Understanding Special Relativity
- Brief explanation of special relativity, using no more than high-school level mathematics; includes an account of the twin paradox, some remarks on faster-than-light travel, and some material on relativistic mechanics. By Rafi Moor.
- http://www.rafimoor.com/english/SRE.htm

Wikipedia: Introduction to Special Relativity
- Encyclopedia article giving a brief outline of the basic concepts of special relativity (including simple formulas).
- http://en.wikipedia.org/wiki/Introduction_to_special_relativity

The Special Theory of Relativity
- Self-tutorial with short essays, questions and answers.
- http://astro.physics.sc.edu/selfpacedunits/Unit56.html

Imaginary In All Directions
- There is a preferred algebra of quaternions and complex numbers that is ideally suited to express the equations of special relativity and classical electrodynamics.
- http://arxiv.org/abs/math-ph/0309061

Space Measurements on a Rotating Platform
- The age-old puzzling problem of Lorentz contraction on a rotating platform, i.e., Ehrenfest's paradox, is explained in its proper mathematical context.
- http://arxiv.org/abs/gr-qc/0309020

Sagnac Effect, Twin Paradox and Space-Time Topology
- When viewed with an alternative synchronization convention, the Sagnac effect on a rotating disk is purely topological and the rim of the disk is essentially an inertial system.
- http://arxiv.org/abs/gr-qc/0403111

The Twin Paradox in a Spatially Closed and Bounded Universe
- Spatially compact spacetimes break global Lorentz invariance and define absolute inertial frames of reference.
- http://www.everythingimportant.org/relativity/general.htm

Nothing but Relativity
- There are many ways to derive the Lorentz transformation without invoking Einstein's constancy of light postulate. The path preferred in this paper restates a simple, established approach.
- http://lanl.arxiv.org/abs/physics/0302045

Deriving Relativistic Momentum and Energy. II.
- The usual relativistic expressions for momentum and kinetic energy are generalized from the one-dimensional to the three-dimensional case.
- http://lanl.arxiv.org/abs/physics/0504095

Deriving Relativistic Momentum and Energy
- Expressions for momentum and energy of a relativistic particle may be derived from the composition law for velocities along one spatial dimension.
- http://lanl.arxiv.org/abs/physics/0402024

On the Electrodynamics of Moving Bodies
- Albert Einstein's first paper on relativity, translated here from Annalen der Physik vol XVII 1905 p. 891-921, is of historical interest.
- http://www.fourmilab.ch/etexts/einstein/specrel/www/

Lorentz Contraction and Accelerated Systems
- Lorentz contraction in systems undergoing constant proper acceleration is proven to be completely self-consistent in the context of special relativity.
- http://arxiv.org/abs/gr-qc/0301050

Relativistic Force Transformation
- Formulas relating one and the same force in two inertial frames of reference are derived directly from the Lorentz transformation of space and time coordinates.
- http://arxiv.org/abs/physics/0507099

Commutative Hypercomplex Special Relativity
- Einstein's special relativity is formulated in terms of 4-D commutative hypercomplex mathematics. The traditional results are obtained, but some additional effects are suggested.
- http://home.comcast.net/%7ecmdaven/special.htm

Geometric Algebra for Physicists
- This is chapter 1 of a book by Chris Doran and Anthony Lasenby on geometric algebra, which is the natural mathematics of spacetime.
- http://assets.cambridge.org/052148/0221/sample/0521480221WS.pdf

One More Derivation of the Lorentz Transformation
- The theory of relativity is constructed from four general group-theoretical assumptions on the structure of space-time: These are homogeneity, isotropy, group structure and a causality condition.
- http://o.castera.free.fr/pdf/onemorederivation.pdf

The Structure of Space-Time Transformations
- This theorem by H. J. Borchers and G. C. Hegerfeldt proves that the constancy of light velocity alone implies the Lorentz group (up to dilatations).
- http://projecteuclid.org/Dienst/UI/1.0/Summarize/euclid.cmp/1103858408

E=mc²
- An article from the Wikipedia encyclopedia.
- http://en.wikipedia.org/wiki/E%3Dmc%C2%B2

