A cosmic slide whistle

In 1894, physicist Albert Michelson said, "It seems probable that most of the grand underlying principles [in science] have been firmly established …  An eminent physicist remarked that the future truths of physical science are to be looked for in the sixth place of decimals."

The irony of this statement is twofold.  First, within thirty years, the entire field of physics would be upended twice, by Einstein's Special and General Theories of Relativity, and from the development by Niels Bohr, Louis de Broglie, and Erwin Schrödinger of the Quantum Model.  Second, it was the null result from the experiment Michelson himself performed with Edward Morley that disproved the existence of the luminiferous aether and directly led to Einstein's revolutionary theories about the nature of light and motion.

The fact is, there is still a ton of stuff we don't fully understand, and then there are all the things that we don't even know we don't know.  The universe is full of mystery, and there will be plenty to keep scientists occupied for a very, very long time.

Take, for example, a paper last week in Monthly Notices of the Royal Astronomical Society about a bizarre twist on an already poorly-understood phenomenon -- the fast radio burst.  These sudden explosive blasts in the radio region of the spectrum, lasting between 0.001 and 3 seconds, pack as much energy in that time as the entire Sun emits in three days.  Some are transient, but others -- like the euphoniously-named FRB 180916.J0158+65 -- have a regular periodicity, in this particular case 16.35 days.

[Image licensed under the Creative Commons ESO/M. Kornmesser, Artist’s impression of a fast radio burst traveling through space and reaching Earth, CC BY 4.0]

Since their discovery in 2007, hundreds of fast radio bursts have been observed.  Given their unpredictability and ephemeral nature -- you have to have your radio telescope aimed at exactly the right place in the sky at exactly the right time, and you have a window of under three seconds to see them -- it's probable that they are insanely common, and we just miss 99% of them.  Canadian astrophysicist Victoria Kaspi estimates that over ten thousand fast radio bursts happen somewhere in the sky every single day, so there's potentially a huge amount of data out there to study if we can only figure out a way to observe them.

Explanations for what these things could be are all over the map, and include hitherto-unknown behavior of neutron stars, magnetars, black holes, collapsing/dying supergiant stars, or some combination thereof.

Or an alien intelligence trying to signal us.  Admit it, you knew this had to come up.

The bottom line is the astrophysicists still don't know what causes fast radio bursts, much less why some repeat and some don't.  And the whole thing just got a lot weirder with the discovery by observers at the SETI (Search for Extraterrestrial Intelligence) Institute, who found a fast radio burst that had 35 explosive outbursts -- and each one slid up the frequency scale before it ended, drawing comparisons to an enormous outer space slide whistle.

What could cause a fast radio burst to sweep up the frequency scale in that fashion is, at the moment, beyond guessing.  All we know is that is that what was already a mystery just became a hell of a lot more mysterious.

So I think Michelson may have been a wee bit hasty in proclaiming science to be settled except insofar as calculating things to six decimal places.  I suspect that a closer estimate -- if it were possible to do such a thing -- is that the bits of the universe we understand well are hugely outnumbered by the bits we still haven't a clue about.  I prefer the assessment made by Carl Sagan: "Out there, something incredible is still waiting to be known."

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Signals of interest

Usually, when people think about finding extraterrestrial intelligence, they think of radio transmissions -- a trope that has been the basis of dozens of movies and television shows (Contact and Starman immediately come to mind).  Just two days ago I looked at a new approach to detecting biosignatures -- traces of living things, usually in the context of life on other planets -- which involved arguments having to do with complex biochemistry.

Then yesterday, I ran into a new study from the SETI (Search for Extraterrestrial Intelligence) Project describing a recently-developed deep learning technique which goes back to radio astronomy -- and that has already uncovered eight "signals of interest" from previously-analyzed radio telescope data.

Now, before we go any further, allow me to state up front that no one (well, no one credible) is saying any of these signals actually come from you-know-who. 

Don't get your hopes up quite yet.

But this finding does give us alien enthusiast types some hope for answering the Fermi paradox -- "If life is common in the universe, where is everyone?" -- with two rejoinders: (1) we've only studied a vanishingly small slice of the star systems even in our own galaxy; and (2) our previous techniques for analyzing the radio emissions of the systems we have studied still missed some signals that by previously-accepted criteria should warrant a closer look.

All eight signals of interest shared the following three characteristics that put them in the "curious" column:

1. They were narrow-band -- i.e. only peak at a narrow range of frequencies.  Radio signals from natural sources tend to be broad-band.
2. They had non-zero drift rates, meaning they were not moving with the same speed as the observatory.  This rules out terrestrial sources, a constant source of interference with radio telescope data.
3. The signals occurred only at specific celestial coordinates, and the intensity fell off rapidly when the telescope moved from being aimed at those coordinates.

All of these are features you would expect from radio transmissions from an extraterrestrial intelligence.

"In total, we had searched through 150 terabytes of data of 820 nearby stars, on a dataset that had previously been searched through in 2017 by classical techniques but labeled as devoid of interesting signals," said Peter Ma of the University of Toronto, who was lead author of the paper, which appeared in Nature Astronomy.  "We're scaling this search effort to one million stars today with the MeerKAT telescope and beyond.  We believe that work like this will help accelerate the rate we're able to make discoveries in our grand effort to answer the question 'are we alone in the universe?'"

I'm delighted astronomers are continuing to push forward with the search for extraterrestrial intelligence.  They certainly could be forgiven for giving up, considering the fact that since the SETI Institute was founded in 1984, they have yet to find anything that has convinced scientists.  Even with arguments like the one I made in my post two days ago, that purely statistical arguments like the Drake equation suggest that life is common in the universe, the complete lack of hard evidence would certainly be sufficient justification for scientists to put their efforts elsewhere.

That they haven't done so is a tribute not only to their dogged determination, but the importance of the question.  Not only would finding extraterrestrial life (or even better, intelligence) have profound implications for our understanding of astronomy, biochemistry, and biology, it would create seismic shifts in everything from anthropology to theology.  Such a finding would fundamentally and permanently alter our perception of the universe and our own place in it.

Myself, I think that'd be a good thing.  Our species needs period reminders that we're not all that and a bag of crisps.  Finding out that we're only one intelligent species of many would further emphasize that we don't occupy the center of the universe in any sense -- and, hopefully, reinforce our sense of wonder at the forces that have produced life and intelligence not only here on Earth, but throughout the myriad galaxies.

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