Is an alien invasion of Earth imminent asks Kurzgesagt

12 April 2023

The latest feature from Kurzgesagt, those veritable video virtuosos of educational storytelling, explores the possibility of Earth being invaded by an advanced extra-terrestrial civilisation. While Kurzgesagt stresses much of what they present here is speculative, some of the points they raise are nonetheless fascinating.

While this video is based on scientific papers, we are presenting interesting ideas based on little data and lots of extrapolation, so take them with a grain of salt.

Kurzgesagt make the seemingly incredible suggestion that our galaxy, the Milky Way, may one day not be big enough to accommodate all the space faring civilisations that could potentially arise. The notion seems astonishing given the amount of space we’re talking about.

It would take one hundred thousand years to travel from end of the galaxy to the other, assuming we could do so at the speed of light — or who knows, less — if we could travel faster than the speed of light. Still, we’re talking about great volumes of space.

It is also possible humanity is the first technological civilisation to emerge in the Milky Way. This call is made on the basis that there is next to no evidence of the existence of other intelligent lifeforms in the galaxy. This thought is backed up by the Fermi paradox, which asks, if the galaxy is teeming with habitable planets, were are all the extra-terrestrials?

Sufficiently advanced extra-terrestrials would be relatively easy to detect, with the technologies we possess. Their Dyson swarms, their presence in numerous neighbouring star systems, would create blips on the radar, so to speak. That’s not to say there are no other technological civilisations in the galaxy, but if there were, they’re possibly at a similar level of development to ours at the moment.

But intelligent civilisations need significant amounts of time to evolve. The process has taken billions of years on Earth. So while the galaxy seems devoid of space faring civilisations at present, that may change in the next billion or so years, as currently in utero lifeforms grow. Intelligent civilisations also need a stable environment in which to germinate, which Earth, and the Sun, has given us, but some good fortune has been involved in our case.

Kurzgesagt suggests suitably located planets orbiting red dwarf, or M-type stars, which are abundant, provide an ideal environment for intelligent life to develop.

Most stars are red dwarfs that can sustain habitable planets for tens of trillions of years! Life on these planets has an incredibly long time window to appear and pass the hard steps.

Red dwarf stars live for trillions of years, as opposed to billions, for G-type stars such as the Sun. Intelligent life would therefore have more chance of taking hold, as it has plenty of time to do so. On Earth, intelligent life took five billion years to emerge, being half way through the Sun’s approximately ten-billion year lifespan.

But if the process had started any later, it may well have been too late. As the Sun ages, it is becoming warmer, and eventually Earth will be too hot to support life. Humanity, it seems, came along at the right moment. Seen in that context, planets hosted by red dwarfs appear to be the perfect incubator for intelligent life. But things are not that simple: red dwarfs pose their own problems for the emergence of life.

For one, any planets in a red dwarf’s habitable zone, a place where the environment is neither too hot nor too cold, would be tidally locked. This means one side of a planet would permanently face the star, and be exceedingly warm as a result. The other side, meanwhile, would always be shrouded in darkness, and likely too cold for life to thrive.

It has been suggested life could flourish on the day-night terminators of such planets, but this would make for an all too narrow habitable corridor. In addition, red dwarfs also emit radiation flares, which can have the effect of “sterilising” planets in their vicinity, rendering them uninhabitable. That’s not too good. Nor is it conducive for the prevalence of intelligent life.

Given life only spawns in what seems like an extremely slender set of circumstances, an extra-terrestrial invasion may be the one thing we don’t have to worry about. There’s simply no one else out there. Given humanity appears to ascendant then, we have the opportunity, as Kurzgesagt suggests, to carve out our own niche in the galaxy.