Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Wednesday, March 12, 2025

The stellar forges

A criticism sometimes aimed at us science types is that our obsession with naming, classifying, and explaining everything in the universe robs us of its wonder.  Why, they ask, do we have to get so damn technical about everything?  Why can't we just look at the stars, or the flowers, or a bird in flight, and appreciate their beauty?

Well, needless to say, I disagree with that pretty strenuously.  My understanding of science -- which, admittedly, is that of a reasonably well-read layperson's -- only adds to my sense of wonder.  For me, it's a case of the more you know, the more amazing it gets.

Let me give you an example of that -- a piece of research out of the University of Arizona that used the James Webb Space Telescope to peer far out into space (and thus, far back in time), and found something astonishing.  Something, in fact, that would appear quite mundane, meriting only a "So what?', if you didn't know some science.

Here's a capsule summary of the research -- then an explanation of why it's way cooler, and more surprising, than it appears at first.

The JWST just released a spectral analysis of a galaxy called JADES-GS-z14-0, which is about 13.5 billion light years away.  That's a pretty impressive feat; this means the light from it left on its journey to us when the universe was only two percent of its current age.  This, in fact, means the galaxy itself formed not long (in astronomical terms) after the cosmic microwave background radiation, the earliest remnants of radiation released when the universe settled down enough to allow photons to travel unimpeded.

Just seeing JADES is amazing enough.  "Imagine a grain of sand at the end of your arm," said Jakob Helton, who led the research.  "You see how large it is on the sky -- that's the size of the region we looked at."

The shocker came when they did an analysis of its spectrum, and found that it had high amounts of oxygen.  But why this is surprising -- why, in fact, it's going to force a rethinking of our understanding of how stars and galaxies form -- is where you have to know some background.

When heated or otherwise energized, each element emits a characteristic fingerprint of frequencies of light known as its emission spectrum.  The fact that these specific frequencies and no others are emitted was key to the development of quantum theory; energy levels in atoms are quantized, or exist in discrete steps, and an atom can no more emit a different frequency of light than you could go down a step-and-three-quarters on your staircase.  Because of these spectral fingerprints, it's now possible to determine the composition of distant stars by looking for the characteristic spectral lines of common elements in the star's spectrum.  This is how Helton et al. figured out that JADES contains large amounts of oxygen.

The emission spectrum of oxygen [Image is in the Public Domain]

Thing is, it shouldn't.  We have lots of oxygen here on Earth because the primordial cloud from which the Solar System condensed had a bunch of it; so, in fact, does the Sun, since it formed from the same cloud.  Alien astronomers could look at the Sun through their telescopes and figure that out the same way that we do.  But oxygen, it turns out, doesn't form all that readily.  The Solar System is oxygen-enriched because the Sun is (at least) a third-generation star.  In the very early universe, when there was nothing much around but hydrogen, helium, and trace amounts of lithium -- the atoms that were formed during the Big Bang itself -- stars had vanishingly small "metal content."  (To astrophysicists, "metals" are any elements heavier than helium.)  As those first stars underwent fusion in their cores, hydrogen was converted to helium, then helium to lithium and carbon; at the end of their lives, those stars that were heavy enough went supernova, and the pressures and temperatures of those colossal explosions not only generated "metals" but distributed them back into space.

Second-generation stars formed from the debris left behind by the explosion of first-generation stars.  Those second-generation stars, during the course of their lives and deaths, would have produced more "metals," and the cycle repeated, ultimately leading to the richness of composition we see in our own Solar System.

But it takes a while.  The amount of oxygen even in early third-generation stars is pretty small.  So where did all the oxygen in an extremely early galaxy like JADES come from?

We don't know.  "It's a very complicated cycle to get as much oxygen as this galaxy has," said study senior author George Rieke.  "So, it is genuinely mind boggling."

So there's evidently something about star formation and galaxy evolution we're missing.  Stars forming only three hundred million years after the Big Bang should be just about entirely hydrogen and helium.  And chances are, JADES is almost certainly not the only anomalous early object.  "The fact that we found this galaxy in a tiny region of the sky means that there should be more of these out there," Helton said. "If we looked at the whole sky, which we can't do with JWST, we would eventually find more of these extreme objects."

For me, it's lovely to look up into the sky on a clear night, but my enjoyment is much enhanced by the fact that I know a little bit about what I'm looking at.  The stars are stellar forges, creating all the matter around us -- we are truly, as Carl Sagan famously said, "made of star stuff."

In short: science itself is beautiful.  Understanding how the world works should do nothing but increase our sense of wonder.  If scientific inquiry isn't accompanied by a sense of "Wow, this is amazing!", you're doing it wrong.  I'll end with a quote from Nobel Prize winning physicist Richard Feynman, who in his 1988 book What Do You Care What Other People Think? had the following to say:
I have a friend who's an artist, and he sometimes takes a view which I don't agree with.  He'll hold up a flower and say, "Look how beautiful it is," and I'll agree.  But then he'll say, "I, as an artist, can see how beautiful a flower is.  But you, as a scientist, take it all apart and it becomes dull."  I think he's kind of nutty. …  There are all kinds of interesting questions that come from a knowledge of science, which only adds to the excitement and mystery and awe of a flower.  It only adds.  I don't understand how it subtracts.
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