On June 25, Friday, SETI Institute CEO Bill Diamond held an AMA (Ask Me Anything) on the popular social news aggregation and web content rating website Reddit. Here are some interesting questions and Bill Diamond’s answer to them.

AMA session of the SETI Institute’s CEO Bill Diamond

This AMA (Ask Me Anything) session was organized on Reddit on June 25, 2020.

  • Q: Given the abundance of exoplanets that have been discovered, are there any that you consider prime candidates to study for signs of life?
  • A: We don’t know enough yet about the newly discovered exoplanets to identify the ‘best’ candidates yet, but we’re learning more all the time. Initially, a planet that is rocky, more or less Earth-sized, and in the habitable zone of its host star, is an interesting candidate. But the type of star also matters, as does the planetary atmosphere, the presence of a magnetic field, and a host of other factors. When the James Webb telescope launches next year (with any luck) we will be able to probe the atmospheres of nearby planets spectroscopically, and thus analyze their atmospheres. Finding biosignatures in these atmospheres, or finding atmospheres that our models suggest could be hospitable to life, will give us a much better idea bout targets to look at more closely. As noted earlier, rocky Earth-like planets in our own galaxy, in the habitable zone, number in the 10s of billions!
  • Q: Even if we find unmistakable signs of life, it seems likely that said life will be a minimum of hundreds of light-years away, and likely very much farther. No signal we could send would reach this other life within an existing human lifetime, and we would have to wait, at an absolute minimum, twice that long before the earliest possible response. This takes your project into the “Clock of the Long Now” territory. Any conversation would require centuries or millennia of caretaking, making it impractical. So… we can’t hope to converse. What working hypotheses does SETI have for what might be learned by mere listening?
  • A: That’s an important question, and of course scientists recognize the practical reality of what you are pointing out. For the scientific community, it’s not about the prospect of having a ‘conversation’ that is important. As you correctly note, the time elements associated with such an idea make it most likely impossible (unless, of course, we find that there’s technological life on a planet around Alpha Centauri, we can’t rule that out). So the real importance of this research is to understand the phenomena of life itself and whether or not it exists elsewhere, and whether evolutionary processes on distant worlds have also led to technological and intelligent life. The discovery itself, even without the prospect of a conversation, would be among the most profound discoveries in the history of humankind. It would provide for a hopeful future about what is possible, and perhaps encourage us to think that we CAN (hopefully) survive our own age of technology and the stresses this puts on planetary resources. So while a conversation would be fascinating, it’s not really the point.
  • Q: Is SETI conducting any research into whalesong, as an analogous model for signals analysis of linguistic or semiotic content or structures from beyond our own species?
  • A: In fact we are. One of senior SETI astronomers, Dr. Laurance Doyle, has been studying non-human communications for many years to learn about the underlying mathematics and patterns of information transfer by multiple means – chemical, optical, sound, etc. He’s currently applying Information Theory to whale communications in the Humpback whale in a funded research project. You can learn about his project and see a video about it on our website.
  • Q: What process would occur when a clear, unmistakable, intelligent alien signal is found?
  • A: First protocol is verification. If we (or someone else) discover a ‘signal’ that appears to be technological in nature, the next thing would be to determine if it contains information. Dr. Laurance Doyle’s work mentioned in a previous response, on non-human communication, might be helpful here. As an example, we might detect a laser beam that was used for propulsion purposes. We could probably determine that this is a techno signature and represents definitive evidence of intelligent life beyond Earth, but it would contain no information. In the case of a signal that clearly contains information, efforts would undoubtedly be made to determine what that information is and how we might access it, and potentially decipher it. Of course, video information if in any kind of format we could ‘open’ would be absolutely amazing, but more likely the information would be streams of data perhaps intended to be a sign of intelligent life, such as a string of prime numbers, for example. If we ever “eavesdropped” on a “conversation” between worlds, there might be some incredible and complex content to try and untangle.

Note: See the “Rio Scale” section below.

