Some Intelligent Civilizations Will Be Trapped on their Worlds

With thousands of exoplanets discovered so far, astronomers are learning how different planets can be. What if intelligent alien civilizations arise on extremely different habitable worlds? Some civilizations could develop space exploration technologies, but others would be trapped underwater, under ice, or in enormous gravity wells. How could they escape? Image Credit: DALL-E

Evolution has produced a wondrously diverse variety of lifeforms here on Earth. It just so happens that talking primates with opposable thumbs rose to the top and are building a spacefaring civilization. And we’re land-dwellers. But what about other planets? If the dominant species on an ocean world builds a technological civilization of some sort, would they be able to escape their ocean home and explore space?

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Cosmic Dust Could Spread Life from World to World Across the Galaxy

Could life spread throughout the galaxy on tiny grains of dust? It would be a perilous journey, but new research shows its possible and calculates how long it would take to spread. Image Credit: ESO

Does life appear independently on different planets in the galaxy? Or does it spread from world to world? Or does it do both?

New research shows how life could spread via a basic, simple pathway: cosmic dust.

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If Earth is Average, We Should Find Extraterrestrial Life Within 60 Light-Years

Illustration: Assortment of exoplanets
Astronomers have detected thousands of planets, including dozens that are potentially habitable. (NASA Illustration)

In 1960, while preparing for the first meeting on the Search for Extraterrestrial Intelligence (SETI), legendary astronomer and SETI pioneer Dr. Frank Drake unveiled his probabilistic equation for estimating the number of possible civilizations in our galaxy – aka. The Drake Equation. A key parameter in this equation was ne, the number of planets in our galaxy capable of supporting life – aka. “habitable.” At the time, astronomers were not yet certain other stars had systems of planets. But thanks to missions like Kepler, 5523 exoplanets have been confirmed, and another 9,867 await confirmation!

Based on this data, astronomers have produced various estimates for the number of habitable planets in our galaxy – at least 100 billion, according to one estimate! In a recent study, Professor Piero Madau introduced a mathematical framework for calculating the population of habitable planets within 100 parsecs (326 light-years) of our Sun. Assuming Earth and the Solar System are representative of the norm, Madau calculated that this volume of space could contain as much as 11,000 Earth-sized terrestrial (aka. rocky) exoplanets that orbit within their stars’ habitable zones (HZs).

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Penn State SETI Symposium Opens with Commemoration of Dr. Frank Drake

Dr. Frank Drake (1930 -2022). Credit: Danielle Futselaar

Is humanity alone in the Universe? Is anyone out there? Where is everybody? And what happens if and when we make contact with them? These and other questions were the subjects of the 2023 Penn State SETI Symposium hosted by the Penn State Extraterrestrial Intelligence Center (PSETI) from June 19th-22nd, 2023. The event featured prominent speakers from various research fields and disciplines discussing the challenges, history, and future of SETI. In the great tradition established by Dr. Frank Drake, they also addressed key issues related to the search for intelligent life and what we might find someday.

The summit opened with a series of overviews, a review of the past year (since the last summit), and a presentation by Dr. Rebecca Charbonneau, a science historian and Jansky Fellow at the National Radio Astronomy Observatory (NRAO). Her presentation, titled “Frank Drake and his Place in History,” provided a retrospective on the life and accomplishments of famed radio astronomer and SETI pioneer Dr. Frank Drake (for whom the Drake Equation is named), how he altered the character of the field, and how history will remember him.

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Legendary Astronomer Frank Drake has Passed Away

Frank Drake by the Green Bank Telescope. Credit: NRAO/NSF/AUI

Legendary astronomer Frank Drake has passed away at the age of 92. Known primarily for his Drake Equation — an estimate of the probability of intelligent extraterrestrial life — he pioneered the field of SETI, the Search for Extraterrestrial Intelligence, and was a noted astronomer and astrophysicist. His work and life have left an indelible mark on humanity and given hope and wonder to all our hearts.

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Maybe We Don’t Hear From Aliens Because They Choose To Go Silent

Artist impression of an alien civilization. Image credit: CfA

How will humanity meet its end?

That’s only a depressing question if you think that humanity will go on forever. Alas, nothing lasts forever, and if something could last forever, it probably wouldn’t be our struggling primate species.

