all images: Ethan Hein
Congratulations all around this week to Yoichiro Nambu, Makoto Kobayashi and Toshihide Maskawa, who share in the Nobel Prize for their paradigm-shattering work into such foundational issues as QCD, strings, and the question of why anything exists.
That last one is a blunt way of describing the way theoretical physics comes at the mysterious imbalance between matter and antimatter in our universe, and while it isn't technically ontology these folks are debating, it's pretty close. After all, without the famous "spontaneous symmetry breaking" that occurred just after the Bang, there wouldn't be much of anything in existence: a haze of radiation and a whole lot of empty space. That's not the existentialist's "nothing," to be sure, but it's still not much in the way of a universe. This is where modern science dovetails into philosophy, and it couldn't be more interesting.
It's also fair to say that without Yochiru Nambu's efforts we would not have the Standard Model, and one could make the case that he is therefore the most successful living instance of a scientist who has asked, and answered, truly Foundational Questions. (Votes for other, more Foundational scientists are welcome.) A tip of the quark to you, Professor Nambu.
Incidentally, how will you react on the day you are awarded the Nobel? My favorite response came from the laconic Toshihide Maskawa, who is reported to have told reporters, "I myself am not that happy." That's dour, but still more tactful than Doris Lessing's now-famous brush off when she was told she had won the Nobel Prize in Literature: "Oh Christ, I couldn't care less."
On the subject of why matter exists, it's odd how frequently the popular press, in reporting on Nambu's Nobel, chose to mention the fact that the one-in-a-billion imbalance of matter over antimatter was necessary for the emergence of life. This is of course true, but hey, it's necessary for pretty much everything else as well, unless you happen to be a photon. Life, that quirky combination of replicating chemical structures that eventually led to Doris Lessing, only happened billions of years later . . . so why bring it up? The implicit suggestion may be that this is more evidence in support of the (untenable, in my view) "fine tuning" argument, and that baryon asymmetry carries some sort of metaphysical implication.
Of course, it may also simply be that our species only thinks in terms of itself. But symmetry breaking isn't really related to the anthropic question in any compelling fashion I can see, except, I suppose, in the most hugely overall kind of way. If the particle / antiparticle ratio had been exactly one to one, there also wouldn't have been any magnetars, or liquid nitrogen volcanoes, or active galactic nuclei, or bunny rabbits, or . . . you name it. Pick anything physical and it will be on the list of stuff that only exists thanks to that mysterious asymmetry. Is that a big deal?
To think about this another way, what would have happened had the baryon asymmetry broken the other direction?
Answer: this.
Meaning: We might well still be sitting here having this blog-based conversation. We would, of course, be antimatter creatures living in an antimatter universe, though we would call the stuff around us "matter" -- as indeed we do. There would still be a CMBR, the last shimmering remnant of the ancient baryogenesis battle in which antimatter came out on top and all matter was annihilated. Cosmic rays from anti-supernovae colliding with our anti-atmosphere would spit out bits of actual matter, short-lived protons and alpha particles and whatnot. Every particle created from energetic collisions at anti-CERN (we might call it ACERN), in the anti-LHC, would be accompanied by this backwards seeming stuff that would vanish in a flash of gamma rays the moment it bumped up against the antimatter environment.
But everything around us, and making us up, would be perfectly stable. It's only when matter meets antimatter that the fireworks occur, and all the matter would have been eradicated in the symmetry break. A given antihydrogen atom, for example, would be composed of an antielectron (positron) peacefully orbiting an antiproton, and so on, up the ladder of atomic, and molecular, complexity. Indeed, we know this would work, because antihydrogen has already been synthesized, as has, I am told, antideuterium.
It's just possible that aggregates of antimatter would have a reversed gravitational field and so repel other masses - dark energy, anybody? - but I don't know of any evidence for this idea, wonderful as it is. The point is that Spock might have a goatee, but other than that, the anti-world should be indistinguishable by its residents from our world. Indeed, if there is such a universe, or such a closed-off region of the multiverse, *we* are its anti-world.
Dan Brown, by the way, wrote a cool if somewhat clunky thriller a few years ago called Angels and Demons in which the Vatican is under threat of demolition by way of a contained-antimatter explosive. I vote that science writers and readers start now in disabusing the public of the notion--always lurking around the corner, it seems, from whatever issue physics hasn't yet explained--that antimatter is God. Brown's novel is only escapist fiction, to be sure, but it makes a great deal out of the notion that the energy released in matter-antimatter collisions is somehow divine. Before Angels and Demons makes it to the theatres, let's all state for the record that a macroscopic chunk of antibaryons hitting a container wall would just make a really, really big explosion. Antimatter weapons, antimatter drives and whatnot will some day be the most efficient energy-release devices possible, but there's no need to bring gods into it.
(We don't have antimatter bombs for the same reason we don't get rich by synthesizing gold, actually. You *could* do it, but the amount of money, effort and time required to make and maintain either substance vastly outweighs the end result. For now.)
So it seems that any fracture produces a universe, though the amount of residual matter or antimatter would presumably be greater or lesser depending on the degree of asymmetry. For every particle that makes up your finger a billion others were vaporized, while another universe, or region of the multiverse, might be far richer in residuals. But in any of these situations you would wind up with physical structures, with *mass*, whatever sentient beings in that region chose to call it. (Anybody who knows quantum field theory and wants to disagree, by the way, come on in.)
Against the anthropic folks, then, it seems the only really *unusual* universe would be the perfectly symmetrical one, in which all particles were annihilated by their anti-particles an instant after the Bang. I don't know the math--if I did, they'd be giving the Nobel to me instead of Professor Nambu--but, given that baryon symmetry evidently can break, as ours did, aren't the chances of a perfectly symmetrical outcome vanishingly small, given the design space of possible universes?
Perhaps we should only really have been surprised, that is, to have found ourselves not here at all.
