[ExI] The Quantum Zeno effect

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

>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.

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? 

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:
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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