Why this book?
I like science fiction. And I like space exploration and exoplanet research. I only want to write books that I would want to read, so it seemed sensible to put them together. A more pertinent question might be, why now? Exoplanet research has developed to the point that we can start to say something about these worlds, even if it’s just from the statistics of the sheer number of worlds that we’re finding.
At the moment, detection of potential life on exoplanets is very indirect - could we have a way of definitively showing this to be true?
There’s no solid evidence for extraterrestrial life, direct or indirect, at the moment. But yes, there are direct means. SETI, the search for extraterrestrial intelligence, could detect a radio signal from another world tomorrow. I wrote about this and the potential consequences in my previous book, The Contact Paradox: Challenging Our Assumptions in the Search for Extraterrestrial Intelligence (2019). The search for technosignatures, be they radio beacons, technosignatures, artificial lights, atmospheric pollution or something else, is very direct, but it is also a long shot at present.
Then there’s biosignatures, which could be direct or indirect, depending upon how ambiguous they are. The presence in an exoplanet’s atmosphere of certain abundances of oxygen, ozone, carbon dioxide, methane, water or other molecules important in life’s processes would be a big clue that there could be life on that planet.
SF uses ‘fake science’ to get its protagonists to exoplanets - do you think it’s ever likely to be possible in the real world?
I think describing it as fake does science fiction a disservice. Yes, there is lots of nonsense science in some science fiction, but other writers well versed in science will go some way to making concepts seem plausible, at least from a theoretical point of view. Take suspended animation for example, which is a staple of SF. Researchers are actively studying suspended animation, mostly for medical procedures, but SF writers can extrapolate on the science. Of course, putting it into practice is the hard part. In theory a warp drive would work, based on a 1990s paper by the physicist Miguel Alcubierre. But in practice, no, because the energy density required is far too great. So I like to describe ideas in SF that are based on the scientific literature as speculative rather than fake. I do think it will be possible to send uncrewed probes to the nearest stars, whether that’s via a fusion drive, a light-sail or by dropping nukes out the back and riding the shockwaves. Interstellar journeys will take decades or centuries at best with these technologies, so I’m not sure it’s feasible for humans without some kind of scientific revolution.
What’s next?
The European Space Agency will soon be launching two new space missions to investigate exoplanets. PLATO (Planetary Transits and Oscillations of stars) will discover thousands of transiting exoplanets, while ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) will characterise the atmosphere of many of these worlds. Further into the future, the Extremely Large Telescope under construction at the European Southern Observatory in Chile and a next-generation space telescope scheduled for the 2040s should both be able to directly image rocky planets, possibly in the habitable zone. As for what’s next for me, hopefully more books if any publishers are game.
What’s exciting you at the moment?
The Breakthrough Listen project has transformed SETI, vastly expanding the search to cover not just radio signals, but also optical laser signals, and searches for less well-defined technosignatures – they often just look for anything out of the ordinary. The funding from Breakthrough Listen has also provided a pathway for more young researchers to get into SETI, as well as increase the diversity of people doing SETI, which in turn results in lots of new ideas. In addition, I’m enthused by the growing list of potential biosignatures – those ambiguous detections I mentioned earlier – of phosphine on Venus, methane on Mars, and dimethyl sulphide on an exoplanet called K2-18b. The latter seems like it could be a kind of ocean planet called a hycean world, with a thick, warm hydrogen atmosphere. On Earth dimethyl sulphide is only produced by plankton in the sea, but that’s not to say some abiotic, geochemical process on another world couldn’t produce it, and the detection of the dimethyl sulphide itself is also considered debatable at present. But it’s exciting that we can even start to have these discussions. There were several false alarms before the first discovery of an exoplanet, and it might be the same case with alien life too.
Interview by Brian Clegg - See all Brian's online articles or subscribe to a weekly email free here
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