The other day, we were talking about the “quantum hair” solution to the black hole paradox (if information truly gets lost, then that violates 2 Thermo, right? … ). Our physics color commentator Rob Sheldon writes to offer some thoughts on the holes in black hole thinking (so to speak)
Speaking naively as a simple-minded experimental physicist, this news blurb and abstract make no sense to me.
Now mind you, I don’t believe that Black Holes are a thing, but rather that the equations of General Relativity have been mangled in order to define “the horizon” or the “Schwarzschild radius” that makes a black hole. If the horizon does not exist, then we don’t have a Black Hole, we have something else. The Yilmaz metric allows a smooth transition from the dense object out to infinity with no horizon at the Schwarzschild radius. I’m relying on papers from Stan Robertson, but others have done this same calculation. But for the sake of argument, we’ll use the standard “vacuum” metric that predicts weird behavior at the horizon and therefore the existence of a surface which lets light and matter fall in, but neither light nor matter escape. That’s why it is called “a Black Hole”, because we can’t see it. It does distort light in its vicinity, so we see light from behind it curving around, and this is the reason you see artist’s depictions of “saturn like” objects they claim are what a black hole looks like. Mind you, these are all artists depictions. (The Radio Telescope photograph of M87 done 3 years ago had a one-pixel resolution three times larger than the Schwarzschild radius, so it was artist’s liberty that called it a photograph of a black hole.)
Okay, so what does it mean that “Black Holes have no hair?” That means that when something falls into a black hole, it is compressed down to a point. So whatever color, shape, texture, chemical composition, etc. that it had is now gone. From the outside, what sort of properties can a point have? Mass, charge, and angular momentum. Mass, because we don’t know how the Higgs field works. Charge, because to the best of our ability, an electron or charged lepton has no size. And angular momentum is weird, because a point doesn’t have extension, so how do we know it is spinning? In field theory, angular momentum only requires mass and rotational symmetry, so perhaps a spinning massive point still has angular momentum. Those are the three things that a point can own, and everything else is gone.
What about magnetic field? A spinning charge has a current, I would think, and currents produce magnetic fields?
Ah, said John Wheeler, but magnetic fields are transmitted by photons, and photons can’t cross the horizon. So whatever magnetic fields the point has, they never escape the inside of the Black Hole, and to all intents and purposes, we can’t see the magnetic field from outside. If we think of magnetic field lines as “hair” erupting from a bowling ball, then his name for this, –the “no-hair” theorem–makes sense.
So what is this recent paper suggesting?
That something DOES cross the horizon, and that is gravity waves, or gravitons.
This is where I’m lost. If the horizon is determined as the boundary for photons, and nothing travels faster than light, how can gravitons cross the boundary? And if we say, “they don’t, but they skim past and sense the inside field” then what are we saying, that information has no mass? If information has no mass, then there goes Langmuire’s limit on computation and the solution to Maxwell’s demon and thermodynamics. So are we willing to trash thermodynamics to resolve the black hole paradox? Aren’t we just digging the hole deeper?
I would answer that the correct resolution to the paradox is to say that the Black Hole horizon doesn’t exist. That what all these paradoxes reveal is the essential nonsense of a Black Hole horizon. For indeed, every astrophysical object thought to be a black hole has a strong magnetic field, something that Wheeler says should not exist. The astrophysicists argue that the matter falling into a BH or “accretion disk” manufactures the magnetic field external to the hole, but actual models of this mechanism are, shall we say, less than convincing. (Astrophysicists are allergic to magnetic fields, actually, it gives them hives.) But if we reject horizons, we can have as much magnetic field as we want, and a helping of gravity too.
Once again, I’m no theorist, and perhaps they have perfectly valid arguments, but what I sense is that false premises and bad assumptions have been coloring the entire field of Black Holes (and Big Bangs and quasars ) for decades now. Perhaps we should stop patching the creaking model and consider a new one. And if we can’t abandon the hoary model, then ask “Why? Is the reason philosophical or perhaps avarice?”
Some of us can’t help wondering if the sheer philosophical pizzazz of the black hole keeps it going in its present state. A glamorous theory is bound to have a long run.
Rob Sheldon is the author of Genesis: The Long Ascent and The Long Ascent, Volume II
You may also wish to read: A new solution for Hawking’s black hole paradox? “Quantum hair” Let’s wait and see re “quantum hair.” But where, oh, where have we heard the signature tune “more complex than originally thought”? NEVER happens in biology? 😉 Funny how the universe in general is not devolving down into a few simple nothing principles …