People tend to take a lot for granted. The sun keeps shining, the earth is full of useful minerals and gravity keeps us from flying off into space. We don’t think about it much, but what if things were different?
What if gravity repulsed rather than attracted? What if we couldn’t sit on a chair because the space between the molecules that make up the chair allowed the molecules in our backsides to fall right through? What if the only atom in the periodic table was hydrogen, and so there was no chemistry?
Cosmology makes a startling discovery
Ever since Einstein, cosmologists have been studying the universe with new understandings, and developing theories and models to describe the history of the universe, from the beginning of the big bang until now. Their growing theoretical knowledge allowed them to examine what would happen if some of the universal laws and numbers were a little different, for example, if gravity was a little stronger or weaker, or electrons a little heavier or their electrical charge a little different.
Almost half a century ago, it became apparent that the universe was in a very special state. A dozen important numbers define physical facts such as the size and charge on elementary particles, the strength of fundamental physical forces and the overall density of the universe. Change any one of these by even a small amount and the universe we know wouldn’t exist and no life would be possible. The universe might have been too short-lived for life to evolve, or it might have expanded so fast and far that there would be enormous space between each atom. Maybe it would have been composed only of hydrogen or inert helium.
The term “fine-tuned” was used to describe these scientific facts. The image is of the universe as a machine with a bunch of dials that change various parameters. Fiddle with the dials any way you like and you’ll end up with a lifeless universe or no universe at all.
Making sense of the fine-tuning
Of course the obvious question is, why did it turn out this way?
Was it inevitable?
Perhaps, if we understood the laws of physics well enough, we could see that it couldn’t have been otherwise?
This would be the hope of scientists – a theory of everything that explains it all. But they don’t think that is the case. There is nothing in our present understanding of physics that requires the universal laws to take on the exact values they have, and it doesn’t look like they are all determined by some deep law.
But even if some fundamental law did make it inevitable it would turn out the way it has, that would still be “fine-tuning”, because we could still ask why couldn’t that fundamental law have been different.
Was it evolution?
Life evolved on earth to produce the human race via mutation and natural selection. Perhaps the universe evolved in a similar manner?
I have heard this argued, but I can’t recall seeing a scientist argue it. There are no real parallels between evolution and the big bang. There is no mechanism in the big bang comparable to natural selection and no evidence that the universal laws and values have evolved through the life of the universe.
Was it just random chance?
Unusual things happen all the time, so perhaps it was just chance it turned out this way. If it hadn’t, we wouldn’t be here to know.
But the cosmologists tell us if our universe was the result of random chance, it was an extremely improbable event. And I mean EXTREMELY.
Lee Smolin has estimated the probability of the universe producing stars to be 1 chance in 10^229 – that number is 1 followed by 229 zeroes! To give us a picture, there are estimated to be about 10^80 atoms in the known universe. The chances of picking one special atom out at random from the whole universe are significantly greater than the probability of a randomly created universe having stars.
But it gets even more amazing. Roger Penrose, an Oxford University mathematician who worked with famed cosmologist Stephen Hawking, estimated the odds of randomly getting a universe with so much available energy like ours to be 1 chance in 10^10^123. I can’t even begin to describe how big that number is, and thus how impossibly small the probability of our universe is.
So most cosmologists accept that simple random chance is too unlikely an explanation.
But perhaps it was the multiverse
There is a way that chance could have produced our universe.
Many cosmologists believe our universe isn’t the only universe. They cannot test this idea scientifically (i.e. by observation), but the mathematics and physics could indicate this. And it would, perhaps, provide an explanation based on random chance.
If there were enough universes (there’d need to be zillions of them), and if they all had different randomly determined laws and values, then many different universes would result. Life would only evolve in the rare universe that had the necessary properties.
This is the favoured explanation for many scientists and philosophers, but it has a number of difficulties:
- It is speculative, with no observable scientific evidence, and (some say) it is impossible we’ll ever get that evidence because there is no connection between our universe and the other hypothetical ones.
- There would have to be an enormous number of universes for the odds of our universe randomly occurring to become reasonable.
- Even if there is a multiverse with an enormous number of universes in it, the chances of being in a large orderly universe like ours is still very small, as Penrose calculated, and it would be far more likely that we were in a small orderly pocket in a disorderly universe. So the multiverse may not explain the fine-tuning at all.
- If zillions of universes exist, each with different physical properties, then we need an explanation for that amazing fact. How were zillions of universes generated or created in the first place, and how did that process come to be so “fine-tuned” that every universe has different properties, as required? Theoretical physics has some answers, but this is still a problem.
So the multiverse remains the only possible satisfactory scientific explanation, and it is a very problematic and speculative one. It is favoured by many cosmologists and doubted by others.
Was it God?
Science doesn’t seem to have an explanation apart from the very speculative multiverse, and we still have to explain how the multiverse turned out so special. The apparent “fine-tuned” design of the universe suggests a designer, and that suggests intelligence and purpose. And an intelligent, purposeful creator and designer sounds just like “God”.
So the explanation that God designed it all becomes a very plausible one, discussed in several of the books on cosmology that I have read. Scientists would prefer a scientific explanation, but perhaps we are left with a “personal” or supernatural explanation instead.
Many philosophers and scientists, whether they be theists, atheists or agnostics, regard fine-tuning as the best of all arguments for the existence of God. The logic is simple and the alternative explanations are difficult.
The scientific discovery of the “fine-tuning” of the universe, combined with the difficulty of explaining the reason why any universe exists (discussed in my last post, Why does the universe exist?), combine to make a formidable argument for the existence of a God.
If there was no God, you wouldn’t expect anything to exist (there’d be no reason why it should), and if something did exist for no apparent reason, you wouldn’t expect it to be so well-ordered that it would result in a universe that could support life. The idea that a God created it seems to me to be a much more reasonable explanation than it all happened by chance and for no reason or purpose.
One step at a time
But we shouldn’t go too fast. Even if this is all true and the universe was designed and created by a God, it doesn’t tell us about that God’s character – whether he cares about us, whether we can know the truth about her, or even whether it is personal.
But the scientific fact of the big bang and fine-tuning do give us a reasonable basis for thinking a God quite likely exists and created a universe for some purpose.
On that basis, we can move forward in our investigation of reasons to believe in God (or not) and what he or she is doing.
Photo: Spiral galaxy M51, about 30 million light years away, that is in the process of merging with a smaller galaxy (NASA).