Another in a continuing series of "five question" email interviews - most recently with prodigious savant, author of "Born on a Blue Day" and speaker at IdeaFestival 2010, Daniel Tammet - the latest exchange features the expansive thinker Paul Gilster, the man behind the popular web site Centauri Dreams. Paul graciously provided the IdeaFestival with the following answers to its questions.
Read on to find out how he would write the first line of a story describing the discovery of a "second Earth."
Paul, could you briefly describe your interests and work?
I started thinking about an interstellar probe back in the 1980s, while watching Voyager 1 and 2 explore the outer planets. There was a speed-of-light delay involved in communications that fascinated me, and I soon asked myself what it would be like to be working on a mission where the delay time was in years rather than in hours. Proxima Centauri is 260,000 times farther from us than our own Sun, after all -- how would be manage such a mission, how would we send it updates, software fixes, and so on?
Then Dan Goldin started talking about an interstellar probe at NASA (this was in the late '90's), and for a brief time we had serious discussions of the idea among people within the agency. Goldin said "We have to set goals so tough it hurts -- that it drives technology -- in semiconductors, materials, simulation, propulsion." My Centauri Dreams book grew out of that, and the subsequent Web site is an attempt to keep track of these technologies and the exoplanet investigations that are ongoing as well. I want to highlight both the extent of the problem, in terms of distance and time, and to emphasize the case that we'll one day manage to make such a journey, even though it might be centuries before we're ready to go. So just as I write and talk about interstellar journeying, I also think a lot about long-term approaches to science, and the need to focus on small goals that can one day pay off in a major breakthrough. Thus my favorite quote, from Lao Tzu: "You achieve the great thing through a series of small acts."
Science fiction can be linked to speculative technologies like space elevators and solar sails. And, in fact, a Japanese team has unfurled the first solar sail in space. In your view, will the first technology that makes interstellar travel possible be traced back to a writer or scientist?
I love science fiction and have a collection of SF magazines going back to the 1920s to prove it -- I collect the old pulp magazines. But SF hasn't really distinguished itself as a predictive medium the way some people think it has. Yes, we have Verne and the submarine, but the rule. Hal Clement has a science team in one of his novels using slide rules as they explore a new planet (I think this was in 'Mission of Gravity'). SF also entirely missed the computer revolution and there is only one SF story I know of that predicted the personal computer. So I tend to think that science fiction is better at reflecting the scientific and social obsessions of its own era than in predicting future eras, and I see this all the time as I look at old SF down through the decades and watch its emphasis change.
But what SF can do brilliantly is to take a far-out concept like solar sails and make it real and personal. Carl Wiley wrote a science article for John Campbell's magazine Astounding Science Fiction back in 1951 (he wrote under the byline 'Russell Saunders'). A decade later you had superb craftsmen like Cordwainer Smith (Paul Linebarger) writing stories like "The Lady Who Sailed the Soul," making Wiley's concept concrete and extending it in magnitude and mission-concept into the far future. This is where science fiction is truly exciting to me, and I think the many mission concepts now being banded about will continue to produce stories that explain them and extend them into new scenarios.
As to my guess on first dedicated interstellar probe: A laser-beamed sail using magsail deceleration at the target, or else a particle-beam driven magsail that uses the same magnetic sail principles to decelerate. Science fiction has treated these, and in fact the great Robert Forward not only came up with some of our most interesting sail ideas for the science journals, but also wrote short stories and novels making them concrete.
On your popular blog Centauri Dreams, you've written that the current period of discovery is "the golden age of exoplanetology." In the next 10 to 20 years how likely is it that a current or planned terrestrial or space-borne observatory will turn up a "second Earth?"
I think it's quite likely, but we have to be careful about what we mean by a 'second Earth.' For example, I've long believed that we'll find a planet around a red dwarf in the habitable zone there before long (and I am not counting Gl 581d, which might just skirt the inner habitable zone). But if we do find a nice, warm planet in the right spot and of the right mass, we're still dealing with a red dwarf, so we have to deal with issues like stellar flares and tidal lock. Both can probably be surmounted, but in any case, life in a place like this would have a lot of differences from what we experience on Earth -- for one thing, the Sun would never move in the sky!
Stars are classified by the characteristics of their spectrum, and those most likely to have life as we know it are probably G-class, like our Sun, or K-class, orange stars a bit cooler than the Sun. Here we might find a planet that rotates in Earth fashion and offers liquid water at the surface. Kepler is going to give us a good read on how common such places are, so I could only guess about the findings. I am not as convinced as many people are that Earth-class planets are all over the place, but I don't think they're completely rare, and I think we'll get hard evidence for a 'second Earth' within the next three years. Be aware, too, that there are three ongoing searches for rocky worlds around Centauri A and B. Centauri A is a G-class star, while B is K-class, and they make up an intriguing binary system with a third, much more distant companion, Proxima Centauri. Finding rocky planets
there would be a major event!
Given the assignment by your editor to report that find, write the first sentence in an article meant for a popular audience.
"The first truly terrestrial world around another star -- like our planet in size, temperature range and potential habitability -- has
been found at last."
What's the most interesting question you've read or heard recently? Why is that so?
"Why has SETI come up short?" It's not really a new question, but there are new answers emerging and it's certainly a hot topic. It's forcing us to re-examine how we to SETI, and asks whether it's sensible to assume that an extraterrestrial civilization would try to contact us by radio waves when even in our own culture, it appears that broadcasting by radio is a very short-lived phenomenon. We're already going increasingly silent at radio frequencies as we turn to cable and get away from broadcast methods.
Many of the new SETI ideas are fascinating, and they include such possibilities as sweeping for deliberate beacons in the galactic plane, or using optical SETI methods looking for laser communications, or studying astrophysical objects to look for anomalies. For example, a society that used much of its solar system to build a so-called 'Dyson sphere' around its star (thus maximizing the use of stellar energy) should be observable by the unique infrared signature thrown by this artifact. We haven't done much in the past to look for such things, and the limited surveys we've had have come up short. But there is an ongoing attempt to refine how we do SETI that I find fascinating. My guess as to a SETI reception: Not in this century. But then, my personal belief is that the number of technological civilizations now operating in the galaxy is between one and ten, so this should come as no surprise. It would be fun to be proven wrong on this.