From owner-metabolic-reg@net.bio.net Tue Jan 04 22:00:00 1994
Newsgroups: bionet.metabolic-reg
Path: biosci!CS.Arizona.EDU!organpipe.uug.arizona.edu!uunet!news.moneng.mei.com!howland.reston.ans.net!pipex!uknet!gdt!aber!hrs
From: hrs@aber.ac.uk (Herbert Martin Sauro)
Subject: Re: Photosynthesis: exothermic or endothermic?
Message-ID: <1994Jan5.170448.3190@aber.ac.uk>
Organization: University College of Wales, Aberystwyth
References: <2gbed2$sje@mserv1.dl.ac.uk> <MARDER.117.2D29A1BB@agri.huji.ac.il>
Distribution: bionet,world
Date: Wed, 5 Jan 1994 17:04:48 GMT
Lines: 23

In article <MARDER.117.2D29A1BB@agri.huji.ac.il> MARDER@agri.huji.ac.il (Jonathan B. Marder) writes:
>In article <2gbed2$sje@mserv1.dl.ac.uk> John Woods <eanv20@castle.ed.ac.uk>
>writes:
>>And I'm still not sure whether
>>photons count as thermal energy or not.
>>                                        ... John Woods
>
>Photons definitely DO NOT count as thermal energy.  Thermal energy is the
>*internal* energy of a substance which is due to vibrations/movements within
>the substance.  You cannot have thermal energy in a vacuum, and photons
>definitely exist in a vacuum.
>Jonathan B. Marder                 '
>Department of Agricultural Botany  |     Internet: MARDER@AGRI.HUJI.AC.IL
>The Hebrew University of Jerusalem | /\/ Bitnet:   MARDER@HUJIAGRI

What happens if a thermometer is put in a vacuum that is bathed in
photons? Does the thermometer register a reading or not? (I think it
must do).

This assumes that an operational definition of thermal energy is by
the application of a thermometer.

H Sauro

.