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Re: Anti-matter questions (fwd)



---------- Forwarded message ----------
Date: Tue, 18 Nov 1997 18:44:57 -0500 (EST)
From: Delphi High School <pmason@wvec.k12.in.us>
To: physhare@lists.PSU.EDU
Subject: Re: Anti-matter questions (fwd)

I asked this question on the PHYSHARE list, but it did not get posted.
Would one the college professors on the list please share information
with me? I just know someone will ask the question tomorrow.
Patti Mason

---------- Forwarded message ----------
Date: Tue, 18 Nov 1997 07:55:45 -0500 (EST)
From: Delphi High School <pmason@wvec.k12.in.us>
To: Sharing resources for high school physics <PHYSHARE@LISTS.PSU.EDU>
Cc: PHYSHARE@LISTS.PSU.EDU
Subject: Re: Anti-matter questions



I need a quick question answered today before noon, if possible! We are
just introducing nuclear physics and are discussing matter and
anti-matter. Question came up: Are there such things as anti-neutrons?
If there are anti-neutrinos, I suppose there are, but I have never read
about them. If so, are they composed of anti-quark triplets?

Yes and yes. This didn't appear 'til 5 PM PST.

Also is there still postulated an "anti-universe" someplace since there
is always antimatter produced when energy is converted to matter? If not,
where did the anti-matter go?

There is no reason to believe in the existence of an anti-universe.
There may be large isolates of antimatter in our observable universe.
Many physicists feel there are not, but there might be no observable
consequences if they do exist. Whenever a physical reaction occurs it
must do so in a manner that conserves baryons and leptons. Effectively
that means the answer to your question is "yes", but the idea of "pure
energy" being converted to matter is unphysical; there is no such thing
as pure energy. For example, two protons can be bashed together with
sufficient kinetic energy to produce a proton-antiproton pair. Two
sufficiently energetic photons can do the same thing (it is thought),
but neither protons nor photons should be characterized as "pure energy".

Leigh