Schroedinger's Cat

Fun Quantum Physics Experiments You Can Do In Your Spare Time!

by Arthur Rudolph (Mag8Bob@aol.com)
written 20 Oct 1996

This article is classified "Real"


In the late 1920s the Austrian physicist Erwin Schroedinger came up with an
ingenious thought experiment.  His proposed experiment was to see if you can
kill a cat without looking at it and without the ASPCA [1] running you down
like those crazed mobs in the bad horror movies.  Just kidding; actually
his experiment was to prove that the field of Quantum Mechanics, which he
himself had helped to pioneer, was in fact completely ludicrous.  He was
like the Cheshire Cat of the physics world:  "We're all mad here.  I'm mad.
You're mad."  (Except he didn't smile constantly and couldn't disappear.)
The experiment consisted of placing three things in a sealed box:  a cat, a
vial of poisonous gas, and a radioactive mineral.  The experiment is set up
so that two conditions are true:  

          1) if the radioactive mineral decays it will release the gas in
             some way and thus kill the cat, and
          2) there is a 50/50 chance of the mineral decaying in the limited
             time the experiment takes up.

According to the Schroedinger Wave Form Equation (developed by none other
than Spiro Agnew, um, that is, Erwin Schroedinger) and the theories that go
along with it, you can not determine what will happen, only the probability
of a certain event occurring.  Strangely, this event does not actually
happen until you observe it.  Let's say you shoot one photon at a
photographic plate divided into two regions.  There is a 50% chance of it
hitting section A, and a 50% chance of it hitting section B.  Until you
develop and look at the plate, these are the probabilities, and both exist
at the same time.  

When you look at the plate, one of two things happen, depending on what
school of Quantum Physics you belong to.  There is the Copenhagen
Interpretation (so named because that was Einstein's brand of chewing 
tobacco), which states that when you look at the plate, the wave form will
"collapse" and the probability of the photon hitting section A will "jump"
to one, while the probability of the photon hitting section B goes to zero.
There is also the Many Worlds Interpretation.  Here, when you look at the
plate, the universe splits into two parallel universes, one where the photon
hits A and one where it hits B.  The Many Worlds Interpretation is the basis
for the popular television show "Melrose Place" (or is it 90210?).

Because the wave form collapses or the universe splits when the system is
observed, not when the event occurs, you can not tell whether the cat is
alive or dead before you look in the box.  Therefore, this deceptively
complex cat manages to be both alive and dead at the same time, until you
actually look in the box.  This defies all common logic and obviously must
be wrong.  This is why Schroedinger created this paradox:  to prove how
stupid our explanations for the sub-atomic realm seem, let alone our
explanations for the normal realm!

There is, however, a way around this problem.  If you could look at the
object without a single particle hitting it, then the wave form wouldn't
collapse or the universe wouldn't split.  While this seems impossible, using
a device known as an interferometer and a series of light polarizers it
becomes a possibility.  You can conclude that something is in a location
by the fact that a photon does not exhibit interference.  Not only that, but
it also makes thousands of julienne fries [2].  This is all thanks to the
wave-particle duality of light, which is a different story altogether [3].
This proves a very important point:  if man concentrates his entire brain
power on one task, eventually he will get too bored, pop open a beer and
watch the Jets lose.
 
[1] ASPCA, American Society for the Prevention of Cruelty to Animals, a fun
    American concept.
[2] A popular American infomercial-like term.  Used often in cheesy
    commercials for Ginsu knives and the like.
[3] Because one path of the interferometer is blocked, the beam splitter
    which usually recombines the two beams split at the entrance of the
    interferometer acts differently.  Even if only one photon is sent
    through the system, and it doesn't hit the object, interference will not
    occur.  This means a photon detector set up in a region that usually
    shows canceling interference now has a 50-50 chance of being hit,
    proving that something is blocking the path.  For information on how to
    do it with better than 50% chances, see the article in October 1996's
    Scientific American, "Quantum Seeing in the Dark" by Paul Kwiat, Harald
    Weinfurter, and Anton Zeilinger.

See also:
  • Quantum Mechanics Of Sandwiches In Lunchboxes
  • Cats
  • Gedankenexperiment
  • Drawing Conclusions
  • Supermarkets
  • Murphic Field In Daily Life, The
  • Alien Invasion, The Likelihood Of
  • Arguments, Infinitely Prolonging
  • Schroedinger's Dog

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