What is Hawking radiation?

The X-ray radiation emitted by material in the accretion disk as it heats up Thermal radiation predicted to be slowly emitted by black holes due to quantum effects near the event horizon, causing them to gradually lose mass Radio waves that escape from a black hole by quantum tunneling The light emitted by Hawking himself when he discovered black holes

Why have we never detected Hawking radiation from a stellar black hole?

Hawking radiation is a theoretical prediction that is now known to be wrong Hawking radiation only comes out of black holes in other galaxies For stellar black holes, Hawking radiation is astronomically faint — the temperature is far too low to detect with current technology Hawking radiation is blocked by the interstellar medium before it reaches Earth

What would eventually happen to a black hole if no more matter fell into it over an extremely long time?

It would remain the same size forever — black holes are eternal It would slowly evaporate through Hawking radiation, eventually disappearing entirely It would eventually explode as a white hole, releasing all trapped matter It would cool down to absolute zero and stop emitting radiation

What is the black hole information paradox?

The fact that we cannot directly observe black holes, making it hard to study their information A contradiction between quantum mechanics (which says information cannot be destroyed) and the apparent loss of information inside a black hole The unsolved problem of how to calculate the size of a black hole from its mass The difficulty of transmitting information through the strong gravitational field near a black hole

What does the equivalence principle say about crossing a black hole's event horizon?

You would be instantly destroyed at the moment you touched the event horizon Time would freeze and you would hover at the event horizon forever You would not feel anything special at the moment you cross the event horizon — it is not a physical surface You would be instantly teleported to the singularity the moment you pass the event horizon

How would gravitational time dilation affect an astronaut falling into a black hole as seen by a distant observer?

The distant observer would see the astronaut accelerate and disappear instantly into the black hole The distant observer would see the astronaut experience a burst of blue light as they cross the event horizon The distant observer would see the astronaut appear to slow down and freeze at the event horizon, never quite crossing it The distant observer would see nothing — the astronaut would become invisible before reaching the event horizon

Why is finding a theory of quantum gravity so important for understanding black holes?

Quantum gravity would allow us to build machines that can enter black holes safely Black holes contain singularities where general relativity breaks down, and only a quantum theory of gravity can describe what actually happens there Quantum gravity would explain why black holes have magnetic fields We need quantum gravity to calculate when the next supernova will form a black hole

What inspired the movie Interstellar, and what black hole science does it depict accurately?

The movie is entirely fictional with no scientific basis The movie was inspired by Kip Thorne's physics research and accurately depicts gravitational time dilation and the appearance of the black hole Gargantua The movie depicted black holes as portals to other universes, which was confirmed correct in 2020 The movie inspired scientists to discover the Hawking radiation that was named after its main character

If a very small primordial black hole (the mass of a mountain) formed in the early universe, what would be happening to it today?

It would still be the same mass — small black holes evaporate more slowly than large ones It would have already grown by collecting interstellar gas into a stellar black hole It would be in its final moments, evaporating rapidly via Hawking radiation and about to explode in a final burst of energy Nothing would be happening to it — primordial black holes are unaffected by Hawking radiation

What is the firewall paradox, and why does it matter?

The fact that black holes generate so much heat that any spacecraft would be destroyed A newer version of the information paradox suggesting that the event horizon might be a violent wall of radiation rather than empty space — in conflict with general relativity The observation that jets from black holes glow as bright as a wall of fire The discovery that magnetar starquakes produce radiation bright enough to see from other galaxies