Re: should c be a subset of c++?

From	glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups	comp.lang.c
Subject	Re: should c be a subset of c++?
Date	2015-11-14 00:03 +0000
Organization	Aioe.org NNTP Server
Message-ID	<n25to2$e9$1@speranza.aioe.org> (permalink)
References	(5 earlier) <lnmvup1t79.fsf@kst-u.example.com> <bd90025c-25d8-409e-bd5f-44904fb81f5c@googlegroups.com> <n1o69b$lkj$1@dont-email.me> <c190514e-a065-4abe-97f6-2496094ba8ab@googlegroups.com> <i5ic4bto7e5vo1savjnbtd4fth5r5b7ap4@4ax.com>

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Geoff <geoff@invalid.invalid> wrote:

(snip, and previous snip, on negative numbers)

> The Kelvin (absolute) temperature scale was derived from the
> interpolation of the previous (relative) scales of Fahrenheit, Celsius
> and other at the time. William Kelvin desired an "absolute cold" point
> or "absolute zero" temperature. He interpolated the slope of the
> Centigrade scale and calculated that -273 degrees Centigrade was the
> absolute zero point he was seeking. 
 
> It was later standardized that the triple-point of water is exactly
> 273.16 Kelvin and this is an arbitrary standard.

Yes. The freezing point of water at atmospheric pressure is close
to 273.15 K, but the definition is on the triple point.
 
> Theoretically, nothing can be colder than 0 Kelvin. All molecular
> motion ceases and all matter is "frozen". There is conceptually, no
> such thing as negative Kelvins and no such concept as colder than
> absolute cold.

Well, actually not:

https://en.wikipedia.org/wiki/Zero-point_energy

quantum mechanics requires motion even at absolute zero, and helium
is a (superfluid) liquid at absolute zero and 1 atmosphere. 

If motion ceases, both the position and momentum would be known
exactly, but Heisenburg uncertainty doesn't allow for that. 
 
> Entropy is the measure of the number of energy states a system can
> assume. The third law of thermodynamics states "The entropy of a
> perfect crystal at absolute zero is exactly equal to zero." An
> arbitrary object of any type can only approximate this ideal. 

Turns out that superfluid liquids, in which all atoms are in the
same quantum state, can also have zero entropy.
 
> Therefore, a state of absolute zero cannot be physically achieved,
> except perhaps, at the end of time and space and the heat death of the
> universe. But even this state defies logic since the second law of
> thermodynamics states that the entropy of a closed system constantly
> increases. A finite universe, being a closed system must obey the
> second law. Only an infinite universe with a finite amount of energy
> can be in a state of absolute zero entropy.

But you can get darn close if you try hard enough.
 
> Hawking has shown that a black hole has maximum entropy of any body of
> equal size. Therefore the end state of the universe is a black hole.
> Internally, the black hole can do no work and it possesses no internal
> temperature gradient. This does not mean the temperature of the
> universe or a black hole is absolute zero. Zero relative entropy means
> zero temperature differences within the system of interest.

-- glen

Thread

Re: should c be a subset of c++? "J. Clarke" <j.clarke.873638@gmail.com> - 2015-11-06 19:06 -0500
  Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-07 00:41 -0800
    Re: should c be a subset of c++? Richard Damon <Richard@Damon-Family.org> - 2015-11-07 10:01 -0500
      Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-07 09:12 -0800
        Re: should c be a subset of c++? Martin Shobe <martin.shobe@yahoo.com> - 2015-11-07 11:58 -0600
          Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-07 10:25 -0800
            Re: should c be a subset of c++? Keith Thompson <kst-u@mib.org> - 2015-11-07 11:54 -0800
              Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-07 14:22 -0800
                Re: should c be a subset of c++? Martin Shobe <martin.shobe@yahoo.com> - 2015-11-08 13:05 -0600
                Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-08 11:39 -0800
                Re: should c be a subset of c++? Geoff <geoff@invalid.invalid> - 2015-11-13 13:20 -0800
                Re: should c be a subset of c++? James Kuyper <jameskuyper@verizon.net> - 2015-11-13 16:36 -0500
                Re: should c be a subset of c++? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-14 00:03 +0000
                Re: should c be a subset of c++? Geoff <geoff@invalid.invalid> - 2015-11-13 17:06 -0800
                Re: should c be a subset of c++? Geoff <geoff@invalid.invalid> - 2015-11-13 13:29 -0800
            Re: should c be a subset of c++? Martin Shobe <martin.shobe@yahoo.com> - 2015-11-08 12:57 -0600
              Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-08 11:37 -0800
                Re: should c be a subset of c++? Keith Thompson <kst-u@mib.org> - 2015-11-08 17:16 -0800
                Re: should c be a subset of c++? supercat@casperkitty.com - 2015-11-08 18:19 -0800
                Re: should c be a subset of c++? Martin Shobe <martin.shobe@yahoo.com> - 2015-11-08 23:25 -0600
                Re: should c be a subset of c++? Gareth Owen <gwowen@gmail.com> - 2015-11-10 22:34 +0000
        Re: should c be a subset of c++? raltbos@xs4all.nl (Richard Bos) - 2015-11-13 22:18 +0000
          Re: should c be a subset of c++? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-14 00:11 +0000
            Re: should c be a subset of c++? raltbos@xs4all.nl (Richard Bos) - 2015-11-17 22:16 +0000
              Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-17 21:09 -0800
                Re: should c be a subset of c++? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-18 05:22 +0000
                Re: should c be a subset of c++? Keith Thompson <kst-u@mib.org> - 2015-11-18 06:03 -0800
                Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-18 08:44 -0800
                Re: should c be a subset of c++? Keith Thompson <kst-u@mib.org> - 2015-11-18 09:11 -0800
                Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-18 09:54 -0800
                Re: should c be a subset of c++? Philip Lantz <prl@canterey.us> - 2015-11-24 01:49 -0800
                Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-24 02:58 -0800
                Re: should c be a subset of c++? raltbos@xs4all.nl (Richard Bos) - 2015-11-24 11:58 +0000
                Re: should c be a subset of c++? Keith Thompson <kst-u@mib.org> - 2015-11-24 09:09 -0800
                Re: should c be a subset of c++? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-25 00:12 -0800
                Re: should c be a subset of c++? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-25 12:35 +0000
                Re: should c be a subset of c++? raltbos@xs4all.nl (Richard Bos) - 2015-11-27 16:30 +0000
                Re: should c be a subset of c++? raltbos@xs4all.nl (Richard Bos) - 2015-11-19 10:37 +0000
                Re: should c be a subset of c++? Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-20 15:40 -0800
  Re: should c be a subset of c++? Gareth Owen <gwowen@gmail.com> - 2015-11-10 22:20 +0000

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