----- Original Message -----
Sent: Wednesday, August 06, 2008 12:02
AM
Subject: Re: How to avoid
mis-interpreting the second law of thermodynamics
Thermodynamic systems divide into three classes, depending on whether
the
system is exchanging energy and/or matter with its
environment:
Table 1. Three classes of thermodynamic
systems
_____________________________________________________________________
Thermodynamic
Systems
______________________________________________________
Exchange
Isolated
Closed
Open
_____________________________________________________________________
Energy
No
Yes
Yes
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
Matter
No
No
Yes
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
Example
Adiabatic
Refrigerator
Biosphere
systems
Thermometer
Cells
Universe* Heating
pad
Animals
Engines
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-
Alternative Microcanonical
Canonical Grand
canonical
names
ensembles
ensemble
ensemble
______________________________________________________________________
*The
Universe by definition doesn't even have any boundary and hence
cannot
exchange any matter or energy with it.
It is important to note that
many physicists and other scientists do not
differentiate between "closed"
and "isolated" thermodynamic systems. When
they say "closed" system, they
usually mean "isolated systems".
Hope this table
helps.
Sung
/discuss/discuss.html===========================
JM:
Isolated (closed?) is a figment, if it is indeed cut off, we do not know
about it at all. When we know about it, it has got to have connections (we
got) so we may miss 'the rest'.
(My mock-definition of the (then) isotherm and reversible classic
thermodynamics (Carnot - Clausius etc.) as a senior chemist-student: "it is
the system showing how things would proceed if they would not proceed as they
do proceed."
We just don't know about the 'universe': we have a figment based on many
millennia of mis-observation and their mis-explanations as our epistemy got
gradually enriched.
Matter: going down the scale we find empty space and some 'effects' - no
matter in matter.
Energy? a good name, assigned what it 'does' and how to 'measure' it
(what?).
They may be "equivalent"<G> figments of our conventional sciences.
Sorry for being facetious
John M
