During his SpaceX Starship Update for 2024, Elon Musk argued that we might be alone in the universe because he had not yet noticed signs of aliens. This immediately raised a question from the history of physics:
In 2010, would Elon be justified in arguing that he did not notice signs of the Higgs boson and hence this theorized particle might not exist?
The actual discovery of the Higgs in 2012 required CERN’s Large Hadron Collider to smash ions at unprecedented energies at a cost of ten billion dollars.
Consider another example. Upon my arrival to Harvard University thirty years ago, I started my research on the first galaxies in the Universe with redshifts larger than 10. At that time, most of my colleagues said that this research was a waste of time because “we all know that galaxies do not exist beyond a redshift of 2.” Hence my question once again:
In 1990, would Elon be justified in arguing that he did not notice signs of galaxies born in the first half of cosmic history, and hence they do not exist?
The discovery of galaxies with redshifts above 10 in 2022 required the Webb Telescope to probe deep into space with unprecedented infrared sensitivity at a cost of ten billion dollars.
We can also go four centuries back in time:
In 1600, would Elon be justified in arguing that he did not notice any celestial object that is not moving around the Earth and hence we must be located at the center of the Universe?
The discovery of moons circling Jupiter in 1610 required the improvement of the telescope by Galileo Galilei, allowing him to conclude that some celestial objects do not move around the Earth.
My point is simple: new scientific knowledge does not fall into our lap without a dedicated effort and a major investment of funds. If Elon wants to know whether we are alone, he should invest billions of dollars in developing new telescopes that would acquire the needed data.
For context, our most advanced survey telescope, the construction of the Rubin Observatory in Chile at a cost of half-a billion dollars, will employ an annular primary mirror of outer diameter of 8.36 meters as well as a 3.2-billion-pixel camera, to survey the southern sky every four days. But even with these unprecedented capabilities, the observatory could only detect the reflection of sunlight from objects larger than Starship at distances comparable to the Earth-Sun separation. As shown in a recent paper that I wrote with my student, Carson Ezell, smaller objects can only be detected if they pass much closer to Earth.
In 2018, SpaceX used Musk’s electric sports car, the Tesla Roadster, as a dummy payload for the Falcon Heavy test flight. Currently, this car orbits the Sun in an elliptical orbit that crosses the orbit of Mars and reaches a maximum separation that exceeds the Earth-Sun separation by a factor of 1.66. At this distance, the reflection of sunlight from the car will not be detectable by the Rubin observatory.
This example illustrates that detecting technological space trash in the form of Musk’s Tesla is impossible even with our most sophisticated survey telescope. If Musk cannot detect his own car with the best existing survey telescope, how can he hope to detect technological space trash from other civilizations?
Asking Fermi’s question: “Where is everybody?” without engaging in the search resembles a single person who stays at home and doubts that there are neighbors in the houses on the same street. These “houses” are metaphorically the numerous habitable planets around other stars, not known to Fermi when he asked this question seven decades ago.
Elon Musk has the ability to fund the instruments that would allow us to conduct a thorough search for aliens. If billions of dollars will be invested in the search for interstellar technological trash, we might find alien versions of the Tesla Roadster. All we need is to imagine that Elon is not the first innovator to engage in ambitious space exploration since the Big Bang, 13.8 billion years ago.
Why should we expect technological space trash from distant stars in our backyard? Because most stars formed billions of years before the Sun and it takes less than a billion years for chemical rockets to move from one side of the Milky-Way disk to the other.
Life is sometimes a self-fulfilling prophecy. By not investing in the search, we will not find evidence for an extraterrestrial Elon who may have launched an electric car to space billions of years ago. On the other hand, by going through the trash of our neighbors, we could learn about technologies that we do not possess as of yet.
Interstellar space offers a new filter for survival of the fittest. If we recover the relics of the most advanced civilizations, we can learn survival skills from the smartest students in our class. In order to learn, we must be humble. In other words, we should be curious enough to imagine that we are not alone in order to find others.
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”, was published in August 2023.
