Much of what is popularly said about black holes is not only wrong, it is nonsense. There is less than no basis at all for assertively-stated speculations one occasionally runs across such as, for example: “the entire record of our physical existence might be fully mapped onto the surface of black holes.”
Suffice it to say that might also and always means might not.
Our understanding of reality can always be improved. For starters, a black hole is not a hole. It’s a ball. And just like any basketball, baseball, ping pong ball, BB or globe of the Earth sitting there in its ornate wooden frame, a black hole is a perfectly round sphere. Just like any other sphere, it has a measurable diameter and radius, a circumference, and a calculable internal volume. The main way in which this black-hole-ball differs from all those other balls is that it is dense—very, very dense—and they are not.
Black holes typically are created when a very large star’s lifetime ends and it implodes. Notice, that’s “im,” not “ex.” There are several variations on how this can happen, but a vast mass of star stuff all suddenly pressing inward upon the star’s center with inconceivably enormous force is the main idea.
Probably the best known variant is the supernova—the explosive final act of a dying star: the massive explosion pushes the star’s outer layers outward into surrounding space, while simultaneously im-ploding its inner parts inward toward the center, driving them ever smaller until they are downsized to a relatively small, massively dense ball. To see this process a bit more clearly in mind’s eye, we can slow it down with words as follows.
Imagine you are hanging somewhere in distant outer space watching the hand of God make a black hole. In order to make an impressively sizeable black hole, He’s going to have to start with something pretty big—let’s say it’s a really, really big star. Let’s say it’s a thousand times bigger than our sun (yes, there are such whopping things out there). And before your very eyes God’s going to turn it into a black hole.
God’s Almighty Hand reaches out, enfolds Itself around this colossally big star—and then squeezes. As God squeezes, that fiery sun-ball gets smaller, and as it gets smaller it gets denser. God keeps on squeezing. That really big star is no longer a thousand times bigger than our sun, it’s been squeezed down until now it’s only ten times bigger. And it’s now a lot denser than it was, because none of its substance is going away anywhere—it’s staying right there inside that sphere, and it’s getting denser as the sphere gets smaller.
God’s squeezing continues. All the gazillions of atoms in that star keep getting forced closer and closer to each other—abnormally close, as the minute distance that formerly separated them from each other keeps getting eliminated by God’s Mighty Squeeze. At last there’s no space left at all, the atoms are all touching each other (some of them don’t like touching, but they ain’t seen nothin’ yet). That formerly gigantic star is now down to the size of our own sun, but it’s now also a whole lot denser than our sun.
And God’s Great Big Hand keeps on squeezing. That once mighty star is now all the way down to the size of our great planet Jupiter, and it has become incomprehensibly dense. Its energy bits that used to be atoms have been crammed so cheek-by-jowl that they are now unrecognizable. What used to be their proton-neutron atomic nuclei are now all smushed together with their formerly-distant electrons, and they’ve all been turned into some primal sort of energetic thick mush, its parts indistinguishable…and we are reminded that E = mc2.
The Almighty Squeeze continues. That formerly-giant star is now squeezed down to the size of our moon…now down to a mere thousand miles diameter…now a hundred…then… And there it is at last: one of the universe’s larger stars has been squeezed down to the size of a softball.
As its size went down its contents remained the same. Not a single atom of that original star has been lost. All the star-stuff it started with is still in there, every smidgin of it, but it’s now squeezed down until it is very, very, very, very, very, very, very, very, very dense. It now qualifies to be called a black hole.
And here’s the interesting part. The gravitational “effect” of its greatly increased density has also changed: it now pulls in everything around it that enters the new empty space the great star so recently occupied. Even light. If it gets too close, light itself cannot escape the new black hole’s ferocious gravity. Therefore, this very dense new small round sphere has effectively become invisible because it cannot be seen. No light can shine upon it, to light it up so that we might see it, because it sucks in the very light itself. And so what can’t be seen looks like a “hole” in the starry sky that surrounds it. And of course we know it’s mis-named as a black hole instead of a black ball, but we go along with the game.
