6 ms·

Feynman was complaining about this error appearing in textbooks back in the sixties[0]. The trouble (of course) is that Celsius properly is not a proper unit,

by Y_Y 1y ago

Feynman was complaining about this error appearing in textbooks back in the sixties[0]. The trouble (of course) is that Celsius properly is not a proper unit, but a "scale", or a "unit of difference" (equal to kelvin), or even torsor[1]. The trouble with the kelvin here is that if you see the 7 kelvin increase as a proportion of the 295K starting temperature the you only get a 2% increase. Nobody is going to buy your newspaper if you're putting up weak numbers like that. [0] https://mathematicalcrap.com/2024/03/05/the-feynman-story/ https://mathematicalcrap.com/2024/03/05/the-feynman-story/ [1] https://math.ucr.edu/home/baez/torsors.html https://math.ucr.edu/home/baez/torsors.html

azernik 1y ago
Then just don't use percentages, and rely on people realizing that a 7 degree difference is big!
buran77 1y ago
To make matters worse, not all ranges and percentages on that scale are equal, whether they're the same in absolute or relative terms. Humans have a narrow relevant "operational" temperature band. Even 20 degrees between 10-30C feel like nothing compared to the 5 degrees between 37-42C.
- hnlmorg 1y ago
  You’re right in principle but that’s probably the worst example you could have given. So bad an example that I think it could easily be argued to disprove your point.
  - deleted 1y ago
    [deleted]
  - paganel 1y ago
    For us people not living in Arabia or South Texas the difference between 37 and 42 Celsius is indeed quite important. 37 feels pretty hot, but yet livable, while 42 (and even 40 for me) means that nothing non-urgent should bring me out of the house.
    - pdpi 1y ago
      And, inversely, the five degree drop from, say, 3C to -2C represents means water can and will freeze, which is another massive change in livability.
      - nkoren 1y ago
        Indeed. At 3C in London, the humidity seeps into every pore and settles into your bones. Riding a bike at 3C, unless you're wearing a balaclava and a ski mask, is an exercise in pure pain, as the wetness sublimating off your face has approximately the same effect on your facial nerves as being flayed. Ok the other hand, -2C in London is crisp and invigorating and entirely preferable in every possible way.
    - deleted 1y ago
      [deleted]
  - yen223 1y ago
    I moved countries just so I can experience 20C weather instead of 30C weather. It is very noticeable haha
- VBprogrammer 1y ago
  Not to mention that wet bulb temperature, measuring the effect of humidity, is actually the most important measure in those temperature ranges.
  - robocat 1y ago
    Humidity in London is also awful as the temperature gets closer to freezing. I found the damp cold in London to be common over the year and truly horrid (a reason to never live there). At home (Christchurch, NZ) we often get dry cold which can be pleasant: however when we do get the occasional vile damp cold I personally call it "London cold" because it made so much impression upon me in my 20s.
    - lostlogin 1y ago
      ‘London cold’ can be found a bit north, in Auckland. The only upside is that your lips don’t split in winter.
      - robocat 1y ago
        I haven't experienced that (but I've only spent months in Auckland or north of Auckland). From your comment I asked my brother and he said he agreed - something like he didn't like the Auckland 14° days that felt like 5°
    - jimnotgym 1y ago
      Humidity in summer is just as bad. At 30 degrees C London feels stifling hot because of the humidity
- magospietato 1y ago
  Your upper band of 30C is making this Englishman sweat just thinking about it. Which I think proves your point about narrow operational temperature even further.
- wodenokoto 1y ago
  Where I live, the current daily temperature is between 33 in the morning and hits forty something mid day, so I have very recent experience with those 5 degrees, and I completely disagree with your assessment. Difference between 10 and 30 degrees C feels, way, way bigger than 37 to 42. One goes from straight up cold to quite hot, while the other just goes from very hot to even more very hot.
  - close04 1y ago
