Black Hole FAQs:

Q: Is a black hole a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it?

A: Yes.

Q: Was a black hole found by Karl Schwarzschild in 1916?

A: Yes, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958.

Q: Were black holes long considered a mathematical curiosity?

A: Yes, it was during the 1960s that theoretical work showed they were a generic prediction of general relativity.

Q: Are black holes found in a class of X-ray binaries called soft X-ray transients?

A: Yes.

Q: Is a black hole very small?

A: Yes, and the radiation effects are expected to become very strong.

Q: Are black holes expected to evaporate even faster?

A: Yes, for example, a black hole of mass 1 TeV/c2 would take less than 10−88 seconds to evaporate completely.

Q: Are black holes not entirely black but emit small amounts of thermal radiation?

A: Yes, this effect has become known as Hawking radiation.

Q: Are black holes expected to shrink and evaporate over time as they lose mass by the emission of photons and other particles?

A: Yes.

Q: Were black holes simple and comprehensible?

A: Yes, and making them respectable subjects for research.

Q: Were black holes physical objects?

A: Yes, and by the end of the 1960s, they had persuaded the majority of researchers in the field that there is no obstacle to the formation of an event horizon.

Q: Is a black hole always approximately spherical?

A: Yes.

Q: Were black holes thought to persist forever this information loss is not that problematic?

A: Yes, as the information can be thought of as existing inside the black hole, inaccessible from the outside.

Q: Are black holes often referred to as Schwarzschild black holes after Karl Schwarzschild who discovered this solution in 1916?

A: Yes.

Q: Is a black hole a volume whose inner boundary is the black hole's oblate spheroid event horizon and a pumpkin-shaped outer boundary?

A: Yes, and which coincides with the event horizon at the poles but noticeably wider around the equator.

Q: Are black holes surrounded by a region of spacetime in which it is impossible to stand still?

A: Yes, and called the ergosphere.

Q: Is a black hole the appearance of an event horizon—a boundary in spacetime through which matter and light can only pass inward towards the mass of the black hole?

A: Yes.

Q: Is a black hole predicted to be very weak and would thus be exceedingly difficult to detect from Earth?

A: Yes.

Q: Are black holes expected to be the gravitational collapse of heavy objects such as stars?

A: Yes, but there are also more exotic processes that can lead to the production of black holes.

Q: Are black holes announced?

A: Yes.

Q: Are black holes expected to be found in most AGN?

A: Yes, and only some galaxies' nuclei have been more carefully studied in attempts to both identify and measure the actual masses of the central supermassive black hole candidates.

Q: Was a black hole reported?

A: Yes.

Q: Is a black hole lost?

A: Yes.

Q: Are black holes much less dense than stellar black holes?

A: Yes, Consequently, the physics of matter forming a supermassive black hole is much better understood and the possible alternative explanations for supermassive black hole observations are much more mundane.

Q: Are black holes described by the Reissner–Nordström metric?

A: Yes, while the Kerr metric describes a non-charged rotating black hole.