It’s gone four in the morning and I’m trapped on Wikipedia. It all started with an innocent inquiry about the Solar System. The immensity of the universe is endlessly fascinating.
Consider the speed of light (299,792,458 m/s). The special theory of relativity proposes that no physical object or message can travel faster than light. So there’s an upper bound – how far can we go?
Light from the Moon takes just 1.3 seconds to reach Earth. Light from the Sun reaches us in about 8.3 minutes. You might have heard this before. Shifting our attention away from the Solar System, light from Alpha Centauri – one of the closest and brightest stars in the sky – takes 4.4 years to reach us. Even if we could hitch a ride on a beam of light, we’d be in for a long haul. Mars is a cakewalk.
Let’s say we discover the secret to travelling close to light speed. Decades pass, and visits to Alpha Centauri become routine, pedestrian. So we consider branching out into the greater Milky Way, and beyond. There are thought to be over 170 billion galaxies in the observable universe – how hard could it be to explore one or two?
As it turns out, galaxies are big. Really big. Our galaxy is about 100,000 light-years wide. That’s a hundred-thousand-year journey from end to end with all dials up to 11. Say we chicken out and try another galaxy. Our nearest neighbour, Canis Major Dwarf, would take 25,000 years to reach, and I doubt we would even be human by the time we made it to the nearest spiral galaxy, Andromeda: that’s 2.5 million light-years away.
We are infinitesimal.