Before all this, when it was a humongously gargantuan star, its “attractive gravitational effect” on the surrounding stars, planets, space rocks and dust reached out to—oh, let’s say about a gazillion miles. And now, in its new disguise as an extremely dense softball, its gravitational effect still reaches out for that same gazillion miles. That’s because its mass hasn’t changed, it only got denser as it got smaller. Same mass, but denser, sorta like the difference between a very big sponge and a tiny diamond. In effect, it’s still the same star, it just got squeezed smaller. And denser. Black holes are all about density.
Einstein’s general relativity taught us that there really is no such thing as a “force of gravity,” as we had misbelieved for several hundred years since Newton first misconceived such a force. What’s really going on, Einstein explained, is that a heavenly body’s mass-density deforms the spacetime surrounding it.
The analogy most popularly used to enable us mortals to visualize this deforming effect is a heavy bowling ball laid on the middle of a mattress. Any marbles that just happen to be laying around nearby are unavoidably “attracted” to roll down into the depression created by the bowling ball’s weight. That “rolling down” effect is what we call gravity—and for so long wrongly identified as a “force.” They’re not really “attracted” by the bowling ball, they’re simply falling into the hole-like deformation it causes.
The “force-of-gravity” concept was akin to magic. Magic was still pretty popular in Newton’s day, and the great man himself dabbled in it more than a little. In our somewhat more modern day, by contrast, the quite non-magical deforming of spacetime by density is not merely akin to reality, it is reality. It’s what really happens. And we still call it “gravity,” and say it “attracts,” because that’s a handy idea everybody thinks they understand (though, in truth, many people really do still regard gravity as a “force”).
Thus if our original gigantic star had “this much mass with exactly this much density,” the new squeezed-down softball version of that same star still contains, inside itself, exactly that same amount of mass. The only difference is, its squeezed-down mass now has a whole lot more density than before it got squeezed. The overall “gravitational attractive effect” of this softball is still the same as it was when it was a massive star, before the supernova.
This has implications about which our reasoning minds may reasonably draw some inferences.
As a massive star, its former “gravitational reach” extended outward for a very great distance into surrounding space, and it had over the ages achieved something like “balance” with the other stars in its neighborhood of the universe. It tugged a bit on them and they tugged a bit on it, but everybody had their home place in the sky and they all pretty much stayed where they were, mostly. Most importantly, our massive star glowed, like all the other stars. It did not pull light in. But now, as a softball-sized black hole, it does. Why is that?
This tale has a Before and an After. Before, our massive star was a thousand times bigger than the sun, it had a gravitational “reach” out to about a gazillion miles, and was in relative balance with celestial neighbors. After, as a softball, it has vacated the space it used to fill in universal space—which is still a thousand times bigger than our sun—and is now empty.
The star’s down-squeezing left a big empty hole in space where the star used to be. So that now-empty space has suddenly become subject to inrushing space stuff that’s arriving from all directions. That inrushing stuff can and does include many things, such as stray atoms and molecules, space dust, space rocks, comets, asteroids, planets and their moons, and—here and there—perhaps even a neighboring star and all its surrounding children. All rushing inward, all heading for the center of a huge newly-empty spherical space which now surrounds the softball, all “falling inward” in response to the tiny softball’s un-reduced massive “attraction” (which, don’t forget, is really a deformation of spacetime).
Everything in the nearby heavens that can find its way into that huge new empty space will find itself gravitationally attracted to the new black hole which sits at the exact center of the new empty space. Space boulders, nearby stars, whatever—all attracted to the new, smaller center. And the closer they get toward that center, the faster they’ll speed toward it. And as soon as they get close enough their fate is sealed. They’re absolutely going to become part of the black hole—gobbled up, eaten, as they say.
A reasonable inference goes like this. At softball size, the black hole’s immense density can pull in light. At massive star size it could not. Therefore, the point at which it attains its new ability to trap light must occur somewhere between the big space it formerly occupied and the small space it now occupies. So where is that?
Exactly where in the downsizing this change occurs we cannot say precisely, but we do know that point has a name. It is called the “event horizon.” Stephen Hawking long ago gave it that name, and it defines the point at which light can no longer escape the black-hole object’s massive density.
