[e2e] Why do we need TCP flow control (rwnd)?

David P. Reed dpreed at reed.com
Fri Jul 11 23:59:58 PDT 2008

Not to be picky, but a pound lump of U-238 by itself is probably not a 
Poisson emitter, either.  Neutrons, etc. do interact with the other 
elements of the generating process, perhaps triggering additional 
events.  And an atom of U-238 generates a single event.  Probably also 
not a Poisson process.

Perhaps U-238 in a very, very low-density empty region of space?

I prefer to think of Poisson processes as entirely in the domain of 
mathematics - a calculation tool - given the difficulty of proving 
anything is a Poisson process.   How do we know that the apparent 
indeterminacy (randomness) of physics is essential in reality or merely 
a determinacy inaccessible to us, below the planck limit?  My philosophy 
of science suggests that it does not matter, but yours may differ.

Ted Faber wrote:
> On Fri, Jul 11, 2008 at 02:59:13PM -0700, Lachlan Andrew wrote:
>> Greetings Ted,
>> 2008/7/11 Ted Faber <faber at isi.edu>:
>>> True Poisson processes are rare; the only one I can think of off the top
>>> of my head is radioactive decay.
>> Just to be picky, that isn't Poisson either, although it is well
>> approximated as Poisson on "short" time-scales (relative to the
>> half-life).
> No observations on my students' Normality? :-)
> You're correct, of course.  I do believe that the radioactive decay of a
> pound of U-238 over a month is a Poisson process, but on timescales
> close to the half-life it is not.  Smaller samples or isotopes with
> shorter half-lives would not be.  That's what I get for
> underspecification. :-)

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