The Milky Way: An Autobiography of Our Galaxy by Moiya McTier

Author:Moiya McTier [McTier, Moiya]
Language: eng
Format: epub
ISBN: 9781538754177
Google: a1lTEAAAQBAJ
Amazon: 1538754150
Barnesnoble: 1538754150
Goodreads: 59802035
Publisher: Grand Central Publishing
Published: 2022-08-16T00:00:00+00:00

Sarge stops me from envisioning what I could be because I’m too busy lamenting what I’ve never been and despairing what I was instead. Of course, that’s not how your astronomers think of black holes. To them, Sarge is just an intellectual curiosity, a dense astronomical mystery whose solution could earn them a fancy prize. In fact, three human astronomers were jointly awarded the 2020 Nobel Prize in Physics for confirming that Sarge is indeed a black hole. That certainly took them long enough! It’s no wonder that human astronomers talk about black holes as if they’re marvelous phenomena to behold; they haven’t known Sarge long enough to understand its true nature.

Physically speaking, black holes are made of two or three parts. There’s the black hole itself, which is the dense part in the middle that light can’t escape, and its outermost boundary is called the event horizon. Then there’s the accretion disk, a ring of material that’s slowly spiraling its way in towards the black hole and glowing because of all the friction between the individual particles in the disk. Finally, some black holes have what your astronomers call jets, which are bright and powerful streams of material shooting up and down—though such simple directions are typically meaningless in space—from the plane of the disk.

Your scientists use three different values to describe black holes: mass, charge, and spin. We’ve come far enough together that I trust I can skip an explanation of what mass is…

Charge refers to its electric charge, which is basically just the difference between the number of protons and electrons, or positive and negative charges. Black holes tend to be neutrally charged, since there are about as many protons as there are electrons in the universe, and they’re both equally likely to be absorbed into the black hole and cancel each other out. In fact, your astronomers usually just assume that the black holes they study have no charge to make their calculations easier, even though the charge is constantly in flux as the black hole accretes—or eats—new material.

A black hole’s spin, or angular momentum, is…exactly what it sounds like. Your astronomers occasionally do come up with sensible names! The greater a black hole’s spin, the more it warps and drags space-time around it. Small stellar-mass black holes spin because they form from the collapse of spinning massive stars. (The stars in turn get their spin from the rotation of the gas cloud I used to build them, and the gas clouds…well, it’s just rotation all the way down. Or up. Or out? See? Useless! Let’s just say that pretty much everything in space is spinning.) Heavier black holes like Sarge get their spin from the momentum left over after the collisions necessary to build something so massive.

Sarge is just about four million times the mass of your sun, though human measurements of its mass have ranged between 3 and 5 million solar masses. Just like you repress your least favorite memories by confining them into

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