There is an observational subtlety to alien observations, which is that when we look out into the universe we are observing only our past light cone. If grabby aliens were expanding at a high fraction of the speed of light (c), the light carrying information of their coming would be only just ahead of them. So even though aliens might be quite close, we wouldn’t see them until just before they arrived…
…if the aliens we see are traveling at high speed toward us, the intermediate state (seen but not met) is unlikely to be longer than a handful of weeks. Choosing our present time at random, there is almost zero chance for humanity to find itself in a time where we’re aware of alien intelligences but haven’t yet met them. That is, Earth is 4.5 billion years old (no aliens), then one day the Vera Rubin Observatory sees a flash that turns out to be an alien spacecraft departing to meet us from 100 light years away, traveling at 99.9% of c. They arrive just five weeks later. For the remaining billions of years of Earth’s existence, we are in the world of aliens among us.
— Read on caseyhandmer.wordpress.com/2026/03/03/notes-on-the-fermi-paradox/
For a while, the Fermi Paradox was my favorite article on Wikipedia. The comments on this post are also worth reading.
