Our resident science expert ponders the extraterrestrial premise
I try my best to keep this column grounded in scientific fact. And I always try to go by the rule, “It’s never aliens.”
But, two different stories have been making the rounds the last month or so, and “aliens!” seems to be a possible (if remote) explanation for both. So, I thought I’d use this month’s column to take a look at these stories and see what’s really going on.
Fast Radio Bursts
The SETI (Search for Extra-Terrestrial Intelligence) project has been going on for several decades now. Heck, you may have even participated yourself, through the “SETI at Home” project that uses the idle time of personal computers to analyze radio signals that have been recorded at various telescopes around the world.
(I have. It’s fun, and it’s still a thing! Visit setiathome.berkeley.edu if you’d like to join the project.)
As of now, only a few truly interesting signals have been observed by SETI. Most have been shown to be “not aliens” and almost none have been known to repeat.
In 2001, however, something new and interesting was detected: a “fast radio burst” or FRB. The “radio burst” part is self-explanatory. These are signals that occur over a wide range of frequencies and last only a short time.
That’s where the “fast” part comes in. These things last just a few milliseconds (that’s thousands of a second), or less. Being so short, they have to be very intense to get noticed. And they are.
Mostly, FRBs are found by going through old, recorded data, and their point of origin is hard to pin down. Our best guess is that they come from outside our galaxy. So, they are fast, strong, and extremely far away.
As I said, they mostly have been found by going through old data, but recently, a couple have been observed “live” as they washed over us. Observations of these FRBs have backed up their extra-galactic origins, but that’s about it. What we need are FRBs that repeat, but until recently, none of them did.
That changed in 2012 with the detection of an FRB in the northern sky that repeated several times over the course of several months. That FRB seems to have kept repeating, with additional signals from the same spot in 2017.
Now, in early 2019, it’s been announced that a second, repeating FRB source has been found. Not much is known about this one yet, but it’s good that a second “repeater” has been identified, as that should help us work out what these things are.
One totally serious suggestion is that these signals are “leakage” from insanely powerful communications devices that an alien civilization is using to transmit messages from one planet to another. We just don’t have the tech (yet) to decode the messages.
Another suggestion is that these are propulsion waves used to push probes between the stars. They just happen to wash over us as they swing to align with the probes to propel them forward. And that brings us to our second “it’s aliens!” story.
Oumuamua: The…Solar Sail?
Remember about a year ago when I told you about Oumuamua, the first interstellar object ever detected passing through our solar system? Well, we’ve had some time to interpret the data from Oumuamua. That data has led to some very surprising conclusions from some very serious people.
Specifically, there’s a serious hypothesis that Oumuamua isn’t an asteroid or comet, but a solar sail! (For those of you who don’t remember, a solar sail is a thin, light, and big reflective surface that uses the pressure of starlight for propulsion.)
The evidence is pretty straightforward: When Oumuamua started moving away from the sun, it began to accelerate. Now, a comet or asteroid will also accelerate, due to both the gravity assist it gets from the sun and from off-gassing as material evaporates due to the heat of the sun.
But Oumuamua showed no signs of off-gassing. In fact, the acceleration curve of Oumuamua matched up almost exactly with that of a solar sail about Oumuamua’s size.
So, was Oumuamua a probe, attached to a solar sail, pushed here by FRBs from an (almost certainly long dead at this point) alien civilization?
No. Absolutely not. Probably not. Nope. Almost certainly not. No.
That said, I wouldn’t object to a sending a probe of our own after it to find out.
Steven W. Disbrow is the proprietor of “Improv Chattanooga” on the South Side of town. He also creates e-commerce systems and reads comic books when he’s not on stage acting like a fool.