- Basics of 4D Spacetime in an animation
 - How fast are you moving?
 - How big is the universe?
 - Why is our visible universe 14B light-years wide while the universe started about 14M light years back?
 - Can you travel faster than speed of light?
 - Sunlight hitting the earth is very old - approx 170,000 years old!
 - How many universes are there? - 0 to infinity predicted by String theory.
 - How will the universe end? - thanks to dark energy
 
1. Understanding 4d space time and the world line https://www.youtube.com/watch?v=ScdLqAA_64E
2. Lorentz transformation https://www.youtube.com/watch?v=aeCsS6PjhK8
3. Gravity and space time - how does it bend? https://www.youtube.com/watch?v=NAXHHBUY9_E