Re: [Phys-L] heat content

[John Denker <jsd@av8n.com>]

In this message, I am not talking about politics, public 
policy, planets, oceans, climate, or weather.  I'm just
talking about basic principles of thermodynamics.


On 02/07/2014 03:13 PM, Robert Cohen wrote:
> Just curious but does it bother anyone that NOAA refers to the "ocean
> heat content" as opposed to "ocean thermal energy content" or some
> such phrase?


Well, many physicists see the word "heat" as a red flag.

Speaking for myself, I see something like the red flag 
in the diagram shown below:  A guy is standing on top of 
Mt. Baldy during a raging thunderstorm.  He is holding 
up a tall metal pikestaff bearing a little red flag that 
says "heat".

Very indirectly, the flag might call attention to the fact 
that the guy is doing something stupid.

HOWEVER ... changing the terminology on the flag isn't
going to solve the problem.  In particular, changing it
to say "thermal energy" is no improvement whatsoever.

The problem is with the physics of the situation.  Making
the terminology more politically correct will not change
the physics of the situation.

Some non-metaphorical discussion appears below the diagram.


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                    \        \ |  /  /





                               |______
                               |      |
                               | heat |
                               |______|
                               |
                               |
                               |
                              / \
                              | |
                              | |
                              | |
                              | |
                              | |
                              | |
                              | |
                              | |  \  |  /
                              | |   \_|_/  /
                              | |  ."   "./ /
                              | | /(O)-(O)\/
                             /_)||   /     |
                             |_)||  '-     |
                             \_)|\    _    /   |\/|_
                              | | \  /_\  /   _|  '/
                              |_|\ '.___.'    \ ) /
                              \   \_/\__/\__   |==|
                               \    \ /\ /\ `\ |  |
                                \    \\//     \|  |
                                 `\        |  /   |
                                   |       |\____/
                                   |       |
                                   |       |
                                   |-------|
                                   |   |   |
                                   |   |   |
                                   |   |   |
                                   |   |   |
                                   |   |   |
                                   |   |   |
                                   | _ | _ |
                                   /___|___\



In physics, the word "heat" is used with at least four or five
different technical meanings ... and that's not even counting
the various non-technical, metaphorical, and/or jocular usages.

We are dealing with just one of the usages here, namely "heat 
content" ... which for present purposes is exactly synonymous 
with "thermal energy content".

The problem is, these terms refer to something that does not exist,
except possibly in trivial cases.  It does not matter what you call
it.  You can call it "heat content" or "thermal energy content" or
"caloric" or whatever ... and it still does not exist.  The basic
rule is that energy is energy, and "thermal" energy cannot be
distinguished from any other kind of energy.  This has been pretty
much known in the literature since 1798, although that's not the
whole story.

The other part of the story has to do with /entropy/.

When somebody says there is too much heat in the ocean or anywhere
else, they might mean that there's too much energy, or too much
entropy, or quite possibly both.  It should be obvious that you
cannot use one number ("heat content") to quantify two things 
(energy and entropy).  I guarantee that choosing a more politically-
correct name for this one number will *not* solve the problem.

  For the tiny minority of people who care about the history of 
  science, we note that there is precedent for this.  The idea
  of "phlogiston" was widely used in the scientific community,
  and remained in use for many decades even though it was known
  to not fit the facts particularly well.  There were many attempts
  to replace phlogiston with something else, but none met with
  much success until it was realized that phlogiston had to be
  replaced by *two* ideas, namely energy and oxygen.

  So it is in our time.  The whole idea of "heat" is as dead as
  phlogiston.  "Heat" needs to be replaced by two ideas, namely
  energy and entropy.  Trying to quantify the "heat" is a fool's
  errand.  Don't do it.  Quantify the energy and entropy instead.

BTW this is one more nail in the coffin, as if any were needed,
demonstrating that you can't believe what you read in the PER
literature.  I'm referring to the holy wars over how "heat" 
supposedly "must" be defined ... plus long, detailed disquisitions
on how to explain irreversibility in terms of energy, et cetera.
People who have some understanding of the actual subject matter
hold their noses and run away screaming.