Relativity Park: Walking Speed of Light (https://fonts.googleapis.com) (https://fonts.gstatic.com) (../../fonts.googleapis.com/css2@family=Azeret+Mono%253Awght@400%3B500&family=Saira+Condensed%253Awght@500%3B600%3B700&display=swap.css) (css/style.css)    Relativity Park Special relativity with c = 5 km/h   Field guide (Help) H  Settings Tab   Your velocity 0.00 km/h  β:  v / c 0.0000  γ:  Lorentz factor 1.000  Lengths ahead × 1.0000          Doppler at crosshair 1.000 at rest    Elapsed Your watch 0:00.0  World clock 0:00.0   World clocks tick × 1.000 faster than yours.    Galilean view (aberration off) Arrows / W A S D: accelerate Mouse: look Space: stop  L G C B: toggle effects R: reset   Light is slow here In this park, the speed of light is 5 kilometers per hour — a brisk walk.
      Just like in the real world, the speed of light is not attainable, only approachable asymptotically.
      The more you speed up, the more relativistic effects will become apparent:
      length contraction, time dilation, Terrell rotation, etc. The Doppler effect of light
      also becomes apparent, with objects in front of you blueshifted, objects behind you
      redshifted, and transverse Doppler effects visible on objects in motion.  Click to look around   Settings ×  Effects Light-travel delay L You see each object where and when its light left it.   Aberration & contraction G The Lorentz boost of apparent position.   Doppler color C Spectra blueshifted and redshifted according to motion.   Relativistic beaming B Light piles up ahead of you and thins out behind.    World Speed of light 5.0 km/h  (5)  Eye adaptation Your retina adjusts to the average brightness ahead.    Debug Beaming exponent D^4.0  (4)  Exposure 1.00  (1)  Render scale 100%  (1)  Ground detail High  (2)   Adapt to speed Retessellate the ground with finer detail as the observer approaches c.   — fps — vertices    By (https://dmitrybrant.com) Dmitry Brant , 2026  (https://github.com/dbrant/relativity) source code   Field guide ×  All of the motion effects you see are physically accurate, in a world where the speed of light
    is greatly reduced, so it can be observed more easily on human scales.  Controls W A S D accelerate  ↑ ↓ ← → accelerate  Mouse look around  Space stop  Q drop / E rise  R return to start  Tab settings  Esc release mouse   Effects Play around with what effect causes which phenomenon to be observed.  L light-travel delay  G aberration & contraction  C Doppler color  B relativistic beaming   Things to try Accelerate by pressing the Up arrow. Your field of view begins to condense
      in the direction you are traveling, and becomes blueshifted. If you look
      behind you by using your mouse to turn, that field of view is redshifted
      and stretched out. This is relativistic aberration . Press Space
      to stop any motion, and observe how the field of view returns to normal.  The lamp posts all flash once per second of world time. Move toward a lamp
      and the flashing speeds up; move away and it slows down. Also observe the timers
	    labeled "Your watch" and "World clock", and see time dilation in effect.  The Ferris wheel and carousel cars move at 75% of the speed of light.
      They are contracted by their own motion, and you see each one at a different moment in its trip
      around the circle. As the cars move around, you can see the effects of relativistic
      contraction and Terrell rotation .  The shuttle near the end of the corridor runs back and forth, also attaining a speed
      of 75% of the speed of light. Notice how it also contracts and undergoes Terrell rotation as it moves.   What's NOT accurate Obviously a Ferris wheel spinning at relativistic speeds would fly apart, and if you travel through
      the atmosphere at relativistic speeds, you would be vaporized instantly. Even if you travel near
      the speed of light in interstellar space, you would be cooked by the cosmic microwave background radiation
      blueshifted to gamma rays.  The rendering of blueshifts and redshifts is a rough approximation.
      At extreme redshifts, the color fades to black. And at extreme blueshifts (past violet),
      the color turns to a metallic silver to represent x-rays, then to bright white
      to represent gamma rays (totally unphysical, but just to get a sense of it).