  • Q: Is there any favor in masking our presence? If there is a nearby hypothetical omnidirectional transmission, do we respond with anything? Or just listen?
  • A: I think it’s impossible to truly mask our presence. As long as we broadcast radio and TV transmissions, use airport radar, use radar to look for asteroids, communicate with spacecraft, etc, it would be nearly impossible to go completely dark. I also don’t think there’s any point. Any truly advanced civilization that might have the technology to actually visit us, almost certainly knows that we’re here, and probably without our transmissions. Life has been on Earth for billions of years and imparts a signature on the planet that can in principle be detected from very far away! If we get a message – and can actually decipher it – should we respond? I guess that would depend in large part on the content of the message – and the distance and time over which it traveled.
  • Q: Any comment on the USS Nimitz and USS Theodore Roosevelt videos released by the US Navy?
  • A: We did cover this story on our website. We certainly concur that there are things we call “Unidentified Flying Objects” because they are precisely that – things we don’t quite understand or can’t quite explain. I personally don’t think (nor does the scientific community in general) that these are spacecraft from other worlds or small craft from a mother ship.
  • Q: Other than carbon, are there any other elements that you’re looking into to possibly be the base of alien life?
  • A: Well, I know silicon is a possible candidate. It has similar chemical properties to carbon, as it is in the same group (column) in the periodic table. But any silicon-based life would probably be quite simple (like slime or something) because silicon just can’t form as many large, long, and complex molecules the way carbon can. Carbon is really special.
  • Q: With the vast amount of stars in this galaxy alone, do you believe 100% that there is life in other galaxies and solar systems?
  • A: I do personally believe 100% that there is life beyond Earth, and I also believe that based on pure math and statistical probabilities, it is likely that intelligent and technological life exists or has existed elsewhere in our own galaxy and thus most likely in other galaxies as well.
  • Q: Based on your experiences with the SETI, how long do you think it will take for us to detect the first proof of life beyond our earth? When can we finally say “here look at this proof of a microbe” etc.?
  • A: It’s a popular and good question. I personally think that the discovery of life beyond Earth at perhaps the microbial – or even more complex level, will be made within the next couple of decades, within our own solar system. The Mars 2020 mission, launching July 20th, includes instrumentation on the “Perseverance” rover that is designed to detect biology. It will also pick up samples and secure them for subsequent pick up in a so-called sample-return mission. Life could certainly still exist on Mars, albeit below the surface and sheltered from radiation. Enceladus and Europa are also intriguing candidates for life, and missions are planned to Europa already. Of course, intelligent life detected through radio or optical telescopes outside our solar system could in principle be detected at any time!
  • Q: Do you personally think there is a nontrivial chance that the rare earth or firstborn hypotheses are correct and that there is no other intelligent life in our galaxy right now?
  • A: Even the people who put forth the idea believe that life is probably common in the Universe. However, there is a large set of circumstances beyond the prevalence of single-celled life that make it more or less likely that there is intelligent life capable of interstellar communication using technology. I won’t go through all the arguments about the earth having a large moon to stabilize our precession, whether or not Jupiter sucks up potentially dangerous comets etc. But just on a statistical basis, there is a lot of merit to the hypothesis. It took about half a billion years to develop single-celled life on earth, therefore this type of life is probably common. However, it took another 2 billion years to get to multi-celled life. Clearly, then, this is not a given that it will happen and it might put a big funnel on the number of planets where intelligent life exists. Further, the dinosaurs ruled for about 180 million years. In all that time they developed a lot of somewhat intelligent species with large brains. Further, if you consider birds as descendants of dinosaurs it is clear many of them have high intelligence. Likewise, many cetaceans have enormous encephalization coefficients and are highly intelligent. Therefore, it took about 4 billion years to come up with creatures that were intelligent by our common definitions. And yet only one species out of the millions of multi-celled creatures that have evolved has been capable of constructing radio-telescopes. Therefore, it is likely that it is not likely to develop species capable of developing radio telescopes. Let’s recapitulate this argument for humans. If one includes Modern Humans, Denisovans, and Neanderthals as potentially being capable of building radio telescopes, then one can say such a species has existed on the earth for about 400K years. And yet for only 150/400K years, have humans been capable of building a radio telescope. It took about 390K of the 400K years just to have an agricultural revolution. What took so frikkin long? No one really knows. This argument works again for civilizations. Civilization (i.e. cities and their accompanying cultures) have been around for 10K years. And yet, many of those advanced civilizations that were around for thousands of years never had a scientific revolution. Maybe a scientific revolution is not a given. If you add up all these statistical arguments/filters and then include the geophysical/cosmological filters that may exist for planets in the “Goldilocks Zone” it isn’t improbable that civilizations capable of interstellar communication are rare.
  • Q: When searching for life are we only searching for life that follows our genetic makeup (i.e breathes oxygen, needs water/food), or are we looking for life that could follow other forms of genetic makeup that wouldn’t traditional make sense to us?
  • A: It’s actually a great question and one that we grapple with all the time. It is fair to say that for the most part, we are looking for ‘life as we know it’ for the obvious reason that it’s easier to look for something you know than something you don’t – as you might not recognize it when you find it. We are constantly asking “how do we search for life as we DON’T know it?” and in fact, we hosted an amazing workshop at the SETI Institute two years ago, called “Decoding Alien Intelligence” which was specifically addressing this question. We hope to host a follow-on workshop next year. We do believe, however, that the laws of physics are the same throughout the known universe, and the laws of chemistry and biology are as well. Our own biology was formed of the most abundant elements (like carbon, hydrogen, and oxygen) and as such, it’s likely that life on other worlds would also use these same basic and abundant building blocks. Nevertheless, we have to keep our minds open for life as we don’t know it. By the way, there’s not a very good or universally accepted definition for what life is! Check it out! We know what life DOES, but we don’t really know what it is. Are robots that can build other robots and evolve ever more intelligent and capable versions of themselves as a form of life?


