2012-06-23

Rebutting the New York Times Review of "A Universe From Nothing"

I was talking to my family today, and they mentioned that this week, Stephen Colbert interviewed physicist/author Lawrence Krauss on The Colbert Report, where he promoted his new book "A Universe From Nothing". They also talked about how they saw a review of this book on the New York Times that seemed rather critical of it, and they suggested that I read that review.

In fairness, I have not read the book, nor have I (yet) watched the interview on that show. But reading this article made me laugh and cringe simultaneously, and I am going to lay out why. I should also say that the book, which is supposed to explain how quantum field theory lays the groundwork for the universe springing from nothing, is for a popular audience. I would say that among the scientific community, the predictions of relativistic quantum field theory have been accepted for decades. Follow the jump to see what else I think about this.



The first paragraph starts out almost antagonizing Krauss from the get-go. I do agree that the notion [of the universe emerging from nothing] sounds rather weird upon first encounter, and I get the feeling that Richard Dawkins coauthored the book just to put his few words in about how this once again means the end of religion. But there is no reason for that level of snark right at the beginning.

My family mentioned that the author of this book review is a philosophy professor at Columbia University (and that is stated in the byline at the end of the article). The second paragraph immediately gives that information away. Who else would ask what it means to explain something? I'm not saying it's not a valid question to be asking at all, but while I can see how the author's philosophy background would cause him to ask a question like that rather than examining the science presented, I don't know if it's really relevant to a book that is about physics rather than philosophy. (Then again, physics is natural philosophy, and philosophy is sometimes also called metaphysics.) The third paragraph, which follows immediately from the second paragraph, questions from where the laws of quantum mechanics have arisen and criticizes Krauss for failing to adequately answer that.
I suppose I should also criticize Krauss for not answering that question, because the answer is fairly straightforward. Scientific theories do not spring forth from some higher source, unlike religious texts which claim to originate in just that way. The way things are supposed to work is that people make observations about the world, hypothesize what might happen under different conditions, do experiments (or simulations or math), and demonstrate whether said hypothesis may or may not be rejected (because it is never possible to call a hypothesis "true"). Eventually, enough observations and predictions are made that a theory can be assembled that can make much broader predictions over a much wider range of situations. This theory will need to be tweaked through further observation, and may even be scrapped and replaced entirely if proper observations stop matching up with the theory.
So quantum mechanics did not spring forth from some fountain of eternal knowledge. It was assembled by scientists in the late 19th/early 20th centuries who realized that electrons behave very differently from classical particles in that they interfere with themselves, their classical observable properties can be probabilistic, and there is inherent uncertainty in certain pairs of observable properties. Given that the reigning theories of classical physics at that time were the Lagrangian and Hamiltonian formulations of classical mechanics along with classical wave mechanics, wave mechanics and classical optics led to the wavefunction and its properties while Hamiltonian mechanics led to the Schrodinger formulation of quantum observables and operators. This did not happen all at once; the process was quite messy, and in fact some early iterations of quantum mechanics looked much more like classical mechanics and did not really do as good a job at explaining quantum processes. This is just my basic understanding of the history of quantum mechanics, but frankly, I would have thought that Krauss could explain something like that.
And really, the "truth" of any physical law comes from its ability to explain what is out there right now and to make predictions about other systems that we do not have full knowledge about either. So questions about some deeper meaning of the "truth" of quantum mechanics seem fundamentally wrongheaded. There is nothing inherently wavefunctionlike about the electron. It's just that describing the dynamics of an electron by a wavefunction is the most accurate in terms of describing existing phenomena and predicting new phenomena.

The fourth paragraph seems mostly innocuous, although it seems odd that the author should have such an issue with physical laws describing a universe full of stuff. If we accept that we exist and that the universe as we observe it exists, from a physical perspective why shouldn't we do that? Furthermore, it isn't absolutely clear what happened in the very early stages of the universe, and research in that is ongoing. Yet the author uses that fact as a strike against pretty much all physical laws, which is bogus; it's basically the same tactic used by critics of biological evolution, which is that somehow the absence of evidence equates to evidence of absence.
The fifth paragraph is trying hard to sound highbrow in its existentialism, but of the four questions it asks, three of them can be answered by the information we do have from theoretical cosmology about what happened to the universe in its infancy and when its density became perturbed (because the rest is time evolution which is usually deterministic, as far as I have learned), and the remaining one is again one which believes that the very notion of a quantum field itself springs from some higher source. That's not how it works; we describe the universe by quantum field theory not because quantum fields are somehow inherent to the very nature of the universe, but because quantum field theory is our best attempt yet to describe the universe and predict what happened and what will happen. (Here I am using quantum field theory as a synonym for fundamental theories like general relativity as well.)

The sixth and seventh paragraphs tie closely together, and they basically consist of the author petulantly lashing out at the fact that there is no true vacuum anymore in quantum field theory, and quantum field vacuums have nonzero energy and are not stable states. The absence of fields is not a "true quantum vacuum", as the author would like the reader to believe; the absence of fields is a repudiation of quantum field theory itself, because the author simply can't come to terms with what quantum field theory entails. It postulates that quantum fields pervade all of spacetime. Furthermore, some fundamental particles are bosons, meaning that their wavefunctions are symmetrized; this means that they preferentially colocate (even more than distinguishable particles do), so their number is not conserved, meaning they can pop in and out of existence so long as the total energy is conserved. Given those two facts, it isn't hard to imagine how the universe could emerge from a singularity in a quantum vacuum (although the details are much messier, of course).

The last two paragraphs deal with Krauss's skirmishes with theologians. I would agree that given that he wrote a popular book, he doesn't do his material justice by calling the quantum vacuum "nothing". In fact, there are a few different quantum vacuums, including but not limited to the QED vacuum and the QCD vacuum, and the properties of such vacuums are different. Plus, I feel like Krauss could have written a better book by simply presenting the positions of quantum field theory and what they may imply about the origin of the universe without explicitly picking a bone with religious people. But the author appears to have a total misunderstanding of the quantum vacuum; it does not contain protons and neutrons (or tables and chairs), but it instead contains virtual particles, and while I know nothing about them beyond what I can decipher from Wikipedia, it seems like there is a good mathematical distinction between virtual and real particles.
That last paragraph just seems like the ramblings of someone who has forgotten to take their medications. It just didn't seem coherent (no pun intended) at all.

Finally, the byline indicates that David Albert (the author of the book review) has authored a book called "Quantum Mechanics and Experience". I was disappointed to read that because I figured that someone who authored a book about quantum mechanics should know better than to write this. But then I figured that the combination of the terms "quantum mechanics" and "experience" coming from a philosophy professor indicates that this professor has about as much real knowledge of quantum mechanics as Deepak Chopra (which is to say, virtually none at all).

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