When the Weird Unit is the Perfect Unit

“Light years”. It is one of those highly misleading units in science. It suggests we are talking about time: light years. Instead, it is a unit for distance: the distance light would travel in those years.

Why come up with such misleading names, right? Except in one scenario, where it is the perfect unit, as I discovered while reading Cixin Liu’s sci-fi novel, The Dark Forest where mankind makes contact with an alien civilization. But it is not human-to-alien contact, but radio contact (radio signals sent into space).

Now the distance between the human and alien is stated in (what else?) light years. The aliens then decide to come to earth. But of course, they can’t travel at the speed of light, which means it would take them centuries to get here. See why it is the perfect unit now? All we want to know is how long it will take them to get here. After all, if the aliens are hostile, surely having centuries to prepare for their arrival is a good thing, right? And if they’re weaker than us, then who cares?

Aha, now we run into the risk of “technological explosion”, writes Liu:

“Modern technology was developed over the course of three hundred years. On the scale of the universe, that’s not development. It’s an explosion! … There’s no reason why humanity should be the fastest of all cosmic civilizations. Maybe there are others whose technological explosions were even more sudden.”

In other words, we may be stronger today but who’s to say that by the time we contact them (remember it’ll take them centuries to get here), they haven’t experienced a technological explosion that makes them stronger than us?!

Ergo, it follows that for any two cosmic civilizations:

“One, letting you know I exist, and two, letting you continue to exist, are both dangerous to me.”

In such an environment, the rationale course of action then becomes:

“If he finds other life… there’s only one thing he can do: open fire and eliminate them.”

Because:

“In this forest, hell is other people.”