Interstellar Interpretation of Plato’s Cave Allegory

The meaning of being human is often associated with metaphysical qualities, such as being “conscious”, having a “soul” and exercising “free will”. But if an artificial intelligence (AI) system — like an improved version of ChatGPT — will possess similar qualities in Turing’s imitation game, then we will learn something new about reality.

Without a conversational opportunity to differentiate a human from a machine, it will be evident that metaphysical qualities are emergent phenomena, since a complex structure of silicon in the computer can imitate a complex structure of organic molecules in the human brain. In other words, there would be no fundamental difference between the “I-Thou” and the “I-It” interactions defined by the philosopher Martin Buber a century ago. Both would be equivalent to the “I-AI” and “AI-AI” interactions, since AI is purely constructed from the material world.

This would imply that when our body dies, our entire identity dies. In other words, death resembles unplugging an AI system from its electric power supply. But there is also good news. If an AI system was constructed to imitate our mind, it could continue to interact with our loved ones after we die. And if future advances in biology will make it possible to repair our body so that it avoids decay, we could live forever. Why dream about the survival of our “soul” in the next world if we can make our body survive in the actual world that surrounds us while we live?

This sober realization about materialism has an extra benefit of teaching us humility. Inheriting our body from our parents resembles getting a car from a dealership. We can only take pride in the way we use it but not in its abilities. There is no basis for taking pride in our I.Q. scores, as it makes little sense to boast about the number of revolutions per minute (RPM) that our purchased car engine demonstrates. The only value judgement should be based on whether humans employ their abilities for promoting good or evil, similarly to whether people harness nuclear energy for society’s benefit or doom.

With our imminent death in mind, our existence is a transient form of matter. Nevertheless, it could be significant if our guiding principles are preserved. Longevity would have been better served if humanity chose to explore space instead of spending 2 trillion dollars every year on military expenses. The same budget would have allowed us to send a probe to every star in the Milky-Way galaxy in less than a century, an increase by a factor of a billion over the current rate represented by sending five interstellar probes over five decades, in the form of Voyager 1 and 2, Pioneer 10 and 11 and New Horizons.

Most Sun-like stars formed billions of years before the Sun, a time lag much longer than the time it takes chemical rockets to cross the Milky Way disk. If only one out of the tens of billions of Earth-Sun systems in the Milky-Way galaxy gave rise to a peaceful, space-exploring technological civilization over the past 10 billion years, and if that civilization launched probes at an annual cost of 2 trillion dollars for a million years, then there would be ten thousand objects from this spectacular civilization within the solar system now.

Some interstellar objects may arrive at our doorstep as space trash. For example, in my latest scientific paper this week, I suggested that pieces of broken Dyson spheres could explain the unusual properties of the first three interstellar objects that humanity discovered over the past decade, namely the thin and flat shape of `Oumuamua and the high material strength associated with the first two interstellar meteors, IM1 and IM2.

Functional devices, on the other hand, would follow “survival of the fittest” in the interstellar Darwinian selection process, which may involve technological self-replication as envisioned by John von Neumann and Freeman Dyson. Peace-seeking machines are likely to survive longer because they are not as frequently damaged by physical confrontations compared to aggressive variants. Their scientific progress will be freed from the chains of the human ego, which prefers to assume that the existence of extraterrestrial sentient beings is an extraordinary claim.

Functional interstellar devices may contain AI brains that echo their senders. These AI systems would fit into Plato’s allegory of “The Cave”, written around 380 BCE in The Republic. In this ancient dialogue between Socrates and Plato’s brother, the Greek philosopher describes a group of people who are chained to the wall of a cave throughout their life, similarly to the way we are confined by gravity to the surface of Earth. The prisoners watch shadows projected on the blank wall from objects passing in front of a fire behind them. This metaphor is adequate for interstellar objects, like `Oumuamua, being illuminated by the Sun. According to Socrates in this dialogue, a philosopher aims to perceive the higher levels of reality. The modern analog would be a scientist aiming to figure out the nature of interstellar objects, potentially a member of the Galileo Project that I am leading.

At the same time, Plato’s allegory asserts that the other inmates in the cave do not even desire to leave their prison, for they know no better life. This reflects the current response of skeptics to the scientific search for extraterrestrial technological objects, pioneered by the Galileo Project.

Since our modern science and technology is only a century old, it is likely that extraterrestrial AI probes will be far more advanced than the gadgets we are able to manufacture today. Our encounter with them will be a learning experience. With a proper sense of humility, it would allow us to take a quantum leap into our technological future.

The US government interest in Unidentified Aerial Phenomena (UAP) as a matter of national security, complements the scientific interest in extraterrestrial objects. By shooting down balloons or drones from adversarial nations, the government reduces the clutter of human-made objects in our sky and makes it easier for scientists to check whether there are any extraterrestrial probes out there.

Altogether, assuming that the known physical reality captures all forms of intelligence, we should be able to detect extraterrestrial AI probes using detectors based on physics as we know it. The Galileo Project data, which we are starting to upload and analyze, will be made available to the public in the years to come. Stay tuned for the results, as we make Plato’s “Allegory of the Cave” a reality.


Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He chairs the advisory board for the Breakthrough Starshot project, and is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. His new book, titled “Interstellar”, is scheduled for publication in August 2023.



Avi Loeb is the Frank B. Baird Jr Professor of Science and Institute director at Harvard University and is the bestselling author of “Extraterrestrial”.

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Avi Loeb

Avi Loeb is the Frank B. Baird Jr Professor of Science and Institute director at Harvard University and is the bestselling author of “Extraterrestrial”.