Oumuamua, Alien Visitors and Occam’s Razor

Image Credit: Gemini Observatory / AURA/NSF/Joy Pollard

Asteroids are a common objects in our solar system. Most of them originate from the asteroid belt between Mars and Jupiter, followed by the ones that come from the distant Oort cloud that encircles us past Pluto. Asteroids can also come from outside of our solar system, originating from distant stars many light years away.

Most astronomers think that Oumuamua is an asteroid that belongs to this latter group. One prominent scientist, on the other hand, believes that it is a space ship.

A strange interstellar visitor

Oumuamua is cigar shaped object a few hundred meters long, tens of meters wide, and traveling at a speed of 500 million miles per year, fast enough to escape the solar system and continue on its journey into deep space. If all of this makes it sound like a space ship to you, then you are not the only one. Naturally, thousands of UFO enthusiasts believe that Oumuamua may have been an alien spacecraft visiting our solar system. What makes this different from other alien conspiracy theories, though, is that this assertion is also backed by Prof. Avi Loeb, a professor of science at Harvard University

Prof. Avi Loeb wants to believe

Needless to say, Loeb has come under fire by the scientific community for supporting this claim in his recent book. They say it’s irresponsible to write off everything that we do not understand as aliens, especially considering there’s a great deal that we do not. So why does Prof. Loeb believe that this case is any different?

Loeb points out that the orbit of the object is not explainable with gravity alone, suggesting that another force is acting upon it. This is not unheard of with asteroids, of course. It is well known that rapid heating causes their surface to sublimate, which in turn can cause jets of gas to propel the asteroid in some direction or another. These jets then manifest themselves as large bright tails, not unlike those of comets. Oumuamua, by contrast, appears to have no such feature. As Prof. Loeb subsequently points out, the object could in fact be powered by an alien designed light sail harvesting the radiation pressure of the Sun, much like a nautical ship uses the wind to move.

Occam’s Razor and the simplest explanation

Of course, most scientists do not agree with these conclusions.

After all, is it more probable that aliens visited us in a disguised spaceship or that Oumuamua is in fact an asteroid, perhaps with a jet pointing in a direction that we cannot see?

As his scientific detractors point out, the principle of Occam’s Razor suggests that the simplest solution is often the correct one. Just saying that we do not understand the object’s acceleration is therefore not strong enough of a finding to conclude that it must presumably be the work of aliens.

Sadly it looks like we may never know for sure. Oumuamua has left our solar system a long time ago, and we have not collected enough observational data for a follow-up. Hopefully, the next time something of this extraordinary nature does occur sometime in the future we’ll have developed the capabilities to study it more accurately.

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