Relativity you can feel
SpecRel is run by a small independent team. We think special relativity is one of the most beautiful ideas in science, and that it’s easiest to understand by playing with it rather than memorising formulas.
Each experience on the site is an interactive simulation paired with a plain-English explanation. You might push a starship toward the speed of light, or watch two light clocks drift out of step. The visuals are artistic, but the numbers aren’t: every effect is computed from the actual equations of special relativity. When we simplify something for the sake of a clear picture, we say so on the page.
What’s here now
- The light-speed flight: aberration, Doppler colour shifts, relativistic beaming and time dilation in one ride.
- The Light Clock: time dilation derived from a single triangle.
- The Twin Paradox: send one twin to the stars, watch both clocks, and see why the traveler comes home younger.
- Length Contraction: watch a starship shrink as it speeds past, ride along to see the universe shrink instead, and solve the barn–pole paradox.
- E = mc²: turn a paperclip into pure energy, then see how much mass burning, fission, fusion and antimatter really convert.
More experiences are in progress: spacetime diagrams, relativity in GPS, and eventually black holes.
Corrections
Spotted a mistake in the physics or the explanations? We want to know. Write to contact@specrel.com.