Near the beginning of The Beginning of Infinity, David Deutsch writes, “One of the most remarkable things about science is the contrast between the enormous reach and power of our best theories and the precarious, local means by which we create them.” This remarkable thing first struck me when I read a book called The Universe written in 1966 by Isaac Asimov. Before reading this book, I had some vague notion that science had some sort of black box into which light went and out of which came all sorts of information. In Asimov’s book, for the first time, I recognized that every piece of knowledge we have is a prize that had to be won with imagination and hard work.
Lawrence Krauss’s new book A Universe From Nothing takes me down the same path I first traveled with The Universe. Krauss’s book is quite short, but doesn’t shy away from the thing that makes science so different from every other field. In science, it’s not just what you know, it’s how you know it. It’s how you got there, what were your methods, your tools, your approach. Beginning with Einstein’s update of Newton, Krauss takes us through the discovery of the Big Bang, the flatness of space, inflation, dark matter, and the surprising discovery of dark energy. It all hangs together so elegantly, and has the added benefit of serving as a logical sequel to The Universe.
One of the very best parts of the present book is Krauss’s contrast of two predictions. One he calls the best prediction in all of science. The other he calls the worst prediction in all of science. Amazingly, they both have to do with the same idea: virtual particles.
The best prediction is of the affect of virtual particles on a hydrogen atom. A hydrogen atom looks pretty simple; a single electron moving around a single proton. Yet the forces between these two charged particles didn’t come out right until virtual particles, particles that pop in and out of existence all the time between and near the proton and electron, are taken into account. When these affects are included, the answer matches experiment to within one part in a billion. That’s pretty good figuring, and is powerful evidence that scientists are on to something.
And yet, when virtual particles are included in the calculations of empty space, the result is wrong by 120 orders of magnitude, making this the worst prediction in the history of science (the same terrible prediction Leonard Susskind discussed in The Cosmic Landscape.)
Clearly there’s a lot we still don’t understand about virtual particles.
So why is there something rather than nothing? “Nothing”, it seems, is unstable. Given enough time, something like our universe appears inevitable. There’s also a nice discussion of why, when we consider gravitational as well as other forms, the total energy of the universe is in fact always zero. The universe is the ultimate free lunch. It’s just one of those things, like particle-antiparticle pairs, that happens from time to time. Given the levels of uncertainty we still have about the dark energy problem, quantum gravity, and so on, there’s certainly nothing like a proof that the universe emerged from nothing. However, as Krauss points out, just the fact that such an idea is now plausible is quite telling. There’s still lots more to learn, and of course that’s the best part.
One part of the book that I have to disagree with, though, is Krauss’s pessimism about the future, on at least two counts. First, Krauss says that in the far future cosmology will be impossible. All the galaxy clusters will have disappeared beyond the horizon, and even the glow of the cosmic background radiation will be too faint to detect over the light noise of the galaxy. Second, Krauss says that even farther in the future, life itself will become impossible as the universe becomes utterly dilute and void of useful energy.
As David Deutsch points out, this need not be so. Krauss’s vision is one in which knowledge plays no role. But Deutsch recognizes that knowledge is a fundamentally different, and transformative, thing. With the right knowledge, anything is within our grasp. Just as today we are not dependent upon cloudless skies to do astronomy, in the far future we may not be dependent on seeing through the “noise” of our own galaxy. And as we gain even more transformative ability, we may well discover new sources of evidence that today we don’t dream of. Given the history of science so far, it would be surprising were this not to happen.
The far future is also not so gloomy as Krauss suggests. Given enough knowledge, we may even find a way to harness dark energy. As the universe expands, dark energy expands with it, never growing dilute. This could become a truly infinite, inexaustible supply of energy, with which people (undoubtedly very different from the naked apes that first appeared on Earth billions or even trillions of years earlier) could become masters of the entire universe. Krauss doesn’t think such a people-centered universe could come about, or perhaps just doesn’t consider it. But as Deutsch shows us, we could choose to make it happen. It’s up to us.