Books by Shostak, Seth

Shostak, Seth. Confessions of an Alien Hunter. Washington: National Geographic, 2009. ISBN 978-1-4262-0392-3.

This book was published in 2009, the fiftieth anniversary of the modern search for extraterrestrial intelligence (SETI), launched by Cocconi and Morrison's Nature paper which demonstrated that a narrowband microwave beacon transmitted by intelligent extraterrestrials would be detectable by existing and anticipated radio telescopes on Earth. In recent years, the SETI Institute has been a leader in the search for alien signals and the author, as Senior Astronomer at the Institute, a key figure in its ongoing research.

On the night of June 24th, 1997 the author, along with other researchers, were entranced by the display on their computer monitors of a signal relayed from a radio telescope in West Virginia aimed at an obscure dwarf star named YZ Ceti 12 light years from the Sun. As a faint star prone to flares, it seemed an improbable place to find an alien civilisation, but was being monitored as part of a survey of all stars within 15 light years of the Sun, regardless of type. “Candidate signals” are common in SETI: most are due to terrestrial interference, transmissions from satellites or passing aircraft, or transient problems with the instrumentation processing the signal. These can usually be quickly excluded by simple tests such as aiming the antenna away from the source, testing whether the source is moving with respect to the Earth at a rate different than that of the distant stars, or discovering that a second radio telescope in a different location is unable to confirm the signal. Due to a mechanical failure at the backup telescope, the latter test was not immediately available, but all of the other tests seemed to indicate that this was the real deal, and those observing the signal had to make the difficult decision whether to ask other observatories to suspend their regular research and independently observe the source, and/or how to announce the potential discovery to the world. All of these difficult questions were resolved when it was discovered that a small displacement of the antenna from the source, which should have caused a Gaussian fall-off in intensity, in fact changed the signal amplitude not at all. Whatever the source may have been, it could not be originating at YZ Ceti. Shortly thereafter, the signal was identified as a “side lobe” reception of the SOHO spacecraft at the Sun-Earth L1 point. Around this time, the author got a call from a reporter from the New York Times who had already heard rumours of the detection and was trawling for a scoop. So much for secrecy and rumours of cover-ups in the world of SETI! By the evidence, SETI leaks like a sieve.

This book provides an insider's view of the small but fascinating world of SETI: a collective effort which has produced nothing but negative results over half a century, yet holds the potential, with the detection of a single confirmed alien transmission, of upending our species' view of its place in the cosmos and providing hope for the long-term survival of intelligent civilisations in the universe. There is relatively little discussion of the history of SETI, which makes sense since the ongoing enterprise directly benefits from the exponential growth in the capabilities of electronics and computation, and consequentially the breadth and sensitivity of results in the last few years will continue to dwarf those of all earlier searches. Present-day searches, both in the microwave spectrum and looking for ultra-short optical pulses, are described in detail, along with the prospects for the near future, in which the Allen Telescope Array will vastly expand the capability of SETI.

The author discusses the puzzles posed by the expectation that (unless we're missing something fundamental), the window between a technological civilisation's developing the capability to perform SETI research as we presently do it and undergoing a technological singularity which will increase its intelligence and capabilities to levels humans cannot hope to comprehend may be on the order of one to two centuries. If this is the case, any extraterrestrials we contact are almost certain to be these transcendent machine intelligences, whose motivations in trying to contact beings in an ephemeral biological phase such as our own are difficult to imagine. But if such beings are common, shouldn't their cosmological masterworks be writ for all to see in the sky? Well, maybe they are! Vive l'art cosmologique!

What would be the impact of a confirmed detection of an alien transmission? The author suggests, and I tend to concur, probably a lot less than breathless authors of fiction might expect. After all, in the late 19th and early 20th century, Percival Lowell's case for an intelligent canal-building civilisation on Mars was widely accepted, and it did not cause any huge disruption to human self-perception. When I was in high school, many astronomy texts said it was likely Mars was home to lichen-like organisms which accounted for the seasonal changes observed on the planet. And as late as the landing of Viking I on Mars, which this scrivener observed from the Jet Propulsion Laboratory auditorium on July 20th, 1976, the President of the United States asked from the White House whether the lander's camera would be able to photograph any Martian animals rambling around the landscape. (Yes, it would. No, it didn't—although the results of the microbial life detection experiments are still disputed.)

This book, a view from inside the contemporary SETI enterprise, is an excellent retrospective on modern SETI and look at its future prospects at the half century mark. It is an excellent complement to Paul Davies's The Eerie Silence (December 2010), which takes a broader approach to the topic, looking more deeply into the history of the field and exploring how, from the present perspective, the definition of alien intelligence and the ways in which we might detect it should be rethought based on what we've learnt in the last five decades. If I had to read only one book on the topic, I would choose the Davies book, but I don't regret reading them both.

The Kindle edition is reasonably well produced, although there are some formatting oddities, and for some reason the capital “I”s in chapter titles have dots above them. There is a completely useless “index” in which items are not linked to their references in the text.

March 2011