Aliens are everywhere. Sci-fi thriller Arrival landed on Veterans Day, and the US presidential election reminded us of them nearly every day! There was one mention, however, that came in under the radar, yet created its own waves within the astronomy community. Under the unassuming title ‘Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars’ in the respected journal Publications of the Astronomical Society of the Pacific, researchers Borra and Trottier claim ‘[w]e find that the detected signals have exactly the shape of an [extraterrestrial intelligence] signal predicted in the previous publication and are therefore in agreement with this hypothesis.’ In other words… Aliens!
The response to Borra and Trottier from the SETI Institute, on astronomy.com, was swift and discouraging. While a discussion of the personal, political, and pecuniary aspects of this story would make an entertaining study, I want to draw attention to one point concerning the limits of science and the evaluation of evidence.
The SETI response on astronomy.com cited another the reaction to the Borra and Trottier article, this time from a new alien search project entitled Breakthrough Listen, endowed by the likes of Stephen Hawking and Mark Zuckerburg. While encouraging further study and independent verification, Breakthrough Listen went on to say ‘extraordinary claims require extraordinary evidence.’ Really? Why? Doesn’t any kind of claim require clear and reliable evidence, evidence that is not only consistent with the claimed phenomenon, but also sharply narrows the possible explanations toward it? 'Extraordinary' will always be in the eye of the beholder and there is no measure of it. It is not a scientific concept and I would be extraordinarily cautious of anyone who holds ideas to ransom with that kind of slogan.
It is a mantra I have heard used most often in relation to evidence for historical claims from the Bible, such as Jesus rising from the dead, but it also comes up in the context of climate change. It provides a way for people to acknowledge that there is reasonable evidence for the claim, while at the same time not acting on the implications of the claim. There's the rub.
An atheist student in my Science and Religion tutorial was assigned one week to report on the historical reliability of the Bible. He began by saying that the research he had done led him to conclude that the Bible was a significant source of reliable historical information and that he could understand why so many people put their trust in it. He then went on to say he could also see why so many people reject it: not because it's historically unreliable, but because it calls on them to change and challenges our common understandings about ourselves, the world, and eternity.
We reject claims when the existential cost is too high, not necessarily when the quantity and quality of evidence is too low. This principle seems to apply to extra-terrestrials as well as to God and climate change. An article in Physics Today demonstrated a tantalising anti-correlation between the percentage of people in a given country who believe global warming is anthropogenic and the tonnes of coal that country digs out of the ground every year. It appears we human beings are not always driven by the evidence to accept the claim, but can be driven by the implications of the claim to denigrate the evidence.
Enjoy the discoveries of science and be clear on the difference between claims and their implications even when our media outlets aren't. Both are interesting. Only one is science. The other is part of a conversation that everyone can, and should, join without special knowledge or lab coats; a conversation about what's important for humanity.
Dr Lewis Jones received his PhD in Astrophysics from the University of North Carolina, and moved to Australia to do postdoctoral research at the University of NSW. He subsequently completed the Bachelor of Divinity at Moore Theological College, and is now the Director of The Simeon Network, the postgraduate and academic arm of AFES. Lewis also serves on the Human Research Ethics Committee at UNSW, and attends Randwick Presbyterian Church.
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