Physics has gotten so arcane that I must struggle to make sense of even popular expositions of its advances, and my understanding always breaks down when someone claims that the notion of time doesn’t mean what I think it does, or could even be illusory. In modern physics, trying to understand things using common-sense notions just doesn’t work. I’m not comfortable in such a realm, which is why I’m happy to have people like Sean Carroll try to explain it to the rest of us.
The latest brouhaha in popular physics is, of course, the question of why there is something rather than nothing—a question that has pushed to the fore with Larry Krauss’s new book, A Universe from Nothing. If you haven’t been in Ulan Bator, you’ll know that that book was handled roughly by David Albert in his New York Times review. Since then, the principals have been sniping at each other, leaving folks like me a bit confused.
Enter physicist Sean Carroll, who gamely tries (and, I think, succeeds) in unravelling the controversy in a post at his website Cosmic Variance: “A universe from nothing?” He thinks that Albert and Krauss are talking at cross purposes: that there are really two sets of questions that are fundamentally different, and each physicist faults the other for not considering his pet question. I’ll post a few excerpts from Sean’s piece, which is not easy reading but will well repay your attention. These are not substitutes for reading his whole post, but will at least outline the debate, and why it’s gone nowhere:
Very roughly, there are two different kinds of questions lurking around the issue of “Why is there something rather than nothing?” One question is, within some framework of physical laws that is flexible enough to allow for the possible existence of either “stuff” or “no stuff” (where “stuff” might include space and time itself), why does the actual manifestation of reality seem to feature all this stuff? The other is, why do we have this particular framework of physical law, or even something called “physical law” at all? Lawrence (again, roughly) addresses the first question, and David cares about the second, and both sides expend a lot of energy insisting that their question is the “right” one rather than just admitting they are different questions. Nothing about modern physics explains why we have these laws rather than some totally different laws, although physicists sometimes talk that way — a mistake they might be able to avoid if they took philosophers more seriously. Then the discussion quickly degrades into name-calling and point-missing, which is unfortunate because these are smart people who agree about 95% of the interesting issues, and the chance for productive engagement diminishes considerably with each installment. . . .
Carroll then explains the two ways Krauss considers how one gets something from nothing: one way sees time as a fundamental property of the universe, the other as an emergent property—indeed, even an illusory one. (Don’t ask an aging biologist to explain how time can be illusory; that’s above my pay grade.)
So modern physics has given us these two ideas, both of which are interesting, and both of which resonate with our informal notion of “coming into existence out of nothing” — one of which is time evolution from empty space (or not-even-space) into a universe bursting with stuff, and the other of which posits time as an approximate notion that comes to an end at some boundary in an abstract space of possibilities.
What, then, do we have to complain about? Well, a bit of contemplation should reveal that this kind of reasoning might, if we grant you a certain definition of “nothing,” explain how the universe could arise from nothing. But it doesn’t, and doesn’t even really try to, explain why there is something rather than nothing — why this particular evolution of the wave function, or why even the apparatus of “wave functions” and “Hamiltonians” is the right way to think about the universe at all. And maybe you don’t care about those questions, and nobody would question your right not to care; but if the subtitle of your book is “Why There Is Something Rather Than Nothing,” you pretty much forfeit the right to claim you don’t care.
And that’s apparently Albert’s criticism: Krauss doesn’t explain why we have laws of physics that permit the creation of something from nothing. According to Sean, we have no idea why the laws of physics are what they are instead of something else.
And sometimes, on the other hand, modern cosmologists talk about different laws of physics in the context of a multiverse, and suggest that we see one set of laws rather than some other set for fundamentally anthropic reasons. But again, that’s just being sloppy.. . . We are still left with the question of there are those deep-down laws that create a multiverse in the first place.
Now having read Carroll over the past few years, I think he’s previously answered that question with the simple end-of-regress statement, “That’s just the way it is.” I may be wrong, but he now seems to consider that we can potentially investigate the question:
We should be good empiricists and be open to the possibility that what we think of as the universe really does exist within some larger context. But then we could presumably re-define that as the universe, and be stuck with the same questions. As long as you admit that there is more than one conceivable way for the universe to be (and I don’t see how one could not), there will always be some end of the line for explanations. I could be wrong about that, but an insistence that “the universe must explain itself” or some such thing seems like a completely unsupportable a priori assumption. (Not that anyone in this particular brouhaha seems to be taking such a stance.)
Sean’s conclusions are two:
1. Krauss’s book is useful at dispelling the theological notion that God is required to create something from nothing:
Lawrence’s book makes a lot more sense when viewed as part of the ongoing atheism vs. theism popular debate, rather than as a careful philosophical investigation into a longstanding problem.
2. Carroll sees Krauss as having screwed up badly when he dismissed philosophy in his post-book statements and interviews. I, too, find all the philosophy-bashing on my site and on Pharyngula (P.Z. also posted about Krauss’s philo-bashing and subsequent not-apology) regrettable and indefensible. Yes, I see some forms of philosophy as unproductive exercises in mental masturbation, but a good dollop of it is interesting and, yes, useful to scientists. Here’s how Sean concludes his piece; I’ve put in bold the part I like, because, of course, I agree with it:
Second, after David’s review came out, Lawrence took the regrettable tack of lashing out at “moronic philosophers” and the discipline as a whole, rather than taking the high road and sticking to a substantive discussion of the issues. In the Atlantic interview especially, he takes numerous potshots that are just kind of silly. Like most scientists, Lawrence doesn’t get a lot out of the philosophy of science. That’s okay; the point of philosophy is not to be “useful” to science, any more than the point of mycology is to be “useful” to fungi. Philosophers of science aren’t trying to do science, they are trying to understand how science works, and how it should work, and to tease out the logic and standards underlying scientific argumentation, and to situate scientific knowledge within a broader epistemological context, and a bunch of other things that can be perfectly interesting without pretending to be science itself. And if you’re not interested, that’s fine. But trying to undermine the legitimacy of the field through a series of wisecracks is kind of lame, and ultimately anti-intellectual — it represents exactly the kind of unwillingness to engage respectfully with careful scholarship in another discipline that we so rightly deplore when people feel that way about science. It’s a shame when smart people who agree about most important things can’t disagree about some other things without throwing around insults. We should strive to be better than that.
At the end of all this, I regret that Carroll didn’t write that book instead of Krauss. Caroll’s own exposition in the piece I’ve highlighted above is, by his own admission, dense and a bit of a brain-stretcher. But I have the feeling that, given the space of a book, Carroll could have explained the issue a lot more clearly than Krauss. Go read Carroll’s piece, and also his earlier essay, “Turtles much of the way down,” where he consider the question, “Why are the laws of physics like they are?”
Modern physics is an Alice-in-Wonderland world to many of us, and I worry that it will reach the point that, like modern mathematics, it’s become impenetrable to the layperson, for it invokes notions that run completely counter to our own experience.
The quote “If you think you understand quantum mechanics, you don’t understand quantum mechanics” is always attributed to Richard Feynman. It turns out that he probably didn’t say that, and it may be a paraphrase of a quote attributed to Niels Bohr: “Anyone who is not shocked by quantum theory has not understood it.” For me, the frustrating part is my inability to be shocked because of my inability to understand. (The two-slit experiment and experiments on Bell’s inequality, do, however, discombobulate me.)