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snowflakeuniverse: Could matter itself be expanding? How could you tell if all the rulers also expand?
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You're right, if we lived in a universe where the rulers are expanding right along with the universe, it would be difficult to tell. Except - in order to measure expansion in a universe in which the rulers are expanding wouldn't it require that space be expanding faster than the rulers?
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snowflakeuniverse: Regarding the date of formation of Jupiter issue, I think present models have a hard time explaining a 14 to 15 billion year old universe. If our solar system formed 5 billion years ago (plus or minus a half a billion) what happened in the previous 10 billion years?
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Stars are forming constantly. The prevailing view is that the universe began about 13-14 billion years ago and previous generations of stars produced the heavier elements that have been incorporated into our solar system. There is really not a problem here. Is there some reason why you think our solar system should be the same age as the universe?
Oh, this must be what you're thinking:
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snowflakeuniverse: If galaxies are observed to be formed this early in the evolution of the universe, shouldn’t other celestial structures such as solar systems be also similarly formed at about the same time? Should our solar system be assumed to dislike those observed in the past?
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Again, star formation - and solar system formation is an ongoing process that is being observed even now. There is no reason to think that it won't continue for a very long time. Its expected that solar systems will have different ages. One thing that can be compared is metallicity of stars in the Milky Way. In general it is expected that the older stars should have lower metal contents. The metallicity content of the Sun is consistent with it not being one of the first generation of stars.