this post was submitted on 03 Mar 2024
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Showerthoughts
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Technically yes and no. Kevin is absolute temperature, since the offset is zero it measures the total temperature. Celsius is relative, since the offset places its zero at a conventionally useful place it measures deviation from that baseline. That's why you have temperatures always in K and never °K, but always in °C and never just C. But yes, the sizes of the units are the same.
Kelvin and Celsius can both be used interchangeably and you can always get the same answer every time using either; they are equally as precise. So is fehrenheit for that matter, although the conversion would get even more complicated.
It's just usually using the one with zero offset makes the math easier, which is why it tends to be the one used for scientific calculations.
When the measurement being used is ∆T, change in temperature, this is correct. Occasionally, like in the ideal gas law equation, the measurement is T, or absolute temperature, which requires zero offset. In these cases, Celsius will give the wrong answer.
As I said
You can use Celsius in the ideal gas law. You just have to make sure to include the offset in your calculation. There is no loss of precision by using Celsius, and it isn't wrong. It's just the math is easier if you use kelvin, because as you point out (in this case) it's the ratio of the absolute T that's important, and a delta T is not enough.
By including the offset in the calculation, you have converted to kelvin.
Yes, as I said repeatedly, the math is easier which is the reason. If you didn't include the offset in the calculations, you wouldn't lose precision, you'd just be wrong.
I'm at a loss as to what you don't understand.
I suspect you may have mistaken me for the first poster in this comment chain. I never disagreed with your statement that precision is not a factor, I was clarifying only that they are not totally interchangeable. Interchangeable in relative measure yes, easy to convert in absolute measure yes, equally precise yes, but they are different things, albeit extremely similar.
I literally used the term precision in every post, it's what my initial is about, and you're just now telling me that's not what you were talking about? Also my first post I did not say they were perfectly interchangeable, I pointed out there is no loss of precision, and explicitly noted that you have to include the offset.
So now I'm confused as to why you chimed in at all.
No? I said as much in my very first comment.
And technically, that's only the case as of 2019, when Celsius was decoupled from the properties of water. Before that, kelvin was more precise, since it did not depend on controlling for pressure. Before 2019, there were precision discrepancies between K and °C.