Celsius Didn’t Invent Celsius

>>DEREK: How did Celsius define his scale?>>MICHAEL: Uh… He took the temperature water freezes at and said that’s zero and then he took the temperature it boils at and says that’s a
hundred. And he figured a hundred was a good amount of demarcations to make in between the two. Right?>>DEREK: Yeah. Except that’s not what he did.
>>MICHAEL: Really?>>DEREK: Celsius never devised nor used the scale that now bears his name.>>MICHAEL: Are you kidding me?
>>DEREK: No, Michael, I’m not! This is the Swedish town of Uppsala,
located 70 kilometers north of Stockholm. So this is the house where Celsius lived.
In 1741 he was professor of astronomy at Uppsala University. And this is the
first ever Celsius thermometer… or is it?>>This is the first scale of Anders Celsius
added onto… or, added onto an old thermometer. So we have Delisle’ scale on the left
hand side and Celsius’ new scale in the right.>>DEREK: These few markings show that Celsius came up with the idea of separating the freezing and
boiling points of water by 100 degrees. He made his first observations with the
scale on Christmas Day 1741. But have you noticed something strange about this scale? I mean, 50 is marked in the middle but
the numbers increase down towards the bulb of the thermometer. So, Celsius had
his scale upside down. He set zero degrees at the boiling
point of water and a hundred at the freezing point. Why would he do this? Well, for one thing Celsius was just following the
convention of the other scale on the thermometer. Delisle’ scale also had
zero degrees for the boiling point of water increasing down to 150 for his
freezing point. And a likely reason both of them used upside down scales is
because they avoid negative numbers. In Sweden it gets much colder than freezing
but never warmer than boiling water so you don’t have to worry about pesky
minus signs and this helps avoid logbook errors. I think it would be really weird if you
had water boiling zero degrees and freezing at a hundred.
Wouldn’t that be strange? Although it might seem strange today,
there is no objectively good reason for preferring an ascending scale over a
descending one for measuring degrees of something, like hot or cold. In fact, when Celsius died of
tuberculosis in 1744, he was still using this inverted scale. So who reversed it? Who do we have to
thank for the modern Celsius temperature scale? Well in 1745, just a year after Celsius’
death a new column appears in the Uppsala
temperature record using the modern scale and at the top it’s got the
heading “Ekström” Now Ekström was the instrument maker at Uppsala. In 1747
another column is added with the heading Strömer who was Celsius’ successor
as professor of astronomy. Again, it’s got the same modern scale. But it’s another professor at Uppsala who claims that he reversed the scale: That’s the famous biologist Carl
Linnaeus. He says he reversed the scale when he ordered a thermometer from
Ekström for his greenhouse. Whoever it was, we know that by 1745
there was an operational thermometer at Uppsala University with a scale that we
now all know as the Celsius temperature scale. Except… this was not the first such
thermometer ever created. In 1743 the year before Celsius died, a French
scientist working independently in Lyon created a thermometer with zero degrees
at the freezing point of water and a hundred at the boiling point. his name was Jeane Pierre Christin.
So why isn’t it called a degree Christin instead of a degrees Celsius? Well, for a long time this temperature
scale wasn’t referred to using either of their names and instead it was just
called the “centigrade scale,” meaning a hundred steps. The problem with this was “centigrade”
has other meanings in French, Spanish and Italian, where a grade specifically
refers to one one-hundredth of a right angle. So to eliminate this confusion the
International Bureau of Weights and Measures in 1948 decided to rename the
centigrade scale after a scientist bringing it into alignment with other
temperature scales like Kelvin and Fahrenheit. They chose Celsius
possibly due to a popular 1800’s German chemistry textbook by a guy named Berzelius. In it, Berzelius identified Celsius as the first to devise a
temperature scale with zero at water’s freezing point and a hundred at its
boiling point propagating the myth that Celsius created this scale. So is Celsius
undeserving of having his name immortalized on weather maps around the world? Well, no. I mean making two marks and
deciding on a number of degrees in between them that is the easy part which
others could, and as history shows, did do… but what Celsius did was he established
which physical processes could reliably produce a fixed temperature. At the time
when he was working, there were some 30 different temperature scales in use. Some
thermometers had 18 different scales on them, some more reliable than others. For
fixed reference points one scale used the deepest cellar of the Paris observatory, others used the melting temperature of
butter, the internal temperatures of certain animals, or the hottest day in
summer in Italy, Syria or Senegal. These dubious scales combined, with
inconsistent thermometer construction made recording accurate temperatures
nearly impossible, not to mention sharing those temperatures with other scientists
elsewhere. Celsius solved this problem in a number of ways: he demonstrated that
melting snow maintains a fixed temperature regardless of latitude or ambient
pressure. He also determined the precise relationship between boiling point of
water and the ambient pressure, so that thermometers could be calibrated under
any conditions. He made it possible to establish a
universal reliable system of temperature measurement and this is why Celsius’ name is a unit of temperature, even though the scale itself was not created
by him and in fact today the Celsius scale is no longer defined by either of
water’s phase transition points, instead it is based off the Kelvin scale and
that scale is defined by setting the triple point of water, where solid, liquid, and gas all exist in
equilibrium at exactly 273.16 Kelvin. This fixes the size of a degree Kelvin,
which is exactly the same as the size of a degree Celsius. The zero point of the
Celsius scale is set a 273.15 Kelvin. And what all this means
is that today pure water boils at 99.974 degrees Celsius and freezes at negative 0.0001 Celsius. This precision in a
nearly universal system of temperature measurement is thanks to a huge number
of scientists so the C after the degree symbol
stands not only for Celsius or Christin or Carl Linnaeus, but for the community
of scientists whose work over centuries made a scale so robust that we take it
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99 thoughts on “Celsius Didn’t Invent Celsius

