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From: kurtze@plains.NoDak.edu (Douglas Kurtze)
Newsgroups: sci.physics,sci.bio,sci.chem,sci.med
Subject: Re: Forgotten Entities: Do You Remember Any?
Keywords: Ones that we keep being reminded of.
Message-ID: <6530@plains.NoDak.edu>
Date: 31 Oct 90 19:33:22 GMT
References: <1990Oct25.232546.12357@portia.Stanford.EDU> <1990Oct27.093037.2024@uoft02.utoledo.edu> <1990Oct28.004012.19939@wpi.WPI.EDU>
Organization: North Dakota State University, Fargo
Lines: 64

In message <1990Oct28.004012.19939@wpi.WPI.EDU>, avenger@wpi.WPI.EDU
(Samuel Joseph Pullara) writes:

>The ether was thought to exist all the way up to the 1920's... I don't
>know, maybe someone still believes it...


In message <1990Oct31.015907.17684@cbnewsd.att.com>, jfb200@cbnewsd.att.com
(joseph.f.baugher) writes:

>How about "caloric", the substance which was imagined to be responsible for
>thermal phenomena?  Heat was transferred from one object to another by means

and in message <85178@lll-winken.LLNL.GOV>, loren@tristan.llnl.gov
(Loren Petrich) replies:

>	I would not laugh too hard at "caloric". Thermal energy is now
>known to be present in any of several forms. Some forms are
>"stationary", like the vibrations and rotations of molecules, while
>some forms are actually fluid-like. These include phonons (sound
>quanta) in most condensed materials, the excitations of electrons in
>conductors, and the motions of molecules in gases.

>	However, there is no "law of conservation of heat", as Count
>Rumford had successfully demonstrated -- heat can be produced by
>(large-scale motions) --> (small-scale motions) -- the heat itself.

This brings up a more subtle category of "forgotten entities":
those which return in a more refined form, with some of their
(more or less) incidental properties changed, and possibly under
new names.

Ether is an example -- we now talk about the QED vacuum, which is the
medium in which elecromagnetic waves propagate (I'm willing to ignore
QCD or TOE effects for the sake of argument here).  The old concept is
less sophisticated, assuming properties of the ether which are like
those of air, but the concept of an "ether" is back.

Caloric may be another example, as in the quotes above -- the key point
here is that the idea of heat as a fluid dragged along the excess
baggage of a presumed conservation law.  Once that idea is rejected,
the "heat as fluid" idea can become useful again (think of ballistic
heat propagation, for example).

Of course, there's atoms -- the Greeks were thinking about indivisible
particles of matter (hence the word "atom"), and we've been thinking
about elementary particles ever since.  They just keep getting less and
less like pebbles.

Seems I had more of these in mind last spring when I was reading Kuhn
and Bronowski on airplanes (I was on the airplanes, not Kuhn and Bronowski
writing about airplanes) and if I ever remember them I'll post them later.

Anybody else care to volunteer any?


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Doug Kurtze                   kurtze@plains.NoDak.edu
Physics, North Dakota State

"Patience is its own reward" -- Flann O'Brien

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