Re: the inflence machine

[LUDWIK KOWALSKI <kowalskil@alpha.montclair.edu>]

On 4/8/97 Bob Sciamanda asked:

> Were the statistics of radioactive decay not yet understood - when 
> (and by whom) was this subject first understood? Anyone know?
Here is what I see on page 5 of my "Nuclear and Radioactivity" by 
Friedlander, Kennedy, Macias and Miller (John Wiley & Sons, 1981).

"In 1905 E. von Schweidler ... formulated a new description of the process
in terms of disintergration probabilities. His fundamental assumption was
that the probability p of a particular atom of a radioactive element 
disintegrating in a time interval dt is independent of the past history
and the present circumstances of the atom; it depends only on the lenth
of the time interval dt and for sufficiently short intervals is just
proprtional to dt; thus p=lambda*dt, ....". 

The law of exponential decayis is then shown to be a direct mathematical 
consequence of this assumtion. I did see the exponential decay formula, 
I(t)=I(0)*exp(-lambda*t), in the 1903 paper by Rutherford and Soddy but 
that was simply a description of experimental data.
  ...................................................................
  : Gedanken-ing is not enough; physics is an experimental science! :
  :    Inspired by thinking about phys-L messages on capacitors     :
  :                         Ludwik Kowalski                         :
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kowalskiL@alpha.montclair.edu   http://www.csam.montclair.edu/~kowalski