Special Relativity Applet
Decades ago I played a Flash game that did something similar to this. I can’t find it anymore, so I remade it.
I’ve been reading a lot about special relativity lately and having a blast. I hope to write a blog entry about it soon. I was able to come up with a very simple and beautiful derivation of Lorentz boost from the same 2 principles Einstein started off with:
- The speed of light is constant in all inertial frames of reference
- Principle of Relativity: laws of physics are the same in all inertial frames (and any law that isn’t the same, like $F=ma$ is incorrect)
Until then, here is the applet. Note: there’s a toggle for desktop and mobile-friendly modes.
The universe in the applet is distance-accurate. Every planet, star, nebula, galaxy, cluster, and quasar sits at its real distance from the Sun and has its real size. The edge is 13.8 billion light-years out, which is how far light has traveled since the Big Bang.
The speed is real too. Hold full thrust and you reach the edge in 10 minutes on your own clock. Nothing is sped up or faked! At a steady 2 million g you get so close to the speed of light that length contraction squishes the universe in front of you, and 13.8 billion light-years fits into 10 minutes of your time. Meanwhile, about 13.8 billion years go by back on Earth.
The universe here is static, so it doesn’t expand while you fly. In reality, the expansion is superliminal and accelerating, so far enough galaxies are receding too fast for you to ever reach them, no matter how fast you go. Also, the engine…holding 2 million g for 10 minutes takes roughly 100 trillion tonnes of fuel for every kilogram that arrives. Everything else is real, though: the distances, the sizes, and the physics of what you’d see and measure along the way.