the most massive explosion that ever was.
At the moment the Big Bang began, everything that exists—matter, energy, the three dimensions of space, and the fourth dimension of time—emerged from a single geometric point, expanding at the speed of light. The Big Bang actually created space and time.
Had the Big Bang been weaker, the cosmos would have soon fallen back on itself in a big crunch. On the other hand, had it been stronger, the cosmic material would have dispersed so rapidly that galaxies would not have formed. … Had the explosion differed in strength at the outset by only one part in 1060, the universe we now perceive would not exist. To give some meaning to these numbers, suppose you wanted to fire a bullet at a one-inch target on the other side of the observable universe, twenty billion light-years away. Your aim would have to be accurate to that same part in 1060…. Channeling the explosive violence into such a regular and organized pattern of motion seems like a miracle.
If the explosive force of the Big Bang not been perfectly balanced and incredibly fine-tuned, life would be impossible and you and I could not exist.
At first, the laws and constants of the universe were simply accepted as a matter of fact—no one wondered why this or that force or constant of physics was not slightly stronger or weaker than it is. Eventually, physicists began to realize (as George Greenstein observes in The Symbiotic Universe) that the “laws of nature could have been laid down only in the very instant of the creation of the universe, if not before.”
Paul Davies recalls that when he was a student, the question of where the laws of physics come from was off-limits. A scientist was supposed to simply apply those laws, not inquire into their origin. They would say, “There’s no reason the laws of physics are what they are—they just are.” Davies concluded, “The idea that the laws exist reasonlessly is deeply anti-rational. … It makes a mockery of science.”
As it became clear that the laws of nature might have been different than they are—that they appeared to have been deliberately selected to produce life—scientists began to look at these forces, laws, and constants with new sense of awe. The entire universe seemed to be constructed out of an incredibly unlikely series of cosmic coincidences. Some examples:
There are four forces governing the structure and behavior of subatomic particles—the electromagnetic force, the gravitational force, the strong nuclear force and the weak nuclear force. These forces determine everything from how an electron orbits the nucleus of an atom to how stars and galaxies are formed. Each force has a specific mathematical value called a constant (because its value never varies).
The gravitational force constant is finely tuned to permit life. Slightly greater, and stars would burn too hot, too quickly, and too unevenly to produce life-giving elements. Slightly smaller, and stars would be too cool, so that nuclear fusion could not take place and there would be no life-giving heavier elements.
The electromagnetic force is also fine-tuned. If its constant were slightly larger or smaller, the chemical bonding required for making living things could not take place.
There is a fine-tuned balance between the gravitational and electromagnetic forces. If the constant of the ratio between these two forces were larger, there would be no stars smaller than 1.4 solar masses, and the lifetime of stars would be too short to generate life-giving elements. If the constant were smaller, there would be no stars larger than 0.8 solar masses—and again, no production of life-giving heavier elements.
If the strong nuclear force constant were slightly larger, there would be no hydrogen in the universe and no stars. If this constant were smaller, the universe would consist of nothing but hydrogen.
If the weak force constant were larger, most of the hydrogen in the universe would have converted to helium during the Big Bang. If it were smaller, there’d be too little hydrogen converted to helium—a roadblock to the production of life-giving heavier elements such as carbon and oxygen.
The proton-to-electron mass ratio: A proton is 1,836 times more massive than an electron; if this ratio varied slightly in either direction, molecules could not form and life could not exist. The ratio of the number of protons to the number of electrons is also finely balanced to permit the electromagnetic force to dominate the gravitational force, allowing the formation of galaxies, stars, and planets.
The unusual properties of water are also a fine-tuned condition for life. Water plays an essential role in almost every biological function. It is necessary to photosynthesis, the foundation of the food chain. In photosynthesis, plants use sunlight to convert carbon dioxide and water into sugar, giving off oxygen as a “waste product.”
Water is one of the few liquids that expands when it freezes. Most substances contract and become more dense when they freeze, but frozen water is actually 9 percent less dense than liquid water. This is because, at freezing temperatures, the hydrogen bonds that connect water molecules make an adjustment to keep negatively charged oxygen atoms apart. This adjustment creates the crystal lattice that enables ice to float in liquid water.
If water didn’t have this extraordinary property, ice would sink, which would cause lakes and rivers to freeze solid. If ice did not float, observes George Greenstein, life on Earth “would be confined to a narrow strip lying close to the equator.”
And the list goes on: the proton decay rate, the neutron-proton mass difference, the matter-antimatter ratio, and on and on—it’s as if dozens of completely unrelated laws of nature plotted together in a vast cosmic conspiracy to produce life. As Paul Davies observes:
It is tempting to believe, therefore, that a complex universe will emerge only if the laws of physics are very close to what they are. … The laws, which enable the universe to come into being spontaneously, seem themselves to be the product of exceedingly ingenious design. If physics is the product of design, the universe must have a purpose, and the evidence of modern physics suggests strongly to me that the purpose includes us.
And physicist Fred Hoyle adds, “I do not believe that any scientist who examines the evidence would fail to draw the inference that the laws of nuclear physics have been deliberately designed.”
Is our life-giving universe the result of an inconceivably improbable series of cosmic accidents? Or is it the product of calculated, deliberate design?
Is the universe evidence—even proof—of the existence of God?