In late 2017 astronomers detected an interstellar interloper in our solar system for the very first time. In subsequent years the object, named ‘Oumuamua, quickly rose to fame via speculation led by renowned Harvard astrophysicist Avi Loeb that it might actually be an alien probe of some kind, rather than a natural body like an asteroid.
For those wishing to better understand the claims made by Loeb – and the subsequent rebuttals by his critics – I recommend watching the video below posted by the ‘Cool Worlds‘ YouTube channel back in January. It does a good job of examining them in a open-minded, but level-headed and skeptical manner, by working through the claims made by Loeb in his short 2018 paper “Six Strange Facts about our First Interstellar Guest, `Oumuamua“, and the rejoinder article in Nature by the ‘Oumuamua International Space Science Institute team (which included the lead author of the original ‘Oumuamua discovery paper).
Host Professor David Kipping notes that the positions of the opposing sides of the debate could be summed up with two quotes: Loeb himself has quoted the Sherlock Holmes aphorism “If you exclude all other possibilities, whatever remains, however improbable, must be the truth”, while the approach of Loeb’s critics is more along the lines of Carl Sagan’s “Extraordinary claims demand extraordinary evidence”.
As the video points out as it works through Loeb’s claims, the problem for his theory – and his philosophy via Sherlock Holmes – is that there do indeed appear to be “other possibilities” that haven’t been excluded. Which doesn’t mean he’s wrong…but does mean that his alien probe theory may not be quite as solid as he says it is.
Kipping sums up the evaluation with the following words:
The principle of searching for out-of-the-box non-conventional ideas is something that I think actually we should commend and support. In that sense Professor Loeb is advancing a truly fascinating discussion and I think that that in itself is very worthwhile… ‘Oumuamua reminds us that the universe will always surprise us. In the near future we will surely detect more anomalies, just like the Martian canals, fast radio bursts, Boyajian’s star or the ‘Wow! signal’, each of which has had the alien hypothesis invoked in an attempt to explain it.
At the core of this debate is the very approach to science. Invoking aliens to explain new phenomena is undeniably feasible because after all we can almost always think of some way in which aliens might explain odd data. But that greatest strength is also its Achilles heel, because the alien hypothesis is very much a ‘god of the gaps’ explanation – a band-aid to neatly cover over phenomena which we just haven’t yet thought hard enough about to truly understand. What caused the Big Bang? Aliens. Why is there more dark matter than baryonic matter? Aliens. What is responsible for the next weird thing that we detect in our telescopes? Aliens.
Ultimately, though the evaluation of Loeb’s claims found them to be weaker than the Harvard astrophysicist has suggested they are, there still are curiosities. And Kipping ends by saying “I don’t want to dismiss the idea of aliens inhabiting the universe out of hand or even sending probes out between the stars because one can make very good arguments as to why such a hypothesis is not extraordinary at all. It really just depends on your assumptions.”