Movie 19 (:58)

Script : These effects can be seen in the real universe. But the real speed of light is very fast, three hundred thousand kilometers per second. Because relativity effects are most pronounced at very high speeds, the real visual effects of relativity must occur on a much larger scale than the simulations you've just seen.

For example : light delay in the "light echoes" of exploding stars, the Doppler shift of fast-moving astronomical bodies, and the headlight effect in the incredible brightness of gas jets directed towards us.

Because light is normally so fast, humans do not notice these effects. Someday, it may be possible, though not practical, to build a space ship with today's technology that could travel fast enough to see these effects directly.