Weighing global matter over lunch Here’s an interesting example of the power of estimation. Anyone can calculate the Earth’s weight, approximately, sitting in a chair without recourse to a computer, or even paper. It’s a good lunchtime exercise. We just need a few rough facts: the volume of a sphere is about 4 times its…

In early December, followers of BBC news will have seen David Shukman’s reports from the U.N’s 24th Climate Change Conference in Poland.  The reports showed Polish coal miners hard at work and smoke from power station chimneys billowing into the air.  They emphasized the irony of a climate conference taking place in a country wedded…