Note, again, this is all my layman understanding.

Warp wrote:
>   Does that mean that the reason why objects can't pass through each other
> is fundamentally electromagnetic?

Yes. There's only four forces: gravity, electomagnetic (aka electrostatic or 
quantum electrodynamic), the weak force (which I think is what holds the 
nucleus together) and the strong force (which I think is what holds the 
quarks in a proton or neutron together).  The QED force is photons 
interacting with electrons, and nothing else. So, basically, anything not 
gravity or "nuclear" is electromagnetic.

>   A photon is the basic unit (quantum) of electromagnetic radiation and
> although it has no mass, it's also the force carrier of electromagnetic
> force. But how exactly does this work in this situation? What forces are
> acting what?

Photons and electrons interact. It makes the electrons change which 
direction they're going.

>   Additionally, photons have a frequency. If the gaps are full of photons,
> what produces them. 

Quantum uncertainty, apparently. At this point, I'm not sure anyone knows 
the "why" of spontaneous photon generation. Basically, every possible 
combination of giving-off-photons and absorbing-photons is averaged together 
(with the appropriate math for "averaged") and the probability that 
something happens is based on that.

> what is the frequency of these photons and why?

There are apparently many frequencies. Altho, as I understand it, a photon 
doesn't have an actual frequency on its own. Every photon is identical. What 
gives a photon its frequency is the relative motion of the source and 
destination of the photon. Otherwise relativity wouldn't work.

>> The photons last only a very brief time.
> 
>   Where do they disappear to, and why? 

They get absorbed again. It's like saying the contact between billard balls 
lasts a very brief time.

> Certainly their energy has to go
> somewhere, it cannot simply disappear.

Yes, it is imparted to the electrons. Which is what's holding your ass up in 
spite of gravity. The photon pushes chair down and ass up, for a net change 
of zero. :-)

The emission of the photon from an electron causes that electron to have 
less energy. The absorption causes it to have more energy. Net result is zero.

Very often, photons will be emitted from an electron and almost instantly 
reabsorbed by the same electron. That's where the photons come from.

Read the first instance (i.e., the #10 negative energy) of this article:

http://listverse.com/2010/11/04/10-strange-things-about-the-universe/

Essentially, vacuum isn't empty. It's constantly full of random virtual 
particles that come into existence, last for a tiny amount of time, and then 
annihilate each other (being equal-and-opposite). Photons do this, and 
electrons do this, as far as anyone can tell from measurements. So at 10nm 
distance, the two plates have excluded enough random particle possibilities 
that there's an entire atmosphere of pressure on the outside more than there 
is between them, just as an example of how tiny is "tiny".

>> When the electrons from one atom are close enough to the other that 
>> the photon has time to go between, they interact.
> 
>   Why doesn't this happen with electrons orbiting the same atom?

It does. That's why all the electrons don't collapse onto the 
oppositely-charged nucleus. That is the source (I think) of the Pauli 
exclusion principle.

>   If the repulsive force of the photons produced by electrons is so strong
> as to completely forbid two atoms from passing through each other, why are
> the electrons in one atom exempt from this same repulsion force?

Because they're also exchanging photons with the protons. The protons have 
an opposite charge, which means they basically move in the opposite 
direction (of how an electron would move) when they absorb or emit a photon, 
and this causes the electrons to move closer to the proton instead of 
farther away. So the electrons are pushing each other apart, but the protons 
are pulling them closer, so the more protons, the more electrons it'll hold 
onto. Then you can look at the periodic table and see how the "holes" and 
"overages" of ionic behavior follow.

Alternately, and I might be misunderstanding/misremembering this, one of the 
"nuclear" forces (strong or weak) might be involved here. Oh, OK, according 
to wikipedia, the strong force holds protons to other protons (i.e., holds 
the nucleus together) *and* holds quarks together. Weird. The weak force 
apparently deals with neutrinos, beta decay, and other stuff I understand 
nothing about. :-)

Basically, the nuclear forces work on essentially the same principle, except 
they have different particles, different likelihoods of interaction, etc.

-- 
Darren New, San Diego CA, USA (PST)
   Serving Suggestion:
     "Don't serve this any more. It's awful."

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