    I bet you’re casually discounting the fact that you spend most of that time with 40+C temps in an air conditioned space. At 42 degrees your body can’t cool down and this causes a lot of deaths or even the “casual” fainting described in the article due to hyperthermia. This goes way beyond your subjective feeling.
    - wodenokoto 1y ago
      You right in the sense that I rarely spend more than 10 minutes in either 37 nor 42 degrees at a time. I thought this thread was discussing the subjective feelings of temperature.
      - close04 1y ago
        I think the whole thread is to show the Celsius scale in particular but temperature degrees have different impacts in different places in general, but especially in the range supporting human life. One degree can mean nothing or be the difference between being alive or dead, depending on where that degree is on the scale and maybe other compounding factors like humidity. Talking about relative temperature differences without anchoring to an absolute reference is meaningless. Using percentages is even worse.
  - Peteragain 1y ago
    I'm with you: very hot to more very hot. I think the real issue in the fainting story is that he/she had to take their coat off. 42 is just not life threatening if one knows when to take one's coat off (and drink water).
colechristensen 1y ago
There are few or no human scale situations where percentages of absolute temperature are meaningful, absolute zero is too far away and we live in a too narrow range of temperatures. Unless you're in a scientific context just don't use percentages on absolute temperature, only on rates.
ghaff 1y ago
People who complain about Fahrenheit vs. Celsius are correct to the degree (sorry) that the Celsius degree unit of difference is the standard in a lot of engineering calculations. But Celsius as a temperature scale is no more logical than Fahrenheit, which is arguably more practical for day to day use--and Kelvin is more likely required for a lot of engineering and chemical calculations anyway.
- delta_p_delta_x 1y ago
  > which is arguably more practical for day to day use No, it is not. Americans say this only because they're used to it. The common arguments are that is that it is more precise, and 'you see temperatures from zero to one hundred degrees Fahrenheit throughout the year'. Firstly, the problem with Fahrenheit is that its realisation is inaccurate by modern standards—which is why every single non-SI unit is now just an exact multiple of a corresponding SI unit with the same dimensions; the mediaeval and early modern definitions having been entirely forgotten. A bowl of salted ice and his own armpit? Truly an 18th-century invention. Next, the extra precision that a difference of one degree Fahrenheit gives you is frankly useless. Within a single room one can experience a difference of over five degrees Celsius or more, depending on what's in the room—a radiator or air conditioner running, or the gas stove in a kitchen, or a high-end PC. Forget rooms. On the human body itself there can be a two to three degree Celsius difference between the extremities and the thorax/torso/head. Any field that requires extreme precision will naturally end up using SI units, so kelvin (or some related scientific unit). (Excluding the absolutely crazy bunch of American machinists who like using thousandths and ten-thousandths of an inch—at this point the joke writes itself). As for climates, there are places that see very little difference in temperature, and definitely not the 'nice 0 – 100' range that Americans claim. Even in the US there are places like southern Louisiana and Florida that have borderline tropical climates, and don't really go below ~15 °C or above 35 °C. All of this is not really logical either, and all end up being a manifestation of familiarity.
  - andrewflnr 1y ago
    I'm not generally a Fahrenheit defender, but I think it's silly to deny the user-friendliness of having more integer values in the day-to-day temperature range, without going too far out of the two-digit measurement range. It lets you have a little more precision without being much effort to do casual math on. Milli-kelvin are far too small, a single kelvin is too big a perceptual range, and decimals are too annoying when we just want to talk about the weather.

