Stephen Hawking famously warned: “If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans.”
I advocate a more relaxed narrative. To imagine that aliens care to kill us is as arrogant as to assume that the Earth is at the center of the Universe. There are billions of similarly habitable planets throughout our Milky Way galaxy alone, and Earth’s resources are commonplace.
Furthermore, our modern science and technology are based on quantum mechanics and General Relativity, which represent knowledge acquired merely over the past century, whereas most stars formed several billion years before the Sun. Survival of the fittest implies that the most successful travelers through interstellar space reflect scientific knowledge that is billions of years ahead of ours. It takes less than half a billion years to traverse the Milky Way with chemical rockets. If the travelers wanted to sterilize Earth, they could have done so long ago.
We develop fear from predators through our experiences on Earth. But interstellar space is a vast backdrop, spanning a temporal scale of ten billion years and a spatial scale encompassing billions of habitable planets. Both extend orders of magnitude beyond our history of merely a few million years as the human species on Earth.
At the very least, the finite speed of light is our savior. The fastest possible response of predators is delayed by the light travel time on a round trip from Earth to their locations. Our first radio message was transmitted by Guglielmo Marconi on May 13, 1897, almost 126 years ago. Only civilizations within a distance of (126/2)=63 light years could have noticed that we are capable of radio communication. This distance is merely 0.0026 of the way to the Galactic center. It contains less than a millionth of all the stars in the Milky Way. To imagine a predatory civilization within this distance is equivalent to assuming a million of them within the Milky Way galaxy right now.
Chemical rockets would allow a predatory civilization from a distance of 63 light years to reach us in a million years. This is a huge delay. In fact, we should count our blessings if world politics would allow us to survive that long. Moreover, in a million years we are likely to venture to interstellar space ourselves and be a multi-planet civilization. If that happens, we will not be vulnerable to a single planet invasion. In other words, once the invaders arrive — they will not find all of us at home. Their motivation will be out of date.
In a Q&A online forum of the Pangburn Hangout yesterday, I was asked what form of aliens we might encounter and whether they would be interested in eating us. I explained that the encounter will most likely involve technological gadgets with artificial intelligence (AI) and potential 3D printing capabilities to repair damaged parts or self-replicate. Such technological gadgets are better suited for survival than biological creatures, given the long journey duration and the hazardous bombardment by interstellar particles and radiation. Our habits of eating biological entities or burning oil — formed out of the remains of dead organisms, use chemical reactions to fuel our body and our technological needs. However, advanced civilizations surely realize that nuclear fuel is a million times more efficient at powering their interstellar gadgets than chemical fuel and so they are unlikely to eat us or consume the remains of dead organisms as biofuel.
On the vast interstellar scales, we are not as interesting as we might want to be. We tend to think that we are central actors in the cosmic play, but this reflects our limited perspective and arrogance. Encountering the products of far more advanced scientists can teach us modesty as well as novel scientific and technological knowledge that we do not possess.
For now, most of what happens on Earth stays on Earth. The radar air-defense signals transmitted from the border between Ukraine and Russia were of little interest to NASA’s Orion spacecraft during its recent trip to the Moon. Why would an interstellar traveler care more about them?
We might not hear back from distant extraterrestrials for a while, either because we are not searching correctly or because we are not interesting enough to deserve attention. At any event, the Galileo Project under my leadership will continue to search our mailbox near Earth for old interstellar packages, and study them with curiosity and humility rather than with fear and arrogance. Exhibiting childlike curiosity will improve our ranking in the class of intelligent civilizations and enhance the likelihood that we will survive longer by gaining a broader perspective.
The common thread of spirituality and interstellar travel is that they both explore the unknown. For both endeavors, it is prudent to follow the advice of the Cohanim’s blessing in the Temple of Jerusalem , as depicted on the mosaic of the Enschede Synagogue in the Netherlands: Live long and prosper!
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 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.
