Okay so I’ve read a black hole can have a charge, and I’ve read in quantum mechanics forces are transmitted by virtual partials.
How does a force carrying particle escape a black hole? Seems like if it has charge then it has to be releasing virtual particles? How?
Virtual particles are not constrained by the speed of light and can therefore ignore the horizon and escape the hole.
The pithy answer is that while “real” particles can’t travel faster than light (and thus can’t escape a black hole), “virtual” particles can travel faster than light (and so can influence things outside of the black hole).
And this isn’t a problem with any of the laws of physics because virtual particles can’t carry any information about the interior of the hole. Or at least, no interesting information: All you can learn is the hole’s mass, electric charge, magnetic charge, and angular momentum.
Thanks. I wasn’t quite expecting that answer. The universe is a weird place.
So this means an electromagnetic, that fell beyond the event horizon, could transmit information to the outside universe?
Followup question - would a graviton be a virtual particle or a real particle??
Nope. Electromagnetic effects are mediated by photons, which are limited to the speed of light, else we’d be able to get information about what’s inside a black hole by looking at it in an appropriate waveband.
The “nothing can travel faster than the speed of light” paraphrase is a bit misleading actually – its more accurate to say that information cannot be transmitted faster than the speed of light in a vacuum.
No. Read Chronos’ post.
Either. But the force mediating particle would be virtual.
EM interactions are mediated by virtual photons. Read Chronos post.
Apologies. But, speaking as an observer, we still can’t get information about the interior of a black hole.
Wait so being virtual photons they are therefore photons that can escape transmitting charge information?
If so that brings back the question of if you have a charge you can turn off or on, Say an electrically chargeable plate, why couldn’t you use that to transmit information through the event horizon?
Charge is conserved, and the charges (being “real” particles rather than virtual particles) have to stay inside the black hole. In other words, the charge of the black hole can’t change — there’s no such thing as a charge you can “turn on and off”.
You can’t have a charge you can turn off or on. If you put a positive charge on one electrode in an experiment, you must necessarily put a negative charge on something else, and the net charge of your apparatus remains the same. But the only information you can get from the virtual photons in the vicinity of a black hole is the net charge of the hole.
nvm
So the entire contents are blurred together? I couldn’t travel around the event horizon and go “well there’s something negative, and here something positive here?”
That’s why we call black holes “singularities.” As far as we can tell from outside, there’s nothing there but a single point of mass with infinite density, uniform distribution of charge, etc.
Now… it’s possible there’s something much more complicated going on inside, but not only do we not know, but it’s entirely possible there is no way to know.
Hmm… as I have no time to look up the likely literature on the subject, I’d be interested in hearing insight on the time evolution of the electric dipole moment of an inspiraling black hole binary system involving two oppositely charged holes (which is directly related to the OPs most recent post, so I figure it isn’t a hijack). The system has a measurable EDM at some point, and then it doesn’t at some time in the future. Is there ever a time when there is only one topologically connected event horizon yet there remains a non-zero EDM? Or, must the EDM vanish prior to this? (Surely the latter, but the dynamics of this transition seem like they could be interesting.)
As I understand it, Just for uncharged holes, the solution would have to account for the gravitational radiation, the inspiraling, and the coalescing.
I’m almost positive this can’t be solved analytically and hasn’t yet been solved numerically. However I don’t know much, and hope Chronos comes along shortly.
Strictly speaking, the no-hair theorem doesn’t state that a black hole can have no hair, but that it can’t keep it, or more specifically that any distinguishing traits a black hole might have other than mass, electric charge, magnetic charge, and angular momentum must exponentially decay on a timescale proportional to the black hole’s mass. There does exist a short window in which the two holes would be merged (in the sense that the event horizon is topologically a sphere) but yet there is still an electric dipole moment. I’m pretty sure, though, that the evolution of that dipole moment would be deterministically determined by the behavior of the charges prior to the time of merger, and so could still not transmit information from the inside.
Oh, and while merging black holes can’t be solved analytically, there’s been some truly phenomenal work done in the numerical modeling in the past few years, and it can be done now at least for simple cases (I don’t think anyone’s done it for charged holes, but that’s mostly because there’s little motivation for it, since black holes in nature are expected to have effectively zero charge). What’s really relevant here, though, are the semi-analytic calculations of black hole ringdown, which have been solved for decades (it’s basically just a spherical-harmonic expansion of a damped oscillating shell).