What, or when, would aliens see, if they looked at the earth?
Answers to Physics Questions
Physics, cosmology, astrophysics, electricity, energy, forces, gravity, light and maths...
04 December 2011
27 November 2011
Why couldn't I focus on a reflection when close to the mirror?
25 October 2011
Why do sunbeams appear to spread out?
16 October 2011
If it takes a very massive star collapsing to form a black hole, and Hawking radiation eats it away, then why doesn...