[00:00]	Black Holes
[00:42]	Escape Velocity
[05:34]	Black Hole Physics
[10:59]	Pilot & Explorer
[18:19]	Twin Paradox
[26:36]	Lensing
[35:51]	Observing Black Holes
[37:35]	Solar Black Hole
[40:00]	Solar Mass Black Hole
[43:04]	Million Solar Mass Black Hole

Learning Objectives

1. Relate the concept of escape velocity to a black hole (an object whose escape velocity is greater than the speed of light within the event horizon).

2. Visualize a black hole as an object with finite mass, infinite density, and zero size.

3. Understand how the strong increasing gravitational force of a black hole will separate your toes from your nose (due to the differential tidal force).

4. Visualize the consequences of gravitational fields affecting the passage of time.
   • Time passes slower in the presence of a stronger gravitational field.
   • Time is thus a relative quantity - there is no absolute clock keeping correct time.
   • The difference in clock speeds can actually be measured by placing clocks closer to or further from the Earth's surface.

   • A spacecraft approaching the event horizon of a black hole will thus appear to travel slower and slower, from the point of view of a distant observer.
   • A spacecraft approaching the event horizon of a black hole will thus observe the rest of the universe fast-forwarding through the rest of its lifetime, from the point of view of the pilot.

5. Visualize the effect of gravitational lensing on a star field (strong gravity can bend light rays).

6. Understand how a black hole in a binary star system can gain fuel from its companion, creating an accretion disk.

7. Comprehend the consequences of replacing the Sun with a black hole.