Eli5 Why 80 degree Celsius is not four times as hot as 20 degrees celsius?

Question

Eli5 Why 80 degree Celsius is not four times as hot as 20 degrees celsius?

In: 0

Answer 1

in order to say something is “4 times as X” as something else, that scale MUST have a true zero point. That means, the 0 has to mean “nothing”. So you can say $4 is 4 times as much as $1 since $0 is “no money at all”.

But in degrees celsius, 0 isn’t nothing, it can and does go below 0, so ratios are meaningless. No multiplying or dividing. You can only add or subtract. 80 degrees is 60 degrees hotter than 20, but it is not 4 times as hot.

You could however say that on the Kelvin scale, since 0 Kelvin IS a true zero point.