About That Black Hole...
In which I talk about black holes, a book I wrote, and about the tedium of these times
I wasn’t going to write all that much about astrophysics, especially if there are no pictures. But given that the Nobel Prize just went to three scientists working on black holes (one theorist and two observers) I might as well ditch the rules I’ve set for myself.
“Half of the prize goes to Roger Penrose, a mathematician at the University of Oxford, for his work in the 1960s on the formation and stability of black holes. The other half is shared by two astronomers: Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics and Andrea Ghez of the University of California, Los Angeles. Since the 1990s, they led rival research groups that tracked stars at the center of the Milky Way and showed that their orbits were bent by what’s known as a supermassive black hole (SMBH).” (source)
We live in a relatively uninteresting galaxy, with our planet orbiting a pretty mediocre little star. All the crazy stuff — massive explosions etc. — usually happen very far away, and that’s good: in all likelihood we would not be around if things were different.
We now know that there are massive black holes at the centers of galaxies (astronomers call them supermassive). If you think about it, this makes sense: if there’s a black hole at the center of an object as huge as a galaxy, shouldn’t it be a lot more massive than those in its spiral arms?
Unfortunately, when you want to look at the “our” supermassive black hole, you run into two problems: first, by construction black holes are invisible; second, there is a lot of material between us and the center of our galaxy. So if you want to investigate the black hole, you need to come up with a nifty idea.
Visible light, the one we use for photography, constitutes only a small part of the full electromagnetic spectrum. The spectrum ranges all the way from radio waves to X- and gamma rays. The only reason why visible light is any different for us humans is because we come with sensors that can detect it: our eyes (we also have sensors to detect some other types of radiation — we feel heat).
But for a physicist, light is just light, and for astronomers, visible light isn’t necessarily all that interesting. Sure, you can take great pictures. As I explained in an earlier email, you can use those pictures to learn something about the temperatures and ages of stars, or you can map otherwise invisible material.
But other types of radiation directly speak of very interesting events. For example, newly forming stars emit a lot of infrared radiation, which is able to travel right through the gas clouds in which these stars are embedded. When you use an infrared telescope, you can literally see where stars are forming. Or some of the most violent events in the Universe (such as supernova explosions) produce short bursts of very intense X rays (in fact, such radiation precedes what can be observed in visible light).
Thus, there are all kinds of interesting things you can do when you work with any of the radiation that’s not visible to the human eye. That’s what the two observers did in the case of the black hole at the center of our galaxy. Specifically, they worked with infrared radiation, which not only can travel through the gas and dust that prevents us from seeing the center with our eyes (or telescopes), it also conveniently doesn’t get too distorted by turbulence in our planet’s atmosphere.
Short aside: there is a lot of dust in the Universe. Not just in your home. It’s obviously not the same kind of dust. But astronomers call it dust because it’s somewhat similar to what you find in your home. (That’s all you need to know, trust me.)
The basic idea of locating and measuring the black hole was very simple (it’s known as Sagittarius A* — Sgr A* — from its location on the night sky): if there are stars around it, then those stars ought to orbit following very basic physics (simple Newtonian mechanics). All you need to do is to locate the stars for a while to get their positions; and you can then infer the mass of the black hole from how the star moves.
(image source: ESO/MPE/S. Gillessen et al.)
In this case, both teams (the leaders of the teams got the Nobel Prizes…) focused on a single star called S2. You can see the actual configuration in the image above. The orange cross marks the location of the black hole. Ignore the different colours (it’s not an optical image so the colours encode astronomical information). But you see a lot of objects, and out of all those objects, we’re interested in S2, which in the image sits right to the north of Sgr A*.
Using the largest telescopes available (precision was key), they managed to track S2 over the course of a few years:
“In 2002, S2’s elliptical orbit appeared to reach its closest point to Sgr A*. It came within 20 billion kilometers or 17 light-hours, and traveled at 5000 kilometers per second, 3% of the speed of light.” (source)
S2’s orbit could only be explained if there was a black hole with a mass of roughly 4 million suns. There’s no other explanation for the orbit of S2:
When they zoom in that one star is S2. A nice elliptical orbit. Keep in mind these are actual astronomical observations. You’re seeing these stars move.
