He does tend to bend the truth to try to trick Alan though.
I'm still not completely convinced that we do know though - it's a bit like saying that you can tell the shape of a forest that you are standing in by knowing the distance and direction to each tree. It's true, but it's a very slow process collecting the data
Also you could accept "c" for the speed of light. :)
Been into astrophysics since I was 8.
Could inflation be accepted for the cosmic expansion one? Of course Big Bang is an acceptable answer but the huge expansion you see when you look at a timeline of the universe in today's models and which you were probsbly referring to) is actually the inflation. It occurred 10^-30s after the Big Bang which is t=0.
And I kind of second the suggestion to accept c for speed of light though it's a boring 1-letter answer, as it is a fundamental constant which would exist even in a world without light, and actually everything (light, the Earth, your dog...) move at that speed in spacetime. The question is, when u set a reference frame, how much is converted into time movement and how much goes to space movement. But speed of light (in vacuum) is correct too.
These are just suggestions. I like this quiz as it is now too.