An encounter with Charybdis

At the center of our seemingly tranquil galaxy, there's a black hole massive enough that it significantly warps spacetime, swallows any matter that gets close enough, and in the process emits truly colossal amounts of radiation.  Named Sagittarius A*, it was discovered in 1954 because of its enormous output in the radio region of the spectrum.  [N. B.  Throughout this post, when I refer to the black hole's radiation output, I am not of course talking about anything coming from inside its event horizon; that's physically impossible.  But the infalling matter that gets eaten by it does emit electromagnetic radiation before it takes its final plunge and disappears forever.  Lots of it.]

This thing is a real behemoth, at an estimated four million times the mass of the Sun.  There is a lot of interstellar dust between it and us -- after all, when you're looking at the constellation of Sagittarius, you're looking down a line going directly along the plane of the galaxy toward its center -- but even without the dust, it wouldn't be all that bright.  Most of its output isn't in the visible light region of the spectrum.  This doesn't mean it's dim in the larger sense; not only are there the radio waves that were the first part of its signal detected, but it has enormous peaks in the gamma and x-ray part of the spectrum as well.

Earlier this month, the European Southern Observatory released the first actual photograph of Sagittarius A*:

[Image licensed under the Creative Commons EHT Collaboration, EHT Sagittarius A black hole, CC BY 4.0]

How could something that enormous form?  We have a pretty good idea about how massive stars (over ten times the mass of the Sun) become black holes; when their cores run out of fuel, the gravitational pull of its mass collapses it to the point that the escape velocity at its surface exceeds the speed of light.  At that point everything that falls within its event horizon is there to stay.

But we're not talking about ten times more massive than the Sun; this thing is four million times more massive.  Where did all that matter come from -- and how did it end up at the center of not only our galaxy, but every spiral galaxy studied?

A step was taken in our understanding of galactic black hole formation by a team of astronomers at the University of North Carolina - Chapel Hill, in a paper that appeared this week in The Astrophysical Journal.  It's long been known that most large galaxies are attended by an array of dwarf galaxies, such as the Milky Way's Small and Large Magellanic Clouds.  (Which, unfortunately, are only visible in the Southern Hemisphere.  This is why they're named after Magellan.  Typical of the Eurocentric approach to naming stuff; clearly indigenous people knew about the Magellanic Clouds long before Magellan ever saw them.)  It's also known that because of the gravitational pull of the larger galaxies, the smaller ones eventually collide with them and merge into a single galaxy.  In fact, that even happens to big galaxies; gravity has a way of winning, given enough time.  The Milky Way and the Andromeda Galaxy, which are about the same size, will eventually come together into a single blob of stars, but what its final shape will be is impossible to predict.

As an aside, there's no need to worry about this.  First, it's not going to happen for another four and a half billion years.  Second, when galaxies (of any size) collide, there are relatively few actual stellar collisions.  Galaxies are mostly empty space, and when they merge the stars that comprise them mostly just pass each other without incident.

But not the black holes at their centers.  Those, being the center of mass of the entire aggregation, eventually slam together in a collision with a magnitude that's impossible to imagine.  And the team at UNC found out that this is one of the ways that galactic black holes become so large; they discovered that even dwarf galaxies have central black holes, and when they get swallowed up, that mass gets added to the central black hole of the larger galaxy.

Sagittarius A* sits in the middle of the whirling vortex of stars, like the sea monster Charybdis in Greek mythology, sucking down anything that comes close enough -- including, apparently, other black holes.  The celestial fireworks with a collision between two large black holes, such as the ones in the Milky Way and Andromeda, must release a fantastic amount of energy.

Wouldn't that be something to see?

From a safe distance, of course.

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Defeating the trolls

I'm a firm believer in the idea that most people, most of the time, are trying as hard as they can to do the right thing.

Yes, we often differ about what that right thing is.  Yes, sometimes we try and fail.  But my point is, we are usually working to do the best we can for ourselves and our loved ones.

But.

There is a minority of people who, to put it bluntly, are assholes.  These are the people who can't stand it if others get recognition, are furious when their pet ideas turn out to be wrong, or are simply spiteful and nasty.  And that ugly minority can, unfortunately, be extremely loud at times.

Look at what happened last week to Dr. Katie Bouman, the astrophysicist who spearheaded the project to generate the world's first actual photograph of a black hole.

You'd think that anyone with a scientific bent would have been thrilled, both for her and because of the extraordinary image she helped create.  And honestly, most of us were.  But there was a handful of trolls who couldn't stand the fact that she was getting accolades for her work -- and that she showed great modesty in highlighting the work of the rest of her team.

