When the deepest and most powerful thinker of the Twentieth Century, Stephen Hawking, passed away just one year ago, I was saddened, but grateful that he had lived as long as he did. He, who endured the great curse of a terrible disease, was very lucky to have achieved a certain stature by the time he became so severely disabled. Having a body that others must tend to, because he could not, he was free to live a life of the mind, which he certainly did, and yet he was always a persistent and preternaturally clear communicator, with a love of both teaching and dialogue.
He was working on a last book when he died. With a little tidying up by good friends and editors, it was released a few months later. So this past week Brief Answers to the Big Questions worked its way to the top of my reading stack. What a joy to spend a few days in the presence of such a clear-headed thinker!
After a foreword by Eddie Redmayne, who portrayed Hawking in The Theory of Everything, and an introduction by Hawking's good friend Kip Thorne, ten big, big questions are addressed. Naturally, "Is there a God?" comes first. He was asked that question frequently, sometimes to an irritating extent. I won't dig into his answer, but mention two things that impressed me. I'd had the idea in recent years that he was trying to disprove God's existence. He explains that, for science to be theory of nature, it must confine its explanations to natural effects and forces. If it is possible to develop a theory that fully explains the origin of the universe, then that is a complete natural theory. He does not express hostility toward God. Secondly, he mentions Laplace, who replied to Napoleon's question about the "author of the universe" by saying, "Sire, I have no need of that hypothesis", and he explains that, while we often take that for an anti-God statement, it was, rather, Laplace's way of saying that supernatural causes did not need to be added to his useful scientific methods, for they were sufficient. I'll mention just a few things I found interesting in other chapters; it would be presumptive to try to riff upon them all.
In "What is inside a black hole?" he tells us of the deep connection between the theory of black holes and that of the Big Bang, because both involve a singularity, that is, a location in space-time where our theories cannot probe, because phenomena such as density and the dilation of the flow of time reach infinite values…perhaps. To solve one would be to solve the other.
He discusses, "Will artificial intelligence outsmart us?" he comes at the answer from a few angles, without digging much into how soon such a thing might eventuate. It is clear that the techniques called "artificial intelligence" today, while quite capable and useful, are various expressions of massive data manipulation to winkle out the answers to questions that are posed. He mentions Moore's Law, which has been bent entirely out of shape, compared to how Dr. Moore posed it: that the density of transistors that could be fitted onto a unit area of silicon seemed to be doubling every 18 months. We know that law must come to an end because there are atoms, whose very name "a-tomos" is Greek for "can't be cut". Since a transistor has to have a few layers to operate, and each layer has to have at least a few atoms, the limit to Moore's Law, as stated, will be reached before the size of a transistor has shrunk to perhaps 20 atoms. That will still take a while, as today's CPU transistors still have millions of atoms. But other effects seem to be limiting things; it appears that the Law stalled out about ten years ago. Hawking does not go into certain issues that might be necessary for a machine intelligence to become "more like a human", before becoming "more than human", such as whether intelligence has to be embodied, not just because it is running on a physical substrate of some kind, but because it gets sensory input from thousands or millions of sensors, the way our brains receive input from the tens of millions of sensors of many kinds in our own bodies.
Here and there are side questions and very short answers. I was tickled by one in the "AI" chapter:
Q: Why are we so worried about artificial intelligence? Surely humans are always able to pull the plug?His view is similar to mine, that such an event is far in the future, though he perhaps thought it to be "far" in the sense of a few decades, while I tend to believe it is more like centuries.
A: People asked a computer, "Is there a God" And the computer said, "There is now," and fused the plug.
His answer to another side question surprised me, and made me wonder if he blundered. Asked what is the biggest threat to the future of Earth, he dwelt on global warming, because it is more immediate than the threat of asteroid impact. He warns that it could lead to Earth getting a "climate like that of Venus with a temperature of 250°C (482°F)." The temperature of the near-surface environment on Venus is about 460°C (over 860°F). If Venus were moved to Earth's orbit, the difference in sunlight intensity would allow it to "cool off" to 350°C (~660°F). Apparently, the differences in the possible carbon dioxide composition of our atmosphere would reduce the effect by another 100°C. Maybe. By my own calculations, raising carbon dioxide from the current 400 ppm to Eocene levels of around 2,000 ppm would result in temperatures like that of the Eocene thermal maximum, about 8°C warmer than now. The secular increase in the sun's brightness since the Eocene, 55 million years ago, was less than 0.4%. I think that Hawking relied on material about global warming that I consider to be little better than propaganda.
On a more positive note, he believed we must colonize other places in space, first the "nearby" planets and their satellites in our own solar system, and eventually those of other stars. He does not believe that science will become a kind of static thing, as portrayed in Star Trek. Scientific progress shows no signs of slowing down, though it is evident that the "low hanging fruit" seems to have all been picked, and the "gentleman scientist" of the Enlightenment period is necessarily being replaced by ever-larger consortia of scientists working together.
By his own example, a heady mix of individual effort on his part, and intense collaboration with others such as Kip Thorne, Dr. Hawking showed a way for science to continue far into the future. And he urges us to re-emphasize the need for science education and popularization. Wouldn't it be something if the science lectures of the Enlightenment period could be resumed, and achieve similar levels of popular success? Scientists such as Humphrey Davy and Michael Faraday were like rock stars in their generation, largely because of popular lecture tours. We need more rock star scientists!
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