Guess what burns 4 million tonnes of stuff per second?

The sun. Well, it’s not really burning I suppose. Still, it’s an incredible number: and ever-so-slightly worrying, in a totally irrational kind of way. This and more from a fascinating episode of Horizon, which you can view until the silly DRM kills it, here. (Hat tip to Simon) Certainly the most amusing thing in the programme was the predictions, following the vein of a long standing joke: that fusion power is always 50 years away. At the end of the show, they had all the contributors give their estimate for when fusion power will finally happen. They averaged out at 23 years, so I guess we should update the joke. That is, unless we started telling the joke in 1982, in which case it becomes a meta-joke, which would be pretty cool in itself…