Is the universe too amazing to have just happened, or has science explained it all now?
For millennia people have look at the grandeur of the skies at night, and felt that it reflected the handiwork of God. Typical is Psalm 19 in the Bible (probably written almost 3,000 years ago): "The heavens declare the glory of God; the skies proclaim the work of his hands."
These thoughts were developed into an argument, based on the idea that if you were walking in the country and found a watch, and it was something you'd never seen before, you'd immediately surmise that it wasn't natural, but someone had designed it. So, the argument went, we should assume someone designed the universe.
But science has put a real dent in that argument. Granted the laws of physics and chemistry, scientists believe they can, or soon will be able to, explain the shape of the universe from conditions at the time of the big bang, and explain the complexities of life on earth by natural selection. There is no need for a designer.
But the argument has received a new lease of life in the last few decades, and the key is the phrase "granted the laws of physics and chemistry", especially those operating at a cosmic scale. For scientists have discovered that some of the basic laws of the universe include numerical values that could only have led to a universe if they were within extremely narrow bounds. For example:
- Following the big bang, the rate of expansion of the universe had to be "just right" for the universe to form. If it was a millionth part (0.00001%) larger, everything would have flown apart and there'd be no stars, or planets or anything; an even tinier percentage smaller and everything would have quickly collapsed in on itself.
- The cosmological constant, a measure of "the energy density of empty space", is an important factor in Einstein's relativity equations. Theory suggests the constant should be quite large, in which case matter would not coalesce to form stars and planets (if positive) or the universe would quickly collapse in on itself (if negative). However the actual very small number is extremely fine-tuned (it has to be exact to 56 decimal places) to allow our universe to exist.
- The physics of atoms is also "just right". If the difference in mass between a proton and a neutron was not exactly as it is (approximately 2 electrons), then all neutrons would be protons or vice versa, and we would have no chemistry and no life. If the mass of a neutron was only 0.14% larger and there would be no nuclear fusion in stars and no energy source for life.
- There are four fundamental natural forces: the strong nuclear force, electromagnetism, the weak nuclear force and gravity. Changes in the strength of these forces, or the ratios between them, would have significant impacts on the universe.
- If the nuclear strong force was only 2% stronger, the universe would be composed of hydrogen and if 1% stronger there would be no oxygen; if only 5% weaker, there would be no stars, and if only 1% weaker there would be little hydrogen, and hence little water.
- The nuclear weak force is much larger than gravity; if it was only slightly weaker, all hydrogen would be helium and we could have no water, but if only slightly greater, the elements necessary for life would not been produced.
- Gravity is much weaker than electromagnetism. If it were only one part in 10 to the 30th power larger, stars would be billions of times less massive and burn a million times faster.
- The ratio between the nuclear strong force and electromagnetism is exactly right to create conditions that allow carbon to be synthesised.
Some say there are 15 different constants which have to be "just right", but others say there are only 4. But regardless, the argument goes, the odds against the universe occurring "by chance" are so enormous as to be unthinkable. This argument is well summarised in Stephen Davis' book God, Reason and Theistic Proofs, which I discussed in proving and disproving god.
Opponents of this argument have many responses, some of which I outlined in cosmic jackpot?. The most popular seem to be:
- The universe just happened, and it is meaningless to ask why. We are only here to wonder because it did happen.
- There is some underlying fundamental reason for these values that we just don't know yet. Perhaps some cosmic form of evolution has occurred.
- Maybe there are absolutely zillions of universes (a concept called "the multiverse"), so the odds of one of them being just right for life may not be so high.
- If the laws and constants had been different, a different universe would have occurred, and a different form of life might have evolved. The argument is too anthropocentric.
- The argument might show that belief in a god is possibly reasonable, but is not strong enough to compel belief.
But interestingly, Robin LePoidevin, whose book Arguing for Atheism I also discussed in proving and disproving god, doesn't rely on any of these arguments. Instead he argues that what we are doing here is assessing probabilities - the probability that these factors could be fortuitous by chance, and the probability that God exists. But, he argues:
- Probabilities are based on looking at a number of examples and seeing how often they turn out favourably - such as how often a Royal Flush will turn up in millions of Poker games. But we only know about one universe, so probability simply can't be applied in this case.
- The chance of an outcome depends on the circumstances that caused the outcome. But there is no process the we know of that can produce God, so it is nonsensical to talk about the mathematical probability that God exists.
Therefore, LePoidevin says, the argument fails, and disbelief in God is the most reasonable option.
I still think that the alternative explanations are unconvincing; they seem to be either wildly speculative or highly improbable. Those who say that if the constants had been different, a different form of life would have evolved, seem to ignore that the odds were zillions to one against any stable and long-lasting universe forming at all.
LePoidevin's statistical argument seems to me to fail the commonsense test - maybe we can't apply mathematical probability, but we all know what seems likely and unlikely. In fact, his argument that we cannot sensibly talk of the probability of God's existence undercuts a common theme of modern atheism, that God's existence is highly improbable. As I said before, the counter arguments seem to me to only show the strength of this argument that the universe does appear to be carefully designed.
What do you reckon?
Read more about the "fine-tuned universe" on Wikipedia.
Read a theistic summary by Holmes Rolston or James Hannam, or an atheistic view from Michael Hurben or Stephen Weinberg.
Read some quotes from scientists about design (selected from a theistic viewpoint).
Read about the multiverse (from an atheistic viewpoint).
Read my own longer discussion of the topic.