by Y_Y 1y ago

azernik 1y ago

Then just don't use percentages, and rely on people realizing that a 7 degree difference is big!

buran77 1y ago

To make matters worse, not all ranges and percentages on that scale are equal, whether they're the same in absolute or relative terms. Humans have a narrow relevant "operational" temperature band. Even 20 degrees between 10-30C feel like nothing compared to the 5 degrees between 37-42C.

hnlmorg 1y ago
You’re right in principle but that’s probably the worst example you could have given. So bad an example that I think it could easily be argued to disprove your point.
- deleted 1y ago
  [deleted]
- paganel 1y ago
  For us people not living in Arabia or South Texas the difference between 37 and 42 Celsius is indeed quite important. 37 feels pretty hot, but yet livable, while 42 (and even 40 for me) means that nothing non-urgent should bring me out of the house.
  - pdpi 1y ago
    And, inversely, the five degree drop from, say, 3C to -2C represents means water can and will freeze, which is another massive change in livability.
    - nkoren 1y ago
      Indeed. At 3C in London, the humidity seeps into every pore and settles into your bones. Riding a bike at 3C, unless you're wearing a balaclava and a ski mask, is an exercise in pure pain, as the wetness sublimating off your face has approximately the same effect on your facial nerves as being flayed. Ok the other hand, -2C in London is crisp and invigorating and entirely preferable in every possible way.
  - deleted 1y ago
    [deleted]
- yen223 1y ago
  I moved countries just so I can experience 20C weather instead of 30C weather. It is very noticeable haha
VBprogrammer 1y ago
Not to mention that wet bulb temperature, measuring the effect of humidity, is actually the most important measure in those temperature ranges.
- robocat 1y ago
  Humidity in London is also awful as the temperature gets closer to freezing. I found the damp cold in London to be common over the year and truly horrid (a reason to never live there). At home (Christchurch, NZ) we often get dry cold which can be pleasant: however when we do get the occasional vile damp cold I personally call it "London cold" because it made so much impression upon me in my 20s.
  - lostlogin 1y ago
    ‘London cold’ can be found a bit north, in Auckland. The only upside is that your lips don’t split in winter.
    - robocat 1y ago
      I haven't experienced that (but I've only spent months in Auckland or north of Auckland). From your comment I asked my brother and he said he agreed - something like he didn't like the Auckland 14° days that felt like 5°
  - jimnotgym 1y ago
    Humidity in summer is just as bad. At 30 degrees C London feels stifling hot because of the humidity
magospietato 1y ago
Your upper band of 30C is making this Englishman sweat just thinking about it. Which I think proves your point about narrow operational temperature even further.
wodenokoto 1y ago
Where I live, the current daily temperature is between 33 in the morning and hits forty something mid day, so I have very recent experience with those 5 degrees, and I completely disagree with your assessment. Difference between 10 and 30 degrees C feels, way, way bigger than 37 to 42. One goes from straight up cold to quite hot, while the other just goes from very hot to even more very hot.
- close04 1y ago
  I bet you’re casually discounting the fact that you spend most of that time with 40+C temps in an air conditioned space. At 42 degrees your body can’t cool down and this causes a lot of deaths or even the “casual” fainting described in the article due to hyperthermia. This goes way beyond your subjective feeling.
  - wodenokoto 1y ago
    You right in the sense that I rarely spend more than 10 minutes in either 37 nor 42 degrees at a time. I thought this thread was discussing the subjective feelings of temperature.
    - close04 1y ago
      I think the whole thread is to show the Celsius scale in particular but temperature degrees have different impacts in different places in general, but especially in the range supporting human life. One degree can mean nothing or be the difference between being alive or dead, depending on where that degree is on the scale and maybe other compounding factors like humidity. Talking about relative temperature differences without anchoring to an absolute reference is meaningless. Using percentages is even worse.
- Peteragain 1y ago
  I'm with you: very hot to more very hot. I think the real issue in the fainting story is that he/she had to take their coat off. 42 is just not life threatening if one knows when to take one's coat off (and drink water).

colechristensen 1y ago

There are few or no human scale situations where percentages of absolute temperature are meaningful, absolute zero is too far away and we live in a too narrow range of temperatures. Unless you're in a scientific context just don't use percentages on absolute temperature, only on rates.

ghaff 1y ago

People who complain about Fahrenheit vs. Celsius are correct to the degree (sorry) that the Celsius degree unit of difference is the standard in a lot of engineering calculations. But Celsius as a temperature scale is no more logical than Fahrenheit, which is arguably more practical for day to day use--and Kelvin is more likely required for a lot of engineering and chemical calculations anyway.

delta_p_delta_x 1y ago
> which is arguably more practical for day to day use No, it is not. Americans say this only because they're used to it. The common arguments are that is that it is more precise, and 'you see temperatures from zero to one hundred degrees Fahrenheit throughout the year'. Firstly, the problem with Fahrenheit is that its realisation is inaccurate by modern standards—which is why every single non-SI unit is now just an exact multiple of a corresponding SI unit with the same dimensions; the mediaeval and early modern definitions having been entirely forgotten. A bowl of salted ice and his own armpit? Truly an 18th-century invention. Next, the extra precision that a difference of one degree Fahrenheit gives you is frankly useless. Within a single room one can experience a difference of over five degrees Celsius or more, depending on what's in the room—a radiator or air conditioner running, or the gas stove in a kitchen, or a high-end PC. Forget rooms. On the human body itself there can be a two to three degree Celsius difference between the extremities and the thorax/torso/head. Any field that requires extreme precision will naturally end up using SI units, so kelvin (or some related scientific unit). (Excluding the absolutely crazy bunch of American machinists who like using thousandths and ten-thousandths of an inch—at this point the joke writes itself). As for climates, there are places that see very little difference in temperature, and definitely not the 'nice 0 – 100' range that Americans claim. Even in the US there are places like southern Louisiana and Florida that have borderline tropical climates, and don't really go below ~15 °C or above 35 °C. All of this is not really logical either, and all end up being a manifestation of familiarity.
- andrewflnr 1y ago
  I'm not generally a Fahrenheit defender, but I think it's silly to deny the user-friendliness of having more integer values in the day-to-day temperature range, without going too far out of the two-digit measurement range. It lets you have a little more precision without being much effort to do casual math on. Milli-kelvin are far too small, a single kelvin is too big a perceptual range, and decimals are too annoying when we just want to talk about the weather.