Dear Friend,
Black holes don’t destroy information. According to Classical, “billiard-ball” physics, once something goes into a black hole, it is gone. But Quantum Mechanics—physics at the subatomic level—says that information can not be destroyed, it can only be transferred or transformed. Information is the blueprint of the thing—everything that made it what it was. If it’s lost, then the chain of cause-and-effect breaks. You get a cause with no traceable consequence. Or an Effect no cause, because nothing’s there to tell you what happened before. That doesn’t happen. Not in a lawful universe. The laws of physics demand that: Something always follows/ Something always remains. It means even when it’s gone we can still make sense of it, understand what we can’t. What QM means is that you can always reconstruct the original state of something from the given information you have, i.e., the past can always be reconstructed from the present. But there’s been a longstanding paradox: either a black hole does, or does not destroy information.
The long standing belief is that if something falls into a black hole, everything about it is gone, destroyed. A black hole’s gravity is so immense that it generates what’s called tidal forces on objects: If you fall into a black hole feet first, very soon your feet will experience much stronger gravity than your head. The difference in gravity felt between your feet and your head is the tidal force, and because your feet experience more gravity than your head, your feet are going to be pulled in faster than your head and very quickly your feet will literally get away from you. You will be stretched like an ever thinning and lengthening noodle. It’s called “spaghettification,” and is likely as gruesome as it sounds.
It’s so strong that eventually even your atoms get pulled apart into their constituent protons and electrons. Those protons then get shredded into things with names like quarks, leptons, bosons. Ironically, the atom’s buzzy little electrons get separated from the rest of the atom, but they don’t break down. Who knew that the wee electron was the strongest. Eventually, whatever falls in reaches the singularity: the center of a black hole where our most advanced math insanely predicts that there’s an infinitely dense point, generating infinite gravity with zero volume. Anything that reaches the singularity is erased including the object’s information.
At the boundary of a black hole, where something is irreversibly caught by the black hole and cannot escape, is called the event horizon. Think of paddling down a lazy river until you reach the top of the waterfall. As the current’s speed picks up, there’s going to be a moment when you will not be able to paddle away, and down you will fall. Usually on rivers, they will have a safety line or a buoy warning boaters and kayakers of the falls ahead. Think of the current’s speed as the black hole’s gravitational force. Think of the warning line as the event horizon, the border between the black hole and regular space. It is the point of no return. But it’s defined, and real, and it’s something you could actually touch… once.
It is here at the border, at the event horizon, that a new hypothesis is quickly developing about black holes. Think of the event horizon as the surface of the black hole. As mass falls past the event horizon, seemingly trapped forever, the black hole’s event horizon gets bigger. We don’t know, and currently can’t know, what’s happening to that mass inside the black hole, but we know it’s there because the gravity it adds expands the event horizon. The black hole grows.
As objects fall into a black hole, something happens as they cross the event horizon: they get entangled with it. Einstein called it “spooky action at a distance.” There is no known explanation. Not even an educated guess. It feels like something fundamental is being revealed about how the universe works. And it’s this bizarre-but-real phenomenon that may be the key to why black holes don’t actually destroy information.
Steven Hawking first made his mark in his 1974 paper stating the black holes don’t last forever. They shrink. They lose mass as they emit—what was to be named—Hawking radiation and eventually dissipate. Once they have sucked everything that they can, they will disappear as radiation given off into the rest of space. Up until then it was believed, that nothing…nothing could escape from a black hole, at least not through the same entrance. That it can is astounding.
The radiation was, as far as we could tell, random. It contained no measurable information. Just random noise. So as a black hole disappears, everything that went into it is erased as so much white noise wafting off into the rest of the universe. New research is pointing to the idea that that noise isn’t random. It’s encoded by quantum entanglement, just so fine grained, we aren’t able to read it. The event horizon is where it’s written, a ledger of everything that has passed. It’s read back to the universe as Hawking radiation. The information, all of it, will finally escape the black hole. Whatever fell gets released back into the universe. Its information is not destroyed. It may be spread out, but with great difficulty, it could be pieced together, again. They don’t get rendered into the nothingness of oblivion by the singularity. Something always escapes.
So when an object disappears over the waterfall, it might feel like it’s gone. But it’s not. It’s still there in the plume of mist at the bottom of the large waterfall. Everything that fell down the waterfall shapes that plume. If you get good enough, you can know everything that went down that waterfall. If it once was there, then it will always be there, and it can, like I said, with enough care, be recreated. Once something gets entangled, it’s never really, ever, truly separated. Not even a black hole can destroy it.