Re: quantum mechanics of small objects

["John S. Denker" <jsd@MONMOUTH.COM>]

At 04:04 PM 5/23/01 -0500, cliff parker wrote:
> Wouldn't the infinitely small volume of the singularity of a black hole
> require the position of any object that is part of that black hole to have a
> fixed and known position?

No.

Compare:
 -- Knowing _where_ something is, and
 -- Knowing _how big_ it is.

Those are just completely different concepts.

Classically speaking:  Suppose I see a finch on a twig.  I look away.  When
I look back, he is gone.  After a few minutes my knowledge of the finch's
position is uncertain by hundreds of meters.  But the finch hasn't gotten
any bigger.

Quantum mechanically speaking:  the position of a hydrogen atom has an
uncertainty given by the thermal deBroglie wavelenth. At milliKelvin
temperatures, this is on the order of microns.  But this does not mean that
these hydrogen atoms are the size of bacteria.

If (!) you know the position $R$ of the right edge of something and the
position $L$ of the left edge, then by subtraction you know its size.  But
(!) that is not the only way of knowing its size.  It is possible, indeed
common, to know $L-R$ without knowing either $L$ or $R$.