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09.10.10

The 6 Smartest Ideas From Stephen Hawking's New Book

The world's most famous physicist’s latest book, The Grand Design, has been causing a storm with its views of God, but just what is the book all about? Josh Robinson gives you the book in a nutshell.

The world's most famous physicist’s latest book, The Grand Design, has been causing a storm with its views of God, but just what is the book all about? Joshua Robinson gives you the book in a nutshell.

This isn’t your typical popular science book. It doesn’t explain how black holes work. It doesn’t discuss the conditions for time travel. And there isn’t a single Star Trek reference. The Grand Design, by Stephen Hawking and Leonard Mlodinow, is far more ambitious than that. They propose a framework for discovering the answer to life, the universe, and, well, everything else. And, they promise, the answer is not just 42.

The book’s conclusions are so sweeping and address such fundamental questions of existence that it often borders on philosophy. But Hawking and Mlodinow, who have more than half a century of experience between them and several bestsellers between them, see no problem with dabbling beyond the realm of traditional physics. “Philosophy is dead,” they assert. “Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge.”

It’s a bold claim. Appearing as it does on page 5, it can also be an intimidating one if you’ve just picked up the book. So here is The Daily Beast’s executive summary of six of the book’s biggest ideas. It won’t be enough for you to stroll into your nearest graduate-level cosmology class and ace the midterm. But it should help you navigate a conversation at a cocktail party.

What We See is Real. Unless It’s Not.

Physicists have all sorts of tools for describing the universe around us. Some are neat and elegant, like Einstein’s theories of relativity (which come in special and general flavors). Others are more ugly and unwieldy, like the Standard Model. And all of them purport to explain reality when in fact we have no idea what is objectively real.

The way the problem is often summed up in popular culture is, “What if we were just the playthings of some all-powerful being?” or “Could we all be the stars of an alien reality show?” The answer is: Maybe. But physicists have come to terms with this problem. Hawking and Mlodinow’s conclusion is, “There is no picture- or theory-independent concept of reality.” All we can use is model-dependent realism. We come up with mathematical models to explain observations with a set of narrowly defined rules. And that’s the best we can ever do.

“It is not necessary,” Hawking and Mlodinow write, “to invoke God to light the blue touch paper and set the universe going.”

A Brief History of Quantum Physics…

Hawking and Mlodinow don’t deliver anything new on this front, but there are a few baffling elements of quantum physics worth knowing. Quantum theory explains the interactions of the universe’s fundamental particles. And when things get that minute, mind-boggling things happen. One crucial tenet is that light behaves simultaneously as a particle and as a wave—which is always a neat fact to toss out there.

But perhaps more relevant to this discussion is the importance of the Heisenberg uncertainty principle, which states that we cannot accurately know both the position and velocity of a particle. From there, some very smart people, like Richard Feynman, deduced what is known as the sum over histories. (Brace yourself for this one, it defies all intuition.) It means that when a particle travels from point A to point B, it doesn’t simply take the path of a straight line. It takes— every possible path simultaneously. Only once it is measured does it appear to have taken the straight-line path. The wider implication of this is that the universe has no definite past. This is a vital point in any multiple universe, or multiverse, model.

Amazingly enough, it has widely stood up to experimental testing.

… And Why It Doesn’t Always Work With Classical Physics

What 20th-century quantum physicists found is that in the world of the infinitesimally small, classical Newtonian physics breaks down and quantum theory takes over. A troubling discovery. Even Einstein could not wrap his head around the possibility that so much of the universe’s fundamental interactions were left to chance, famously stating that “God does not play dice.” In wider philosophical terms, the claim that objects do not have single definite histories flies in the face of scientific determinism—the idea that a single set of laws should be able to explain past events and predict future physical behavior to a great degree of accuracy.

That conflict shaped the direction of physics for much of the 20th century and into the 21st. The science’s Holy Grail became a grand unified theory of everything, which brings together all four fundamental forces (gravity, the electromagnetic force, the strong nuclear force, and the weak nuclear force).

Dial M for M-Theory

The most compelling model we have to unify the various conflicting, and often inelegant, frameworks for understanding the universe is known as M-Theory. It isn’t quite the single, beautifully economical theory that Einstein spent his latter days vainly searching for. It is more like “a whole family of different theories, each of which is a good description of observations only in some range of physical situations.” In that way, it incorporates both classical physics and quantum theory to explain the most general range of phenomena yet.

Most importantly, it explains that at the moment of creation (whatever form it took), a huge number of universes were created simultaneously and spontaneously, all arising from physical law. The number of universes could be on the order of 10 500—that’s 1 with 500 zeroes after it. And all of them have many possible histories. Only a few, however, present the rare combination of factors required for intelligent life to exist. As Hawking and Mlodinow describe it, M-Theory is “a model of a universe that creates itself.” In fact, they argue, it is “the only candidate for a complete theory of the universe.”

It all makes missing the bus this morning seem pretty insignificant.

Anthropic Principle 101

With so much randomness in the universe, it seems like a miracle that we could be at all. Unimaginable numbers of conditions over billions of years had to develop just so for humans to be here, asking the universe’s biggest questions.

This observation has led to one of the most divisive points in modern physics: the anthropic principle. The strong anthropic principle suggests, according to Hawking and Mlodinow, “that the fact that we exist imposes constraints not just on our environment but on the possible form and content of the laws of nature themselves.” In other words, our very existence is proof that the laws of nature must behave in an extremely narrowly tailored way, which must allow for the development of intelligent life. It almost seems like an argument in favor of a creator. But while Hawking and Mlodinow argue in favor of the anthropic principle, they leave out any implication of an almighty designer.

So Where Does That Leave God?

Bad news for pretty much every organized religion. The door that so many physicists from Newton, to Kepler, and even Hawking himself (in A Brief History of Time) had left open for the big guy upstairs is shut, according to The Grand Design. Hawking and Mlodinow even rule out the necessity for God as a grand watchmaker, an all-powerful being who created the universe and then left it to tick away on its own, which had been the preferred interpretation of many classical physicists and philosophers. As they explain, the complex consequences of gravity mean that there is enough negative energy in the universe to cancel out the positive energy that comes with the spontaneous formation of new matter without disrupting the overall equilibrium. The technical physics behind this are only within the grasp of a handful of people in the world, but there is a powerful upshot to their conclusions. “It is not necessary,” Hawking and Mlodinow write, “to invoke God to light the blue touch paper and set the universe going.”

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Joshua Robinson is a freelance writer based in Manhattan. His work has appeared in The New York Times, The Wall Street Journal, The Washington Post, and Sports Illustrated.