PhysicsGroupie

Has anyone used the Sky Server (SDSS) for conducting astronomy experiments? I really like the facility, but I have a question of anybody who has used it. The data dictionary they publish is nice, but it is shy on details regarding the definition of each data element. For example, the sample 20 SQL queries provided to new users are straightforward in structure, but in terms of how the fields are used, more in-depth knowledge seems to be required. Has anyone else figured out where to get more detailed scientific background info? Thanks!

I've never fully understood where the scale of the expanding universe is limited on the lower end. That is to say, what is the distance (scale) boundary of expansion? For example, why isn't the matter contained inside of a galaxy expanding? Further, why isn't the matter inside our solar system expanding? Further, why isn't matter on the tip of my finger expanding? If everything were expanding relative to everything else, we wouldn't notice any difference. But we do since the expansion is only prevalent in the large scale structure of the universe, but why?

Hello, I just joined SFN and I think it is great!. I wanted to ask if it is cool to include the URL to my blog "Science Lifestyle Blog" in my signature? On my blog, I write mini-essays on various science topics. It would be great to discuss some of the topics here on SFN, but I don't want to offend anyone if I post a link to a particular essay, so we could discuss it here. For example, the most recent essay is regarding Richard Feynman. It could be great to discuss Feynman here on SFN. Anyway, I just wanted to make sure I know the rules before I do anything. Thanks!!