5 ms·

I wonder why this gets downvoted - seems pretty reasonable to me...

by paulhilbert 8y ago

pjc50 8y ago
It's a rather odd argument and it falls apart as soon as you ask about 0 Kelvin.
- thaumasiotes 8y ago
  > it falls apart as soon as you ask about 0 Kelvin Huh? The whole point of Kelvins is that their zero point is an actual 0 value. That's why Kelvins are a unit and °C aren't. Q: An object's temperature is 20°C. The object's temperature increases by 10%. What is the new temperature of the object? A: 49°C.
  - peteretep 8y ago
    > That's why Kelvins are a unit and °C aren't Could I ask that you update Wikipedia with your discovery? Sadly the page appears to be erroneously using the word "unit" all over the place! https://en.wikipedia.org/wiki/Celsius https://en.wikipedia.org/wiki/Celsius Also, NIST might benefit from your guidance: https://physics.nist.gov/cuu/Units/kelvin.html https://physics.nist.gov/cuu/Units/kelvin.html
    - thaumasiotes 8y ago
      It's already there, if you know enough to recognize it: > The degree Celsius (°C) can refer to a specific temperature on the Celsius scale or a unit to indicate a difference between two temperatures In other words, you can add a quantity of °C to a temperature value and you'll get another temperature value. But you can't measure a temperature in °C. Compare how, for example, the python datetime library uses a datetime type and a timedelta type. A datetime plus a timedelta is a datetime. datetimes refer to points in time, and timedeltas don't. °C measures a temperature delta, but not a temperature.
      - peteretep 8y ago
        > It's already there, if you know enough to recognize it "As an SI derived unit", "or a unit to indicate", "the unit was called" Three mentions of it being a unit in the first paragraph, alone. I understand the point being made; the conclusion that "celsius is not a unit" is bogus, however, by any common definition, including NIST's. In a now-deleted comment, you linked to a Wikipedia page on Dimensional Analysis, which includes the sentence "to convert from units of Fahrenheit to units of Celsius".
        deleted 8y ago
        [deleted]
- rusk 8y ago
  Except when you take into account that 0 Kelvin actually is theoretically "nothing" with regards to temperature. It's not a floating point, it's an absolute.
BlackFly 8y ago
I imagine because the post is not pedantic but is just wrong. If you want to be pedantic and correct, the symbol 0 represents a real number, an integer, and other numbers. The symbol 0 is not a cardinal (counting) number. Some people consider the natural numbers to be either the cardinal numbers or the whole numbers which include 0. So some people consider 0 to not be a natural number. As a mathematical entity it doesn't represent the absence of anything. It is just a symbol that has certain properties associated with it. There isn't a hole in the real number line where 0 should be: there is a number there. It isn't pedantic to insist that 0 isn't a number, it is equivocal to do so. In most contexts it does not need to be treated like a special value. Temperature measured in degrees is an example where you don't need to treat 0 specially, at least not more than other values...

I wonder why this gets downvoted - seems pretty reasonable to me...

pjc50 8y ago

It's a rather odd argument and it falls apart as soon as you ask about 0 Kelvin.

thaumasiotes 8y ago
> it falls apart as soon as you ask about 0 Kelvin Huh? The whole point of Kelvins is that their zero point is an actual 0 value. That's why Kelvins are a unit and °C aren't. Q: An object's temperature is 20°C. The object's temperature increases by 10%. What is the new temperature of the object? A: 49°C.
- peteretep 8y ago
  > That's why Kelvins are a unit and °C aren't Could I ask that you update Wikipedia with your discovery? Sadly the page appears to be erroneously using the word "unit" all over the place! https://en.wikipedia.org/wiki/Celsius https://en.wikipedia.org/wiki/Celsius Also, NIST might benefit from your guidance: https://physics.nist.gov/cuu/Units/kelvin.html https://physics.nist.gov/cuu/Units/kelvin.html
  - thaumasiotes 8y ago
    It's already there, if you know enough to recognize it: > The degree Celsius (°C) can refer to a specific temperature on the Celsius scale or a unit to indicate a difference between two temperatures In other words, you can add a quantity of °C to a temperature value and you'll get another temperature value. But you can't measure a temperature in °C. Compare how, for example, the python datetime library uses a datetime type and a timedelta type. A datetime plus a timedelta is a datetime. datetimes refer to points in time, and timedeltas don't. °C measures a temperature delta, but not a temperature.
    - peteretep 8y ago
      > It's already there, if you know enough to recognize it "As an SI derived unit", "or a unit to indicate", "the unit was called" Three mentions of it being a unit in the first paragraph, alone. I understand the point being made; the conclusion that "celsius is not a unit" is bogus, however, by any common definition, including NIST's. In a now-deleted comment, you linked to a Wikipedia page on Dimensional Analysis, which includes the sentence "to convert from units of Fahrenheit to units of Celsius".
      - deleted 8y ago
        [deleted]
rusk 8y ago
Except when you take into account that 0 Kelvin actually is theoretically "nothing" with regards to temperature. It's not a floating point, it's an absolute.

BlackFly 8y ago

I imagine because the post is not pedantic but is just wrong. If you want to be pedantic and correct, the symbol 0 represents a real number, an integer, and other numbers. The symbol 0 is not a cardinal (counting) number. Some people consider the natural numbers to be either the cardinal numbers or the whole numbers which include 0. So some people consider 0 to not be a natural number. As a mathematical entity it doesn't represent the absence of anything. It is just a symbol that has certain properties associated with it. There isn't a hole in the real number line where 0 should be: there is a number there. It isn't pedantic to insist that 0 isn't a number, it is equivocal to do so. In most contexts it does not need to be treated like a special value. Temperature measured in degrees is an example where you don't need to treat 0 specially, at least not more than other values...