## Thursday, July 15, 2010

### David Gross gives fine answers to 24 questions

The Nobel Prize foundation has simply convinced Gross - by various tools - to spend about 3 minutes on each question. Here are the answers:

The playlist has 25 entries or so. Click the tape in the left lower corner to choose another element of the playlist if one of them fails or if you find it boring. I've rearranged the original playlist so that it plays at the beginning.

I would say many things almost equally but not all of them. For example, when David is asked "How big is space?", he answers that the observable one is 13.7 billion light years in radius. However, that's wrong.

The age is 13.7 billion years but the most distant places we see are actually showing how they looked like in the past when their distance was smaller. So the most distant objects, as we see them, were actually not as much as 13.7 billion light years away from us but much closer.

Alternatively, you may ask where the most distant objects that we observe (in their past state) are today, according to the "cosmic time" (even though we don't yet see what they're doing today). But in these conventions, the radius of the visible Universe is actually 46.5 billion light years, about 3 times more than 13.7 billion light years!