These two questions below are not from the Reddit AMA, they’re from SETI Institute’s FAQ page.

Why do we think that there is extraterrestrial life?

K2-18b artist conception

Over the last half-century, scientists have developed a theory of cosmic evolution that predicts that life is a natural phenomenon likely to develop on planets with suitable environmental conditions. Scientific evidence shows that life arose on Earth relatively quickly (only 100 million years after life was even possible), suggesting that life will occur on any planets that have the requisite characteristics, such as liquid oceans (either on the surface or underground). With the recent discovery that the majority of stars have planets – the number of potential habitats for life has been greatly expanded.
In addition, exploration of our own Solar System and analysis of the composition of other systems suggest that the chemical building blocks of life – such as amino acids – are naturally produced and very widespread.
There are several hundred billion other stars in our Galaxy, and more than 100 billion other galaxies in the part of the universe we can see. It would be extraordinary if we were the only thinking beings in all these vast realms.

Have SETI Institute scientists found life, or evidence of life, on any other planets?

Inflatable aliens

No, scientists have found no clear indications of life, past or present, beyond the Earth. There have been several tantalizing suggestions – that the Viking mission might have detected evidence of microbial life on Mars or that there are fossil microbes in some Mars rocks or meteorites – but none of these claims has been verified.

SETI Institute

The SETI Institute logo
The SETI Institute logo

SETI is an acronym for the “Search for Extraterrestrial Intelligence”. As its name suggests, the institute is home to research and educational projects relating to the study of life in the Universe. Incorporated in 1984, it is a non-profit corporation that conducts research in a number of fields including astronomy and planetary sciences, chemical evolution, the origin of life, and biological and cultural evolution.

SETI Institute has suites of activities in three areas:

  1. Astrobiology (see notes 1), the efforts to find and understand the prevalence of life in general (for example, microbial life under the parched landscapes of Mars or the icy crust of the Jovian moon (Jupiter’s moon) Europa);
  2. SETI, experiments designed to detect radio or light signals that would reveal the presence of technically sophisticated beings; and
  3. Education and outreach projects that inform the public about their research, encourage young people to become more proficient in science, engage the general public in scientific research, and train teachers in STEM (abbreviation for Science, Technology, Engineering, and Mathematics) subject areas.

The Institute consists of three primary centers:

  1. The Carl Sagan Center – devoted to the study of life in the universe. It is named in honor of Carl Sagan, a former trustee of the Institute. The Carl Sagan Center is home to over 80 scientists and researchers.
  2. The Center for Education – focused on astronomy, astrobiology, and space science for students and educators.
  3. The Center for Public Outreach – producing “Big Picture Science,” SETI Institute’s general science radio show and podcast, and “SETI Talks” weekly colloquium series.

Rio Scale

First developed in 2001 by the astronomers Iván Almár and Jill Tarter, the Rio Scale is a tool used by astronomers searching for extraterrestrial intelligence (ETI) to help communicate to the public “how excited” they should be about what has been observed. The Scale measures the consequences for humans if the signal is from aliens, as well as the probability that the signal really is from aliens, and not a natural phenomenon or human-made. The scale gives a score between 0 and 10 so that the public can quickly see how important a signal really is.

  1. Extraordinary
  2. Outstanding
  3. Far-reaching
  4. High
  5. Noteworthy
  6. Intermediate
  7. Moderate
  8. Minor
  9. Low
  10. Insignificant
  11. None

In August 2019, a new Rio Scale (Rio 2.0) has now been submitted to the International Academy of Astronautics Permanent Committee on SETI for official ratification.


  1. Astrobiology, formerly known as exobiology is the multidisciplinary study of life in the universe. It addresses some very basic questions: How does life begin? How common is life in the Universe? How can we detect extraterrestrial life? And what is the future of life on Earth and beyond?


M. Özgür Nevres
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