Whenever matter and antimatter mingle, they quickly annihilate in a burst of gamma rays.... So that presents a puzzle: how did the big bang make 1050 tons of matter without also making 1050 tons of antimatter?.... however it is done, the story of the origin of matter would go something like this. The heat radiation released after the big bang created copious quantities of both matter and antimatter, all mixed together, but containing a slight excess of matter. As the universe cooled, the antimatter would be totally destroyed by virtue of its being in intimate contact with matter, leaving unscathed the small residue of excess matter--about one part in a billion. (p. 105)The coincidence of my coming upon this book just a few weeks after I wrote my post about pantheism, which covers similar ground, wasn't lost on me. Both deal with the question of why the dead universe around us seems uniquely suited for life. To rephrase the old conundrum, how come anyone's around to hear the tree make a sound?
Physicists over the past few decades have discovered that many of the physical laws of the universe seem "just right" for the development of life. If the numbers had been slightly lower, or slightly higher, life as we know it could not have come to exist. I will mention just a few examples, because the topic is vast and has been covered thoroughly in numerous books:
1. If the neutron were slightly lighter, the proton would be unstable and atoms probably could not have formed. If it were slightly heavier, nuclear fusion would not be possible and stars could not have formed.
2. If gravity were slightly stronger, all stars would be giants with relatively brief lives. If it were slightly weaker, heavy elements necessary for planet formation would not have been produced.
3. If the nuclear resonance level of carbon were any different, our sun could not have produced high quantities of the element.
One must exercise caution when examining these apparent facts. Perhaps a very different sort of life, or lifelike phenomenon, would have emerged under other conditions. Perhaps we aren't exercising our imaginations enough. But examples like these have piled up, and so far they haven't gone away.
Like me, Davies isn't satisfied with the standard copout, "That's just the way the laws are, and if they weren't that way, we wouldn't be here to discuss it." To illustrate the flaw in this argument, he takes off from an idea in Carl Sagan's novel Contact. The number pi consists of decimal digits going on into infinity. The digits are completely arbitrary except for the fact that the number is derived from nature. Let's say you created a computer program displaying the number in binary, where a light pixel would represent one, and a dark pixel zero. Most likely, the screen would be flooded with meaningless "snow." You wouldn't expect to see a coherent image, such as a circle, much less a smiley face. But what if one did appear after just two minutes? Assuming the program wasn't rigged, the only conclusion most scientists would permit would be that it's just a freakish coincidence.
Davies explores several possible solutions to this dilemma. (I will deal with only a few of them here.) The most popular is the hypothesis of multiple universes. In an infinity of universes, some are bound to produce life. Those that don't will obviously go unnoticed. We're here simply because our universe is one that happened to have the right set of laws needed for our existence.
The multiverse hypothesis isn't purely ad hoc; it seems to follow from certain versions of the Big Bang theory, as well as from certain versions of quantum mechanics. But there are major problems with the hypothesis, as Davies explains. For starters, it is borderline untestable. It also seems to violate Occam's razor, the principle that theories should be as simple as possible. And it leaves unanswered the question of where the universe-generating mechanism came from.
One bizarre twist on this hypothesis bears mentioning. Davies quotes Oxford philosopher Nick Bostrom as saying, "There is a significant probability that you are living in [a] computer simulation. I mean this literally: if the simulation hypothesis is true, you exist in a virtual reality simulated in a computer built by some advanced civilisation. Your brain, too, is merely a part of that simulation."
That's just a modern variation on an age-old philosophical idea, but Bostrom makes a case for it based on the multiverse hypothesis. See if you can follow this. If countless universes exist, there are likely to be ones containing civilizations that have reached the point of creating simulated universes. Any civilization with that capacity is likely to exercise it numerous times. Therefore, there are likely to be more fake universes than real ones, and so, by the laws of probability, we are more likely to inhabit one of the fakes.
Davies has fun with this idea. If we're in a simulation, who is to say we aren't in a simulation-within-a-simulation? "Logically there is no end to this nested sequence.... The real universe could be lost amid an infinite regress of nested fakes. Or it may not even exist at all. Reality might consist of an infinite sequence of simulations, period" (p. 185).
As the saying goes, that way lies madness. Bostrom's argument has many holes, but the most basic is that the conclusion undermines the premises. If we live in a fake universe, how do we know the physical laws we have discovered--on which the multiverse hypothesis rests--accurately describe the reality outside the simulation?
Davies, in any case, prefers a one-universe model, but he still suspects that the seemingly life-friendly laws cannot be due to chance. He proposes that there must be something leading our universe in the direction of producing conscious, thinking beings like ourselves. What that something is, he leaves open, but he puts forward a series of related theories that he maintains are compatible with modern physics.
While I'm not sure I understood all the details, his basic idea is that conscious life itself, in the far future, somehow influences the early universe to produce life in the first place. The laws create life, and life creates the laws, in a sort of circular time-loop with no ultimate origin. I couldn't help thinking of the following Escher drawing:
Davies contrasts this idea with the classic grandfather paradox, where a time traveler kills an ancestor. He says it is more like a time traveler saving the life of a girl who will one day become the time traveler's mother. Davies insists that this scenario, while strange, does not create a paradox.
Actually, the scenario is called an "ontological paradox." One notable example I discussed on this blog is from the movie Somewhere in Time. A man receives an antique watch from an old lady. He later goes back in time and gives it to a young woman, who will become the old lady who gives it to his younger self--and so on, ad infinitum. The paradox is that the watch was never built by anyone, at any time. It just eternally exists, fully formed. Since Davies is as bothered as I am by the question of why anything exists, I would think he'd stay far away from such scenarios, which only compound the question.
Considering the difficulties with all these theories, why not accept the traditional idea of a creator God? Davies thinks this answer presents at least as many difficulties as the others. For one thing, did God choose to create the universe, or was it a necessary act that flowed from His very nature? Either possibility leads to additional questions. Also notice the problem with describing creation as an event in time--God exists outside of time, at least according to traditional religions.
I think that such questions miss the point. God by definition is where rational inquiry ends. To believers, the purpose of belief is to transcend the rational in order to connect with the unfathomable. The usual response by scientists is that God, then, should remain forever outside of scientific discussions. To some extent, I agree. But when scientists are reduced to positing fake worlds within fake worlds, or self-created entities from an unexplainable time-loop, we are justified in wondering if the end has already been reached.
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