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Fahrenheit vs. Celsius vs. Kelvin (i.imgur.com)
submitted 2 years ago by to c/science_memes@mander.xyz
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[–] 73 points 2 years ago (4 children)

Based on human perception, based on water chemistry, based on physics.

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  • [–] 28 points 2 years ago (2 children)

    You'll be shocked to learn that the distance in Kelvin is also adjusted to water "chemistry", albeit changing the aggregate state seems more physics to me, since no molceules are reacting with each other.

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  • [–] 11 points 2 years ago (1 child)

    Thankfully that has been redefined using the Boltzmann constant, so now anyone in the universe can agree on °C and K without needing to measure any Vienna standard ocean water.

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  • [–] 6 points 2 years ago

    I was going to make a joke about how Austria is landlocked, how did we come up with the idea of making an ocean water standard.

    Apparently the IAEA which is headquartered here set that standard, for anyone else curious.

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  • [–] 0 points 2 years ago (1 child)

    You can't change the aggregate state of a single molecule, or how do you mean that? Excluding plasma.

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  • [–] 9 points 2 years ago (1 child)

    you can of a lot of molecules though. and tgat is classically "physics" rather than "chemistry". Classical chemistry is reactiona between atoms or molecules to form new ones.

    If you get deeper into it, the lines between chemistry and physics blur anyways.

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  • [–] 10 points 2 years ago (1 child)

    Zero Fahrenheit is the freezing point of brine (of a certain concentration). That's water chemistry.

    Originally, 90F was based on the average human body temperature, but that later changed to 96F, which just goes to show how arbitrary that scale is.

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  • [–] 9 points 2 years ago (1 child)

    It's all arbitrary. Someone just decided to base a scale off of something and that something isn't fixed from the start. The meter used to be based off the measurement of the earth, but now it's based off of light.

    It's just some random semi-useful starting point that we all agree on so we're using the same language.

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  • [–] 8 points 2 years ago

    The meter did not change, science has merely defined it more precisely and reliably over time. It is a measure of length, still one 40 millionth of the circumference of the earth through the poles. Other definitions like the speed of light definition will give you the same result. These newer definitions have reduced uncertainty and added ways to reproduce its length by natural means. But it's not like the 'original' meter was shorter or longer than today's meter, at least not by any noticeable margin.

    Shifting the top end of a temperature scale by over five percent of the scale is a bit more arbitrary than that.

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