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One of my favourite things from my degree was learning about orbitals.  Orbital shapes are just probabilities. It is purely a probability that you will find that electron orbiting the nucleus at that particular point at that particular time.  They move so fast that you end up with a 3d representation of the orbital shape that looks solid. But in reality if you could freeze at any one moment, there would be dots of electrons in random looking places around the nucleus.

I don't think the concept of a spinning ball in space is hard at all. I'm astounded that we exist, that we are solid. Or we think we are. We are nothing more than a probability.   Each atom is full of empty space.  How am I so solid when I am so full of space?  Why does matter not sift through me as though I were a ghost?

Are ghosts just people with a lower probability of being solid?

I've been neutron scattering.  I've fired streams of neutrons at my samples and collected the scattered hits to tell me what shape my molecules are. The neutrons go into my samples and bounce off from inside the atoms and the angles in the scattering patterns tell me the size and shape.

Electromagnetic radiation goes through me. Photons are both waves and particles.  Particles goes through me, so am I really solid? Am I really here?

by In Wales (inwales aaat eurotrib.com) on Thu Dec 20th, 2007 at 03:03:56 AM EST
[ Parent ]
This guy yesterday was explaining how those elements with....heh....I'll have to go studying, but basically the metals lock together because it is the (you know all this!  I say it so see if I've learnt) metals are willing to share their electrons (hence they conduct electricity)--hence they are solid--locked together.  The noble gasses have perfect outer shells, have no need to bond with anything and so never become solid.  Liquids have strange pairings and water is the strangest of all...I didn't quite get it, but the oxygen can easily transfer its electron (or pick one up) from different hydrogen atoms so there's slippage--liquid.  You and I are mostly made of water so you're not a gaseous ghost--you have spare electrons which are out and about being chucked or hoovered up; but you're not super solid--you're not locked down like rock.  You're fluid, mostly, and so fluidity...

...and yeah, all that empty space!  But we're so huge and the empty space is inside the structures...anyways, I'm gonnae read up on the electron shells...it's a way to learn the names and characteristics of some elements I know nothing about....and I'm sure you're glad I told you that!  

Don't fight forces, use them R. Buckminster Fuller.

by rg (leopold dot lepster at google mail dot com) on Thu Dec 20th, 2007 at 06:06:58 AM EST
[ Parent ]
Water is weird - lots of odd-ish quantum chemistry.

The empty space idea isn't quite so weird. There's a big difference between everyday space, which is full of nothing much, and quanutum space, which is either full of or surrounded by dense probabilities.

So it's not really empty in the same way. :-)

by ThatBritGuy (thatbritguy (at) googlemail.com) on Thu Dec 20th, 2007 at 11:31:04 AM EST
[ Parent ]
I am not sure into how much detail I should get into here, but this is not quite right
In Wales:
They move so fast that you end up with a 3d representation of the orbital shape that looks solid. But in reality if you could freeze at any one moment, there would be dots of electrons in random looking places around the nucleus.
Electrons don't have trajectories, and as you know from molecular bond theory there is such a thing as orbital hybridization which is just a change of basis achieved using linear algebra. For instance, you start with one (spherical) 2s orbital and three 2p orbitals (aligned along the X, Y, Z axes) and you end up with 4 orbitals pointing at the vertices of a tetrahedron. The point is that the decomposition is mostly arbitrary. In particular, there's no reason to choose one collection of five orthogonal 3d orbitals over any other unless there's an external electromagnetic field.
Or we think we are. We are nothing more than a probability.   Each atom is full of empty space.  How am I so solid when I am so full of space?  Why does matter not sift through me as though I were a ghost?
Have you studied the basic Born-Oppenheimer theory of the hydrogen molecule? Have you looked at how the atomic orbitals hybridize into binding and non-binding molecular orbitals? If you have the two electrons in a non-binding molecular state you can see how the two atoms bounce off each other - that is, they behave as if they're solid. It's all a consequence of combining the Pauli exclusion principle and quantum-mechanical superposition of states.
I've been neutron scattering.  I've fired streams of neutrons at my samples and collected the scattered hits to tell me what shape my molecules are. The neutrons go into my samples and bounce off from inside the atoms and the angles in the scattering patterns tell me the size and shape.
Yes, because the neutrons are not charged and so they don't really interact with the electron clouds, only with the atomic nuclei. Well, there is a small scattering cross-section of electrons by neutrons, but if the neutrons are energetic enough the most they'll do is knock an electron off the molecule and go on on their merry way. But photons see the electron cloud because charged particles interact strongly with them.
Photons are both waves and particles.
"Things propagate as waves but interact as particles" would be a possible way of saying this.
Particles goes through me, so am I really solid? Am I really here?
You have a small interaction cross-section with certain particles. Just because a glass pane is transparent doesn't mean it's not solid, isn't it? Now, depending on your definition of solid, you're most emphatically not. Parts of you are liquid, parts of you are gels or emulsions, parts of you are rather elastic. Only your bones and teeth are solid and not througout their whole volume.

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Thu Dec 20th, 2007 at 06:29:16 AM EST
[ Parent ]
I know that, I just like my interpretation of it.  I like taking some of the models to their extreme literal interpretation for want of a better way of putting it, even if it looks warped.
by In Wales (inwales aaat eurotrib.com) on Thu Dec 20th, 2007 at 07:19:16 PM EST
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Like Mr. Tompkins?

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Wed Dec 26th, 2007 at 03:05:52 PM EST
[ Parent ]
Who is Mr Thompkins?  I mean I just like letting my imagination run away with me to all the possibilities, silly or otherwise.
by In Wales (inwales aaat eurotrib.com) on Fri Dec 28th, 2007 at 07:13:14 AM EST
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