From: scerir (scerir@libero.it)
Date: Tue Mar 26 2002 - 00:45:52 MST
from
http://www.nytimes.com/2002/03/26/science/26COSM.html
<snip>
.................... Dr. Wheeler likes to put it:
"How come the quantum?"
The answer is that nature is a kind of computer,
said Dr. Anton Zeilinger, a kind of ringmaster
of quantum tricks at the Institute for Experimental
Physics of the University of Vienna, who gave
the opening lecture.
Reality is quantized, he argued, because it is
in some sense made of information. Paraphrasing
Neils Bohr, the Danish physicist, Dr. Zeilinger
said quantum theory was about what could be known
about nature. And information comes in bits,
irreducible yes-no, on-off, decisions.
That is to say, information is quantized.
The most elementary system is one bit, Dr. Zeilinger
pointed out, one piece of information. Consider,
he said, an observer with one bit to spend on one
of the classic setups of quantum theory: an electron
sailing toward a screen in which there is a pair of
parallel slits.
According to quantum theory, whether the electron
was a wave and went through both slits or was
a particle and went through only one or the other
depends on what measurement the physicist chooses
to carry out. Knowledge of the electron's past path
blurs the knowledge of its present position, and
vice versa.
So if the physicist spends his single bit on saying
which path the photon took through the slits,
Dr. Zeilinger explained, he has nothing left to tell
him where the photon hit the detector. As a result
the photon's position is "irreducibly random," said
Dr. Zeilinger, adding that the this randomness is
an indication of a "reality independent of us."
"The fact that there are events that happen with
no reason is one of the deepest discoveries of physics
in the 20th century," Dr. Zeilinger said. "The whole
idea of physics was to find reasons for things."
<snip>
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