**Pi for all**

Here’s an extract from an article I wrote for New Scientist in honour of Pi Day today.

The stars overhead inspired the ancient Greeks, but they probably never used them to calculate pi. Robert Matthews of the University of Aston in Birmingham, UK, combined astronomical data with number theory to do just that.

Matthews used the fact that for any large collection of random numbers, the probability that any two have no common factor is 6/pi2. Numbers have a common factor if they are divisible by the same number, not including 1. For example, 4 and 15 have no common factors, but 12 and 15 have the common factor 3.

Matthews calculated the angular distance between the 100 brightest stars in the sky and turned them into 1 million pairs of random numbers, around 61 per cent of which had no common factors. He got a value for pi of 3.12772, which is about 99.6 per cent correct.

**A serious science survey?**

The BBC reports that one in 10 children believe the Queen invented the telephone, while others suggest Charles Darwin and Noel Edmonds. The results come from a survey of 1,000 school kids, but rather than despairing at the state of science education, I’m actually amused by this story.

These types of articles seem to crop up fairly often, with children giving nonsensical answers to questions about historical facts. Everyone always interrupts them fairly seriously, but I think it’s far more likely that the kids are just having a laugh.

**High-gravity lava lamps**

Would a lava lamp work on Jupiter? There’s only one way to find out – build a giant, semi-lethal centrifuge out of Meccano, and take your lamp for a spin:

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