Re: temperature

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From: Steve Miller (nanodog2@hotmail.com)
Date: Mon Sep 25 2000 - 20:44:40 PDT

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From: "Steve Miller" <nanodog2@hotmail.com>
Subject: Re: temperature
Date: Mon, 25 Sep 2000 20:44:40 PDT
Message-ID: <F151JFamSUC1Z1Fw2l70000448c@hotmail.com>

Hi All -

I am interested in more discussion of negative temperature, entropy and its
relation to information.

Steve

>From: "Pinhole Listserv" <pinhole@exploratorium.edu>
>To: "Pinhole Listserv" <pinhole@exploratorium.edu>
>Subject: Pinhole Digest #465 - 09/21/00
>Date: Thu, 21 Sep 2000 00:20:01 -0700
>
>Pinhole Digest #465 - Thursday, September 21, 2000
>
> RE: pinhole Exhibit available
> by "Black, Heidi" <BlackH@exchange.esuhsd.org>
> temperature of a vacuum
> by "Paul Doherty" <pauld@exploratorium.edu>
> Re: pinhole temperature of a vacuum
> by "Marc Afifi" <marc_afifi@yahoo.com>
> Re: pinhole temperature of a vacuum
> by "Paul Doherty" <pauld@exploratorium.edu>
>
>
>----------------------------------------------------------------------
>
>Subject: RE: pinhole Exhibit available
>From: "Black, Heidi" <BlackH@exchange.esuhsd.org>
>Date: Wed, 20 Sep 2000 08:38:49 -0700
>
>This message is in MIME format. Since your mail reader does not understand
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>
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>
>Ah, this is one of my favorites! I don't know when I could get up
>there...Heidi
>
>-----Original Message-----
>From: karenk@exploratorium.edu [mailto:karenk@exploratorium.edu]
>Sent: Tuesday, September 19, 2000 5:27 PM
>To: pinhole@exploratorium.edu
>Subject: pinhole Exhibit available
>
>
>Hi all!
>
>Life Sciences has decomissioned an exhibit that we had a duplicate of on
>the floor. It's called Bone Stress, and they would like to donate it to a
>teacher. Here's a description:
>
> There's a real bone and an acrylic bone. You pull down on a lever to
>compress the acrylic bone and it shows the stress points in the bone.
>
>It is about 2 feet wide by 5 feet tall wood frame with a back light, and
>graphic on the front.
>
>It's possible to check it out before you agree to adoption. The Life
>Sciences gang will just need to get some info from you to fill out forms
>for tax purposes.
>
>If you're interested, contact me directly (karenk@exploratorium.edu) and
>I'll put you in touch with the appropriate person.
>
>---Karen
>
>Karen E. Kalumuck, Ph.D.
>Biologist
>Exploratorium Teacher Institute
>3601 Lyon St.
>San Francisco, CA 94123
>415-561-0313
>karenk@exploratorium.edu
>
>
>
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>
>Ah, this is one of my favorites!   I don't know
>when I could get up there...Heidi
>
>
>-----Original Message-----
> From: karenk@exploratorium.edu [<A
>HREF="mailto:karenk@exploratorium.edu">mailto:karenk@exploratorium.edu</A>]
> Sent: Tuesday, September 19, 2000 5:27 PM
> To: pinhole@exploratorium.edu
> Subject: pinhole Exhibit available
>
> 
>
>Hi all!
>
>
>Life Sciences has decomissioned an exhibit that we had a
>duplicate of on
> the floor.  It's called Bone Stress, and they would
>like to donate it to a
> teacher.  Here's a description:
>
>
> There's a real bone and an acrylic bone. You pull
>down on a lever to
> compress the acrylic bone and it shows the stress points
>in the bone.
>
>
>It is about 2 feet wide by 5 feet tall wood frame with a
>back light, and
> graphic on the front.
>
>
>It's possible to check it out before you agree to
>adoption.  The Life
> Sciences gang will just need to get some info from you to
>fill out forms
> for tax purposes.
>
>
>If you're interested, contact me directly
>(karenk@exploratorium.edu) and
> I'll put you in touch with the appropriate person.
>
>
>---Karen
>
>
>Karen E. Kalumuck, Ph.D.
> Biologist
> Exploratorium Teacher Institute
> 3601 Lyon St.
> San Francisco, CA   94123
> 415-561-0313
> karenk@exploratorium.edu
>
> 
> 
>
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>----------------------------------------------------------------------
>
>Subject: temperature of a vacuum
>From: "Paul Doherty" <pauld@exploratorium.edu>
>Date: Wed, 20 Sep 2000 10:30:46 -0800
>
> Hi Professor!
>
