I gave a 20-minute talk last Thursday – a Christmas talk about candles. As usual with these things, I started out knowing a little, but the process of preparing the talk involved learning lots of interesting things. And then not mentioning them.
I spoke to colleagues all over NPL to ask for help: one lent me a precision balance to weigh a candle as it burned, and another built me a device to power an electric torch from a candle! I thought that was very cool.
When I asked my colleagues in the optical team about measuring the spectrum of light from a candle their eyes lit up and I could barely stop them talking – they knew so much.
After lending me a spectrometer, they mentioned that they had an old ‘standard candle’ in their office. In the ‘old days’ it was a candle such as the one in the picture at the top that formed humanity’s standard for ‘an amount of light’.
And even though our modern standard – the candela – is defined quite differently, its magnitude can still be linked back to the amount of light given off by a standard candle.
Gazing at the candle I was astounded. Had a whale really been killed in order to make this candle? The answer was ‘Yes’: I felt like I was holding ivory in my hands.
The idea that we would kill whales in order to extract oil and make candles is now so bonkers that we can hardly credit it. And this made me feel a little better.
It made me realise how desperate people must have been for light, and that for all its faults, our civilisation has now all but solved this problem. And that made me smile – and momentarily reflect on the brighter side of humanity’s adventure with energy.