Question

place the effects associated with stellar black holes into the appropriate category. which would be experienced by an astronaut carrying a clock and a blue - light flashlight while falling into a black hole? which would be observed by someone watching from a safe distance?
answer bank
astronaut would never cross the event horizon
astronaut crosses event horizon
flashlights color would remain blue
astronauts clock would slow down

Explanation:

From the perspective of the astronaut falling into the black - hole, they would cross the event horizon and their clock would not seem to slow down relative to their own frame of reference, and the color of their flashlight would remain blue relative to them. From the perspective of an observer at a safe distance, due to time - dilation effects predicted by general relativity, the astronaut would appear to never cross the event horizon and the astronaut's clock would slow down. Also, the light from the flashlight would experience gravitational redshift and not remain blue.

Answer:

Astronaut: astronaut crosses event horizon, flashlight's color would remain blue
Observer: astronaut would never cross the event horizon, astronaut's clock would slow down