Here's a picture from that link (to the Lawrence Livermore National Labs):
The idea is that as a result of two amazing coincidences, we see emission from Nitrogen at a wavelength of 989 Angstroms in the star I'm looking at.
First coincidence: well, the Universe is made mostly of hydrogen and helium, right? There's a lot of that stuff around, very little (proportionately) of anything else (I'm talking only so-called baryonic matter here, nothing fancy, no dark matter, don't get all smartypants on me bub!) Ok, so the light emitted from Helium, provided that the electrons don't have to behave in any specially kinky way, has got to be really bright. There is a really bright emission line from singly ionized Helium at 303.78 Angstroms. Now that's what they call extreme ultraviolet, and that kind of light not only doesn't make it down the atmosphere, but rarely makes it across interstellar space. So the first amazing coincidence is that 303.78 Angstrom Helium light just so happens to be very close in wavelength to 303.80 Angstrom levels of doubly-ionized Oxygen.
What does this mean? As a result of this cosmic coincidence, the light from Helium can "pump" Oxygen to put out more light. The light at 303.78 Angstroms, if given off by atoms with a moderate amount of motion, can be absorbed by Oxygen atoms, bringing an Oxygen electron up to a higher level.
Once that electron goes to a higher level, it can go back down to the ground level in steps, emitting along the way light with a wavelength of 374.436 Angstroms.
Time for coincidence number 2: the difference in energy levels in doubly ionized Nitrogen is 374.441 Angstroms. Now the Oxygen light "pumps" Nitrogen to give out light that it wouldn't normally give out. It raises an electron in Nitrogen up to a higher level, and as that electron cascades down, it gives off optical light (at something like 4660 Angstroms) and near UV light (3200 A or so I think) and finally what I just saw, far UV light (989 A).
Now it's possible I'm just seeing regular Nitrogen emission not resulting from this complicated booby-trap. But that's science for you: I can add up the numbers and look at the data and test which idea is right!
Ok, I promised musings, not a lecture on freakin' atomic spectroscopy.
I bring this up partly because it makes me think about the anthropic principle, which is a philosophical outlook (or various philosophical outlooks) which says that basically, the reason the world is as it appears to be is that if it were different just a little bit, we wouldn't be here to inquire why it's here in the first place.
This line of thought gained prominence when Sir Fred Hoyle figured out that fusion processes leading to the basic element of life, Carbon, required nuclear reaction rates that were "finely tuned." This page talks about cosmic coincidences in general, and this page talks about Hoyle's work in particular. What Hoyle did was especially impressive because he predicted that Carbon's nucleus had to behave in a special way, based on the fact that we, as carbon-based lifeforms, exist.
Now, some people have taken this idea and run with it. Others have taken this idea and run off a cliff with it. I speak here of Frank Tipler, who has proposed what he calls the Final Anthropic Principle, which says that once evolved, intelligence in our Universe can never die out, for it must, by logical necessity, approach an Omega Point, a hyper-intelligent computer that will become like God, resurrecting all intelligence that existed previously and providing for its eternal happiness. Martin Gardner has dubbed this the Completely Ridiculous Anthropic Principle. In case "completely ridiculous" leaves any doubts as to Martin Gardner's opinion, I suggest you pronounce the acronym out loud.
I once got in a discussion with Alan Guth, promulgator of the inflationary theory of the Big Bang, on the topic of the anthropic principle. Of all big-shot scientists, Guth is the most approachable. He told me that he thought the anthropic principle, in any of its variants, was complete crap!
Now that I am investigating a cosmic coincidence on my own, I'm trying to see what lessons or parallels I can draw:
1. Coincidences happen
Unlike the production of carbon in the centers of stars, Bowen fluorescence does not appear essential for our existence at all.
One could argue that there's a bit of a difference though in that Hoyle predicted that resonance of Carbon, which was unsuspected, whereas Bowen (I know nothing about the person Bowen at all) as far as I know, just looked up tables of atoms to find known wavelengths. Of course the existence of the process in either case is only something inferred from observation: in one case, we observe that we exist, and infer that there must be a way stars can make our carbon. In the other case, I have just seen a strong emission line at 989 Angstroms and infer there must be some way to make its light, even if it's a complicated booby trap. I might be able to go on to infer all sorts of surprising things about what's going on in the star system, all based on the fact that whatever happens, it must cause a strong emission at 989 Angstroms. Which brings me to
2. Our existence is just another observation we make
One thing I think rubs people the wrong way about anthropic arguments is their anti-Copernican flavor. What if I said:
The universe must be the way it is, in order for me to have seen an emission line at 989 Angstroms?
Well, Bowen fluorescence depends on those two extraordinary coincidences, and I suppose those coincidences are linked to the details of atomic structure, which depend on the fine structure constant alpha and the mass of an electron. So if those fundamental numbers that make up the universe were changed just a little bit then Bowen fluorescence wouldn't occur.
But Bowen fluorescence had to have occurred (or at least something had to cause strong emission at 4661 Angstroms and 989 Angstroms)--if it hadn't, I wouldn't have met Jon Schachter, who wrote his thesis at Berkeley on Bowen fluorescence. I remember Schachter as this big Jewish guy with a bristly beard and bushy eyebrows--he used to joke that we must have come from the same Jewish tribe because we both have such eyebrows. Unfortunately, he's left science for computers, and now I have to figure out this Bowen stuff myself instead of just asking him what it all means (in terms of what's going on with the neutron star).
Anyway, what I'm saying is that if you change the Universe a little bit so those lines don't overlap just right, then not only doesn't this obscure astrophysical process occur, but people's lives would change: I presume Schachter wouldn't be Schachter and Bowen wouldn't be Bowen if the academic fields they had staked out as their own hadn't existed.
So this process might be in a sense as essential to their existence as Carbon is to all of us. Presumably it could be essential to my existence too--if for example, I publish an important paper on Bowen fluorescence, which gets me a job somewhere...
Ultimately, whatever way the Universe is must be consistent with everything we observe, whether that's our composition in terms of Carbon atoms, or the possibility of photosynthesis, or Bowen fluorescence, or an experiment in Fermilab. That's just "the scientific method."
I think some people get spooked by anthropic arguments because it seems that the existence of people shouldn't intrude on esoteric fundamental questions of nuclear structure.
In the end, will one theory wrap everything up, or will we have to defer to experiments and admit there is some fundamental arbitrariness in the Universe? I don't know. But I don't think it's so different to say, "it has to be consistent with our being here" and "it has to be consistent with the latest experiment at Fermilab." I think this should be obvious--I just haven't seen it stated.
This has been mostly a literary rambling--I promise (myself) that soon I'll write some philosophizing better grounded in and directed towards science (though not necessarily science as obscure as Bowen fluorescence!)
In less exalted news, the laundry machine in my apartment is down, so I went to the laundromat. For some reason, I never bother to check my pockets in front-loading machines, and always end up with a damn leaking pen coloring all my white clothes with random blue ink.
I also went to The Mustard Seed Market and got some yummy food, including sushi. There were a couple of guys giving free hummus samples, and they looked Arabic, perhaps Palestinian. I think they might have seen that I'm Jewish, and we all were kind of wary, but the hummus was 2 for $3 and had extra garlic and no preservatives so I bought some, striking a blow for Middle-East goodwill and coexistence along the way!