About this blog

Physics can be difficult to learn, but this blog aims to help you get into physics by connecting your GCSE physics lessons with things you see in the world around you.

Tuesday, 17 January 2012

Absolute Zero

You might think that it’s been pretty cold the past few days, especially compared to the warm wintry days we’ve been experiencing recently, but what’s the coldest weather you’ve ever felt?

I’ve probably been in around -10°C, possibly a little colder, although not usually being in the habit of carrying a thermometer with me I can’t say for absolute certain. Most of us, unless we visit the Arctic or climb Mt Everest won’t get the chance to be really really cold, like -40°C.

And yet, there’s still colder, so cold that there’s another temperature scale to make it easier to understand and write about. In the UK we usually use Centigrade to measure temperature, although the older generation often prefer Fahrenheit. These have a complicated relationship and it’s hard to translate one into the other in your head.

The Kelvin scale (symbol °K) starts at absolute zero, the coldest possible temperature, at which even atoms stop their constant vibrations. It’s the same as the Centigrade scale but starts at -273°C. We’ve (well, not me personally, scientists ) managed to measure to within 0.000000000000001 degrees of absolute zero, which is pretty close in my book!

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