[net.physics] Anti-Matter -> Anti-Energy??

btc@hp-pcd.UUCP (05/18/84)

Recently I (a non-physicist) attended a talk on cosmology.  One of
the items mentioned was the concept of matter and anti-matter.  At
the end of the lecture I asked if there was such a thing as anti-
energy, and received a patronizing NO.  Any explanations from out
there in net-land that I can understand? (not simplistic, but not
filled with technical jargon).


                              Thanks,

                              Bob Clark
                              hp-pcd!btc

Craig.Everhart@CMU-CS-A.ARPA (05/23/84)

What's there to know?  There are two species of each kind of particle.
When one of them occurs ``naturally'' (e.g. in abundance in this universe, or
at least on this planet) we unambiguously call it a particle, and its
conjugate an anti-particle.  Other pairs are named more or less by convention.
You can make atoms out of anti-particles just fine, if you have enough of
them--positrons circling a nucleus made up of anti-protons and anti-neutrons.
When a particle and its conjugate (the ``anti-particle'') come within range
of one another, they can annihilate one another to produce energy.
Conversely, if momentum is conserved, a photon of sufficient energy can
produce two oppositely-conjugated particles, one of which we call a particle
and the other of which we call an anti-particle.

You've invented a word (``anti-energy'') by a word game.  How would it behave?
Presumably, you think that turning ``anti-matter'' to energy would result in
``anti-energy.''  What would its properties be?  Would it annihilate regular
old energy and produce some kind of matter?  If there were people made of
anti-matter (in some other galaxy, say) would they have anti-ideas rather than
ideas?  If one of them baked a cake, would their ovens be anti-hot rather than
hot?  Would they experience anti-gravity rather than gravity?  (Actually,as
I understand it, a definite no to the last question; antiparticles and
particles share gravitational attraction, just as they share a concept of
mass.)

csc@watmath.UUCP (Computer Sci Club) (05/25/84)

The idea is that the universe has a fixed amount of energy.  This energy
comes in many forms one of which is Matter (with a capital M).  Matter
comes in two forms matter, and anti-matter.  Both are a form of energy.
(a proton and an anti-proton represent the same amount of energy). 
Certain conservations laws state that if matter is created or destroyed
then an equivalent amount of anti-matter must be created or destroyed.
We do not need an anti-energy in this model.
   One could postulate an anti-energy, call it negative energy, from
which was formed negative matter.  In the same way as a proton and
an anti-proton combine to give a burst of energy, a proton and a
negative proton would comine to give nothing.  The problem with this
theory is that there one would expect the oposite to occur, that is
nothing decay to form a proton and a negative proton (which would
have negative kinetic energy, whatever that means).  We do not
observe protons and negative protons popping out of nowhere (at least
we do not observe protons, we might not be able to easily detect
negative protons, exept perhaps by watching protons disappear) so
this model loses credibility.
                                     William Hughes

Interesting idea though it would alow one to get around the first
law without breaking it.