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

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

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Anonymous 0 Comments

Because the true zero point is at -273°C. 0°C is just a random point chosen for convenience.

So if you double the true absolute temperature (wich is measured in Kelvin) at 0°C you get 273°C.

In Kelvin the temperature is a direct measure of how much energy there is. 0K would mean absolutely no energy (but that’s impossible to reach)

Anonymous 0 Comments

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Anonymous 0 Comments

I’m not a maths person. The difference between 20 and 80 is 60, so, isn’t it fair to say it’s 3 times hotter, not 4?

Anonymous 0 Comments

Because we chose an arbitrary point to be zero. The freezing point of water.

If 0C was the coldest thing anything could possibly be, then 80C would be 4x hotter than 20C. But we know that the real zero (absolute zero) is 0Kelvin or -273.15 Celsius. Your example in Kelvin (which has the same degrees as Celsius but with a different starting point) would be 353K vs 293K

Anonymous 0 Comments

Celsius scale (and Farenheit, btw) does not measure absolute temperature. Both scales use an arbitrary point as zero. Kelvin (and Rankine) take the zero as the state of the lowest energy possible, therefore, it makes no sense to speak of negative temperatures. With this scales, you actually have that 20K is twice as hot as 10K. Given the example you’ve chosen, we’d have 80ºC=353K and 20ºC=293K, so their quotient would be roughly 1.21, just 21% hotter

Anonymous 0 Comments

I believe that 0 c is freezing point of water so not really arbitrary. Fahrenheit on the other hand seems very arbitrary to me

Anonymous 0 Comments

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.

Anonymous 0 Comments

Because 0 degrees Celsius is not “zero temperature”.

The actual coldest possible temperature is -273 Celsius (yes I’m ignoring the decimals on this number).

As an example, -233 Celsius is 40 degrees warmer than zero temp, and -253 Celsius is 20 degrees warmer than zero temp, so -233 is twice as hot as -253.

This scale, with 0 = actual zero temperature is called Kelvin, and it’s used in science because twice as big a number *does* mean twice as hot.

With Celsius, the degrees are the same size, we just chose to pick 273 Kelvin = 0 Celsius because:

1. It gives nice small workable numbers in the range of temps humans often work with (rather than every temp number you encounter in daily life being in the hundreds), and
2. It’s repeatable and reproducible. 0 Celsius is the freezing point of water, so even long ago all you needed was a bowl of ice water and anyone can calibrate temperatures and thermometers to exactly 0 C.

Anonymous 0 Comments

Celsius has 100 degrees between the ice point (0 C, 32 F) and the steam point (100 C, 212 F).

Fahrenheit has 180 degrees between the same two points.

Those two points are 273.15 K and 373.15 K.

80 C is 353.15 K; 20 C is 293.15 K.