The Case for a Creator, Chapter 6
The cosmological fine-tuning argument is one of the more interesting claims in the intelligent-design movement’s toolkit. In fact, I’d go so far as to say that it’s the best argument they have. I’ll let Robin Collins make the point as strongly as he can:
“Over the past thirty years or so, scientists have discovered that just about everything about the basic structure of the universe is balanced on a razor’s edge for life to exist. The coincidences are far too fantastic to attribute this to mere chance or to claim that it needs no explanation.” [p.131]
The fine-tuning argument usually takes the form of claiming that the underlying physical constants of the universe need to be precisely calibrated for beings like us to exist, and even a tiny change one way or another would result in a cosmos completely incompatible with life. ID advocates will point to examples like the strength of gravity, the value of the cosmological constant, the binding energy of protons and neutrons – and they love to stack up the zeroes when describing the allegedly inconceivable odds:
“The fine-tuning has conservatively been estimated to be at least one part in a hundred million billion billion billion billion billion. That would be a ten followed by fifty-three zeroes. That’s inconceivably precise.” [p.133]
I said that the fine-tuning argument is the best argument ID has. Of course, this isn’t to say that it proves the existence of a god, just that it’s not blatantly wrong like the design argument or the ontological argument. It does seem to be true that a small change in the physical constants would result in a drastically different universe and would make life like ours impossible. This doesn’t prove the existence of a god (or some other superintelligence that controls the values of the constants), but that is one possible way to explain the observation.
However, there’s a follow-up question that needs to be asked. Assume for the sake of argument that the constants can vary at random. Now the question is this: How many different sets of physical constants would allow for life of any sort?
After all, if you’re going to calculate how likely it is that the laws of the cosmos would allow for life to exist, you need to know two things: how many possible sets of laws are there, and how many of those sets of laws permit life. Strobel and Collins assume that the first number is a very large one (Strobel says the odds against any particular set of values are “infinitesimal” [p.135]), but never even ask how large the second is. If there are a trillion trillion possible universes, but two-thirds of those could give rise to intelligent beings of some kind, then the odds against our being here are not very large!
Granted, any kind of life that could exist if the physical constants were altered would probably be extremely different from us. We might not even recognize it as life if we encountered it. But Collins is far too hasty in dismissing the possibility out of hand without any real evidence. For instance, he says, if the force of gravity was stronger relative to the other fundamental forces:
“As astrophysicist Martin Rees said, ‘In an imaginary strong gravity world, even insects would need thick legs to support them, and no animals could get much larger.’ In fact, a planet with a gravitational pull of a thousand times that of the Earth would have a diameter of only forty feet, which wouldn’t be enough to sustain an ecosystem. Besides which, stars with lifetimes of more than a billion years – compared to ten billion years for our sun – couldn’t exist if you increase gravity by just three thousand times.” [p.132]
The American physicist Robert Forward, who died in 2002, was a prolific scientist (he published hundreds of papers during his lifetime, far exceeding the scientific output of the entire ID movement so far). He was also a science fiction writer. Among his novels was Dragon’s Egg, which describes an intelligent species living on the surface of a neutron star. They’re made of ultra-dense matter and are the size of sesame seeds, so the massive gravity and smaller diameter of their world aren’t problematic, and because nuclear reactions occur much more quickly than chemical reactions, their existence is greatly accelerated relative to ours (their “year” is about 30 seconds long), thus answering Collins’ concern about shorter stellar lifespans. Although this is obviously speculative fiction, nothing in it is impossible according to our current understanding. Forward described his book as “a textbook on neutron star physics disguised as a novel”.
Collins also says that if the strong nuclear force were slightly weaker, our universe would be composed purely of hydrogen, and:
“…regardless of what they may show on Star Trek, you can’t have intelligent life forms built from hydrogen. It simply doesn’t have enough stable complexity.” [p.134-135]
Fred Hoyle – the astronomer whom Strobel favorably quotes earlier in this chapter as recognizing the apparently fine-tuned nature of the universe – did not agree with this. Like Forward, he was both a scientist and a science fiction writer. His 1957 novel The Black Cloud depicts an enormous alien intelligence in the form of a sentient interstellar cloud of hydrogen (plus, to be fair, some other trace elements). Hoyle said of the novel, “there is very little here that could not conceivably happen” (source).
Neither of these novels are science textbooks, of course. It may well be that Hoyle’s or Forward’s visions of alien life are ultimately not possible in our universe. But even if you believe their conclusions are unfounded, there is little more reason to believe Collins’ strategic pessimism. If we had known only the physical laws of our universe, we could hardly have predicted, from first principles alone, that it would contain life. We simply don’t have the knowledge to proclaim with confidence what other interesting possibilities may be inherent in other sets of physical laws. In the set of possible worlds, there may be strange lifeforms we’ve never even dreamed of. There are no grounds for Strobel’s confidence that our universe is the only possible one that could give rise to life and sentience.
Other posts in this series: