Question

A black hole is so named because

A) no light or other electromagnetic radiation can escape from inside it.
B) its electromagnetic radiation is gravitationally redshifted to the infrared, leaving no light in the optical region.
C) it emits a perfect blackbody spectrum.
D) it is colder than the rest of the universe; that is, its effective temperature is less than 3 K.

Answer 1

A black hole is so named because no light or other electromagnetic radiation can escape from inside it.

Step-by-step explanation:

A black hole is so named because no light or other electromagnetic radiation can escape from inside it. Bodies, like the Earth or the Sun, have what is called an escape velocity. If an object moves straight up from the body, starting at the escape velocity, it will just be able to escape the gravity of the body. However, if the escape velocity is greater than the speed of light, then light cannot escape, which is the case for black holes.