To coin an analogy from football, some of those bosons look more like plays than players.

Great line! - I am gonna steal that.

Phract - you could try the videos of Leonard Susskinds - the theoretical minimum. They are all available on line and range from introduction to einsteins relativity to qcd and particle models. Good stuff - not too easy, but not too hard

I'm still working (sporadically) on my answer to CPT Arkangel's question about black holes, but I'm going to detour for a moment to point out a glaring falacy in Leonard Susskind's

Cosmology Lecture 2. I certainly don't claim to be more knowlegible than Susskind, but nobody is infallible. Occasionally, a child sees thru the falacies of adult thinking, and a dummy occasionally pokes a hole in the logic of a genius.

Newton proved his shell theorem on the assumption that the spheres are finite and that infinite space beyond the outermost sphere is empty. He always referred to the gravity due to the mass inside the finite spheres, while tacitly assuming the absence of any mass outside of those spheres.

Beginning at about 42½ minutes, Susskind explains Newton's shell theorem. Then, at about 54 minutes into the lecture, he tacity assumes that Newton's shell theorem is valid for infinitely large homogeneic spheres, surrounded by more infinitely large homogeneic spheres, with no outermost sphere and no empty space beyond. The remainder of the lecture is falacious. Susskind is not alone in making this glaring error; I think Einstein made it, too, and perhaps others before him. It is a key assumption underlying the big bang bunk.

If you remove a spherical section of an infinite homogeneous universe, the gravity due to the remainder is equal and opposite to the gravity due to the part you removed. This is true regardless of how large a sphere you remove.

Another approach to the problem is to calculate the gravity at the focus of a pyramidal subset of the universe. Each half of the pyramid is equivalent, so the gravity from one half cancels that of the other half. You can truncate the pyramid at +r and -r and prove that the two halves always cancel as r approaches infinity. If you remove a piece of that pyramid, the change in gravity at the focus will be equal to the gravity due to a mirror image (across the vertex) of the piece you removed. Dividing the whole 4π sterradians into pyramids yields zero gravity.

In an infinite homogeneous universe, every point is equivalent to every other point, so every point is at the same gravitational potential. The gravity field is the gradient of gravitational potential, so the gravity field is zero everywhere, and gravity does not have any tendence to slow the expanion of space.

The question remains whether clumping of matter tends to decrease gravitational potential. I suspect the answer is yes, and that may be responsible for the foamy large-scale structure of the universe, but it does not tend to pull the most distant galaxies closer together, it only works on neighboring galaxies. Unless the expansion of space decreases the lumpiness, it does not increase gravitational potential.

It has been claimed that this argument presented by Suskind and others proves that the universe is finite. In fact, it proves only that the shell theorem is valid only for a finite universe.

P.S.: As far as I know, that football analogy is my own original, created

*ad hoc * for that post. I wouldn't mind getting credit when you use it; but I forgive you if treat is folklore.