Hawking also theorized that tiny paired packets of energy constantly “evaporate” snippets of energy away from the black hole at the precise outer edge of its event horizon. After a long enough time, he opined, the black hole could just evaporate totally away. As to whether this is true I am very skeptical, because Hawking based his claim on mathematics—and everybody knows mathematics can be pursued into reaches so bizarre they claim crazy things that are indistinguishable from magic. Not to mention that there is no record of any black hole ever having actually disappeared—from evaporation or any other cause.
This non-rational dependence on mathematics has been going on, for example, for half a century in the purely made-up-out-of-thin-air field called string theory, which remains vague, arcane, unproven and cockamamie, claims that up to eleven dimensions “might” exist [might not!], and is a persistent waste of otherwise useful scientific careers. Never trust a mathematician’s claims about what is and is not real.
But this is real: if you ever venture near a black hole, be sure to keep your feet above—away from—the event horizon. If you carelessly let them stray across that thin, invisible, horizon line, they cannot escape. Just like light, they’re got. And of course as your feet inexorably get pulled in, your ankles, knees and hips must follow—they say it’s a pretty messy way to go—and your former body’s atoms will soon slightly further increase the black hole’s density. Very slightly.
In the first twelve grades they don’t teach much about black holes—or even astronomy for that matter. Even in college one doesn’t get into the really good stuff until well into graduate study. The very predictable consequence is that most people are grievously uninformed about what black holes are, how they got there, and the interesting implications of their existence. This is unfortunate. Even setting aside their seldom-mentioned theological implications, you’d think the gee-whiz factor alone would draw more people’s interest to black holes.
There is, for example, a particularly massive black hole at the center of the nearby galaxy we call Centaurus A, which is actually two galaxies that collided and merged (sort of) in eons past in the constellation Centaurus. The remains of the smaller of those two galaxies is being consumed—drawn into—the black hole’s colossal surrounding gravitational deformation. Think of a three-foot bowling ball lying in the middle of a bed. This super-massive black hole is said to contain the mass of about a billion stars all compressed into an area as “tiny” as the size of our solar system (be reminded, our universe is a really, really, big place). A black hole of this size gives new resonance to the concept of “eating.”
One last thing here. It relates to the big bang. Logically, at least.
Let’s theorize—as all good scientists do—that our black hole didn’t stop at softball size. Let’s say the implosive kick was so enormous that the former star kept right on being pushed down, down—past tennis ball size, past marble size, on past the size of a BB, then a mustard seed, and then… Let’s theorize that it got so tiny it disappeared. It became a dot, then an infinitely tiny dot impossible to be seen with any microscope, and then…just…gone.
What if—we theorize—we run this scenario in reverse? Like an old Hopalong Cassidy movie run backwards? Instead of contracting inward, we’ll imagine it expanding outward. Here’s what we would see. From out of infinite nothingness, there would appear first a tiny dot. The dot would grow in size fast. From dot size up to BB up to marble size, up to soft ball, up to basketball, then moon, planet, small star, huge star… Boom—just that quick. “Inflation,” the astronomers would call it, with typical understatement.
Then, just for fun, let’s say it didn’t stop there. Let’s say it zoomed right on past the size of a star that’s a thousand times bigger than our sun—and it kept on growing. Ever bigger, upward and outward, past the size of a galaxy, a galaxy cluster, then a cluster of clusters. By the time it finally stops inflating outward it is the size of a whole universe. Let’s say it’s the universe we’re sitting or standing in this very minute.
What I’ve just described is what actually happened. The big bang—the real Let-There-Be-Light Big Bang—the biggest explosion of all time, really did create our universe. The French priest/astronomer Georges Lemaitre first proposed the idea way back in in 1927, and his “radical” idea was soon supported by Edwin Hubble’s observation that the universe is expanding. People found it easy to imagine “reversing” this universal expansion, taking it down backward till nothing’s left but a disappearing dot—like running an old movie backwards.
So where did that big bang-through-a-dot come from? What’s on the “other side” of the dot? More importantly, why did it come at all? Does this origin story differ—in any way that matters—from Genesis, or from Native American lore about Manitou, Earth Mother and Old Turtle? And what, dear reader, would you say is the chief difference between the mysterious big bang and all those black holes—some tiny, some super-massive—that float around today and every day throughout our universe?
Do you feel both the mystery and the majesty?