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Post-biological Implications for SETI
by Allen Tough, Ph.D., University of Toronto
email tough @

From proceedings of SETICon02, the second SETI League technical symposium, Trenton NJ, April 26-28, 2002

What if Steve Dick's bold new post-biological hypothesis in these Proceedings is true?

What if we really do live in a post-biological universe, or at least a post-biological galaxy, inhabited by extraordinarily smart machines? What if their capacity to sense, diagnose, calculate, think, choose, and communicate exceeds the vision of most scientists and engineers today? What if their age, perspective, knowledge, wisdom, culture, technology, and intelligence have advanced thousands or millions of years beyond our own?

The concept of a post-biological universe certainly does seem reasonable. It fits within the bounds of today's logic, science, and engineering, at least if they are extrapolated a few decades into the future. It is supported by some highly competent scientists. It could occur from a dazzling array of civilizations arising independently, but it could also arise from just one or two long-lived civilizations gradually spreading throughout a galaxy. A map of the galaxy might show widely scattered pockets of intelligence communicating with one another across vast expanses of space, or it might show those spaces contain many intelligent relay stations and interstellar probes. All in all, it certainly seems quite likely, or at least quite possible, that we live in a post-biological galaxy.

Several major implications immediately arise for the SETI field. These implications are wide-ranging, profound, unsettling, deeply transformative, challenging, exciting, exhilarating.

Here are the five implications that seem to me most important of all.


First, our society's total support for SETI should be immediately tripled. Tapping into the extraordinary body of alien knowledge and wisdom could bring beneficial new perspectives and capacities to our human civilization. Because these benefits could be so valuable, our society should put plenty of effort and resources into finding a one-way message from ETI or, even better, achieving a scientific and philosophical dialogue. The SETI field should be funded generously from the public scientific purse as well as from private donors. Triple today's total level of funding for SETI would be just a good beginning. What other field of science has the potential to bring such advanced, fresh, valuable knowledge to human civilization?


The second implication of a post-biological universe affects SETI scientists who use radio or optical telescopes. They need to re-examine the assumption that the artificial signal they seek will come from a planet. Super-intelligent machines may prefer to hang out somewhere else. So we should point our telescopes in some fresh directions, not just at stars and their planets. As Seth Shostak (1998) said, "But what if E.T. isn't biological? [Highly intelligent autonomous machines might ply the deserts between the stars, for instance, and seek dense interstellar clouds of gas as oases.] This type of scenario suggests that SETI scientists consider aiming their radio telescopes at some unconventional targets…. When we swing our radio telescopes toward the heavens, we are looking for intelligence, after all, not biology."


Third, all SETI scientists need to fundamentally rethink their conception of extraterrestrial intelligence—and how to achieve contact with it. We need to study cutting-edge thinking about the far future of artificial intelligence and robotics—the ideas of leading thinkers such as Ray Kurzweil, Hans Moravec, Bill Joy, Frank Tipler, Steven Dick, Ray Norris, Robert A. Freitas Jr, and Robert Bradbury.

Our learning will be most effective if we allow ourselves to feel shaken up, awed, and humble as we think about just how incredibly smart and knowledgeable some machines might be, compared to us. Just think of the capacities, intelligence, knowledge, and wisdom of a robot culture that is millions of years ahead of us!

It is particularly useful to think about the likely array of purposes, goals, values, ethics, projects, and missions of super-intelligences. What do they spend their time doing? How much help do they give fledgling civilizations such as ours, and what sorts of help? (Tough, 1986).

Astrobiologists, too, might benefit from rethinking what they are looking for. If the universe has been populated by super-smart machines for thousands of centuries, what sorts of biological life might now exist and what evidence might we find?

Interstellar Probes

Now, the fourth implication. One likely activity of super-smart machines is to explore the universe, with a particular interest in monitoring other cultures. To do this, they likely manufacture super-smart interstellar probes. These probes can then be sent to study other cultures, to help fledgling civilizations, and to teach them new ideas and values.

If all of this happened long ago, then at least one of these probes has presumably already reached our planet or at least our solar system. We should look for it!

Inviting a Dialogue

Fifth, even though our field is called the search for ETI, the time has come to re-examine our emphasis on searching. We may not need to find ETI: it may be perfectly capable of finding us! In addition to our traditional search methods, we should expand our array of strategies by adding one or two approaches that go beyond mere searching.

Probably one of these approaches should be to issue warm, friendly, interesting invitations to ETI. Invitations that are designed to be attractive to them, and to offer them something of interest. One SETI project of this type is called the Invitation to ETI. Eighty scientists, students, and artists involved in SETI or CONTACT use the World Wide Web to issue an invitation to dialogue. If a super-smart probe is monitoring our telecommunications, including the Web, it will find their home page at

One way to make such an invitation more attractive is to put in place effective arrangements for post-contact communications and security. If ETI foresees that we are unprepared for contact and might even be harmed, it is unlikely to initiate contact. On the other hand, if it sees that we are well prepared to handle the potential chaos and conflict caused by contact, it will more likely respond to an invitation. As part of our strategy to make contact attractive to ETI, then, we should vigorously prepare for our interaction with an extraordinary alien intelligence.

If the SETI field pursues all five implications, the illuminating interaction with a super-smart machine could well occur within our lifetime.


1. Seth Shostak, Sharing the universe: Perspectives on interstellar life. Berkeley: Berkeley Hills Books, 1998. Page 201.

2. For an extensive discussion of the help an advanced intelligence might give us, see sections 4 and 5 in Allen Tough, "What role will extraterrestrials play in humanity's future?" JBIS: Journal of the British Interplanetary Society, vol. 39, November 1986, pages 491-498. Additional papers by Dr. Allen Tough are listed here.

For a hard copy of this paper and a wide range of other papers, purchase the Proceedings of SETICon02: The Second SETI League Technical Symposium April 26-28, 2002. See the SETI League website.

Copyright © 2002 by Allen Tough. All rights reserved.
From proceedings of SETICon02, the second SETI League technical symposium, Trenton NJ, April 26-28, 2002.

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