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
UET Science Society - You'd launch a Von Neumann probe (that is, a spacecraft that can replicate itself) equipped with an interstellar propulsion system and send it to a neighboring star system.
![Maybe Self-Replicating Robot Probes are Destroying Each Other. That's Why We Don't See Them - Universe Today Maybe Self-Replicating Robot Probes are Destroying Each Other. That's Why We Don't See Them - Universe Today](https://www.universetoday.com/wp-content/uploads/2014/05/ATA-pix14-1280x720.jpg)
Maybe Self-Replicating Robot Probes are Destroying Each Other. That's Why We Don't See Them - Universe Today
![Self-replicating alien space probes could already be in our solar system, say mathematicians | The Independent | The Independent Self-replicating alien space probes could already be in our solar system, say mathematicians | The Independent | The Independent](https://static.independent.co.uk/s3fs-public/thumbnails/image/2013/03/20/17/voyager.ap.jpg)