# special relativity
Special relativity starts from one strange fact — the speed of light looks the same to every observer — and derives from it that time, length and even simultaneity depend on how fast you're moving. This tag holds the site's deepest set of relativity simulations: Special Relativity — Time Dilation & Length Contraction and Lorentz Contraction show how a moving clock runs slow and a moving ruler shrinks, while the Lorentz Transform — Minkowski Diagram and Minkowski Spacetime Diagram let you plot those effects geometrically. Two versions of Einstein's own thought experiment, Relativity of Simultaneity and Relative Simultaneity, work through the train-and-lightning problem that convinced him "at the same time" isn't absolute, and the Twin Paradox applies all of it to the question of why a traveling twin returns younger.
Found: 7 simulations · 0 articles
🧪 Simulations (7)
📊 Facts
How many special relativity simulations are here?
7 simulations — the largest relativity-focused tag on the site, including two independent takes on the simultaneity thought experiment.
Why are there two "simultaneity" simulations?
Relativity of Simultaneity and Relative Simultaneity both model Einstein's train-and-lightning thought experiment, built as separate interactive versions of the same classic argument.
Which sim covers length contraction specifically?
Lorentz Contraction isolates length contraction on its own, while Time Dilation & Length Contraction shows both effects together.
What's the best starting point for beginners?
The Twin Paradox is the most well-known entry point — it applies time dilation to a concrete, famous puzzle rather than an abstract diagram.
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