Dark Alien Technology

When dozens of postdocs at the Center for Astrophysics | Harvard & Smithsonian were asked recently: “What do you want to happen first: (i) Find extraterrestrial life or (ii) Solve dark matter?”, about 90% of them selected the option: (i) Find extraterrestrial life.

As soon as I heard about the poll results today, I wondered whether the two questions might be linked and answered at the same time. Below I offer a scenario for how this might happen.

Data on the dynamics of luminous matter inside galaxies and throughout the Universe at large reveals a strong gravitational influence of invisible matter. The nature of this dark matter is unknown because it does not emit or scatter light. In recent decades, laboratories around the world invested billions of dollars in searching for the possible imprints of dark matter on detectors made of ordinary matter. So far, these searches led to stringent upper limits on the interaction of dark matter with ordinary matter, except for one nuclear-recoil event recorded by the LUX-ZEPLIN (LZ) Dark Matter Experiment on June 16, 2023, during an analysis announced in September 2026.

To accommodate all cosmological constraints, the background medium of dark matter particles must be cold, namely composed of particles with negligible random velocities before they cluster to make gravitationally-bound systems like our own Milky-Way galaxy.

Theoretical models of cold dark matter predict density cusps at the centers of galaxies. However, many observations indicate constant-density cores in galactic nuclei, in contradiction with these expectations. One way to resolve the cusp-core problem is to assume that dark matter particles interact strongly with one another despite their weak interaction with the ordinary matter that we find on Earth. Given data on the cores of low-mass galaxies, this “self-interacting dark matter” model appeals to many cosmologists (as reviewed here).

But suppose we take this model to its logical limit and assume that a small fraction of dark matter is made of particles that interact with each other as strongly as ordinary matter particles do. The two sectors of matter are decoupled in terms of all interactions other than gravity but are characterized by strong interactions of particles within each of them. If this small component of dark matter can cool by emitting dark radiation, this could lead to the formation of dense clouds that make dark planets, on the surface of which dark life might emerge. This could give rise to dark aliens who are undetectable by our electromagnetic sensors.

Another possibility is that a sufficiently advanced technological civilization made of ordinary matter, uses dark matter to construct stealth spacecraft that travel between the stars and probe exoplanets made of ordinary matter without being detected electromagnetically. This would constitute ideal probes which face no risk of destruction by weapons made of ordinary matter. Given the small interaction cross-section with ordinary matter, such probes can go through the entire Earth without being slowed down by friction. They serve as the ultimate trans-medium probes through everything made of ordinary matter, being able to pass without a scar through the core of the Sun at ten-million degrees.

In such a case, the answer to Enrico Fermi’s question: “Where is everybody?” might be “We cannot see them.”

If we are being visited by dark matter entities, we would not even notice their gravitational footprint because it would be too weak for our best gravitational-wave observatories. In a paper published a couple of years ago here, I showed that only objects more massive than a hundred trillion grams that move close to the speed of light would be noticed by LIGO-Virgo-KAGRA. This implies that dark astronauts on a dark spacecraft of any reasonable mass will pass near us like a ship passing in the night. The experience was described in Henry Wadsworth Longfellow’s 1873 poem “The Theologian’s Tale” (written in Craigie House near the Harvard university campus):

“Ships that pass in the night, and speak each other in passing,
Only a signal shown and a distant voice in the darkness;
So on the ocean of life, we pass and speak one another,
Only a look and a voice; then darkness again and a silence.”

In such a hypothetical scenario, the discovery of extraterrestrial life could occur once we develop sensors that are sensitive to self-interacting dark matter.

Based on the above-mentioned postdoc poll, it is apparent that most astrobiologists focus on the search for life made of ordinary matter. But even in that case, an alien spacecraft made of ordinary matter could still avoid detection by our current sensors if it employs material science which is even more advanced than our best stealth technology, or if the vehicle is of small size or moves at exceedingly high speeds so that it is recorded as a faint streak in camera exposures.

In these cases, the Unidentified Anomalous Phenomena (UAP) documented in the Presidential Unsealing and Reporting System for UAP Encounters (https://www.war.gov/ufo/) might be a mixed bag, including birds (as inferred here), human-made tech and the tip of the iceberg for the most visible alien tech.

The challenge of the UAP Science Advisory Council (https://uapsac.com/) is to separate the wheat from the chaff in UAP and use the scientific method as a reality check on their nature. For that reason, my strategic goal as the Council’s chair is to collect higher quality data in the future by deploying new sensors in partnership with the Pentagon. My gratitude goes to Ross Coulthart for supporting this data collection initiative in his recent comments on the “Reality Check” podcast here.

Yes, science should be guided by evidence, but most often the evidence is limited to regimes where the scientists are searching for it. In the coming years, we might be surprised not only to find out that humans are not at the top of the cosmic food chain but also that many forms of dark alien tech were undetectable by the sensors that we employed to search for them.

Authorized publication by Dr.Avi Loeb