What Are the Effects of a Gun in Outer Space?

Here’s a fun experiment to try. Take out your gun and fire a bullet. That bullet will be forever alone. That’s because the universe is expanding, and if you were a few megaparsec’s away from the nearest galactic cluster, on average those galaxies would be 200 km father away from you every passing second. In space terms, 200 km per second is pretty slow.

It’s barely as fast as the solar system orbits the center of the Milky Way. And stars closer to the center of the galaxy can orbit 10 times faster. But a measly bullet travels only a few km every second and would have no chance of reaching the receding galaxies, ever. It makes you realize how tiny we are compared to the scale of the universe. But it also makes you realize how close together we all are here on Earth. Of course, to get from one side of the Earth to the other, you have to fly over half the sphere.