Special Relativity and Maxwell Equations
- A self-contained summary of the theory of special relativity is given, which provides the frame for classical electrodynamics. 26 pages.
- http://www.csit.fsu.edu/~berg/teach/phy4241/Lectures/relativity1.pdf

Generalized Relativistic Velocity Addition with Spacetime Algebra
- The general problem of relativistic addition of velocities – and the successive application of noncollinear Lorentz boosts – is addressed.
- http://arxiv.org/ftp/physics/papers/0511/0511247.pdf

Special Relativity
- Tutorial explains about the postulates, paradox, simulaneity, time dilation, Lorentz transformation constructions, spacetime wheel, and the Fitzgerald-Lorentz contraction. Page includes some animated illustrations.
- http://casa.colorado.edu/~ajsh/sr/sr.shtml

Time Dilation
- The gamma factor and time dilation can be derived using a very simple clock.
- http://www.pa.msu.edu/courses/2000spring/PHY232/lectures/relativity/dilation.html

Einstein Light
- A multimedia tutorial on Special Relativity. The introductory level takes 10 minutes, but has links to over 40 explanatory pages giving greater depth and breadth.
- http://www.phys.unsw.edu.au/einsteinlight/

Relativistic Kinematics
- This is how special relativity is taught by Dr. David Morin at Harvard University. 72 pages.
- http://www.courses.fas.harvard.edu/~phys16/Textbook/ch10.pdf

The Axiomatization of Physics - Step 1: A Derivation of the Lorentz Transformation
- The fundamental equations of special relativity are derived with only high school algebra and toy universes consisting of moving rulers.
- http://www.everythingimportant.org/relativity/special.pdf

Santa at Nearly the Speed of Light
- An estimate of the speed and distances covered by Santa Claus on Christmas night. The physics is unassailable. The article is hosted on the Fermi National Accelerator Laboratory website.
- http://www.fnal.gov/pub/ferminews/santa/

Quaternions in University-Level Physics Considering Special Relativity
- The quaternions are an expansion of complex numbers and show close relations to numerous physically fundamental concepts (e.g. Pauli Matrices).
- http://arxiv.org/ftp/physics/papers/0308/0308017.pdf

Synchronization Gauges and the Principles of Special Relativity
- Synchronization functions set the mathematical clocks represented by the Lorentz transformation and resetting these clocks mathematically only produces a theory equivalent to special relativity in predicting empirical facts. 57 pages.
- http://arxiv.org/abs/gr-qc/0409105

University Lectures on Special Relativity
- Lecture notes on Special Relativity, prepared by J. D. Cresser, Department of Physics, Macquarie University. 44 pages.
- http://www.physics.mq.edu.au/~jcresser/Phys378/LectureNotes/SpecialRelativityNotes.pdf

How Do You Add Velocities in Special Relativity?
- Here is the formula for adding velocities in special relativity when motion occurs in a single direction.
- http://math.ucr.edu/home/baez/physics/Relativity/SR/velocity.html

Relativity Tutorial
- An introduction to relativity using space-time diagrams.
- http://www.astro.ucla.edu/~wright/relatvty.htm

Relativistic Contraction
- Relativists consider it a very important exercise to have students decide how to measure the length of a rapidly moving object.
- http://www.ux1.eiu.edu/~cfadd/1160/Ch27SpRl/ApLrntz.html

Special Relativity Lecture Notes
- A standard introduction to special relativity where explanations are based on pictures called spacetime diagrams.
- http://www.phys.vt.edu/~takeuchi/relativity/notes

Wikipedia: Special Relativity
- Online encyclopedia article.
- http://en.wikipedia.org/wiki/Special_relativity

How Stuff Works: Special Relativity
- The major principles of special relativity (SR) are discussed in an accessible way, via 5 segments, to help you understand the lingo and theories involved.
- http://www.howstuffworks.com/relativity.htm

Jim Doyle's Special Relativity Pages
- A growing collection of pages on special relativity, including Special Relativity in under 15 Minutes!
- http://www.btinternet.com/~j.doyle/SR/sr1.htm

Relatively Simple
- Special Relativity made Relatively Simple offers information and experiments about special relativity.
- http://web.wt.net/~cbenton/relativity.htm