Last semester in my Harvard freshman class, I stated that Proxima Centauri, the nearest star to the sun, emits largely infrared radiation and has a planet, Proxima b, in the habitable zone around it.
“Suppose organisms are crawling on the surface of Proxima b?” I challenged the students.
“What might their infrared-sensitive eyes look like?” you might wonder.
Within seconds, the class’s brightest student responded with an image of a mantis shrimp with infrared vision.
The shrimp’s eyes resemble two ping-pong balls attached to its head by cables. She said, “It looks like an alien.”
When trying to visualize something we’ve never seen before, we frequently fall back on what we’ve seen before.
As a result, we usually look for life as we know it while searching for extraterrestrial life.
Is there, however, a way to broaden our imagination to include existence as we don’t know it?
In physics, a similar method was devised over a century ago and has proven to be successful in a variety of situations.
It entails carrying out laboratory experiments that disclose the fundamental physical rules, which then apply to the entire cosmos.
For example, about the same time as the neutron was discovered in James Chadwick’s laboratory in 1932, Lev Landau proposed that stars could be composed of neutrons.
Astronomers discovered later that our Milky Way galaxy alone contains 100 million neutron stars, with a billion times more in the observable universe.
The LIGO experiment recently discovered gravitational wave signals from neutron star collisions at cosmological distances.
Such collisions are now understood to be the source of the valuable gold used in wedding bands.
The lesson of the narrative is that physicists were able to envisage something new in the universe at large and seek for it in the sky by using what they learned in lab experiments on Earth.
A similar strategy can be used in the quest for extraterrestrial life.
It might be possible to conceive new habitats where life occurs differently than on Earth if we can create synthetic life in various ways from a soup of chemicals in the lab.
It’s like if you’re writing a recipe book with instructions for creating various varieties of cakes.
We need to experiment with a variety of compounds to develop a comprehensive recipe book.
Furthermore, as I mentioned in a publication with Manasvi Lingam, this research might utilize fluids other than water, which is deemed necessary for life as we know it.
Nobel Laureate Jack Szostak, one of my Harvard colleagues, is on the verge of developing synthetic life in his lab.
Any success with a single recipe might lead to variants that create a wide range of results, which could be compiled into our synthetic life recipe book.
We can later seek genuine systems where these environmental requirements are realized in the sky, just as we do with neutron stars, by finding relevant environmental conditions from our laboratory studies.
We should be as cautious as we are when using nuclear energy if we choose this strategy.
The risk of creating artificial life types in our laboratories, as depicted in the Frankenstein narrative, is that it will cause an environmental calamity.
Experiments like these should be carried out in confined situations so that errors with life as we don’t know it doesn’t harm life as we know it.
Extraterrestrial life may be most prevalent beneath the surface of planets and asteroids, even though the surfaces of planets and asteroids can be searched remotely for biological traces.
Not only on moons like Saturn’s Enceladus or Jupiter’s Europa but also free-floating objects in interstellar space, habitable conditions could exist in the oceans beneath thick icy surfaces.
In another work with Lingam, we showed that the number of life-bearing objects in the habitable zone orbiting stars could be many orders of magnitude greater than the number of rocky planets.
Extremophiles on Earth are an example of how life can adapt to severe circumstances in unusual ways.
For example, frozen microscopic organisms were revealed to have survived 24,000 years in Siberian permafrost, while microbial life has been discovered to have survived 100 million years beneath the seafloor.
These bacteria arose during the warm Cretaceous epoch when dinosaurs reigned supreme on the planet.
The closest circumstances to Earth were found on Earth’s nearest neighbors, Venus and Mars, in the solar system.
NASA has chosen two new missions to study Venus, and its Perseverance rover is on Mars looking for signs of life.
The essential follow-up question if extraterrestrial life is discovered is whether it is “life as we know it.”
If we don’t, we’ll discover that natural life has several chemical paths. However, if we find evidence of life on Mars or Venus that is similar to life on Earth, this could indicate a preference for “life as we know it.”
Alternatively, life could have been carried between planets by a process known as panspermia, in which rocks migrate between planets.
My student Amir Siraj and I published a study arguing that planet-grazing asteroids may have mediated the transfer of life.
We should also consider the improbable possibility that life was sown in the inner solar system by an “extrasolar gardener,” i.e. “guided panspermia.”
Dinner conversations in which the grownups in the room pretended to know much more than they did are my most vivid childhood memory.
This was unquestionably a type of “intellectual makeup” that they used to enhance their image.
And if I asked a question that these pretenders didn’t know the answer to, they would dismiss it as unimportant.
It’s no different for me as a senior scientist, especially when it comes to the question, “Are we the smartest child on the cosmic block?”
Science allows us to keep our childlike curiosity alive.
It is impossible to stop the advancement of scientific knowledge through experimentation.
Let’s hope we can come up with a recipe for artificial life that allows us to imagine something considerably more intelligent than the natural life we’ve seen thus far.
This is going to be an eye-opening experience.
Even if we are unable to uncover this greatest intellect in our laboratories, its by-products may appear in our skies as letters from distant Milky Way neighborhoods.
And we’ll be looking for it with the recently announced Galileo Project’s telescopes.
the author is: Avi Loeb is former chair (2011-2020) of the astronomy department at Harvard University, founding director of Harvard’s Black Hole Initiative and director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics. He also chairs the Board on Physics and Astronomy of the National Academies and the advisory board for the Breakthrough Starshot project, and is a member of President’s Council of Advisors on Science and Technology. Loeb is the bestselling author of Extraterrestrial: The First Sign of Intelligent Life Beyond Earth (Houghton Mifflin Harcourt).