Aliens might have been traveling across our solar system for years but humans are unable to detect them because of a unique technology. A scientist suggested that advanced extraterrestrial life potentially built very tiny spacecrafts that cannot be detected from Earth.

Zaza Osmanov, an astrophysicist from the Free University of Tbilisi in Georgia, said there is a chance that aliens have been using micro-machines that are just a nanometer long to travel across the universe. His idea is based on the von Neumann probes, ScienceAlert reported.

Osmanov said that aliens could build and deploy very tiny spacecrafts to explore galaxies, star systems and planets. The spacecrafts may also have the capability to self-replicate to remain hidden or undetected.

It is not the first time that scientists tried to explain von Neumann probes. Previous efforts failed to properly introduce the idea due to problems with self-replication, which would require a stable supply of new materials.

But Osmanov provided some detailed calculations supporting his idea. He focused on microscopic probes that would require less materials during deep space journeys than regular size spacecrafts.

He said the tiny spacecraft would only rely on hydrogen atoms to generate energy, which are already present in the interstellar dust. Osmano also believe having a small size could enable aliens to rapidly replicate nanoscale probes.

An advanced civilization may deploy trillions of billions of the spacecraft to explore the universe.

How To Find Alien Micro-Spacecraft

Osmanov suggested that scientists could spot the exploring probes by looking at luminous emissions coming from the swarm. He said the probes would gather protons during their flight, which will create detectable light.

The micro-machines may appear like a comet several kilometers across in the infrared part of the spectrum.

"All the aforementioned results indicate that if one detects a strange object with extremely high values of luminosity increment, that might be a good sign to place the object in the list of extraterrestrial von Neumann probe candidates," he said.

However, the scientific community has yet to build new tools to spot the aliens that use micro-machines to look at Earth.

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