But we’ll likely be around for a while yet, pondering things as we do. One of the things we love to ponder is: why don’t we hear from any other alien civilizations?

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Humanity Will Need to Survive About 400,000 Years if We Want any Chance of Hearing From an Alien Civilization

Standing beside the Milky Way. Drowming out the night sky blocks us off from nature, and that's not good for humans. Credit: P. Horálek/ESO

If there are so many galaxies, stars, and planets, where are all the aliens, and why haven’t we heard from them? Those are the simple questions at the heart of the Fermi Paradox. In a new paper, a pair of researchers ask the next obvious question: how long will we have to survive to hear from another alien civilization?

Their answer? 400,000 years.

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60 Years Later, is it Time to Update the Drake Equation?

The Drake Equation, a mathematical formula for the probability of finding life or advanced civilizations in the universe. Credit: University of Rochester

On November 1st, 1961, a number of prominent scientists converged on the National Radio Astronomy Observatory in Green Bank, West Virginia, for a three-day conference. A year earlier, this facility had been the site of the first modern SETI experiment (Project Ozma), where famed astronomers Frank Drake and Carl Sagan used the Green Bank telescope (aka. “Big Ear”) to monitor two nearby Sun-like stars – Epsilon Eridani and Tau Ceti.

While unsuccessful, Ozma became a focal point for scientists who were interested in this burgeoning field known as the Search for Extraterrestrial Intelligence (SETI). As a result, Drake and Sagan were motivated to hold the very first SETI conference, wherein the subject of looking for possible extraterrestrial radio signals would be discussed. In preparation for the meeting, Drake prepared the following heuristic equation:

N = R* x fp x ne x fl x fi x fc x L

This would come to be known as the “Drake Equation,” which is considered by many to be one of the most renowned equations in the history of science. On the sixtieth anniversary of its creation, John Gertz – a film producer, amateur astronomer, board-member with BreakThrough Listen, and the three-term former chairman of the board for the SETI Institute – argues in a recent paper that a factor by factor reconsideration is in order.

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Beyond “Fermi’s Paradox” XIV: What is the Aurora Hypothesis?

Credit and Copyright: Stefan Payne-Wardenaar; Magellanic Clouds: Robert Gendler/ESO

Welcome back to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?” Today, we examine the possibility that the reason for the Great Silence is that colonizing other star systems is hazardous to our health!

In 1950, Italian-American physicist Enrico Fermi sat down to lunch with some of his colleagues at the Los Alamos National Laboratory, where he had worked five years prior as part of the Manhattan Project. According to various accounts, the conversation turned to aliens and the recent spate of UFOs. Into this, Fermi issued a statement that would go down in the annals of history: “Where is everybody?

This became the basis of the Fermi Paradox, which refers to the disparity between high probability estimates for the existence of extraterrestrial intelligence (ETI) and the apparent lack of evidence. Since Fermi’s time, there have been several proposed resolutions to his question, which includes the Aurora Hypothesis that states that just because planets are habitable doesn’t mean that intelligent life can colonize there.

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Beyond “Fermi’s Paradox” IX: What is the Brief Window Hypothesis?

A case study of the inhabitants of Easter Island served in part as the basis for a mathematical model showing the ways a technologically advanced population and its planet might develop or collapse together. Credit: University of Rochester illustration / Michael Osadciw

Welcome back to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?” Today, we examine the possibility that we haven’t heard from aliens because intelligent life only survives for so long.

In 1950, Italian-American physicist Enrico Fermi sat down to lunch with some of his colleagues at the Los Alamos National Laboratory, where he had worked five years prior as part of the Manhattan Project. According to various accounts, the conversation turned to aliens and the recent spate of UFOs. Into this, Fermi issued a statement that would go down in the annals of history: “Where is everybody?

This became the basis of the Fermi Paradox, which refers to the disparity between high probability estimates for the existence of extraterrestrial intelligence (ETI) and the apparent lack of evidence. Since Fermi’s time, there have been several proposed resolutions to his question, which include the possibility that civilizations only have a “Brief Window” with which to communicate with the cosmos before going extinct.

Continue reading “Beyond “Fermi’s Paradox” IX: What is the Brief Window Hypothesis?”