NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/sci/physics/19314

Text File | 1992-11-20 | 3.9 KB | 75 lines

Newsgroups: sci.physics
Path: sparky!uunet!newsgate.watson.ibm.com!yktnews!admin!platt
From: [e-mail] (Daniel E. Platt)
Subject: Re: energy, mass, and all that
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Date: Fri, 20 Nov 1992 17:56:53 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
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In article <[e-mail]>, [e-mail] (SCOTT I CHASE) writes:
|> In article <[e-mail]>, [e-mail] (Matthew P Wiener) writes...
|> >In article <[e-mail]>, sichase@csa1 (SCOTT I CHASE) writes:
|> >>If energy and matter are not interconvertible, where does all the energy
|> >>of an atomic bomb blast come from?
|> >
|> >Simple.  The energy that used to be binding is now blast, light, heat.
|> >While it was binding, the energy was localized enough that we could
|> >weigh it directly, and so the bomb weighed E-bind/c^2 more than it
|> >would have otherwise.
|>
|> This follows nicely upon my previous post, in which Dan Platt stretches
|> the definition of mass so as to never convert mass to energy.

This misses my point.  I was just trying to point out that there is no
energy without something to mediate its transmission -- such as mass
or photons, or whatever.  There's no such thing as 'pure energy.'
Another way to look at it is that while the products of a reaction
may have a different mass than the initial constituents, all the
energy that was 'created' from 'destroyed' mass is being carried by
the product particles.

How can I communicate that things 'have' energy, energy can be
transfered between things, but energy isn't something all by itself --
you cannot have a bottle of 'pure' energy; you can have a bottle of
stuff from which you can release some energy.

|>                                                                Now you
|> are going to stretch the definition of energy so that we never have to
|> convert energy to mass.  You are willing to say that when we weigh atoms
|> that we are weighing their energy and not their mass?  This is a strange
|> definition of weight.  How much of what you weigh is energy, and how
|> much is mass?  It seems, surprisingly, that the atom has just enough
|> energy that it is all released in a particular nuclear fission reaction,
|> leaving only the mass behind.  What about other nuclear reactions?
|> Is there any mass at all in this version of the Watts theory of
|> matter/energy nonconvertibility?  How would you go about reconciling
|> this point of view with Dan's version of the Watts argument that everything
|> which you would call energy is really mass?
|>

How much of this is pedantic argument about semantic differences?  I've
seen lots of arguments which carry the idea of mass/energy to the
point that weighing a molecule should show the energy stored as a
part of the mass -- so how much of the molecule is just mass and
how much is the bonding energy?  Or, if you compare a neutron and
a proton, the neutron can decay to a proton+electron (a neutron is
not just a proton and an electron electromagnetically bound --
that's called a hydrogen atom -- but is it possibly something that
is mediated by other forces? then the arguments about uncertainty
principal defined lower bounds and masses comes out, and it is seen
that that doesn't work well) so how much of the mass is just the energy
required to keep a neutron a neutron?

Dan

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Daniel E. Platt                                      [e-mail]
The views expressed here do not necessarily reflect those of my employer.
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