A Harvard professor presenting his opinions on alien life as fact when the field at large doesn’t agree is misrepresenting science, argues Dr Heloise Stevance 

For years now Abraham (Avi) Loeb has been a rather passionate advocate for what I call ‘The Alien Hypothesis’ 一 the idea that extraterrestrial lifeforms are the source of some puzzling astronomical observations, whatever they may be.

Back in 2019 he was telling the Guardian that fast radio bursts – jets of radio signals emitted from halfway across the Universe – could originate from aliens. It is an enticing idea, and if the Chair of the Board on Physics and Astronomy of the National Academies makes such a claim, surely it must be backed by very strong evidence and be representative of a significant portion of the astrophysics community. This could not be further from the truth.

Most recently, Loeb has come out with a book arguing that Oumuamua, an interstellar asteroid that visited our solar system three years ago, is in fact a piece of extra-terrestrial technology. The issue with Oumuamua is that its trajectory, shape and composition are puzzling to scientists; to cut a long story short, we cannot fully explain how it travelled between star systems and ended up here looking like a pancake (or cigar, depending on who you believe). All these troubles could be resolved if it was, say, a piece of spaceship or some form of extra-terrestrial technology.

Loeb has repeatedly complained that the field is unfairly shutting him and his ideas down by asking for “extraordinary evidence”: That is like complaining that the cashier at the store is asking for money when you’re getting your weekly shopping.

A bold claim indeed … so what is the evidence?

There is none. Loeb is relying on the argument that if you exclude all other ‘natural’ explanations, then it must be aliens.

Although “it would be arrogant to think we are alone in the Universe”, as he says, it would be just as arrogant to think we’ve excluded all other possibilities, particularly in the case of Oumuamua: It was already being slingshot away from Earth when we found it, and it will never come back 一 astronomers therefore have no way of gathering more data to shed some light on the as-of-yet unexplained properties of the object. This creates a knowledge void that is unlikely to be filled for some time, and it is therefore a very convenient place to be pushing the alien narrative.

That is not how science works.

Loeb has repeatedly complained that the field is unfairly shutting him and his ideas down by asking for “extraordinary evidence”: That is like complaining that the cashier at the store is asking for money when you’re getting your weekly shopping. What is not clicking?

“Extraordinary claims require extraordinary evidence” (Carl Sagan) and one of the reasons we have such standards, particularly when it comes to extraterrestrial life, is that many new astronomical discoveries have led scientists to believe they may have witnessed alien activity.

One of the most famous examples of this occurred back in 1967 when Jocelyn Bell Burnell discovered an extra-terrestrial radio source repeating every 1.3373 seconds. The beam was so precise that it was believed to originate from a beacon created by intelligent life, and the signal was named LGM-1 – the acronym LGM standing for ‘Little Green Men’. In the end, LGM-1 was the first discovery of a pulsar, the magnetised corpse of a rapidly rotating massive star that died in a violent explosion.

Does that mean aliens are not real? Of course not. I think a large portion of astronomers do believe there is some form of extra-terrestrial life out there in the cosmos – on the whole, planets are easily made, and the building blocks of life commonly found. But if you look at the very successful forms of life on Earth, the ones that outlived others for millions of years and survived extinction events, human-like creatures are not what I would expect to see on other worlds.

On top of that, interplanetary travel is not quite as vigorous as Star Trek and Star Wars led you to believe – even if you could travel at the speed of light (and you cannot), it would take you 100,000 years to cross the galaxy. No matter how hard Loeb tries to sell you The Alien Hypothesis as science, I can promise you that, for now, it confidently remains in the realm of science fiction.

So why is Avi Loeb screaming from the rooftops that we’ve probably found ‘Little Green Men’? Some will say it is good old-fashioned greed (after all he is selling a book), but I am of the crowd that believes he is just overly keen and really wants to be the guy who finds E.T. The issue I do have is an ethical one.

Being a Harvard professor of astrophysics means that people are likely to listen to you, and sharing your opinion as fact when the field at large does not agree is a misrepresentation of the science, no matter how right you think you are. It brings people to say “See! Scientists disagree!” when really, we don’t. In general, the opinion of an individual researcher does not matter, it is always better to consider the current consensus within a field. That is why we have peer-reviewed journals, international conferences and public arguments on Twitter.

So to all the news editors out there, please stop using Loeb for clicks. I know it’s easy, I know it’s convenient, but giving this man a platform implies that the question is up for debate, that there is no consensus in the science community, when in fact there is: Loeb is in the wrong.

Dr Heloise Stevance is a research fellow in the Department of Physics at the University of Auckland.

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