Temperature – Sunday 10th December, 2023

It’s wet and its cold. We swaddle up to keep the heat in. We tell each other it is close to zero. That is the Celsius scale, formally known as Centigrade. The scale was invented by the Swedish Astronomer, Anders Celsius in 1742. 0ºC is the freezing point of water and 100ºC its boiling point. These keys points crop up all the time as water is so important to us. We drink it, bathe in it, cook with it, wash our clothes with it, water our plants, make new chemicals, there’s hardly a process that doesn’t include water somewhere along the line. Our bodies are 60% water, it is essential for life on earth and we are searching for it on Mars as a sign of former life. The Celsius scale is used all over the world, especially in scientific laboratories. This is not so in the USA where Fahrenheit is still the scale used by everyone, except among scientists.

Until recently, the public in the UK used the Fahrenheit scale too. We have slowly jettisoned it; the Met Office began quoting Celsius first in 1962, with Fahrenheit second, but then dropping the latter.  Fahrenheit remained the scale in popular use until the BBC dropped it around 2015. Other channels did the same, so we had no choice but get used to it.

The Fahrenheit scale is an unwieldy scale. It was proposed by a Dutch man, Daniel Gabriel Fahrenheit in 1724, It has the freezing point of water at 32ºF and its boiling point at 212ºF. How come, you might well ask. He tried to avoid minus temperatures, so his 0ºF was the coldest temperature that Fahrenheit could get, using a mixture of ice and brine.

If you need to convert from one to the other, well 1 degree Celsius is 1.8 degrees Fahrenheit. There are a few convenient points. 10ºC is 50ºF, 20ºC is 68ºF. But a popular quiz question is when are they both equal? You are utterly frozen in Celsius and Fahrenheit at – 40º, the only point where both scales agree.

In theory, the coldest temperature possible is -273.15ºC. This is absolute zero. At this temperature everything is solid, atomic vibration is at its minimum and no more heat can be withdrawn. The Kelvin scale has absolute zero as 0ºK. The freezing point of water on this scale is 273.15ºK. Nowhere in the Universe is absolute zero, though. Even outer space is a few degrees above it (average 2.73ºK). We cannot achieve absolute zero. Consider, how any device trying to create the temperature is heating the substrate up. Though, we have got to within a millionth of a degree. At great expense.

The plane tree on Earlham Grove outside the garden has been pruned. When I was working for the parks, they called it knuckling, when all the twigs are cut off to leave a bruised knuckle. Or a gargoyle, each at the end of their branch, impish and evil. I am sure they would eat each other if they could reach on their elongated necks. All the way up Earlham, there are gaggles of gargoyles. Hold onto you head as you walk past.

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