[net.physics] Nature of material interactions

wmartin@brl-tgr.ARPA (Will Martin ) (05/13/85)

I'm far behind in reading many groups including these; please mail
any responses, or mail me copies of ones you post, so I don't miss them.

I recall reading, in some popularized-science book which has now been
otherwise forgotten, that the force one feels when one presses one's hand
against the wall is actually the electromagnetic repulsion between the
electrons in the hand's atoms vs. the electrons in the wall's atoms.

Is this true? If not, what is the origin or nature of whatever is
experienced when objects "push" against each other?

I suppose, on a sub-molecular level, there is a certain amount of 
"blending" together of my hand and the wall when I press it -- when
I remove my hand, there are a discernable number of atoms/molecules
from me left there in the wall, and from the wall in my hand. Since 
it appears that matter is made of really fairly-widely-spread-apart
atoms in each molecule, and the molecules themselves are fairly widely
spread, why don't we move *through* other matter more than we do,
like "colliding" galaxies really pass through each other with little
star-to-star contact? Is there something akin to "surface tension"
that keeps pieces of "solid" matter from merging when pressed together?

Will Martin

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