advanced civilizations Archives

November 13, 2024November 13, 2024 by Matt Williams

New Study Examines How Extraterrestrial Civilizations Could Become “Stellarvores.”

Artist's impression of accretion in a binary system. Credit: ESO/L. Calçada

One of the most challenging aspects of astrobiology and the Search for Extraterrestrial Intelligence (SETI) is anticipating what life and extraterrestrial civilizations will look like. Invariably, we have only one example of a planet that supports life (Earth) and one example of a technologically advanced civilization (humanity) upon which to base our theories. As for more advanced civilizations, which statistically seems more likely, scientists are limited to projections of our own development. However, these same projections offer constraints on what SETI researchers should search for and provide hints about our future development.

In a series of papers led by the Blue Marble Space Institute of Science (BMSIS), a team of researchers examines what Earth’s level of technological development (aka. “technosphere”) will look like in the future. In the most recent installment, they offer a reinterpretation of the Kardashev Scale, which suggests that civilizations expand to harness greater levels of energy (planet, host star, and galaxy). Instead, they suggest that the Kardashev Scale establishes upper limits on the amount of stellar energy a civilization can harness (a “luminosity limit”) and that civilizations might circumvent this by harnessing stellar mass directly.

August 22, 2024August 22, 2024 by Matt Williams

New Study Proposes how a Black Hole in Orbit Around a Planet Could be a Sign of an Advanced Civilization.

Ray traced shadow of a spinning and charged black hole. Credit: Simon Tyran, CC BY-SA 4.0

In 1971, English mathematical physicist and Nobel-prize winner Roger Penrose proposed how energy could be extracted from a rotating black hole. He argued that this could be done by building a harness around the black hole’s accretion disk, where infalling matter is accelerated to close to the speed of light, triggering the release of energy in multiple wavelengths. Since then, multiple researchers have suggested that advanced civilizations could use this method (the Penrose Process) to power their civilization and that this represents a technosignature we should be on the lookout for.

Examples include John M. Smart’s Transcension Hypothesis, a proposed resolution to the Fermi Paradox where he suggested advanced intelligence may migrate to the region surrounding black holes to take advantage of the energy available. The latest comes from Harvard Professor Avi Loeb, who proposed in a recent paper how advanced civilizations could rely on a “Black Hole Moon” to provide their home planet with power indefinitely. The way this black hole would illuminate the planet it orbits, he argues, would constitute a potential technosignature for future SETI surveys.

November 28, 2023November 28, 2023 by Matt Williams

Why Don't We See Robotic Civilizations Rapidly Expanding Across the Universe?

The central region of the Milky Way, also known as the Zone of Avoidance. Credit: ESO/S. Brunier

In 1950, while sitting down to lunch with colleagues at the Los Alamos Laboratory, famed physicist and nuclear scientist Enrico Fermi asked his famous question: “Where is Everybody?” In short, Fermi was addressing the all-important question that has plagued human minds since they first realized planet Earth was merely a speck in an infinite Universe. Given the size and age of the Universe and the way the ingredients for life are seemingly everywhere in abundance, why haven’t we found any evidence of intelligent life beyond Earth?

This question has spawned countless proposed resolutions since Fermi’s time, including the infamous Hart-Tipler Conjecture (i.e., they don’t exist). Other interpretations emphasize how space travel is hard and extremely time and energy-consuming, which is why species are likely to settle in clusters (rather than a galactic empire) and how we are more likely to find examples of their technology (probes and AI) rather than a species itself. In a recent study, mathematician Daniel Vallstrom examined how artificial intelligence might be similarly motivated to avoid spreading across the galaxy, thus explaining why we haven’t seen them either!

September 16, 2023September 16, 2023 by Carolyn Collins Petersen

If Astronomers See These Chemicals in a Planet’s Atmosphere, There’s Likely an Advanced Civilization There

Artist rendition of a potential water-world exoplanet that might support advanced civilizations. Such life could advertise its existence via technosignatures from industrial or other activities. (Credit: ESA / Hubble / M. Kornmesser) — Artist rendition of a potential water-world exoplanet that might support life. Scientists could determine whether to explore this world based on its planetary entropy production. (Credit: ESA / Hubble / M. Kornmesser)

In an age of ever-growing numbers of exoplanets circling other stars, it’s natural that astronomers search for signatures of advanced civilizations. Such signatures may have biological or technological origins.