On-Line Information Sources
Physics -
Introduction
Some general sources. Most of these do not include vast, complex arrays of mathematical formulæ, but do give the opportunity to delve a little deeper than very basic introductions.
Richard Powell's site the Atlas of the Universe is an incredible source of information on astronomy and cosmology. I strongly recommend it.
Discover magazine and Science Daily both have all manner of articles, reviews and comment on all things scientific, not just Physics.
For general introductions to everything from quantum physics to cosmology try the Universe Review (website can be rather slow) and Cambridge University websites; both are excellent.
Home Science: Backyard Astronomy Basics offers an excellent introduction to the basics of astronomy.
The Official String Theory web site has a mass of information in either basic or, optionally, advanced form on all things related to Superstrings and "M" Theory.
MIT has a website The Net Advance of Physics that has a wealth of information on everything to do with physics in the form of an encyclopædia.
I like this Blog, Cocktail Party Physics, also available at here, because it is interesting, amusing and a little irreverent. It even has a selection of cocktails like "Heavy G - The perfect pick-me-up when gravity gets you down". Like me, the author, Jennifer Ouellette aka Jen-Luc Piquant, does not have much time for "alternative" or "new age" ideas, however, so beware.
Then there is the UCLA Frequently Ask Questions in Cosmology. Some of it has not been updated recently, so does not reflect the latest research and measurements, but in general it is an excellent source of information.
Ask the Astronomer presents information in the form of FAQs. It is pretty comprehensive, and groups items into Beginner, Intermediate and Advanced categories.
The National Center for Earth and Space Science Education. To quote them: "The National Center for Earth and Space Science Education, a Project of the Tides Center, creates and oversees national initiatives addressing science, technology, engineering, and mathematics (STEM) education, with a focus on earth and space. Programs are designed to provide an authentic window on science as a human endeavor, and to inspire … then educate". Also check out their Journey through the Universe program, and the Director, Dr Jeff Goldstein, also has his Blog on the Universe. Very interesting and inspiring.
The All Things Science website has many interesting videos.
Deep Astronomy is interesting, educational and amusing. Do take a look. Tony Darnell who runs it put together the Hubble Ultra Deep Field in 3D video you will find on the Hubble Space Telescope page.
A great source for technical papers, generally requiring university level mathematics, is the Cornell University Library's searchable database.