Evidence for Electron Interference
Okay, that's a very nice computer simulation, but how do I know it represents anything real?
Have experiments like this actually been done? |
Well, it's not really possible to set up the experiment just the way we've shown it here, with
electrons being shot at a screen through a pair of slits. The two slit experiment with light
has been done many times--originally by Thomas Young in 1801--but it's just not practical to do
exactly the same experiment with electrons. The equipment would have to be made on an
impossibly small scale to show the effects we've been discussing. So the applet you saw is
what's known as a thought experiment. It shows the results that would be
obtained, according to quantum theory, if a hypothetical experiment like this could
be performed. |
Sounds like you're basically just making up this whole thing. I knew all that stuff
about the electrons
interfering with each other was too weird to be true! |
Hold on--I didn't say there was no experimental evidence for the effects I showed you. Electrons
have been observed to interfere with one another. In the late 1920's, Clinton J. Davisson,
Lester H. Germer, and George P. Thomson observed beams of electrons scattering off of
various metals. The electrons produced interference patterns that could be measured and even
photographed. For
more information about these experiments, take a look at the
following
links:
| |
And those interference patterns must mean that the electrons were
somehow behaving like waves, with crests and troughs that could
cancel or
reinforce each other. |
|
That's right; those experiments showed that electrons sometimes
act as if they were waves, just as quantum theorists, like
Schrödinger and de Broglie, had
predicted. So we know that if the two slit experiment could be
done with electrons the way it's done with laser light, an
interference pattern like the one you saw would show up on the
screen. |
6th
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