Woster: Brushing up on black hole knowledge
I haven’t punched in to a regular job for five years, but I’m discovering that the COVID-19 stay-home guidelines are giving me more time than ever to surf the web and read newspapers and magazines cover-to-cover.
It isn’t strange, then, that I recently happened upon a marvelous article about a thing called the Abell 85 galaxy cluster. It seems that cluster “is home to the largest black hole known in the universe.” The article said astronomers have measured this black hole. They’ve discovered that “it is 40 billion times the sun’s mass, or roughly two-thirds the mass of all stars in the Milky Way.’’
Fascinating, right? It’s probably more fascinating to someone who can even vaguely comprehend the notion of something 40 billion times the sun’s mass. I don’t have the slightest idea what the sun’s mass might be. Mass is weight, though, isn’t it? So when they say the measured this black hole, that must mean they weighed it? And if so, apparently someone had already weighed the sun?
How do you even weigh something like the sun? I learned back in grade school that the sun is 93 million miles from Earth, something like that, anyway. Back at Shanard’s Elevator in Reliance, I used to drive a truckload of wheat up the ramp and through the door, where I’d stop on the scale, a big rectangle of thick timbers. Ab Vehle would weigh the load. Then I’d open the tailgate, hoist the truck box and empty the grain through a grate in the middle of the scale. Ab would weigh the truck again and hand me a scale ticket that I’d toss in the glove compartment of the truck before I dropped the gearshift into low and headed back for the field.
I understand that sort of measuring, just like stepping on the bathroom scale, only with less cussing than when I read the weight on the scale in the bathroom. But I was never 93 million miles from the elevator scale.
On a site called “Phys.org’’ I learned that Abell 85’s galaxy cluster is 700 million light years from Earth. Say what? That’s twice the distance of any previous black hole measurements, the site says.
And, get this: a scientist named Jens Thomas is quoted as saying, “There are only a few dozen direct mass measurements of super massive black holes, and never before has it been attempted at such a distance.” Boy, so much to unpack in that sentence. Thomas and his team weren’t the least bit daunted, apparently, because he continued, “We already had some idea of the size of the black hole in this particular galaxy, so we tried it.’’ And I’m not the one who’s going to tell him he got it wrong.
At that point, I needed a refresher on black holes. The National Aeronautics and Space Administration defines them as “a place in space where gravity pulls so much that even light cannot get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.’’
I was still trying to wrap my brain around that concept when I read on: “Because no light can get out, people can’t see black holes. They are invisible.’’
Well, that reminded me of the days after the Homestake gold mine became a deep underground physic lab. I talked with some scientists who were searching deep in the mine for a thing called dark matter. Dark matter may compose 85 percent of the universe, but like black holes, it can’t be seen directly.
I didn’t understand a word those dark-matter researchers said to me, but I admired their search. It isn’t easy looking for something that, even when you find it, you don’t see it.
As I read further, I suddenly remembered how Sherlock Holmes once solved the mystery of a stolen horse because a dog didn’t bark in the night. If Holmes could do that, I suppose someone else could find dark matter by not seeing it. If that’s possible, then I see no reason why someone else couldn’t measure a black hole nobody can see.
Holmes might say, “Elementary, my dear Watson.’’