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Smaller Than an Electron
Name: Ryan J.
Status: student
Age: 17
Location: N/A
Country: N/A
Date: Saturday, May 18, 2002
Question:
What is smaller than an electron?
Replies:
Ryan,
Current research shows that an electron has no size at all. It is a "point
particle". As a result, there are no particles that are smaller in size,
although there are particles with smaller mass. These are neutrinos. A
neutrino has no electric charge and a mass that is one-millionth of the
electron mass, perhaps even smaller.
Dr. Ken Mellendorf
Physics Instructor
Illinois Central College
Protons, neutrons, pions, quarks, and other sub-atomic particles are
"smaller" than electrons. Having said that I will make the disclaimer that
it is not accurate to talk about the "size" of an electron or other atomic
and sub-atomic particles. They do not have a "size" in the sense that a
bowling ball or baseball do. How "big" the atomic/sub-atomic particle is
depends upon how it is measured and its surroundings. For example, an
electron in a hydrogen atom has a different size than a "free" electron. The
reason for this is that in quantum mechanics, which is the only correct way
to discuss electrons and other "smaller" particles, the term
"size" loses its meaning -- in fact it has no meaning.
Scientists, teachers, and texts continue to associate the behavior of
atomic and sub-atomic species (I will not even call them particles, because
that too is not rigorously defined either) with familiar concepts from
classical, Newtonian mechanics -- like size, position, speed etc. These
atomic / sub-atomic particles behave paradoxically when described in
classical terms. An electron is surely a "wave" because it can be
diffracted, and that is clearly a property of "waves". But electrons can be
"scattered" deflected like little bullets, and that is clearly a property of
particles.
To the best of my readings into the matter (at varying levels of
mathematical sophistication), the particle / wave duality of electrons,
photons, etc. has not really been resolved. Young's double slit experiment
(look up on some web sites) has not, or maybe cannot be explained. The
paradox is this:
If I have two narrow slits and pass light through the two a diffraction
pattern appears on detectors on the other side of the slit, that is
alternating bright and dark images. If I close either one of the slits, a
single spot is detected on the other side of the slit.
This different behavior occurs even if the experiment is set up in such
a way that photons are produced one at a time, and if which slit I choose to
close is a random choice. It is as if the photon "knows" whether there is
one slit, or two slits present.
Those are the results of the experiment. How the photon "knows" is the
paradox -- as yet not resolved I believe. By the way, the same experiment
using electrons instead of photons gives the same results. Hope that's not
more "answer" than you wanted, but we should not deceive ourselves that
there are still some unanswered questions out there.
Vince Calder
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Update: June 2012
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