SV: Capacity of the brain
bernd.paysan at gmx.de
Thu Oct 21 16:47:23 EST 1999
patrik bagge wrote:
> >> Quantum physics allows information to be stored in the entanglements
> >> between particles. We don't know if there's a limit on the amount of
> >> information stored in the enganglements with the environment, that the
> >> brain can decode...
> >Except that "information" doesn't correspond very well (if at all) to
> >what we normally think of as information.
> ok, that does it, my curiosity is reaching enormous proportions ;-)
> what do you mean ?
Entangled states are one of the more popular mysteries of Quantum
Mechanics (short QM). What they "store" can be best called "destiny".
That is, you can create a pair of entangled particles (e.g. photons),
and send them out to two polarizer. While non-entangled photons would
create random coincidences on parallel adjusted polarizers, entangled
photons create a significantly higher amount of coincidences.
This also works for single photons (or any other lightweight enough
particle). If it is possible that it passed more than one way in the
experiment, it "knows" of all the ways it could have passed, and you
have to add the corresponding wave functions to find the probability
pattern of the resulting particle - it can't appear where the
probability is zero, although this might have been a straight way on one
The information "stored" in such a particle (classical QM doesn't think
this way) however is limited, though. You can test the particle or
photon about its knowledge, and it will always only reveal one "fact" -
after that, the wave function has collapsed, and all the other "facts"
it would have to remember (the rest of the probability function) is
Note that there is a hint that this idea of "remembering" might actually
be true, since a time variating experiment could tell the difference
between the "remembering" interpretation and the classical QM
interpretation (which doesn't talk about how the particle obtains the
state at all - the state simply is there). Aspect et al. did *one*
time-variating EPR experiment (with two entangled photons, named after
Einstein, Podolsky, and Rosen, who initially wanted to contradict QM and
failed on hundrets of static tests). Aspect et al. reported just one
result: at 50 MHz switching frequency and a distance of 6 meters between
source and switched polarizers, it works as QM predicts. Unfortunately,
50 MHz has a wavelength of 6 meters, so they proved nothing, and no
variations in distance and/or frequency have been published. Anton
Zeilinger, who found that flaw, promised to do a more concise
experiment, but up to now, nothing happend.
There is a speculation about being able to "clone" a particle, which
would allow a non-destructive test, but so far, the only successful
"teleportation" (done by a team around Zeilinger) only succeeds in one
fourth of the time (the rest is lost), and has the important flaw that
the experimentators left the switch out that would "kill" the failed
clones. Since this would make the experiment time-dependent, it bogs
down back to what I said above.
Baseline: we don't know yet how much information is stored in
entanglements, but given that all experiments that do give hints only
succeed when assuming the conventional limit I won't put too much hope
in that. It would be strange if you really could trick out the
uncertaincy relation of QM by using the wave function variation of QM,
which has been proved as equivalent quite early.
"If you want it done right, you have to do it yourself"
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