Fundamental Physical Constants : Information at the foundation of modern science and technology from the Physics Laboratory of National Institute of Science Technology.

The Particle Adventure : Introduces the standard model theory of fundamental particles and forces and explores the experimental evidence and reasons why physicists want to go beyond this theory. Feedback from teachers will be appreciated.

Relativity on the World Wide Web : For the curious novice, there is a collection of links to "equation-free" explanations of Einstein's theory by expert relativists and science fiction writers. For more detail, click on an online tutorial or download a set of lecture notes from graduate-level physics classes.

Quantum Mechanics: This site should help high school students and college nonscience majors understand the essential concepts. It offers interactive animations that demonstrate, without using mathematics, the quantum mechanical origins of atomic spectra, laser action, diffraction of matter, and other phenomena.

String Theory: A tutorial on string theory, the framework that many physicists believe will allow them to tie down a unifying "theory of everything." The tutorial explains strings at two levels of difficulty: advanced for the calculus-savvy and basic for those stymied by the first chapter of Stephen Hawking's A Brief History of Time.

The Physics of Microwave Background Anisotropies
Cosmic microwave background anisotropies provide a vast amount of cosmological information. Their full physical content and detailed structure can be understood in a simple and intuitive fashion through a systematic investigation of individual mechanisms for anisotropy formation. Beginner through Advanced presentations.

Interactive Guide to Diffraction : This is a "pictorial guide to crystal structures and their Fourier transforms," or what scattering data look like after they've been processed by a computer. The site includes eight interactive simulations that allow users to tweak an atomic structure and see its Fourier transform.

Eric Weisstein's World of Physics : To look up "brown dwarf," "pendulum," or "Navier-Stokes equations," you could consult any number of free Web dictionaries. Treasure Troves of Science is a storehouse of definitions for math, astronomy, physics, and other topics. Brief biographies of more than 1000 scientists.

The Net Advance of Physics : Need to review the latest Bose-Einstein condensation studies or brush up on the Kuiper asteroid belt? A resource for physics students and researchers seeking background on such topics.

Physics Central : Wondering why the sky is blue, or how lasers can cool atoms to absolute zero? Find out at this educational site from the American Physical Society. Aimed at the high school level and up, the magazine-style site combines features and articles reprinted from APS and elsewhere.

HyperPhysics Intro : You'll find a huge collection of capsule reviews of material covered in introductory physics, such as electromagnetism and quantum physics. Subjects are linked in flow charts, so visitors can wander intuitively from mechanics to fluids to hydraulic brakes. Use the index to bone up on scores of topics.

Radiation and Health Physics : Several primers and a glossary will set you straight on nonionizing and ionizing (electron-stripping) radiation and becquerels versus curies. A timeline covers not just Three Mile Island but the first reactor "accident" 1.8 billion years ago: a uranium deposit in Gabon that burned for 200,000 years.

X-Ray Data Booklet: A compendium of graphs and tables of values needed for experiments that was first published in 1987. A new Web version of the latest edition lets you find electron binding energies, x-ray emission energies, and more with a few clicks. There's also a primer on synchrotron function and history.

Online Conversion: This handy site performs conversions faster than St. Paul. From parsecs to hogsheads, the calculator handles some 5000 units of length, temperature, weight, speed, volume, time, power, and other measures. You can change metric to metric, English to metric, and for that retro thrill, metric to English.

Electricity, Electronics, and Computers : This e-museum aims to galvanize interest in electricity and information technology among students, teachers, and the general public. Current exhibits investigate the discovery and harnessing of electricity, how we record and play music, and the life of Thomas Edison.

Name of a Number : Ever get tongue-tied trying to read the English name of a multi-multidigit number like 372,469,737,190,393,701 (the number of inches in a light-year? Enter the digits, and out comes the name, in your choice of American (million, billion, trillion, quadrillion) or European (million, milliard, billion, billiard) units.

Internet Learning Network : Offers quizzes based on questions from the Third International Mathematics and Science Study. It's sponsored by the Council on Competitiveness, in response to the poor showing of American high school seniors in general science literacy on the widely cited test.

Math on the Move : The new Journal of Online Mathematics and Its Applications (JOMA) serves up an enticing array of Web-based teaching tools for all levels of college math.

MathGate: A huge collection of annotated links delivers you to scores of math sites on topics ranging from matrix algebra to probability theory to topology. Links to journals, societies, and departments predominate, but the catalog includes several preprint archives, Web texts, historical and educational sites.

World of Mathematics: Treats everything mathematical, from the abc conjecture to Zorn's lemma, with over 10,000 entries and links to references, animated graphics and Java applets. Check out the billiard ball bouncing around inside a tetrahedron.

The Chaos Hypertextbook : Curious readers can find an orderly path through chaos theory here. It covers the basics: one-dimensional iterated maps, strange attractors, fractals, and Lyapunov exponents -- mathematical quantities that measure how chaotic or well-behaved a system may be.

VassarStats: Statistical Computation : Concepts & Applications of Inferential Statistics. Utilities: Note Pad, Pocket Calculator, Randomizer, Data Storage Window, Site Search

Engineering Statistics Handbook : Beef up your stats IQ with this primer from the N.I.S.T. and the microchip consortium SEMATECH. Eight chapters cover topics such as measurement, selecting statistical models, and data analysis, using samples and in-depth case studies that emphasize engineering problems.

Rice Virtual Lab in Statistics : If you're looking for a clear, basic stats how-to, this site includes an online statistics textbook, on-site tools for crunching your own data, and plenty of links to more stats software. It's intended for novices who don't know a t-test from a P value, and for anyone who wants a quick refresher.

Probability Web : Chance, probability, and statistics are the bulwarks of disciplines from nuclear physics to evolutionary theory.

Numeracy, Statistics and Computers : Survival Guide to Maths and Computers for Biologists

Computational Paleontology : This page is devoted to the use of mathematical models, simulation, computer graphics and computers in general in paleontology:

Topics in Statistical Genetics : The notes available here are draft chapters of a book by Simon Tavare´ and Peter Donnelly entitled Ancestral Processes in Population Genetics.