Re: misconception bu omission

[Leigh Palmer <palmer@sfu.ca>]

> The exponential models of radioactive decay and capacitor discharge predict
> infinite lifetimes.  There is always charge left; there is always un-decayed
> matter left.  We know that is not so! I cannot imagine presenting this model
> without a full discussion of the logical origins, implications, etc of this
> absurd mathematical statement.  Can we (should we) use a better model? . . .

No. We should instead tell the student (if he is puzzled) that the
result of his calculation is the expectation value of the amount of
charge left on the capacitor or the number of radionuclides remaining
after time t has elapsed. I am sure even an average student will
figure this out for himself if one presents the derivation of the
model properly.

Why do you pick on these phenomena, Bob? Why not object similarly to
the prediction of the position of a particle having uniform speed
moving in a straight line after an infinite time?

Leigh