What do we touch?

[NevelSmide]

I have recently been exposed to theory that nothing ever touches anything,
here on earth. It was said that the electrostatic charge between two
objects coming very close to eachother is enough to keep them away, but
also enough to give the simulation of actual contact. I am somewhat
skeptical about this, but would like some other input as well.
Thanks,
Gary

[Nathaniel Tagg]

NevelSmide (nevel...@aol.com) wrote:
: I have recently been exposed to theory that nothing ever touches anything,

Depends on what you mean by 'touch', of course. Two electrons
cannot physically bump into each other; they are, after all, mere
wavefuctions in space that interact with each other.
The actual force involved in 'touching' is electromagnetic; it is
certianly not gravitational, weak, or strong.

However... is this just a 'simulation of actual contact'? As I
just pointed out, there ISN'T any such thing.

--
Nathaniel Tagg Physics grad student University of Guelph
"The chances of a neutrino actually hitting something as it
travels through all this howling emptiness are roughly comparable to that
of dropping a ball bearing at random from a cruising 747 and hitting,
say, an egg sandwich." -- Douglas Adams, _Mostly_Harmless_

[Ronald Kunne]

In article <44rn3d$4...@newsbf02.news.aol.com>

nevel...@aol.com (NevelSmide) writes:

>I have recently been exposed to theory that nothing ever touches anything,
>here on earth. It was said that the electrostatic charge between two
>objects coming very close to eachother is enough to keep them away, but
>also enough to give the simulation of actual contact. I am somewhat
>skeptical about this, but would like some other input as well.

Consider that objects are made of atoms, itself consisting of nuclei
and electrons sort-of smeared out in shells around the nuclei.
These shells have diameters of the order of 10^-10 meter and are
negatively charged. Therefore neighbouring atoms cannot approach
each other more than those distances.

However, these shells are more or less empty: classicly you might think
of electrons whirling around the nuclei, but the quantum mechanical
discription is somewhat more elaborate.

All mass is concentrated in the nuclei. Assuming you weigh 70 kg, all
your electrons together weigh only 35 grams. But these nuclei have
diameters much and much smaller than the electron shells that `make'
the atoms. A typical diameter is a few times 10^-15 meter. To put that
to scale: if the atom has the size of a football field, then the nucleus
has the size of the fly on the kick-off point.

You see, an atom is essentially empty... and because of the electromagnetic
repulsion of the atoms the nuclei, those centers where the mass is located
do never touch.

Greetings,
Ronald