6 ms·
Outside observers never see the material cross the horizon, ever. That's why it's called a horizon, you'll never reach it (from the pov of an outside observer).
by Chabs 8y ago
Outside observers never see the material cross the horizon, ever. That's why it's called a horizon, you'll never reach it (from the pov of an outside observer).
Growth-wise, you have to keep in mind that the black hole doesn't grow when matter crosses the horizon, but when the matter gets close enough to the horizon that mass of black hole + mass of new matter creates a blackhole of a larger radius that encompasses that matter.
- doombolt 8y agoHow would you ever observe black hole to grow/accreate matter then?
- qubex 8y agoInfalling matter or radiation becomes ‘simply’ infinitely red-shifted (on account of the slowed time), and hence undetectable to an external observer — and is hence indistinguishable from the bulk of the prior-existing “black hole proper”.
- mcbits 8y agoConversely, a particle on the surface of an object compressed to near its Schwarzschild radius should experience an extreme blue shift and time contraction. Imagine absorbing in one instant a billion years of microwave background radiation blue shifted to gamma and beyond. How could the near-black-hole hang onto it?
- Already__Taken 8y agoInside of a black hole doesn't hang on to anything. There is simply no longer a direction that points out.
- qubex 8y agoYeah... basically looking backwards from the perspective of an infalling particle one would experience the full blast of the Big Bang as it occurred ‘originally’.
- doombolt 8y agoYes, it is indistinguishable. But it seems that actual black hole is more like a hollow crust in this setting and not a point of mass.
- pitaj 8y agoYou can indirectly measure it's mass, charge, and angular momentum.
- takk309 8y agoWould this be one way that information would not be destroyed, at least from the reference frame of the outside observer?
- 0898 8y agoQuestion if you don't mind. This "information being destroyed" thing. What do they mean by information? Isn't information a human construct? How is the universe supposed to know what information is?
- Chabs 8y agoLong answer short: Information has to be a fundamental conserved property of the universe for the second law of thermodynamics to work under some thought experiments.
- takk309 8y agoFrom my limited understanding information is meant to mean the characteristics of a given particle; the waveform, spin, etc.
- ComputerGuru 8y agohttps://en.m.wikipedia.org/wiki/Physical_information https://en.m.wikipedia.org/wiki/Physical_information See especially the section on entropy.
- knodi123 8y agoA fun way to imagine it is with Maxwell's Demon. https://en.wikipedia.org/wiki/Maxwell%27s_demon https://en.wikipedia.org/wiki/Maxwell%27s_demon That is an example of one way in which information can be exchanged for work.
- smogcutter 8y agoThis is me being dense, but I don't see the connection to parent's question. Is it that the demon uses information (the speed of the particles?) to perform work (decrease entropy)? But also not really, bc that would violate the 2nd law of thermodynamics? I understood parent's question to be what the heck does "information" mean in this context to begin with. My question too, because I'm pretty sure I've got the wrong answer myself.