Maybe the Aliens Really Are Here

SETI, as a modern astronomical endeavor, dating to 1959 (first paper) and 1960 (first observation). Modern UFO sightings date to the late 1940s. Though superficially similar, the two fields in practice have had virtually nothing to do with one another. SETI usually requires a graduate degree in astronomy, and its scientists tend to disdain UFOers for requiring nothing more than a camera that takes blurry photos and a butterfly net in case a little green man appears.

However, the two camps may be moving closer together.

In the classic SETI paradigm, stars are observed for artificial signals. But this communication strategy has severe drawbacks from ET’s point of view. In order for it to succeed, ET would have to target each of potentially millions of promising nearby stars (including ours) continuously, and do so over potentially billions of years. Additionally, it would need to maintain a dedicated receiver for each target star to be certain not to miss a return message if and when it arrives. The cost of this strategy to ET in time, energy and materials would be immeasurable. Further, by announcing its presence to so many stars, it invites disaster should any civilization prove aggressive. Added to this is the problem of communicating with a target civilization of which it would know nothing. Perhaps the transmitting civilization communicates in color oscillations like a cuttlefish, while the recipient only understands bee-like waggles.

Building on the work of others, I have hypothesized that aliens would be better served by sending robotic probes. Relatively simple flyby probes might intermittently surveil nascent solar systems, for example, at 200-million-year intervals. Star systems with biogenic planets might be surveilled more often. Highly capable probes might be placed permanently in the vicinity of planets that have achieved multicellularity as indicated by their oxygen-rich atmospheres or other biosignatures.

Once a permanently placed probe had detected artificial electromagnetic leakage, indicating that one multicellular species had become technologically intelligent, it would attempt to decode the species. Using Sesame Street, Khan Academy and YouTube, and even granted its enormous onboard AI capabilities, it would still take time for it to decode Homo sapiens’ languages, science, math and culture. After many decades of work by E.O. Wilson and others, we now know a little something about ant communication but are still far from a complete decoding. How very much more difficult would it be for ET to decode humans? Even if it has been watching episodes of I Love Lucy that have been leaking out into space since that show was first broadcast, it may still not understand them.

The local probe might need to send data back to its home base for deeper analysis and/or instructions on how to proceed. If the probe began transmitting data to its home in 1950 after its detection of early television signals, and if that home base were located at the modest distance of 150 light-years, then the earliest year in which the probe might receive instructions to make contact with Earth would be 2250.

However, when we do finally hear from a local probe, after it has decoded us, its transmissions may be in a terrestrial language. The ensuing dialogue will take place in near real time, as opposed to the painfully slow dialogue between ourselves and an alien civilization transmitting from a star at hundreds or thousands of light years distance. An alien probe need not reveal the location of its home base, obviating any danger to the progenitor civilization. A fully autonomous probe would be able to communicate with us even if its progenitor civilization is long extinct.

Provided that a probe does belong to an existing civilization or network of civilizations, there remains the problem of how it might communicate with them. To do so directly would require an enormous transmitter.  The better solution would be to string communication nodes at close proximity to one another, perhaps one in orbit around every star, and perhaps located at a sufficient distance from the star to enable the use of it as a gravity lens, per Einstein’s theory of general relativity. For the sun, that focal point begins at 550 Earth-sun distances (AU) at which point the node would achieve signal gain of approximately a billion.  

Large numbers of ET civilization might contribute to this nodal system, and the store of information would only grow with time regardless of whether the contributing civilizations persist or have gone extinct. We might contribute Aristotle, Shakespeare, Beethoven and Monet to this Encyclopedia Galactica. However, we will not be in a position to barter our culture; having surveilled our TV and internet for at least 70 years, ET has probably already uploaded all it wants. Nonetheless, ET may wish to recruit us into the galactic club so that we might manufacture probes and nodes, and otherwise take responsibility for the maintenance of the interstellar communication system within our immediate stellar neighborhood. That would be our bargaining chip.

SETI stellar observations presume a very faint signal that would require Earth’s most powerful telescopes to detect. However, highly sensitive telescopes have very small fields of view. Detecting a local robotic probe requires the opposite strategy. Because of a probe’s close proximity to Earth, its signal would be much brighter than an interstellar beacon, even under the conservative assumption that its transmission will be on the order of only a few watts. Consequently, SETI’s best strategy would be to sacrifice great sensitivity in favor of a wide a field of view or, better yet, all-sky-all-the-time observing. Such systems are being built now or planned.

Purported sightings by military pilots of objects that defy all known aerodynamics in their sudden and steep accelerations may be delusions, hoaxes or optical illusions. Nevertheless, many SETI scientists now agree with UFOers that the first alien detection plausibly could occur within our own solar system. Both UFOers and SETI scientists should also agree that if some UFO sightings are genuine sightings of aliens, then they must be of robotic probes rather than vessels crewed by biological beings. If nothing else, such beings would be crushed by the g-forces of their purported, very large, accelerations.

The evidence is still lacking that would fully unify UFOers and SETI scientists—and yet the space between these two groups may not be so far vast after all.

This is an opinion and analysis article; the views expressed by the author or authors are not necessarily those of Scientific American.


J. Gertz, Nodes: A Proposed Solution to Fermi’s Paradox, JBIS, 2017, 70, 454-457.

J. Gertz, ET Probes, Nodes, and Landbases: A Proposed Galactic Communications Architecture and Implied Search Strategies, JBIS, 2018, 71, 375-381.

J. Gertz, ‘Oumuamua and SETI Scout Probes, JBIS, 72, pp. 182-186.

J. Gertz, There’s No Place Like Home (in Our Own Solar System): Searching for ET Near White Dwarfs, JBIS, 72, pp. 386-395.

J. Gertz, Strategies for the Detection of ET Probes Within Our Own Solar System, JBIS, 73, pp. 427-437.

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