Show HN: What if the speed of light was 5 km/h?

	Show HN: What if the speed of light was 5 km/h?(rivendell.dmitrybrant.com)
	606 points by dmitrybrant 45 days ago \| 276 comments
	tl;dr: An interactive browser demo that simulates a park where the speed of light is 5 km/h, letting you walk around and experience relativistic effects firsthand. As you accelerate (via arrow keys or WASD), you can observe length contraction, time dilation, Terrell rotation, and Doppler shifts (blueshift ahead, redshift behind), with toggles to isolate individual effects.
	HN Discussion: ↑Praises the simulation as more accurate than prior similar attempts like MIT's game •Shares philosophical reflections on how slow the speed of light actually is at cosmic scales ~Tried to observe specific relativistic effects (Wigner rotation) but couldn't verify them in the simulation ↓Points out that changing the speed of light isn't physically coherent since it's tied to other constants •Mentions prior art and related works exploring the same concept (Velocity Raptor, MIT game, Mr. Tompkins, Redshift Rendezvous)