Are we lucky to live here and now? We tend to feel good by focusing our attention on abundant circumstances that could have been far worse.
In particular, we recognize that we live on a habitable planet. But the alternative of living on an uninhabitable planet is an oxymoron. If you kept your eyes closed, you could still conclude that your environment allows you to breathe. Once you open your eyes and study astronomy, you would realize that life-as-we-know-it is not possible on a planet like Mercury, where the surface temperature varies between a boiling 430 degrees Celsius (800 Fahrenheit) at daytime and a freezing -180 degrees Celsius (-290 Fahrenheit) at nighttime. And if you choose to become a professional astrobiologist, you would support allocating 11 billions dollars to the construction of the Habitable Worlds Observatory, designed to search for chemical signs of primitive life on planets orbiting other stars. The design of this Observatory acknowledges the privilege that life was granted on Earth. The search for microbes is flattering to our cosmic ego.
Nicolaus Copernicus was first to break the news that aside from inheriting the conditions that are required for our existence, we should not assume that we are privileged. In particular, we are not at the physical center of the cosmos and not even at the center of the local Solar system. The loss of cosmic entitlement was difficult for the Vatican to accept until 1992. It is still difficult for the clergy of astrobiology to accept the notion that the existence of intelligent life beyond Earth is not an extraordinary claim. Their default assumption is that we are alone, for the same reason that the default assumption of the Vatican was that we occupy the best real estate in the cosmos as we are the focus of God’s attention. Copernicus was a priest. Inspired by him, I find it more compelling to argue as an astrobiologist that delusional beings like us likely existed on exoplanets billions of years ago. Cosmic history is likely full of other self-centered civilizations that have perished by now.
The interesting question in that case is: “Who is the luckiest one?” Just as with gossip columns in tabloids, humble astrobiologists might crave information about those cosmic celebrities and influencers who were more fortunate than we are. Who are the luckiest residents of the cosmos? Since the value of real estate is based on three factors: location, location and location, let us start by identifying the best cosmic neighborhood.
On average, the Universe is expanding. But regions where matter started denser than average are collapsing because they are gravitationally bound. This is the reason why the local group of galaxies, which includes our sister galaxy — Andromeda, will merge with the Milky-Way to make a giant elliptical galaxy in the future. I dubbed the merger product Milkomeda in a paper that I wrote with T.J. Cox in 2007. This merger will double the resources of the Milky Way within a few billion years. But the rest of the Universe will accelerate away and leave empty space around Milkomeda in the distant future. If we stay in Milkomeda, the resources contained in its basket will be all we have to sustain the future of life locally.
As I pointed out in an email exchange with Freeman Dyson in 2011, the truly privileged residents of the cosmos live in clusters of galaxies where the mass of resources is a thousand times bigger than in the Milky-Way galaxy. The residents of galaxy clusters could survive far longer in a cold and empty Universe.
It is not too late for us to catch up with luckier residents if we choose to engage in intergalactic travel towards the nearest cluster of galaxies, the Virgo cluster — whose center is 54 million light years away. The second nearest cluster — Coma, is about twice as far. We may not be the first to do so. If other civilizations realized billions of years ago that this was a good idea, their spacecraft might be heading in the direction of clusters of galaxies right now.
A universe like ours, in which the cosmic expansion is accelerating and in which numerous technological civilizations might reside, may be full of cosmic migrants. These are technological civilizations which humbly realize that there are better places for them to live in. Of course, there would be many more civilizations that will perish on their home planet out of the narrow-minded conviction that there is nothing better than local politics. Just like the Vatican before 1992, they are missing the global insight that unprivileged circumstances are far more abundant than privileged ones and therefore the chance of occupying the best real estate in the cosmos is minuscule.
As all migrants know, tourism is far more prevalent in privileged locations. Those who live in unprivileged neighborhoods might wonder: “Where is everybody?” This same question was asked by the Nobel laureate physicist Enrico Fermi in reference to extraterrestrial visitors. The simplest answer to Fermi’s question is that there are more desirable sites for tourism in the cosmos than the solar system. We must keep in mind that the Sun will die in 7.6 billion years, whereas the most common stars — having a tenth of the mass of the Sun, will live for trillions of years.
Our terrestrial swamp will dry up as a result of the brightening of the Sun within a billion years. Hence, our long-term survival hinges on our willingness to admit that we are not the most privileged residents of the cosmos. Before it gets too late, we better allocate billions of dollars to the search for technological signatures of cosmic neighbors. This could increase the chance for finding extraterrestrial life, because the rare technological signatures of advanced alien intelligence might be easier to detect than the faint biochemical signatures of microbes.
If we find aliens, we can compare notes and gossip about the most privileged ones in astrobiology journals. As with any cultural revolution, those who insisted on a sense of privilege, will be ridiculed in future history books. The last words of Marie Antoinette — the last Queen of France prior to the French Revolution, were: “Excuse me, sir; I did not do it on purpose,” apologizing to her executioner for stepping on his foot prior to her execution by guillotine.
ABOUT THE AUTHOR
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 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. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
