Re: Zero Points?

Jerry Friedman <jerry_friedman@xxxxxxxxx> wrote:

On Sep 4, 1:28 pm, nos...@xxxxxxxxxxxxxxxx (J. J. Lodder) wrote:
Jerry Friedman <jerry_fried...@xxxxxxxxx> wrote:
On Sep 4, 3:12 am, nos...@xxxxxxxxxxxxxxxx (J. J. Lodder) wrote:
Jerry Friedman <jerry_fried...@xxxxxxxxx> wrote:
On Sep 3, 1:40 pm, nos...@xxxxxxxxxxxxxxxx (J. J. Lodder) wrote:
Murray Arnow <ar...@xxxxxxxxx> wrote:
Lars Eighner wrote:

Temperature does, of course, have a zero that means zero, but
that is not the zero of several temperature scales. Kelvin uses
the zero that is zero. Celsius and Fahrenheit do not. Their
zeros are as arbitrary as the zero of longitude.

It's when you are absolutely sure, you should question the most.
If the Kelvin zero is zero, then there would be no negative
energies. The fact is all scales are arbitrary. It is convenient
in Statistical Mechanics to set a zero-point temperature, but it
isn't necessary.

It's necessary.
Thermodynamics defines ratios of (absolute) temperatures only,

If you want to use a scale where absolute 0 (T_abs) isn't defined to
be 0, you just change all your temperatures from T to T - T_abs.
Pointlessly inconvenient, but you can do it.

See my reply to Murray.
A multiplicative scale inevitably implies a zero element,
whatever you may want to call it.

You can still do it all with T - T_abs. (On second thought, T_0 would
have been a better symbol.)

You can even do it with any monotonous f(T),
if you really wanted to.

Now you're getting what I'm saying. To return to English usage,
though, I like "monotonic" much better than "monotonous", though I
know both are used.

Monotonic is the standard form.
Just not paying attention.

And anyway, temperature is just energy/degree of freedom,
and negative kinetic energies (1/2 m v^2 after all)
are more than just a little bit inconvenient,

If for some reason you wanted to do thermo in Fahrenheit or Celsius,
you would say, "T - T_abs is just energy p[er degree of freedom".
Inconvenient and unnatural, yes, but it doesn't involve negative
energies.

You can't do thermodynamics in Celsius or Fahrenheit.
Celsius and Fahrenheit are defined in terms of the Kelvin,

So if for some reason someone wanted to do that, they'd use the pre-
Kelvin definitions.

No one ever uses those in physics,
for the simple reason that Celsius
isn't very well-defined,
or very reproducible.

Jan
.

Relevant Pages

  • Re: Zero Points?
    ... that is not the zero of several temperature scales. ... You can't do thermodynamics in Celsius or Fahrenheit. ...
    (alt.usage.english)
  • Re: Zero Points?
    ... the zero of several temperature scales. ... Kelvin uses the zero that is zero. ... Kelvin zero is zero, then there would be no negative energies. ... to set a zero-point temperature, ...
    (alt.usage.english)
  • Re: Zero Points?
    ... not the zero of several temperature scales. ... Kelvin zero is zero, then there would be no negative energies. ... to set a zero-point temperature, ...
    (alt.usage.english)
  • Re: Zero Points?
    ... Temperature does, of course, have a zero that means zero, but that is not ... the zero of several temperature scales. ... Kelvin zero is zero, then there would be no negative energies. ...
    (alt.usage.english)
  • Re: Zero Points?
    ... Temperature does, of course, have a zero that means zero, but that is not ... the zero of several temperature scales. ... Kelvin zero is zero, then there would be no negative energies. ...
    (alt.usage.english)
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