The great physicist Stephen Hawking died yesterday, as I’m sure you know by now. Hawking, and in particular his 1988 book, A Brief History of Time, got me interested in cosmology as a teenager, and while I’m a landlubber in any hard science, the interest has never worn off. I know that Hawking was important to many others for similar reasons.
Hawking’s most important scientific contribution was the idea of Hawking radiation, or radiation that comes from black holes. To landlubbers that sounds crazy—the whole point of the black hole is that it’s black, and nothing comes out of it. But if “things fall apart, the center cannot hold,” or if, as a scientist would put it, the entropy in the world always increases, then the blackness of the black hole is troublesome, because matter, along with the entropy it contains, can be lost to the world when it falls in. Hawking imagined that the entropy wasn’t really lost: the black hole had it. And since anything with entropy has a temperature, and anything with a temperature can radiate its heat, a black hole can radiate! But what about the fearsome gravity that has destroyed so many starships in science fiction novels, and from which not even light is supposed to be able to escape? Hawking reasoned that at the border separating the black hole from the rest of the world, the rules of quantum mechanics tell us that pairs of particles were constantly flickering into and out of existence, and that in some cases one of the pair would be drawn in toward the black hole while the other would escape, the escaping particles being visible to us as radiation. This predicted radiation will keep astronomers and physicists busy for the foreseeable future. Can we observe it? What about its philosophical implications for the conservation of energy in the world? Does it help us understand how gravity, the calling card of the black hole, is to be harmonized with quantum phenomena? Most ideas, like the doomed particles at the threshold of the black hole, live for only a very short time and have no lasting consequences in our world, but some, like Hawking’s, radiate outward.
Hawking was to be admired not just for his results but for his courage in the face of ALS. He showed by his example that physical disability did not have to limit one’s ability to lead a meaningful life or to achieve great things in one’s profession.
Since Hawking was a man of ideas, I’m sure he wouldn’t take it amiss if I criticize one of his ideas. Hawking claimed that the problem of existence could be solved by reference to the laws of physics alone, i.e., without regard to metaphysics let alone (gasp!) theology. This kind of view is pretty common these days, and not just in physics. Biologists and computer scientists make similar claims about the traditional problem of consciousness. As I’ve said, I’m just a landlubber, but it seems to me that if you think that physical laws could explain, even in principle, the problem of existence or the problem of consciousness, then you haven’t understood the problems, or you’ve defined away the problematic aspects as meaningless (because not answerable by science). And you might wonder why landlubbers are to accept the authority of those who have studied and mastered the hard sciences on matters within their expertise when those scientists are not to accept or even take seriously the authority of those who have studied the great metaphysical problems. I do not say “studied and mastered,” since the result of that study is increasing wonder at the mystery rather than provable results.
To everyone in sympathy with this kind of scientism, I recommend a great non-technical polemic by the Orthodox (Christian) theologian, David Bentley Hart, The Experience of God: Being, Consciousness, Bliss (2013). But Hawking had a great mind, which is to say an open mind, and so if contrary to his expectation he finds himself in the afterlife of one religious tradition or another, I think he would give the same excuse that Bertrand Russel said he would give: “O Lord, why did you not provide more evidence?”