Message-Id: <v01540b00b05c262c0699@[12.64.2.139]>
To: pinhole@exploratorium.edu
From: kstreet@worldnet.att.net (Karen Street)
Subject: Re: Matter in a vacuum
Date: Sun, 5 Oct 1997 01:11:47 +0000
Eiger,
Well I gave other people the chance to tackle this and no one did!
And no question is stupid unless you haven't listened to the answer many,
many times (at least it often takes me several go rounds to get it).
Mass is resistance to acceleration. When a force operates on a mass, it
accelerates according to a = 1/m F. Both matter (a baseball) and energy
(photons) demonstrate this in gravitational fields. Now we may need a
gravitational field set up by a star to see clearly the evidence of photon
paths bending in a g field, but baseballs are more obliging.
Energy is the capacity to do work (exert a force on an object over a
distance d). It may be kinetic energy, energy of motion. It may be
potential energy: for each force there is an associated potential energy.
We classify them as gravitational, electromagnetic and nuclear potential
energies. Electromagnetic has a whole slew of subclasses: spring, chemical,
... Then there's heat energy, or energy of random kinetic (thermal) motion.
And photon energy = hf. If I missed any, you might supplement this list.
Where is potential energy stored? If we lift a baseball up, it makes sense
for us to say the baseball has potential gravitational energy to solve
problems. But it's really the gravitational field that stores the energy.
All fields have stored energy. This includes the Higg's field, if it exists.
So where does the mass of a proton come from? It is the combination of the
matter particles (quarks) and the energy of the strong nuclear interaction
that holds them together. In a nuclear particle, the energy has more mass
than the matter. In an atom, the mass of the energy holding the atom
together is relatively small compared to the masses of the constituent
particles (protons, neutrons and electrons).
Matter can become energy (pair annihilation that produces photons) and
energy can become matter (pair production from photons or the energy stored
in fields).
Gravity acts on masses. Electromagnetism operates on charges and magnetic
particles, etc. The nuclear interactions involve quarks, etc.
Now even with this very complete explanation, there may be more questions.
I'll try my best to keep answering if you keep asking.
Best wishes,
Karen