Part 10 of my Mapping the Kalam series.
Last time, I finished discussing the philosophical problems with the notion of an infinite past, problems which “are now being recognized in scientific papers by leading cosmologists and philosophers of science.” The example given by Craig is a 2003 paper by Ellis, Kirchner, and Stoeger, who write that:
…a realized past infinity in time is not considered possible [because] it involves an infinite set of completed events or moments.
…The arguments against an infinite past time are strong – it’s simply not constructible in terms of events or instants of time, besides being conceptually indefinite.
Now, we turn to Craig & Sinclair’s scientific arguments in defense of premise 2 of the Kalam Cosmological Argument: “The universe began to exist.”
The Big Picture
Nearly all cosmologists now agree – on the basis of good evidence – that the universe is expanding. They also agree that this expansion began about 13.7 billion years ago, at which time everything in the universe was condensed into a space smaller than a speck of dust.
One interpretation of Big Bang theory is that the spacetime began from a singularity. Craig & Sinclair quote P.C.W. Davies:
If we extrapolate [back into the past], we reach a point where all distances in the universe have shrunk to zero. An initial cosmological singularity therefore forms a past temporal extremity to the universe… For this reason most cosmologists think of the initial singularity as the beginning of the universe. On this view the big bang represents the creation event; the creation not only of all the matter and energy in the universe, but also of spacetime itself.1
But other cosmologists disagree that the evidence suggests a singularity, and Craig & Sinclair survey their arguments and theorems over the course of 50 pages.2 Unfortunately, this discussion is far too technical for non-physicists to judge, much less understand.
The short story is that Craig & Sinclair defend two major works that ‘prove’ an initial singularity: the Penrose-Hawking singularity theorems and also a 2003 paper by Borde, Guth, and Vilenkin. I will save the conversation about what cosmologists think about the force of these works for a later time, except to mention that Hawking has now repudiated his position on the initial singularity, and now spends his time “trying to convince other physicists that there was in fact no singularity at the beginning of the universe.”
Until then, we follow Craig & Sinclair’s logic:
Our survey shows that contemporary cosmology is quite supportive of the second premise of the kalam cosmological argument…
It seems that the field of cosmology, therefore, yields good evidence that the universe began to exist.
This concludes our discussion of Craig & Sinclair’s defense of premise 2 of the Kalam Cosmological Argument:
(2) The universe began to exist.
Next, we consider their defense of the first premise:
(1) Everything that begins to exist has a cause.
- “Spacetime singularities in cosmology” in J.T. Fraser (ed.), The Study of Time III, pages 78-79. [↩]
- The Blackwell Companion to Natural Theology, pages 132-182. [↩]
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