This site is not maintained. Click here for the new website of Richard Dawkins.

Comment

← The Kalam Cosmological Argument

Oystein Elgaroy's Avatar Jump to comment 206 by Oystein Elgaroy

I apologize for the length of this post, particularly since I probably repeat some of the points already made by others.

I want to start with premise 2: The universe began to exist. The empirical basis for saying this is not as strong as one would like in a convincing argument for the existence of god. All cosmologists can assert with some confidence is that the universe we observe around us today has expanded from a hotter, denser state some 14 billion years ago. You can extrapolate the model further back and hit the infamous singularity, but we have every reason to think that the model breaks down at very early times because we don’t understand quantum gravity.

Inflation, the idea that the universe underwent an early phase of accelerated expansion has become a standard add-on to the Big Bang model, and is not without empirical support. One intriguing aspect is that it is possible to build models of so-called eternal inflation, where bubbles of expanding spacetime branch off from an exponentially expanding background. This is one variant of the multiverse idea, and it was long thought that the background spacetime had no beginning in time, or more precisely geodsically complete: all particle paths can be extended arbitrarily far back. In the context of classical (non-quantum) general relativity, Penrose and Hawking proved that non-inflating spacetimes are geodesically incomplete, and a few years ago Borde, Guth and Vilenkin proved that the same is the case for most inflating spacetimes as well. WLC loves to quote this result, but it should be noted that there are loopholes: Sean Carroll has constructed a model that evades the theorem, see his “From eternity to here” for a popularized description. Also, the theorem works for classical spacetimes. What a quantum gravity theory will have to say about this issue, nobody knows.

This is where I should point out that WLC’s argument needs talk of a moment when the universe began to exist to be meaningful. But this is a view that does not fit well with relativity. Space and time do not exist as separate entities. There is a spacetime manifold, and like a loaf of bread it can be sliced in different ways yielding different views of the history of the universe. When we say (loosely) that the universe is 14 billion years old, this is the age measured on clocks that are carried along with the expansion. Since we are approximately so-called commoving observers, this is the natural time coordinate to use. But there is no unique choice, and it is possible to find coordinates where the expansion started in the infinite past. WLC has some idiosyncratic views on relativity, and if you want to learn more about them you can check out his “Time and the metaphysics of relativity”. Based on his discussion of the twin paradox I would say that he doesn’t understand relativity very well.

His philosophical arguments for why the past cannot be infinite also rely on his idea that there can be, in spite of relativity, an absolute time (“metaphysical time”). Given that, he argues that the notion of an infinite series of past events is absurd, since actual infinities cannot exist. Some of these arguments fail because he confuses time without beginning with a beginning in the infinite past, some because of misleading anologies (libraries with an infinite number of books). Both Wes Morriston and Quentin Smith have dealt with these arguments in some details, just Google them and you will find papers to download and read.

To sum up: Premise 2 is not in good shape.

I don’t know what to make of premise 1. Have I ever seen anything “begin to exist”? I don’t think so. I have seen one kind of stuff turning into another kind of stuff. And whenever I have found a cause for the transformation, it has been a spatiotemporal one. So the form of premise 1 I would be prepared to support, leaving quantum mechanical issues aside, would be “Transformations of one kind of stuff into another kind of stuff have physical causes”. One should also bear in mind that quantum mechanics seems to say that in many cases, there are limits to how deep the explanations can go. If I have a bunch of radioactive nuclei, I can predict that within a given time 50 percent of them, say, will decay. But I cannot predict which ones will and which won’t. If I ask why one particular nucleus happened to decay, all quantum mechanics allows me to say is that there was a 50 percent chance that it would, a 50 percent chance that it wouldn’t. That’s where the explanation stops.

To sum up again: the only form of premise 1 we have any reason to endorse does not support the conclusion of the argument.

Some other thoughts: If we insist that there has to be an explanation for the existence of the universe, which I am inclined to doubt that we can find, why should it involve a personal being? There is a principle in physics which says that any process that is not forbidden by a symmetry (i.e., a conservation law) will occur. It has a lot of empirical support. And there is no conservation law that forbids universes to pop into existence. In fact, this is one reason for thinking that a multiverse is more likely than just a single universe. The universe has zero charge, no angular momentum, and, crucially, conservation of energy is not a problem because there is no law of energy conservation in general relativity. Universes can appear out of the quantum vacuum without violating energy conservation because there is no energy to be conserved.

Even if the Kalam argument were successful, one could argue that it would also show that the god of the Bible does not exist. The creator that fits the bill in the Kalam is a very different entity from Yahwe. The latter may be good at “Smite the Amalekite”, but if he claims to be the creator of the universe, the Kalam argument exposes him as a liar.

Tue, 31 Aug 2010 20:39:47 UTC | #508822