Friday, June 19, 2020

Book Review: Brief Answers to the Big Questions

From Brief Answers to the Big Questions, by Stephen Hawking:

Open quoteThe obvious next step would be to combine general relativity—the theory of the very large—with quantum theory—the theory of the very small. In particular, I wondered, can one have atoms in which the nucleus is a tiny primordial black hole." Brief Answers to the Big Questions

Don't have time to learn quantum mechanics? Read this instead. It's short. Accessible. Still deep. Stephen Hawking talks about the beginning and end of the universe, life, artificial intelligence, time travel, space colonization, and more. A-

Grade: A-

This is Stephen Hawking's last book, one he worked on the last year of his life. This is a popular science book, very accessible to anyone with a high school understanding of science. No equations. No specialized vocabulary. It's arranged in chapters, each devoted to a very big question. Hawking provides answers to the questions that science has figured out. He admits ignorance to the questions science hasn't figured out (yet). He speculates on how he thinks things will turn out.

He praises Einstein for his imaginative thought experiments. He proves he shares that gift in that excerpt above in which he imagines a tiny black hole in the nucleus of an atom. Some of Stephen Hawking's greatest scientific contributions started by imagining how black holes behave.

I've long known that asking what came *before* the Big Bang was like asking what is *south* of the South Pole. It's a nonsensical question. You can't have a *before* without having time. And time, and space itself, came into existence with the Big Bang. But Hawking extends the concept into our universe today. "Inside the black hole time itself doesn't exist. And that's exactly what happened at the start of the universe."

People still can't let go of the feeling that the universe (without a Creator) had to come from something. Hawking denies this premise. He insists, "The universe is the ultimate free lunch." And it's still going on today, in quantum fluctuations that create matter-antimatter pairs to in the so-called vacuum of space, which we now understand is not so empty after all. Something from nothing. When those matter and antimatter particles subsequently collide, they annihilate each other, leaving nothing behind.

Hawking applies the same principle to the Big Bang. "When the Big Bang produced a massive amount of positive energy, it simultaneously produced the same amount of negative energy. In this way, the positive and the negative add up to zero, always...the universe itself, in all its mind-boggling vastness and complexity, could simply have popped into existence without violating the known laws of nature."

Hawking admits what we still don't know have it all explained. "In order to understand the origin of the universe, one therefore has to incorporate the Uncertainty Principle into Einstein’s general theory of relativity. This has been the great challenge in theoretical physics for at least the last thirty years. We haven't solved it yet, but we have made a lot of progress."

Hawking doesn't confine himself to just physics. He also looks at evolution and contrasts its slow pace with the accelerating pace of technological evolution. He speculates on how long it will be before artificial intelligence exceeds human intelligence and what will happen then. Will humans survive our own invention? Hawking lays out some possibilities, most of them scary.

"World militaries are considering starting an arms race in autonomous weapon systems that can choose and eliminate their own targets." Remember stock market crashes caused by out-of-control autonomous trading programs? Stock exchanges have had to insert circuit breakers to stop the trading programs. What happens when autonomous weapons systems escalate too quickly for humans to control? Imagine what the equivalent of a stock market crash is in this instance. And eventually it won't just be world militaries. Is it more likely that the American love of guns would lead to an end of gun violence or an out-of-control escalation when AI starts making it down to weapons you can buy in your neighborhood gun store?

Hawking is known as an optimist, but he admits, "The Earth is under threat from so many areas that it is difficult for me to be positive. The threats are too big and too numerous." Perhaps his optimism lies in a recognition that the survival of the human species depends in the end on escaping Earth. He explores our options in the way of candidate Earth-like planets surrounding nearby stars and candidate technologies to reach those stars in reasonable amounts of time. He describes a proof-of-concept project to use miniaturised spacecraft, light propulsion and phase-locked lasers to accelerate a tiny spacecraft to 20% of the speed of light, allowing it to reach Alpha Centauri in as little as 20 years, instead of the tens of thousands of years it would take a spacecraft using conventional propulsion systems. Before Hawking's optimism infects you, note that he admits this tiny proof-of-concept spacecraft won't have brakes.

He closes the book with questions that don't have answers (yet). "The huge questions of existence still remain unanswered—how did life begin on Earth? What is consciousness? Is there anyone out there or are we alone in the universe? These are questions for the next generation to work on." Hawking's thoughts on what the answers might look like are worth reading. All of Hawking's brief answers to the big questions are worth reading.

"Brief Answers to the Big Questions" is available in hardcover and eBook formats from the Richardson Public Library.

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