That was a little bare bones, wasn’t it? A decade later, someone made another animation (even adding the inevitable slightly technoish soundtrack):
Ghez and Genzel received their Prize for these observations. Penrose, the theorist, received the prize for his work on black holes. I’m thinking that Stephen Hawking would have been included in this year’s list of recipients if he were still alive. Typically, theorists only get awarded a Nobel Prize if there’s an observation that confirms their work.
Originally, I was going to write a little bit more about black holes, in particular their event horizons. But maybe that’s for a future email.
This past decade, my summers tended to be rather uneventful, with a lot of free time at hand. Not this year, though. Besides working on my own photobook, I was also invited to contribute to MACK’s relatively new DISCOURSE series.
The idea was to expand something I had written about in a number of photobook reviews before. As it turns out, when Michael Mack asked me I already had the beginnings of a draft for such an expansion on my computer. So over the summer, I worked on what would become Photography’s Neoliberal Realism.
In the book, I focus on the work of Annie Leibovitz, Gregory Crewdson, and Andreas Gurksy. But the topic at hand is much larger than the output of these three widely celebrated photographers: to what extent does contemporary photography serve as a propaganda tool for the type of aggressive neoliberal capitalism we have to live under?
We typically tend to think of propaganda as something that happens elsewhere, usually in repressive regimes. In the book, I’m arguing that we should look at the visuals we live with and start thinking about them with a much more critical eye — especially if we’re hoping to reign in the excesses of neoliberal capitalism.
I don’t know about you, but I’ve reached the stage where times have become tedious. I know I’m not alone. A good friend emailed me from Germany and told me she felt the same way. It’s not even “just” the state of politics, with its endless combination of sheer cynicism and outrage. It’s also the pandemic, which appears to have most of taught us absolutely nothing. The other day, I saw an article that spoke of the third wave in the US, and in many countries in Europe, they’re now entering the second wave. Are we going to be stuck in this for much longer?
If you’re now thinking “Oh my god, I don’t even want to hear any more of this,” then, believe me, I’m with you. I also don’t want to hear any more of this. The other morning, though, I found an interesting article that I thought I should share. In The Atlantic magazine, Quinta Jurecic published a piece entitled The Tedium of Trump. It starts off with an observation that’s not surprising but that somehow took the edge of the state of affairs a little:
“Trump is boring in the way that the seventh season of a reality-television show is boring: A lot is happening, but there’s nothing to say about it. The president is a man without depths to plumb.”
Beyond that, though, Jurecic then speaks of how one is possibly react to all of this, whether as a journalist (honestly, can you imagine having to write about that stuff?) or as some regular person (like you and me). Diving into withdrawal from the daily news, this then leads to the Soviet Union:
“Writing in The New York Review of Books in 2019, the British writer Viv Groskop wondered whether Westerners overwhelmed by the news might wish to adopt the Soviet tradition of “internal exile” and curl into themselves to find peace away from politics.”
The article makes it clear that this withdrawal might not be such a terrible choice.
I remember a year to two ago, there was an article about a man who simply hadn’t followed Trump news, who then ended up being the target of a lot of vitriol. Say what you want, though, that man’s mental health might have been a lot better than everybody else’s.
Don’t get me wrong, I don’t mean to write this in a flippant manner. The term “internal exile” is also part of East German history (originally, I’m a West German, so I only have second-hand knowledge of it). Certain things would just not be talked about in public. Even in private you’d be extremely careful. As a consequence, private relationships often developed a depth that from what I understand were a lot more meaningful than the ones in capitalist Western Germany.
With Germans of a particular age - those who grew up and lived in East Germany — you can still sense this reluctance to be too public; yet when you become friends with them, you’ll experience an enormous sense of friendship.
I’ve been thinking about this for a while now. In my last email, I wrote about sending physical pictures to people to reach out. As terrible as these times are, at the very least they provide us with a challenge that’s also an opportunity, namely to consider the personal relationships we have: are they as close as they could be?
Is there solace to be had and strength to be gained from the truly social — as opposed to the weird simulation of “social” on social media?
With that I’m going to conclude for today. Wherever you are, please wear a mask and stay safe!
As always thank you for reading
— Jörg
I’m a freelance writer, photographer, and educator currently living and working in the US.
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