From: "Perry E. Metzger" <perry@piermont.com>
Date: Sat, 4 Nov 1995 10:26:40 +0800
To: Peter Monta <pmonta@qualcomm.com>
Subject: Re: Sources of randomness
In-Reply-To: <199511032324.PAA22269@mage.qualcomm.com>
Message-ID: <199511040044.TAA00751@jekyll.piermont.com>
MIME-Version: 1.0
Content-Type: text/plain



Peter Monta writes:
> I'm puzzled by the implication that thermal noise or avalanche or Zener
> noise is somehow inferior to noise from radioactive sources.  It's not.

I didn't contend that its inferior. I contended that its difficult to
distinguish from sources of electronic interference and is easy to get
wrong.

> Take as an example Johnson noise, the voltage noise from a
> resistance.  It's the result of the interaction of vast numbers
> of electrons.  It is unpredictable in the same way that individual
> radioactive decay events are unpredictable, and they are both
> results of friendly quantum mechanics.

However, its very easy to be sure that the event in a radiation
detector was a radioactive decay event. It takes expertise to make
sure that the noise you hear off a noisy circuit isn't just
interference from other parts of the machine feeding back into the
circuit. The reason I like radioactive sources is that they are simple
and unambiguous in this way.

Someone can gimmick a zener diode or get it "wrong" a lot more easily
than they can get a radation event wrong.

Perry