"No one algorithm or person made this image," Dr. Bouman wrote.  "It required the amazing talent of a team of scientists from around the globe and years of hard work to develop the instrument, data processing, imaging methods, and analysis techniques that were necessary to pull off this seemingly impossible feat.  It has been truly an honor, and I am so lucky to have had the opportunity to work with you all."

So said trolls decided that this was Dr. Bouman's way of admitting she really hadn't had much to do with the research, and set out to destroy her reputation.

Fake Twitter accounts and YouTube channels started popping up, all with the aim of casting doubt on her role in the project.  Many of them focused on her colleague Andrew Chael, who it was implied had done nearly all the research, which was then swiped by Bouman.  Chael himself was having none of it; he posted on Twitter a complete disavowal of the claim, and a demand that the attacks on Dr. Bouman stop.

The trolls then created a fake account in Chael's name and accelerated the nastiness.

Nota bene: if your opinion about something is on such shaky ground that in order to get people to believe it, you have to create a fake Twitter account, impersonate someone else, and then lie outright, you might want to consider whether you're right in the first place.

Twitter, to its credit (a credit that it must be said it often doesn't deserve), pulled the fake accounts as fast as it could, but not before there were thousands of people who had followed them, and tens of thousands of times that the false messages had been retweeted.  As with most false claims, it's damn hard to fix the damage once the claim is out there, regardless of how many times it's debunked, retracted, or deleted.  Witness the ongoing anti-vaxx idiocy, due largely to Andrew Wakefield, whose "studies" were withdrawn and whose work has been shown to be worthless.  Witness "chemtrails," whose genesis was due to a misquoted number on a Louisiana news broadcast.  Witness the ten thousand (literally) public lies Donald Trump has uttered in the last three years.

Undoing all that would be about as easy as putting toothpaste back into a tube.

As far as why anyone would be such a complete dick as to attack Dr. Bouman, most people are attributing it to sexism -- that the trolls couldn't believe that a woman had made such an achievement, and set out to prove that she'd relied on her male colleagues and then stole their glory.  Sadly, this explanation for the trolls' behavior is entirely plausible.  Despite considerable advances, it's still difficult for women to succeed in science.  Consider the 2017 study that showed teams led by women only receive 7% of the total grant money allocations, and a team led by a woman receives on average 40% of the money that a similar project receives if led by a man.  These figures are appalling, even if you take into account that only 17% of working scientists in physics and engineering are female -- the fields with the lowest diversity.

Which is itself appalling.

So this disgusting episode is yet another reason to be careful about what you believe online.  Double, triple, quadruple-check your sources before you pass along links.  That is especially true if the link supports something you're already inclined to believe; we all fall prey to confirmation bias.

Despite all this, I still think that humanity is, in the majority, good.  But being good means you speak up against the ugly minority who are determined to attack, demean, and degrade others.  Defeating the trolls takes an effort by all of us.  To paraphrase Edmund Burke (the paraphrase is to remove the sexist verbiage, the irony of which does not escape me): "All that is necessary for the triumph of evil is that the good do nothing."

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Monday's post, about the institutionalized sexism in scientific research, prompted me to decide that this week's Skeptophilia book recommendation is Evelyn Fox Keller's brilliant biography of Nobel Prize-winning geneticist Barbara McClintock, A Feeling for the Organism.

McClintock worked for years to prove her claim that bits of genetic material that she called transposons or transposable elements could move around in the genome, with the result of switching on or switching off genes.  Her research was largely ignored, mostly because of the attitudes toward female scientists back in the 1940s and 1950s, the decades during which she discovered transposition.  Her male colleagues laughingly labeled her claim "jumping genes" and forthwith forgot all about it.

Undeterred, McClintock kept at it, finally amassing such a mountain of evidence that she couldn't be ignored.  Other scientists, some willingly and some begrudgingly, replicated her experiments, and support finally fell in line behind her.  She was awarded the 1983 Nobel Prize in Physiology and Medicine -- and remains to this day the only woman who has received an unshared Nobel in that category.

Her biography is simultaneously infuriating and uplifting, but in the end, the uplift wins -- her work demonstrates the power of perseverance and the delightful outcome of the protagonist winning in the end.  Keller's look at McClintock's life and personal struggles, and ultimate triumph, is a must-read for anyone interested in science -- or the role that sexism has played in scientific research.

[Note: If you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]