We mentioned that astronauts can tell whether they are in outer space or “falling around Earth” by observing a drop of water in the corner of their spacecraft. What are the tidal forces that were...

We mentioned that astronauts can tell whether they are in outer space or “falling around Earth” by observing a drop of water in the corner of their spacecraft.

What are the tidal forces that were mentioned, and where do they come from? Why are they called “tidal” on Earth?

Why can we conclude from Equation (15.1) that the inertial and gravitational masses are equal?

 Explain why it’s expected that primordial black holes should not last for a long time before evaporating completely. Why is the last part of such a black hole’s lifetime described in the text as comparable to numerous hydrogen bomb explosions?