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50 Years of SETI: One Cup of the Cosmic Ocean

By Jill Tarter, SETI Institute


Jill Tarter photo smallerJill Tarter holds the Bernard M. Oliver Chair for SETI Research and is Director of the Center for SETI Research at the SETI Institute in Mountain View, California. Tarter served as Project Scientist for NASA’s SETI program, the High Resolution Microwave Survey, and has conducted numerous observational programs at radio observatories worldwide. Currently, she serves on the management board for the Allen Telescope Array, a joint project between the SETI Institute and the UC Berkeley Radio Astronomy Laboratory.

Tarter’s work has brought her wide recognition in the scientific community, including numerous awards. In 2004 Time Magazine named her one of the Time 100 most influential people in the world, and in 2005 Tarter was awarded the Carl Sagan Prize for Science Popularization at Wonderfest, the biannual San Francisco Bay Area Festival of Science. Read full bio

Frank Drake conducted the first radio search for extraterrestrial intelligence fifty years ago; radio and optical search programs have been ongoing ever since. Many people think that means that we’ve searched exhaustively and should now draw pessimistic conclusions from our lack of success thus far. Carl Sagan knew better. His imagery of the vast cosmic ocean puts our efforts into context. We have barely begun to search!

Consider the following experiment to answer the question of whether there are any fish in the Earth’s oceans. Fill an 8-ounce cup with water from an ocean, and look to see if you captured any fish in your cup. That experiment could work; the smallest fish is about a millimeter in size, and while you couldn’t fit a great white shark into your cup, many species of fish would fit just fine. There are no fish in your cup. What do you conclude? That there are no fish in the ocean? That you were just unlucky and scooped your cup of water from an unusually barren patch of ocean? Or that your cup is a poor tool, and that you haven’t yet sampled enough of the Earth’s oceans to draw any conclusions about the prevalence of fish?

The Earth’s oceans contain 1.4x1018 m3 of water, or 6x1021 cups of water. One cup out of 6,000,000,000,000,000,000,000 cups is just about the right fraction of the electromagnetic search space to represent the past fifty years of SETI efforts. If you’d like to check that calculation, I’ve posted it on my TED blog.

To make progress, we need bigger cups, the ability to dip them into the ocean faster, and maybe new ways of searching altogether. In partnership with the University of California Berkeley, the SETI Institute has now built its own telescope – the Allen Telescope Array – for doing traditional radio astronomy and SETI in commensal mode, nearly all the time. Moore’s Law will continue to expand the speed with which we can sift through the cosmic noise collected by the ATA to search for engineered signals. Optical SETI researchers also have a dedicated survey instrument at Harvard’s Oak Ridge Observatory. Frank Drake is dreaming about space technologies that will allow us to harness the Sun as a gravitational lens, thus gaining billions and billions of times the sensitivity of our current efforts. And the magic of many different information technologies now makes it possible for us to invite the world to join in the search as creative and active participants who can shape what we do and improve our sampling of the cosmic ocean.

setiQuest is a fledgling community of Earthlings around the globe who are volunteering domain-expertise, ‘thinkons’, and the pattern recognition prowess of their brains, eyes, and ears “to become active participants in the ultimate search for cosmic company” in accordance with my 2009 TED wish to change the world. How could this change the world? Carl Sagan understood perfectly. In searching the shores of the cosmic ocean we are persuaded to adopt a different point of view – to see ourselves as intimately connected to the universe through billions of years of evolution. His powerful “We are made of starstuff” helps us to see ourselves as the same and trivialize the differences among humans that we find so difficult to deal with today. As the world signs on to help us search, we may be able to help the world. If Carl had had access to today’s technologies, I’m pretty sure that the first entry on his Facebook page would have been “Carl Sagan: Earthling, Solar System, Milky Way Galaxy, the Cosmos”, and his friends would be limitless.