I have a question.

[DropLogic]

It should be noted also that they aren't actually moving, but that space is expanding between them, giving the illusion of moving.

Ok, this makes a lot more sense to me now.  Thank you for explaining.

My back yard is quite dark at night.  Usually at around 2:30 am, i'll go out on the deck with my dogs and stare up for 30-40 minutes; at least when it's a clear night.  The universe overwhelms my feeble mind almost to the point of panic sometimes.  I wish I had a better understanding of why it works this way.  Could you recommend some books for an astronomy/physics/quantum layman?

[hackenslash]

It should be noted also that they aren't actually moving, but that space is expanding between them, giving the illusion of moving.

Ok, this makes a lot more sense to me now.  Thank you for explaining.

My back yard is quite dark at night.  Usually at around 2:30 am, i'll go out on the deck with my dogs and stare up for 30-40 minutes; at least when it's a clear night.  The universe overwhelms my feeble mind almost to the point of panic sometimes.  I wish I had a better understanding of why it works this way.  Could you recommend some books for an astronomy/physics/quantum layman?

An excellent place to start would be the book that has recently hit the top of my recommended reading list, the brilliant Why Does E=MC2 by Brian Cox and Jeff Forshaw. Once you've got to grips with that, Hawking's A Brief History Of Time is excellent, although some of it is a little outdated now. Brian Greene's Fabric Of The Cosmos is very good, apart from a very woolly treatment of entropy throughout.

Let me know when you've read those, and I'll recommend some more advanced reading.

[tymygy]

It should be noted also that they aren't actually moving, but that space is expanding between them, giving the illusion of moving.

Exactly, Think of it like a balloon being blown up, if you draw small galxies all over the balloon and start blowing it up, they will start growing in distance in relation to each other. The spots didn't move at all, but the space that the spots were occupying became larger therefore making it scale to its size on which it originally started.

[DropLogic]

It should be noted also that they aren't actually moving, but that space is expanding between them, giving the illusion of moving.

Exactly, Think of it like a balloon being blown up, if you draw small galxies all over the balloon and start blowing it up, they will start growing in distance in relation to each other. The spots didn't move at all, but the space that the spots were occupying became larger therefore making it scale to its size on which it originally started.

If that is true, and galaxies stay constant in size themselves...what about the space within galaxies?  Does that not expand because of gravity's influence?

[tymygy]

It should be noted also that they aren't actually moving, but that space is expanding between them, giving the illusion of moving.

Exactly, Think of it like a balloon being blown up, if you draw small galxies all over the balloon and start blowing it up, they will start growing in distance in relation to each other. The spots didn't move at all, but the space that the spots were occupying became larger therefore making it scale to its size on which it originally started.

If that is true, and galaxies stay constant in size themselves...what about the space within galaxies?  Does that not expand because of gravity's influence?

I never said anything about galaxies having a constant size. I'm talking about all the matter in the galaxy. the galaxy as a whole, doesn't move by itself, the space around it expands.

Gravity is what holds the galaxy together. So no the space inside the galaxy is not affected in the same way.

[Tank]

It should be noted also that they aren't actually moving, but that space is expanding between them, giving the illusion of moving.

Exactly, Think of it like a balloon being blown up, if you draw small galxies all over the balloon and start blowing it up, they will start growing in distance in relation to each other. The spots didn't move at all, but the space that the spots were occupying became larger therefore making it scale to its size on which it originally started.

If that is true, and galaxies stay constant in size themselves...what about the space within galaxies?  Does that not expand because of gravity's influence?

The same thought crossed my mind regarding the expanding galaxies and went on to consider if I am also expanding? The answer is; apparently not. Trouble is I can't bloody remember where I found out that galaxies don't expand.  

[hackenslash]

Indeed. Galaxies are gravitationally bound, so are not subject to cosmic expansion.

[Tank]

Indeed. Galaxies are gravitationally bound, so are not subject to cosmic expansion.

That's what they said, I'm glad somebody else knew it!

[Tank]

Indeed. Galaxies are gravitationally bound, so are not subject to cosmic expansion.

Does this not imply that gravity is an aberration and that expansion is the norm? Thus as the universe expands, and the effects of gravity are diluted, that accelerating expansion would be expected to occur?

[tymygy]

Indeed. Galaxies are gravitationally bound, so are not subject to cosmic expansion.

Does this not imply that gravity is an aberration and that expansion is the norm? Thus as the universe expands, and the effects of gravity are diluted, that accelerating expansion would be expected to occur?

Just because the universe expands does not mean gravity will be "diluted". Gravity depends on the amount of mass of an object(s) and the amount of mass will constitute for the strength of gravity, not the space around it.

[Tank]

Indeed. Galaxies are gravitationally bound, so are not subject to cosmic expansion.

Does this not imply that gravity is an aberration and that expansion is the norm? Thus as the universe expands, and the effects of gravity are diluted, that accelerating expansion would be expected to occur?

Just because the universe expands does not mean gravity will be "diluted". Gravity depends on the amount of mass of an object(s) and the amount of mass will constitute for the strength of gravity, not the space around it.

The effect of gravity is expressed as square law, doubling the distance reduces the effect by a factor of four. As the universe is expanding the galaxies are moving apart this will dilute the effect of gravity as the existing mass is expressing gravity within a greater volume.

[Thumpalumpacus]

Kip Thorne's Black Holes and Time Warps is a little more esoteric, but packed with info.

[ablprop]

It's outdated now, but I have very fond memories of reading "Coming of Age in the Milky Way" by Timothy Ferris.

[tymygy]

Just because the universe expands does not mean gravity will be "diluted". Gravity depends on the amount of mass of an object(s) and the amount of mass will constitute for the strength of gravity, not the space around it.

The effect of gravity is expressed as square law, doubling the distance reduces the effect by a factor of four. As the universe is expanding the galaxies are moving apart this will dilute the effect of gravity as the existing mass is expressing gravity within a greater volume.

Do you mean from each other? Or the galaxy itself is "unwinding"?

[Thumpalumpacus]

From each other.  Gravity is a spatial sink-hole.