Like a good radio: fine-tuned

One of Craig's 5 reasons from https://www.reasonablefaith.org

One of a series following this post.

God makes sense of the fine-tuning of the universe for intelligent life.

During the last 40 years or so, scientists have discovered that the existence of intelligent life depends upon a complex and delicate balance of initial conditions given in the Big Bang itself. Scientists once believed that whatever the initial conditions of the universe, eventually intelligent life might evolve. But we now know that our existence is balanced on a knife's edge. The existence of intelligent life depends upon a conspiracy of initial conditions which must be fine-tuned to a degree that is literally incomprehensible and incalculable.

This fine-tuning is of two sorts.

First, when the laws of nature are expressed as mathematical equations, you find appearing in them certain constants, like the gravitational constant. These constants are not determined by the laws of nature. The laws of nature are consistent with a wide range of values for these constants.

Second, in addition to these constants there are certain arbitrary quantities which are just put in as initial conditions on which the laws of nature operate, for example, the amount of entropy or the balance between matter and anti-matter in the universe. Now all of these constants and quantities fall into an extraordinarily narrow range of life-permitting values. Were these constants or quantities to be altered by a hair's breadth, the life-permitting balance would be destroyed and life would not exist.

For example, the physicist P. C. W. Davies has calculated that a change in the strength of gravity or of the atomic weak force by only one part in 10100 would have prevented a life-permitting universe. The cosmological constant which drives the inflation of the universe and is responsible for the recently discovered acceleration of the universe's expansion is inexplicably fine-tuned to around one part in 10120.

Roger Penrose of Oxford University has calculated that the odds of the Big Bang's low entropy condition existing by chance are on the order of one out of 10 10 (123). Penrose comments, "I cannot even recall seeing anything else in physics whose accuracy is known to approach, even remotely, a figure like one part in 1010 (123)." [5] And it's not just each constant or quantity which must be exquisitely finely-tuned; their ratios to one another must be also finely-tuned. So improbability is multiplied by improbability by improbability until our minds are reeling in incomprehensible numbers.

Now there are three possibilities for explaining the presence of this remarkable fine-tuning of the universe: physical necessity, chance, or design.

The first alternative holds that there is some unknown Theory of Everything (T.O.E.) which would explain the way the universe is. It had to be that way, and there was really no chance or little chance of the universe's not being life-permitting.

By contrast, the second alternative states that the fine-tuning is due entirely to chance. It's just an accident that the universe is life-permitting, and we're the lucky beneficiaries. The third alternative rejects both of these accounts in favor of an intelligent Mind behind the cosmos, who designed the universe to permit life.

Which of these alternatives is the most plausible?

The first alternative seems extraordinarily implausible. There is just no physical reason why these constants and quantities should have the values they do. As P. C. W. Davies states,

Even if the laws of physics were unique, it doesn't follow that the physical universe itself is unique. . . . the laws of physics must be augmented by cosmic initial conditions. . . . There is nothing in present ideas about 'laws of initial conditions' remotely to suggest that their consistency with the laws of physics would imply uniqueness. Far from it. . . . . . . it seems, then, that the physical universe does not have to be the way it is: it could have been otherwise. [6]

For example, the most promising candidate for a T.O.E. to date, super-string theory or M-Theory, fails to predict uniquely our universe.

In fact, string theory allows a "cosmic landscape" of around 10500 different universes governed by the present laws of nature, so that it does nothing to render the observed values of the constants and quantities physically necessary.

So what about the second alternative, that the fine-tuning of the universe is due to chance?

The problem with this alternative is that the odds against the universe's being life-permitting are so incomprehensibly great that they cannot be reasonably faced. Even though there will be a huge number of life-permitting universes lying within the cosmic landscape, nevertheless the number of life-permitting worlds will be unfathomably tiny compared to the entire landscape, so that the existence of a life-permitting universe is fantastically improbable.

Students or laymen who blithely assert, "It could have happened by chance!" simply have no conception of the fantastic precision of the fine-tuning requisite for life. They would never embrace such a hypothesis in any other area of their lives—for example, in order to explain how there came to be overnight a car in one's driveway.

Some people have tried to escape this problem by claiming that we really shouldn't be surprised at the finely-tuned conditions of the universe, for if the universe were not fine-tuned, then we wouldn't be here to be surprised about it!

Given that we are here, we should expect the universe to be fine-tuned. But such reasoning is logically fallacious. We can show this by means of a parallel illustration.

Imagine you're traveling abroad and are arrested on trumped-up drug charges and dragged in front of a firing squad of 100 trained marksmen, all with rifles aimed at your heart, to be executed. You hear the command given: "Ready! Aim! Fire!" and you hear the deafening roar of the guns. And then you observe that you are still alive, that all of the 100 trained marksmen missed!

Now what would you conclude?

"Well, I guess I really shouldn't be surprised that they all missed. After all, if they hadn't all missed, then I wouldn't be here to be surprised about it! Given that I am here, I should expect them all to miss."

Of course not!

You would immediately suspect that they all missed on purpose, that the whole thing was a set-up, engineered for some reason by someone. While you wouldn't be surprised that you don't observe that you are dead, you'd be very surprised, indeed, that you do observe that you are alive. In the same way, given the incredible improbability of the fine-tuning of the universe for intelligent life, it is reasonable to conclude that this is not due to chance, but to design.

In order to rescue the alternative of chance, its proponents have therefore been forced to adopt the hypothesis that there exists an infinite number of randomly ordered universes composing a sort of World Ensemble or multiverse of which our universe is but a part. Somewhere in this infinite World Ensemble finely-tuned universes will appear by chance alone, and we happen to be one such world.

There are, however, at least two major failings of the World Ensemble hypothesis:

First, there's no evidence that such a World Ensemble exists. No one knows if there are other worlds. Moreover, recall that Borde, Guth, and Vilenkin proved that any universe in a state of continuous cosmic expansion cannot be infinite in the past. Their theorem applies to the multiverse, too. Therefore, since the past is finite, only a finite number of other worlds can have been generated by now, so that there's no guarantee that a finely-tuned world will have appeared in the ensemble.

Second, if our universe is just a random member of an infinite World Ensemble, then it is overwhelmingly more probable that we should be observing a much different universe than what we in fact observe.

Roger Penrose has calculated that it is inconceivably more probable that our solar system should suddenly form by the random collision of particles than that a finely-tuned universe should exist. (Penrose calls it "utter chicken feed" by comparison. [7]) So if our universe were just a random member of a World Ensemble, it is inconceivably more probable that we should be observing a universe no larger than our solar system.

Or again, if our universe were just a random member of a World Ensemble, then we ought to be observing highly extraordinary events, like horses' popping into and out of existence by random collisions, or perpetual motion machines, since such things are vastly more probable than all of nature's constants and quantities' falling by chance into the virtually infinitesimal life-permitting range.

Observable universes like those are much more plenteous in the World Ensemble than worlds like ours and, therefore, ought to be observed by us. Since we do not have such observations, that fact strongly disconfirms the multiverse hypothesis. On atheism, at least, it is therefore highly probable that there is no World Ensemble.

So once again, the view that Christian theists have always held, that there is an intelligent designer of the universe, seems to make much more sense than the atheistic view that the universe just happens to be by chance fine-tuned to an incomprehensible precision for the existence of intelligent life.

We can summarize this second argument as follows:

1. The fine-tuning of the universe is due to either physical necessity, chance, or design.
2. It is not due to physical necessity or chance.
3. Therefore, it is due to design.