![How many calories are there in a brain? - podcast episode cover](http://ichef.bbci.co.uk/images/ic/3000x3000/p0d8lrz7.jpg)
Episode description
The mailbag was bulging, so we dived in to answer your science questions this week.
Including how many calories you'd find in a human brain, why methane's a worse greenhouse gas than CO2, and the claim that MI5 phoned up the makers of a James Bond movie for advice on making a special agent gadget.