# [ExI] The Quantum Zeno effect

The Avantguardian avantguardian2020 at yahoo.com
Wed Dec 15 02:25:20 UTC 2010

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>From: John Clark <jonkc at bellsouth.net>
>To: ExI chat list <extropy-chat at lists.extropy.org>
>Sent: Mon, December 13, 2010 9:36:33 PM
>Subject: [ExI] The Quantum Zeno effect (was: CQT Researcher)

Suppose there were a radioactive atom with a half life of 60 minutes, in Many
Worlds one way of looking at it, that's not really correct mathematically but
can help getting an intuitive feel of it, is that if you look at it after 60
minutes the universe will have split into 2 with the atom decaying in one and
not in the other. If you look after 30 minutes there is a 25% chance it will
decay so the universe will have split into 4 with 3 having no decay and one with

decay, if you look after another 30 minutes each of those 3 will have split yet
again with 3 having no decay and one with decay. If you looked after just a
nanosecond one universe will see decay and many billions will not, you can see
that the number of Damiens (who splits just like everything else) who see no
decay of the atom vastly outnumbers the Damiens that do see decay, and more
often you check the larger the outnumbering. There will never be a 0% chance you

will see a decay but you can approach it asymptotically if you keep checking on
the atom at smaller and smaller time intervals, and this is just what we observe

in the Quantum Zeno effect.
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The Quantum Zeno effect has me perplexed. Riddle me this, quantish thinkers: If
simply observing unstable

particles can keep them from decaying, then why do Geiger counters work at all?
Each

time a decay happens the Geiger counter clicks so I suppose it could be thought
of as a continuous measurement of radioactive decay. Does a Geiger counter not
count as a "quantum measurement" for some reason? Is it because it is continuous

and not

discrete? Does the measurement have to be active instead of passive i.e. do you
have to shoot photons at the unstable particle for the Quantum Zeno Effect to be

observed? Is it because the geiger counter doesn't cover a complete 4*pi
steradians around the sample and many decay events go unnoticed? I have Googled
on the subject and the actual experiment that demonstrated the Quantum Zeno
Effect by Itano et al uses energy level

transitions of an electron from a berylium ion and not radioactive decay of any
type. So it really did not shed much light on my questions. Here is a summary of
their experiment:
http://www.ph.utexas.edu/fogs/symposium/Movies/5-QuantumZeno/3_Itano.pdf

And if the Quantum Zeno Effect does apply to radioactive decay, then
wouldn't the radioactivitity detector that triggers the poison inside the box
with Schrodinger's cat,

keep said cat alive by constantly checking on the decay of the isotope?

Stuart LaForge

"There is nothing wrong with America that faith, love of freedom, intelligence,
and energy of her citizens cannot cure."- Dwight D. Eisenhower

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