Re: Quantum Leap

[John Denker <jsd@MONMOUTH.COM>]

Hi Folks --

At 01:16 AM 9/29/99 -0400, Bob S. wrote:
> > Compared to an infinitesimal classical transition, any finite quantum
> > leap is BIG :)

And then At 03:49 AM 9/29/99 -0600, Jim Green wrote:
> Bob, I am not sure that I understand what you say here

Let me take a whack at it.  There is a common figure of speech that says
that the classical limit is where "hbar goes to zero".  But if you want to
get picky, that's not right.  Obviously hbar is not zero, and it's not even
a variable.  So the correct way to say it is that the classical limit is
where your system is so big that hbar seems small compared to every
(energy*time) and (momentum*distance) product that you care about.

Turning that last sentence around, we get the answer to the original
question:  In a quantum-mechanical system, hbar seems *large* compared to
the (energy*time) and (momentum*distance) products that you care about.  So
the quantum world is the world of big transitions, with no intermediate stages.

This usage is consistent with the ancient Latin roots:
        Quantum (adv):    How much.
        Quantulum (adv):  How little.

So it is 100% correct and appropriate to use the term "quantum leap" to
describe a large, qualitative change with no intermediate stages.

OK?

______________________________________________________________
copyright (C) 1999 John S. Denker             jsd@monmouth.com