This is part of my series where I read physics articles in Scientific American, and rant about barely related tangents in order to provide “context”.
After the November issue, which didn’t really have any physics articles at all, the December issue has two major articles! One is astronomy, the other one is about the fusion reactor, ITER. But, after complaining about how all the physics articles are about astronomy, it looks like I’m still choosing the astronomy article. The ITER article is just a bunch of photos of the engineering, and I don’t have much to say about that.
So, the astronomy article is “Explosions at the Edge” (or that’s how it’s titled in print). It’s about the surprisingly diverse ways that massive stars can go supernova. For example, rather than simply exploding, a star may first shed a layer of gas, and then the subsequent explosion will collide with that gas, producing a prodigious burst of light.
As I hinted in the intro, I’m about to rant about something that is barely related to the article. There’s a saying, “the more you know, the more you know you don’t know.” Very true when it comes to astronomy, and stellar evolution in particular. Popular astronomy does a great job teaching the basics: how stars become red giants, white dwarfs, neutron stars, black holes, and so on. You might even know that red giants form because stars run out of hydrogen fuel for the fusion reactors at their cores. And if you’re not a physicist, you might be satisfied with this explanation.
But as a physicist who never studied astronomy, I understand that it is barely an explanation at all! It’s a summary of unexplained observations. One major question remains: why does running out of fuel lead to expansion? If I may point out, I’ve run out of fusion fuel, and yet that didn’t cause me to become a red giant. In frustration, I wonder, why do astronomers withhold the explanation from their popular writings? Is it because it’s not entirely understood, or because it’s only understood by a few astronomers, or because it’s too complicated for popular audiences, or because they know popular audiences are too incurious to ever ask?
Since this is a public blog, I felt obligated to take a moment to look up the answer. This article seems to be a good summary of the mechanism of red giant formation. Running out of fuel causes the core to collapse, which triggers fusion in a larger shell, which generates even more heat and causes the star to expand. I probably understood that explanation much better than the average person, but I still have so many questions about it.
The SciAm article isn’t even about red giants. It’s about stars in a more massive range, that go supernova instead. All I’m saying is I already knew stellar evolution is a lot more complicated than it’s usually made out to be. So if the thesis is that supernovae are more complicated than we thought, who is “we”?
An infographic within the article explains that under the classic model of supernovae, the kind of supernova depends on the mass of the star. There are six distinct categories, including a “Type-Ibc core-collapse supernova”, a “electron-capture supernova”, and a “Pair-instability supernova”. Now, that may be simple enough…
Wait you’re saying it doesn’t sound simple at all? Exactly, this is what I’m saying!
When this article says supernovae are more complicated than we thought, what it really means is that supernovae are more complicated than astronomers previously thought–basically, the article is about a handful of events that don’t fit into the classic model. But what astronomers previously thought was already way way more complicated than what lay people think. This article suffers from a problem that is common to many popular science articles: it’s dedicated to explaining how cutting edge research modifies the established scientific understanding, but it ignores the much larger distance between established scientific understanding and popular understanding.
And honestly? What can the article do? Explain all six types of supernovae, and exactly how and why they occur? To popular audiences? Not happening.
The angle this article takes instead, is to tell a more personal account of the author’s research experience. Yeah… that’s probably the better way to go. But to me, not particularly exciting, because I already know what research is like.
So, this is the final issue of Scientific American I’ve subscribed to, and please, no gift subscriptions. Later, I’ll post a wrap-up post. As for 2021, I might continue this series, if I receive enough reader requests. I’ll talk about that more in the wrap-up.