GoKawiilInteractive simulation lets users experience relativity with light speed set at 5 km/h
A new browser-based demo, shared on Hacker News, simulates a park environment where light travels at only 5 kilometers per hour instead of its real-world speed. As users move through the space, they can observe relativistic effects like length contraction, time dilation, and the Doppler shift, all normally imperceptible at everyday speeds.
GoKawiil's interpretation of the reporting above, not reported fact.
Relativistic physics is notoriously hard to grasp because its effects only appear near light speed, far beyond human experience. By artificially slowing light down in an interactive visualization, the project makes abstract concepts like time dilation and Terrell rotation tangible and explorable, serving as an accessible teaching tool for physics education.
- The demo sets light speed at 5 km/h to make relativistic effects observable during normal walking motion.
- Users can see length contraction, time dilation, Terrell rotation, and Doppler shifting in real time.
- The project was shared as a Show HN post, aimed at making relativity intuitive through interactive visualization.
Relativity: The Special and the General Theory" by Albert Einstein — If walking through a park where light crawls at 5 km/h sparked your curiosity about time dilation and length contraction, go straight to the source. Einstein wrote this book for general readers, explaining the ideas behind the very effects this simulation renders in real time.
See Relativity: The Special and the General Theory" by Albert Einstein on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: rivendell.dmitrybrant.com, 2026-09-10
Published there as: “Show HN: What if the speed of light was 5 km/h?”
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