Monday, March 8, 2021

Harvard’s Avi Loeb Argues That ‘Oumuamua’ Was Really An Interstellar Alien Probe

Unless you’ve been living under a rock on the far side of the Moon, you will likely have heard of ‘Oumuamua,’ the bizarre interstellar object that paid a brief visit to our solar system in September 2017.

While a majority of astronomers hailed this object as the first-identified interstellar space rock to make a close loop around the Sun, one astronomer took the decidedly contrarian view that it may not be wholly natural.

In his well-written and compelling new book, “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth,” Harvard University astronomer Avi Loeb wholeheartedly embraces the idea that this object is an alien lightsail. That is, a probe that is propelled by the propulsive radiation of starlight itself. 

Loeb writes that Oumuamua’s extreme shape, bizarre orbit, and no evidence of outgassing or debris along its path, as well as its luminosity make it “statistically different, by a large margin, from all other objects cataloged by humanity.”

Although Loeb may have taken many of his colleagues aback with his provocative opinions about this particular object, I applaud his courage in taking this contrarian view. In so doing, he has opened the door to imagining robotic interstellar travel by what may turn out to be a plethora of advanced civilizations out surfing the cosmos. 

And for those who scoff at such notions, let me remind you that an overwhelming majority of astrobiologists routinely posit that the universe is absolutely teeming with intelligent life.

The Oumuamua story began on October 19, 2017 when astronomer Robert Weryk at the Haleakala Observatory in Hawaii found the object in Pan-STARRS images that showed it as a point of light speeding across the night sky, Loeb notes. But there is still no crisp photo image of the putative asteroid.  But it was immediately flagged as interesting due to its nearly perpendicular trajectory into our solar system. 

So, for the next 11 nights, astronomers around the world collected data from Oumuamua that would help them characterize the object in more detail. They were particularly interested in how it reflected sunlight. 

 Oumuamua approached our solar system from the direction of Vega

On September 6, 2017, Oumuamua intercepted our solar system’s orbital plane from the direction of Vega, a massive bright blue star, some 25 light years away in the constellation of Lyra.  After reaching its closest point to the Sun, Loeb writes that the object began exiting the solar system at very high-speed relative to our own Sun, or about 58,900 miles per second, more than enough to ensure it would escape our star’s gravity.

By October 7, 2017 it was moving toward the Pegasus constellation, heading for points unknown. By then, with today’s technology, there was no possible way to catch up with and photograph Oumuamua in close proximity. Thus, the data at hand is all that we will ever have, writes Loeb.  

Even so, here are a few points of evidence that Oumuamua may be artificial, as Loeb notes in his book, “Extraterrestrial.”

 Oumuamua’s brightness varied tenfold every eight hours.

Oumuamua’s observed dramatic variability in its brightness indicated that its shape was extreme, five to ten times longer than it was wide, notes Loeb, with a length of about a hundred yards and a width less than ten yards.

 Its bizarre acceleration around the Sun

Loeb notes that as Oumuamua sped away from the Sun, its trajectory deviated from the expected. In fact, it accelerated in a very smooth and steady manner, writes Loeb, totally contrary to what is expected from a rough and irregular comet during outgassing of its ices.

Loeb expected to see what he terms a “herky-jerky acceleration.” Instead, what he gleaned about Oumuamua’s acceleration was that it was quite smooth. He likens the odds of such behavior from a naturally occurring comet as “about the same as the odds of natural geological processes producing a space shuttle.”

Is there any way to trace Oumuamua back to its star of origin?

Loeb says no. That’s because most stars are surrounded by large cometary clouds that graze other stars like billiard balls, he writes. Our solar system’s own such cloud, the Oort cloud, already extends halfway to the Alpha Centauri system, our nearest stellar neighbors. 

“Any line of motion would intersect a huge number of Oort clouds, so it would be impossible to isolate the parent star,” he writes.

Loeb asserts that astronomers need to devote more time on the search for extraterrestrial intelligence and less on multiverse string theory. Of the latter, Loeb is particularly critical, as he notes that CERN’s Large Hadron Collider has yet to find evidence for any sort of multiverse. 

Doubling down on such ideas, notes Loeb, is a waste of precious time and money and talent, as most young researchers are too cowed by their superiors to pursue other avenues of research. 

“Today, a young theoretical astrophysicist is more likely to get a tenure-track job by pondering multiverses than by seeking evidence of extraterrestrial intelligence,” Loeb writes.

This is the crux of Loeb’s book and its most valuable lesson. Oumuamua is a lost cause; we will never know for certain whether it in fact is an alien probe. A century from now, a great grandchild of one of Loeb’s current Harvard students may be answering ‘What was Oumuamua?’ in a Cambridge pub quiz. 

But by then, let’s hope that we have proof of alien techno-signatures from some nearby star system.

 by Bruce Dorminey

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