  1. 4:11: The "German" textbook was indeed printed in Germany, but was written by Jöns Jacob Berzelius, a Swede (born in Sweden, dead in Sweden, and of Swedish ancestry). The language of Swedish simply has never been much of a world language (irony). Swedes have always had to adapt to the languages of greater powers when they have written scientific texts to be considered outside of the Nordics — Latin, French, German, and English, depending on the time.

  2. Your videos are so entertaining and well made! I've been watching your channel for a while now but first time commenting on one! Blessings!

  3. this video taught me that centigrade is actually not the name anymore. Always figured it was interchangeable or the long-form version of Celsius.

  4. If any one of my teachers in high school was nearly as good as Veriasium is, then maybe i could be a good student too.

  5. Actuallty in Turkey it is still called centigrade degrees except in universities which calls it as it was in SI conversion system

  6. But wait –
    water doesn't always boil
    at 100 C. The scale clearly
    begins breaking
    with sufficient reduction
    in atmospheric pressure.


  7. How about donating the Patreon money to someone that actually needs it, for instance cancer research, or any number of diseases, for spinalchord injuries, for victims of natural disasters, something that is above selfish reasons, I'd definitely donate to that.

  8. Only Americans call them “degrees Celsius” in my experience. I grew up in Italy and the UK, centigradi and centigrade. No celsi or Celsius.

  9. Actually, in italian "grado" doesn't mean a hundredth of a right angle (that'd be silly). "Grado" simply means degree, both in the geometric and thermic sense, and almost everyone (except academics) usally says "grado centigrado", centigrade degree, to refer to Celsius degrees.

    Not that big of a deal, but we don't wanna have people believing us italians have a name for 0.9 degrees.
    The US, on the other hand…

  10. Just to be clear, the freezing point of water is not independent of pressure. However, under normal conditions it basically is. This independence only breaks down at very low pressures, where water starts to vaporize/sublimate at low temperatures and cannot be a liquid, and very high pressures where water can be solidified above its typical freezing point. Though interestingly, if you look at a water phase diagram, there is a blip between 10 MPa and 251 MPa where increasing pressure actually lowers the freezing point.

  11. Yo know what’s funny ? You say they changed centigrade to Celsius because of the Latin languages, yet in spanish we still use “centígrado” as a the temperature reading. Lol I always translate from English to spanish when speaking to visiting family and I would say Celsius and forget they don’t call it that lol.

  12. Sooooo both Farenheit AND Celsius just could not grasp the idea of negative numbers. I guess positive thinking is way older than people are inclined to believe…

  13. 3:54 wow srsly? Did they do it for that? Lol I mean nowadays in Italy we call it a "grado centigrado" (centigrade degree, i think) lol

  14. 4:17 This J. Jacob Berzelius of the German text book was a Swede, considered one of the four founders of modern chemistry. He just used to publish in German, English was not the universal lingua franca at that time. If he favoured a Swede, that might be just a way to fuss to a colleague professor.

  15. Is the point of this video that Carl von Linné flipped the scale? I thought this was basic knowledge. I'm going to watch the video now and we'll see.

  16. One of the best. Thank you, from a rarely used portion of my heart. Honest, well meaning, and nice to listen to.

  17. "…made a scale so robust that we take it for granted, unless you're in the comment section of a video on YouTube about why America doesn't use Celsius, and a heap of Americans take offence, using some rather flaccid arguments, getting super defensive, as they feel their rights and freedoms are being attacked, when, in reality, no one really cares, as both scales work perfectly well, and America kind of does use the Celsius scale anyway, then though many of them don't know it."

  18. Its fun to hear how you spell swedish words like uppsala, and its not to far away from the actual spelling

  19. You implied 0C and 100C "could be calibrated under any conditions at ambient pressures" . Clearly ambient pressures vary as a barometer demonstrates. You should have said: Celsius is calibrated at the mean barometric pressure at mean sea level.

  20. Hum, pure water doesn't freeze at 0C (or 0.001), I guess it does melt at 0C however. To freeze at 0, it needs some impurities to start the process.
    (all at 1atm pressure)

  21. 6:12 the triple point of water is shown as 273.16K which is 1/100th of a degree from the freezing point of water which is shown as 273.15K 6:22. Why is the triple point of water (273.16K) 1/100th of a degree warmer than 0C in Kelvin (273.15K) ? I thought they would be the same.
    Could someone who understands this stuff chime in with an explanation please.

  22. Wowowowowo, so, they change the name from Centigrade (Centígrados, in Spanish) to Celsius, because Franch and Spanish and other lenguages use already that word, but here, in Spain, we use more oftem "Centígrados" than "Celsius :v

  23. It’s a shame that the country you’re from doesn’t use this easy system, you have to be awkward and use Fahrenheit instead.

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