Is there intelligent life beyond Earth?

As our technology has gotten better at scanning the skies so has serious study of the universe. In this newest addition to our Big Questions Series, Learning Life’s Craig Gusmann interviewed three prominent astronomers — Dr. Seth Shostak of the Search for Extraterrestrial Intelligence (SETI), Dr. Dick Carrigan of SETI and Fermilab, and Dr. Jason Dworkin, Chief of the Astrochemistry Branch at NASA Goddard — on the big question: is there intelligent life elsewhere in the universe, beyond Earth?  Their answers below offer stimulating perspectives on the question and the nature of life itself.  


Dr. Dick Carrigan: I tend to take the view that the environment around our Sun is not that unique. We’re not a particularly unusual place. In fact, it seems that we’re quite average. Other Solar Systems have planets, so we may eventually stumble on environments that are substantially better for intelligence. There are a lot of stars out there, a lot of galaxies, so there are many, many opportunities for life and intelligence out there.  Further, in the universe, there are some things that run fast and some things that run slowly.  There is probably a wide variety in the amount of time it takes for intelligence to evolve. There may be intelligent life in the universe that is evolving much faster, and if we make contact with such life, we could be dealing with a much higher brand of intelligence than our own.


Dr. Jason Dworkin: The universe is an awfully big place. So, throughout the past and future of the universe and all of time and space it seems likely. Now, is there intelligent life outside the Earth right now elsewhere in the galaxy? Maybe. Elsewhere in a ten light-year radius? Possibly, but the chance seems small. There’s no evidence for or against. Furthermore, if life does exist elsewhere it’s hard to understand how you would even recognize it unless it was microscopic.

Life is actually really hard to define. You know it when you see it, but a good chemical definition of life doesn’t exist. The best definition is a chemical-replicating system capable of Darwinian evolution. So that means you can only know it’s alive if you see it’s reproducing and evolving. There are a few cases where, according to that definition, it’s not clear if a virus is alive or not. Fire is not. Crystals are not, because they don’t evolve. But they do replicate and they do consume energy.

There’s no evidence of life outside of Earth yet.  It may exist.  There are environments where life could exist, but there’s no proof that life is there. We very much want to find it, but right now we only have one example of life and that’s terrestrial life. If we have a second example we’d understand life a whole lot better by being able to compare it against something. All life on Earth is intimately related using all the same biochemistry. You start to wonder, is that the only solution to making life work — using DNA, RNA, protein, carbon bonds, water, membranes, that sort of thing?  Is that the only way to make life?  Is that the best way it works or is that just the way the Earth makes it?


Dr. Seth Shostak: We now know, thanks to work of NASA’s Kepler Space Telescope and others, that most stars have planets.  In addition, roughly one in five stars will have a planet similar in size to Earth, and at a temperature that could support liquid oceans and an atmosphere.  In other words, it could be habitable.  That amounts to tens of billions of “Earth-like” planets just in our galaxy.  It would be extraordinary if our world were the only one to have developed not just life, but intelligent life.  Although just having a lot of planets with life is not sufficient to guarantee that many of them (or any of them!) also develop intelligent creatures, in the last fifty million years many species on Earth have become more clever.  Simians, dolphins, some birds…and of course us.  So, it seems that intelligence has some survival value, and in any Darwinian system, you might then expect intelligence to arise eventually.



Dr. Seth Shostak developed an interest in extraterrestrial life at the tender age of ten, when he first picked up a book about the solar system. This innocent beginning eventually led to a degree in radio astronomy, and now, as Senior Astronomer, Seth is an enthusiastic participant in the Institute’s SETI observing programs. He also heads up the International Academy of Astronautics’ SETI Permanent Study Group.

In addition, Seth is keen on outreach activities, interesting the public — especially young people — in general science, but particularly astrobiology. He has co-authored a college textbook on astrobiology and continues to write trade books on SETI.  In addition, he’s published nearly 300 popular articles on science, gives many dozens of talks annually, is the editor of the SETI Institute’s Explorer magazine, and host of the Institute’s weekly science radio show, “Big Picture Science”.

Asstronomy1.JasonDworkinDr. Jason Dworkin began research into the origins of life as a high school intern with Professor Joan Oró at the University of Houston, where he helped to investigate the prebiotic syntheses of amino acids and co-enzymes.  He completed his Ph.D. in biochemistry at the University of California in San Diego, where he investigated pre-RNA nucleobases.  He then carried out postdoctoral research at NASA Ames Exploration Center, studying complex organics from UV processed interstellar and cometary ices in the laboratory.  He founded the Astrobiology Analytical Research Group at NASA Goddard Space Flight Center to study extraterrestrial organic compounds relevant for the origin of life via analytical chemistry.  He is currently Chief of the Astrochemistry Branch at NASA Goddard and the Project Scientist for NASA’s OSIRIS-REx Mission, which launches in 2016 to return samples of primitive near-Earth asteroid Bennu in 2023.  For further learning, Dr. Dworkin recommend’s NASA’s graphic novels that explain the evolution of astrobiology with clear prose and engaging illustrations.

Astronomy1.DickCarriganDr. Dick Carrigan is an active physicist and Scientist Emeritus in the Accelerator Division at the Fermi National Accel­era­tor Laboratory (Fermilab) pursuing an on-going physics program there. He is also interested in investigations of the possibility of life and intelligence in the Universe. His major technical interests have included channeling of high energy particles, hyperon physics, the magnetic monopole conjec­ture, high energy scatter­ing, pi and mu mesic atoms, photo production, and facility plann­ing.  He has been associated with several joint USA‑USSR col­laborations studying high energy particle behavior at Fermilab and in Russia.

Dr. Carrigan is the author of more than a hundred scientific publications and the author or editor of a number of books and monographs including Non-Accelerator Astroparticle Physics (World Scientific 2005 with G. Giacomelli, A. Masiero, and N. Paver), Particles and Forces: At the Heart of Matter (Freeman 1990 with W. P. Trower), Particle Physics in the Cosmos (Freeman 1989 with W. P. Trower), Relativistic Channeling  (Ple­num 1986, with J. Ellison), Magnetic Monopoles (Ple­num 1983, with W.P. Trower),  The State of Particle Accelerators and High Energy Physics and Physics of High Energy Particle Accelerators  (AIP 1982, with F. Huson and M. Month).  He is also a member of Sigma Xi, the American Physical Society, and the American Association for the Advancement of Science.