Everything is empty, how do I see it?

[mudslidexc]

Hey guys, I have a question that's been bothering me lately and I'm hoping someone can give me the scientific explanation.

 

Everything is made up of atoms.. myself, the table in front of me, etc.. correct? And atoms are pretty much just empty space right? (I seem to remember an analogy along the lines of "if the nucleus is a basketball in New York, then the electron would be a golf ball in London".. or something to that effect).

 

So it stands to reason that my body and everything around me is pretty much entirely empty space right? If this is the case, how is it that I can see and feel these objects? What am I seeing and feeling?

 

Thanks so much in advance.

[Sisyphus]

You see when photons - "particles of light" - enter your eye and hit your retina. Your brain interprets the sum of these as the various objects you see around you (correctly or not), but technically, you're not "seeing" these things at all. You're seeing what is inside your eye.

 

The atoms of your finger and of a table might not be "solid" in the sense of being made of continuous "stuff," but they still can't pass through one another, because their electrons repel one another. It is that repulsion that you feel when you touch an object.

[tvp45]

There are really two effects that account for this. One is that atoms are quite a bit smaller than the wavelength of visible light and so you can't "see" them with your eye.

 

But, the other is what your brain does with light that enters the eye; look at a Monet painting, both closely and at a comfortable viewing distance. The individual cells in your retina respond to specific colors, edges, orientations, etc but your visual cortex organizes all that into something that makes sense.

[Mr Skeptic]

Though matter does not have traditional volume, all matter is in the form of wave-particles, which have a probability density over a volume. Their distribution is based on the momentum and mass of a particle, such that particles with more momentum have a shorter wavelenth (so are more localized), and more massive particles are also more localized. Particles are considered point particles (with zero size or volume) when measured, but are smeared out in a probability distribution.

 

So the nucleus of an atom is a fuzzy blob in the center, and the electrons are a fuzzy cloud around the nucleus. The whole thing is a fuzzy probability distribution. The whole thing about basketballs and golf balls may give you a sense of scale, but it is not accurate.

 

For macroscopic objects, the atoms themselves don't touch, but are repelled by Van der Waal forces.

 

You see things with photons, as Sisyphus said. The photons don't generally "hit" the electrons, rather they move them from one orbital to a higher one. If light at that frequency cannot move the electron to a higher orbital, it will pass right through.

[mudslidexc]

Thanks much fellas, very helpful explanations all around. Much appreciated!

[Riogho]

Photons hit the atom and are absorbed and then re-emmitted, that is what you see.

 

They usualyl hit the elctrons.