07 June 2013

Randal Rauser on reading Stephen Hawking

Randal Rauser recently invited me to do part of a series he did which he called Why they don't believe, in which he's invited various heathens like myself to offer a brief overview of why we're not believers. You can read my entry at Randal's blog here.

Randal was kind enough to offer a reply, and although I responded briefly in the comments on the post itself, I wanted to explore some of the other topics he touched upon – in this case, his response to the influence that A Brief History of Time had on my deconversion (from agnostic theist to atheist; my deconversion from Christianity was some nine years prior).

A quick recap: there's a chapter in ABHoT called "The Origin and Fate of the Universe". Prior to my budding interest in cosmology, I'd held firmly to various cosmological arguments for the existence of God. There had to be a Creator, I reasoned, to bring such a marvelous, complex, and ordered universe into existence. It couldn't just come from "nothing", or "chance". It was my belief that the laws of physics as we knew it simply came to an impasse at the beginning of the universe, and there was no plausible way of explaining the mere existence of the universe without a deity.

In a nutshell, Hawking pulled the rug out from that assumption. He proposed a way, wholly embracing and consistent with all the known laws of physics, for the universe to simply be. It wouldn't come from anything (or 'nothing'), it wouldn't have a beginning or an end. It's speculative, of course, and Hawking doesn't shy away from that. However, his theory has at least made one falsifiable prediction (regarding the anisotropy of the cosmic microwave background), and that's one more piece of scientific evidence than exists for any 'god hypothesis'.

So, what does Randal think of all that?
I first bought A Brief History of Time back in 1988. I think I read half a chapter. I returned to the book in 1996 at which point I read the entire book. When I did finally read it I found a brilliant scientist offering a speculative theory to a general audience. Remember how I observed a moment ago that scientific theories are always changing. Given that fact you might think that scientifically literate folks might be chastened in granting assent to particular speculative proposals. (And the Hawking-Hartle attempt to remove the singularity is certainly speculative with its application of the concept of imaginary time.) So it was surprising to see how widely and enthusiastically Hawking’s book was received (straight on down to Carl Sagan’s adulatory foreword). But then maybe it wasn’t that surprising. After all, many people desperately wanted Hawking to be right because they didn’t want a singularity or any perceived need for a creator. Hence, Hawking’s less than subtle suggestion that should his theory be true, we’d no longer need an agent cause to kick things off. “What place, then, for a creator?” Hawking asked.
I’m not commenting on Mike D at this point, mind you, but rather on the general reception Hawking’s book and its highly speculative proposal received. The way that Hawking’s speculative model was received reflects motivated reasoning at its baldest. And yet the irony is that Hawking’s book doesn’t eliminate the metaphysical problems at all, for the book doesn’t even discuss the supporting reasoning for Thomistic and Leibnizean cosmological arguments.

Randal seems to take some comfort in the fact that this is basically speculative physics. It doesn't totally rule out a role for God simply because it's just a proposal, not a formal working theory. And one theistic physicist posited that even if Hawking is right, you'd need God to "sustain the laws of nature". Whatever that means.

But I think Randal is missing the forest for the trees. The power in Hawking's idea isn't that he's disproved some particular theology, but that he's shown that we have more options than believers are usually comfortable admitting that we have. It may be true that the universe requires an external cause in the form of a deity to bring it into existence; but as we best understand it, there's no logical or scientific reason to make that assumption. It's entirely plausible that the universe can simply be. For someone with a commitment to theism, this obviously won't cut it since it doesn't actually disprove God (as though that could ever happen). But it shows that theists aren't justified in assuming that the explanation for the universe must be God. I think that's a pretty powerful idea because it shows that the old all-purpose atheist defeater "If there's no God, where did the universe come from?" is full of hot air. The truth is that we simply don't know.

But there's another comment Randal makes that doesn't sit right with me, namely this:
After all, many people desperately wanted Hawking to be right because they didn’t want a singularity or any perceived need for a creator.
Uh... no.

What we often call the "cosmic singularity" (its description in General Relativity) is what physicists refer to as the "boundary condition". It's generally accepted that GR, since it can't describe gravity at the quantum scale, is an incomplete theory – as Hawking says in The Grand Design:
"Although one can think of the big bang picture as a valid description of early times, it is wrong to take the big bang literally, that is, to think of Einstein’s theory [general relativity] as providing a true picture of the origin of the universe. That is because general relativity predicts there to be a point in time at which the temperature, density, and curvature of the universe are all infinite, a situation mathematicians call a singularity. To a physicist this means that Einstein’s theory breaks down at that point and therefore cannot be used to predict how the universe began, only how it evolved afterward.” [p.128]
Since we don't yet have a quantum theory of gravity, we're not really sure what the boundary condition actually is. According to Alan Guth, Arvind Borde and Alexander Vilenkin, it's a "closed spacelike hypersurface". Y'know, one of those. Hawking's idea is a bit different – that the boundary condition is that there is no boundary.

It's also more than a little ridiculous to suggest that anyone wants to get rid of the singularity because it would seem to get rid of a need for a creator. The singularity is and always has been little more than an artifact of GR, which simply doesn't work at quantum scales. We know it's wrong – or rather, incomplete. Attempts to resolve some of these issues have given rise to all sorts of interesting ideas, most notably String Theory. These boundary-condition proposals arise as either attempts to explain observable features of the universe, or as implications of the mathematics of other theories (as in Guth/Borde/Vilenkin's "hypersurface" idea, which arose as a consequence from inflationary theory).

Lastly, I think Randal stumbles here, too:
And yet the irony is that Hawking’s book doesn’t eliminate the metaphysical problems at all, for the book doesn’t even discuss the supporting reasoning for Thomistic and Leibnizean cosmological arguments.
I think it makes both those arguments irrelevant. They both begin with  the assumption that the universe is "contingent". Yeesh... talk about assuming the consequent. Hawking's proposal shows that the universe itself can exist, to borrow the philosophy-speak, "necessarily".

I've always found this to be a subject on which the theist seems to be in a much thornier, and frankly more arrogant position than the non-believer. The theist has to make the assumption that the universe cannot be described by the laws of mathematics a la Hawking or Guth et al. In other words, the thiest has to assume the universe is contingent, even though there are no scientific or logical grounds to do so. As an atheist, I'm not committed to any particular idea – I can remain agnostic about the origin of the universe, which frankly is the only intellectually honest position one can take. And yes, this will come as a shock to theists everywhere who don't actually know what atheism is, but I don't even have to assume that the explanation for the universe couldn't be some sort of God. Maybe it is. But until the evidence is there, I'm content to live with my non-belief.

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