>I¥ve started to teach physics now, and I get all kinds of strange questions
>from kids. Most of them I¥ve been able to find answers for, but this one I
>need help with:
>
>What temperature is there in a vaccuum? If there is nothing there that can
>be
>hot or cold, how can you tell?
>
>Can you give me a grade 7-level answer for this?
>
>If you don¥t have the time to be my physics-oracle, just tell me, but I
>really
>appreciate being able to ask you.
>
>I really hope I¥ll see you and the Exploratorium next summer.
>
>Per Sporrong,
>
>Hi Per
>
>A great question.
>
>Let's define remperature as what is measured by a thermometer, a good 7'th
>grade definition.
>
>Put a thermometer in air and it comes to the same temperature as the air.
>Same thing in water.
>
>But what about a vacuum?
>There is no matter in a vacuum.
>However there are light and radiowaves in a vacuum.
>Put a thermometer in sunlight and it gets warmer than the same thermometer
>in the shade both in contact with the air. So light can change the
>temperature of a thermometer as well as matter.
>
>The vacuum of space far from a star is full of radio waves and dim light.
>The radio waves are left over from the big bang. A sensitive thermometer
>placed in a vacuum will record a temperature of just under -270 degrees
>celcius. (Or 3 Kelvins)
>
>Hope this helps
>
>Paul D
>
>Paul "But it is more complicated than that!" Doherty,
>Senior Staff Scientist, The Exploratorium.
>pauld@exploratorium.edu, www.exo.net/~pauld
>
>
>
>----------------------------------------------------------------------
>
>Subject: Re: pinhole temperature of a vacuum
>From: "Marc Afifi" <marc_afifi@yahoo.com>
>Date: Wed, 20 Sep 2000 13:52:24 -0700 (PDT)
>
>That is a great question, and here's a follow-up for
>those of us past seventh grade who still don't
>understand. If we imagine the sensitive thermometer
>that Paul cites, then isn't the temperature that is
>read by it really just the temperature of the
>thermometer? In other words, the thermometer absorbs
>radiation which excites its atoms/molecules which
>jiggle the thermometer into reading 3K. But what is
>the temperature of a photon? Is it the same as its
>energy which, when measured, can be correlated to the
>common conception of temperature? And if photons are
>particles then doesn't their presence mean it isn't a
>vacuum at all? I remember my cosmology professor
>talking about photon pressure. Would we say that a
>hypothetical vacuum with no electromagnetic radiation
>has a temperature of absolute zero? And this reminds
>me of Jay Goldberg's question about negative kelvins
>which, to my best recollection, was not answered.
>Anyone care to address that one?
>
>Sorry, but once started I'm hard to stop. I love it
>when students ask such thought provoking questions.
>
>-Marc
>
>=====
>Marc Afifi
>Chemistry, AP Chemistry, Physics
>Pacific Grove High School
>Pacific Grove, CA
>
>__________________________________________________
>Do You Yahoo!?
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>----------------------------------------------------------------------
>
>Subject: Re: pinhole temperature of a vacuum
>From: "Paul Doherty" <pauld@exploratorium.edu>
>Date: Wed, 20 Sep 2000 15:21:15 -0800
>
>Hi Marc
>
>Temperature is not defined for 1 molecule or for 1 photon, so it is
>certainly not defined for no particles i.e. a vacuum.
>
>In the classical definition of temperature for an ideal gas, it is
>the average, random, kinetic energy of translational motion per molecule.
>
>the "average random" part means that you take a group of molecules, find
>their center of mass motion, exclude that, then take the average energy of
>translational motion relative to the center of mass. A single particle has
>no translational motion relative to its center of mass so therefor
>temperature is undefined.
>
>According to this classical definition negative temperature has no meaning.
>
>However there is a more modern definition of temperature in which negative
>temperatures have meaning.
>
>More on this later.
>
>Paul D.
>
>Paul "But it is more complicated than that!" Doherty,
>Senior Staff Scientist, The Exploratorium.
>pauld@exploratorium.edu, www.exo.net/~pauld
>
>
>
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