Von Neumann machines are self-replicating space probes sent out to multiply and explore the universe. Any advanced alien civilization would have such probes, so does the fact that we haven't yet seen
![We'll be Building Self-Replicating Probes to Explore the Milky Way Sooner Than you Think. Why Haven't ETIs? - Universe Today We'll be Building Self-Replicating Probes to Explore the Milky Way Sooner Than you Think. Why Haven't ETIs? - Universe Today](https://www.universetoday.com/wp-content/uploads/2021/03/probe.jpg)
We'll be Building Self-Replicating Probes to Explore the Milky Way Sooner Than you Think. Why Haven't ETIs? - Universe Today
![Aliens have already invaded earth on self-replicating space-ships, scientist claims | Science | News | Express.co.uk Aliens have already invaded earth on self-replicating space-ships, scientist claims | Science | News | Express.co.uk](https://cdn.images.express.co.uk/img/dynamic/151/590x/1193947_1.jpg)