44:32

Time Wars & Alternate Timelines

34:24

Lost Space Colonies

42:05

The Fermi Paradox: Searching For Dyson Spheres

35:55

Stargates

30:20

Using Asteroids As Spaceships

45:41

The Fermi Paradox: Absent Megastructures

2:32:23

What Is Reality?

34:27

Mega-Cities