Lightsails, aliens, and the greatest discovery ever
By now, you have probably heard of Oumuamua (Hawaiian for “scout”), the interstellar object hurtling out of our solar system past the orbit of Jupiter.
Oumuamua “is a lightsail, floating in interstellar space as . . . debris from an advanced technological equipment,” Harvard astrophysicist Avi Loeb wrote with his colleague Shmuel Bialy in Astrophysical Journal Letters last November. Yep, you read that right. They say that Oumuamua is, in a word, a piece of an alien spacecraft.
Uh, just a second. A lightsail? I remember lightsails from my boyhood reading in science fiction. But the scientific theory behind it goes back a long way.
Johannes Kepler, the great seventeenth-century astronomer, first helped us understand why comet tails always point away from the sun, no matter what direction the comet is actually traveling. A “solar wind” pushes the debris from the comet away from Sol, our star.
James Clerk Maxwell, the brilliant Scottish scientist of the nineteenth century most famous for his theory uniting electricity and magnetism, showed that light actually has momentum and thus exercises a tiny push on whatever it encounters.
And Jules Verne may be the first author to speculate on technology that could harness that light for propulsion. Later authors took the cue and suggested, among other possibilities, a gigantic sail driving a ship through space.
So why does the head of one of the world’s most distinguished astronomical departments think this object, which he guesses is about a millimetre thick but vastly extended, is a lightsail rather than, say, just some unusually shaped rock ejected from a distant star?
As a recent Washington Post profile summarizes him, Loeb thinks so because “it’s moving too fast for an inert rock— zooming away from the sun as if something is pushing it from behind. And if it’s a comet spewing jets of steam, the limited observations astronomers made of it showed no sign.”
So far, so fascinating. Yet this is a column on religion and culture. Why are we talking about lightsails?
“It changes your perception on reality, just knowing that we’re not alone,” Loeb says. “We are fighting [about] borders, [about] resources. . . . It would make us feel part of planet Earth as a civilization rather than individual countries voting on Brexit.”
Ah, yes. As I’m sure many an activist worried about global climate change has concluded, we human beings seem capable of working together only if we are faced with a gigantic, obvious, and imminent challenge—which, in Hollywood, typically means…an alien invasion.
Loeb doesn’t spin the situation that negatively–he doesn’t fear an “Independence Day” anytime soon–but his scenario is of the same sort. We need, he thinks, a perspective that transcends our petty provincialisms, a perspective that views our humanity in contrast to an impressive, strange intelligence from beyond our world. Only such a worldview could possibly draw us all together into global cooperation.
Like if, one wants to suggest in this season between Christmas and Easter, the Supreme Being visited our planet, made contact, and offered to help us all, globally and without preferring one nation over another, sort out our many problems.
But that’s surely just silly ancient fiction, isn’t it? The stuff of irrational religious legend?
Meanwhile, lightsails shed by interstellar spacecraft engineered by unimaginably distant civilizations are now seriously suggested by serious scientists. And equally famous scientists, such as Nobel Prize-winners Fred Hoyle and Francis Crick, have speculated that life originated on earth from seeds sown by extraterrestrial intelligences.
Well, then: You have your wondrous stories, and I have mine. And I agree with Professor Loeb, and countless novels and movies: encountering a vastly superior alien intelligence would be, indeed, the greatest discovery of all time.
Want to compare notes?