Chapter 24 - 24.5

The astronomer who first worked out the mathematical description of black hole event horizons was

Karl Schwarzschild

What type of main sequence star is most likely to become a black hole?

an O-type star

A handsome, rich, but vain movie star notices that he is starting to age, and consults you as his astronomy expert, to see if you can find an astronomical way to slow down his aging. Putting aside practical considerations (such as the fact that we cannot travel to other stars), which of the following strategies would IN THEORY allow him to age more slowly than the rest of humanity.

he should travel to a black hole, and spend some time in orbit just above the event horizon

To predict whether a star will ultimately become a black hole, what is the key property of the star we should look at?

mass

Wearing a very accurate watch, you volunteer to go on a mission to a black hole in a spaceship that has powerful rockets. You are able to orbit the black hole and stay a little distance outside of the event horizon. Compared to watches on Earth, your watch near the black hole will run:

more slowly

The region around a black hole where everything is trapped, and nothing can get out to interact with the rest of the universe, is called

the event horizon

In the far future, a starship becomes trapped inside the event horizon of a black hole. Although the crew discovers that their ship cannot out, they at least want to send a message to other ships in the area to stay away from the danger zone. If they send out a message in the form of a radio wave, what will be its fate?

the message will never emerge from the event horizon

Which of the following can a black hole not "eat" (swallow)?

you can't fool me, black holes can eat anything

Suppose each of the following objects could collapse into a black hole. Each black hole would have a sphere around it that is the limit for escape -- once you are inside this region, you cannot get away. For which object would this region be the largest in diameter?

an entire galaxy of stars (with about a billion stars in it)

When scientists say that "black holes have no hair", what do they mean?

that once a black hole forms, very little information can be extracted from it about the material that is now inside

Deep inside a black hole (and hidden from our view) is the compressed center, where all the "stuff" of the star goes. Astronomer call this central point

a singularity

Once a black hole forms, the size of its event horizon is determined only by

the mass inside the event horizon