Re: psychoceramics: Dilberts double-slit -Reply

[Samantha Fleming <s.fleming @ elsevier.co.uk>]

So, how exactly does this experiment work?
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Well. It's really very easy, but not too simple to explain without pictures.
You will just have to use your imagination.
You need a SINGLE light source. This is incredibly important, and I think it
might be ehere Scott has gone wrong. The whole point being, that we are looking
at the pattern of interference of two waves, and the two waves HAVE to be
exactly the same to get the right pattern. I don't know how good your physics
is, so I'll start from basics.
When you drop something in a bath, you get ripples. If those ripples were to
pass through a gap - lets say the entrance to a lego harbour - they would spread
out to either side, with the crests getting longer as they got urther away from
the gap. This is called diffraction. You can try it for yourself in the bath.
With two waves, they would interfere - crests would add up to give higher
crests, troughs would add up to give lower troughs, and the crests and the
troughs would add together to give flat bits. The first two are constructive
interference, the last is destructive interference.
This is what is happening with the double slit experiment. The light from the
single source is coherent - the waves are synchronised, with the crests and the
troughs of each wave group occuring at the same distance out from the slits, so
you get a regular pattern of interference, showing up as dark bands for
destructive interference and light bands for constructive interference. Where it
starts getting strange is if you put a photon detector at one of the slits. It
is possible to detect single photons, as if they know that you are looking for
them.
This is not a very detailed description, but it's the best I can do off the top
of my head. I'm not sure where Scott is getting his blob from. A single slit? A
non-coherent light source? Perhaps he just doesn't understand the whole point of
the experiment. I can go look up a more detailed description in one of the heavy
tomes bending my bookshelf if you want.
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about 'cerealogists'--the folks who
study crop circles, how they got started, their squabbles, how they
altered their theories as the circles got more complicated, and how they
reacted when those two old guys confessed to making many of the circles.
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I used to run a group at Southampton University called Human Potential Society
which was nothing to do with Human Potential, but was a chance to get together
in the bar and talk about weird stuff. We had a resident cerealogist, and he
refused to believe that they could be anything other than marks made by aliens
trying to communicate with us. I have met a few other cerealogists as well (and
the guys who perpetrated at least some of the hoaxes, although I didn't know it
at the time), and they were mostly the same. Although the theories changed, the
obsession, the rigidity was the same. I mean, if you look in the clasified at
the back of Fortean Times at the right time of year you can see adverts reading
"Night owls wanted. Own rope and wood. No time wasters".

Rev. hippy