Room for exploration

As a followup to yesterday's post, about my generally dubious take on the claim of a Mexican scientist that he'd discovered fossilized alien bodies, today we're going to look at why we haven't run across aliens yet.  As big as the universe is, it seems like we should have heard from someone by now.  What are we, a bad neighborhood, or something?  Do the aliens go zooming by the Earth, making sure their windows are rolled up and their doors are locked?

I mean, Elon Musk alone would be justification for their doing so, but it's still kind of disappointing.

I've discussed the Fermi Paradox here at Skeptophilia before -- and the cheerful idea of the Great Filter as the reason why we haven't heard from alien life.  As I explained in a post a while back, the explanation boils down to three possibilities, nicknamed the "Three Fs."

We're first, we're fortunate, or we're fucked.

Being an aficionado of all things extraterrestrial, that has never sat well with me.  The idea that we might be all alone in the universe -- for any of the three Fs -- is just not a happy answer.  

Yes, I know, I always say that the universe is under no obligation to act in such a way as to make me happy.  But still.  C'mon... Vulcans?  Time Lords?  Ewoks?  G'gugvuntts and Vl'hurgs?  There's got to be something cool out there.  With luck, lots of cool things.  The Dentrassi, the Ood, Quantum Weather Butterflies, the Skithra, Andorians, the Vashta Nerada...

Okay, maybe not the Vashta Nerada.  But my point stands.

The Andromeda Galaxy [Image licensed under the Creative Commons Adam Evans, Andromeda Galaxy (with h-alpha), CC BY 2.0]

So I was considerably cheered yesterday when I ran into a study out of Pennsylvania State University that attempted to estimate what fraction of the universe we actually have surveyed in any kind of thorough fashion.  The authors, Jason Wright, Shubham Kanodia, and Emily G. Lubar, write:

Many articulations of the Fermi Paradox have as a premise, implicitly or explicitly, that humanity has searched for signs of extraterrestrial radio transmissions and concluded that there are few or no obvious ones to be found.  Tarter et al. (2010) and others have argued strongly to the contrary: bright and obvious radio beacons might be quite common in the sky, but we would not know it yet because our search completeness to date is so low, akin to having searched a drinking glass's worth of seawater for evidence of fish in all of Earth's oceans.  Here, we develop the metaphor of the multidimensional "Cosmic Haystack" through which SETI hunts for alien "needles" into a quantitative, eight-dimensional model and perform an analytic integral to compute the fraction of this haystack that several large radio SETI programs have collectively examined.  Although this model haystack has many qualitative differences from the Tarter et al. (2010) haystack, we conclude that the fraction of it searched to date is also very small: similar to the ratio of the volume of a large hot tub or small swimming pool to that of the Earth's oceans.  With this article we provide a Python script to calculate haystack volumes for future searches and for similar haystacks with different boundaries.  We hope this formalism will aid in the development of a common parameter space for the computation of upper limits and completeness fractions of search programs for radio and other technosignatures.

The actual analogy Wright and his colleagues used is that saying our current surveys show there's no intelligent life in the universe (except for here, which itself seems debatable some days) is comparable to surveying 7,700 liters of seawater out of the total 1.335 billion trillion liters in the world's oceans.

So basing a firm conclusion on this amount of data is kind of ridiculous.  There could be intelligent alien species out there yelling, "Hey! Earthlings!  Over here!  We're over here!", and all we would have to do is have our radio telescopes pointed a couple of degrees off, or tuned to a different wavelength, and we'd never know it.

Which is pretty cool.  Given the fact that my all-time favorite movie is Contact, I'm hoping like hell that people don't read Wright et al.'s paper and conclude we should give up SETI because it's hopeless to make a thorough survey.  When I think about what poor Ellie Arroway went through trying to convince her fellow scientists that her research was valid and deserved funding... yecch.  And if anything, the current attitudes of the government toward pure research are, if anything, worse than those depicted in the movie.

But despite all that, it's awe-inspiring to know we've got so much room to explore.  Basically... the entire universe.  So my dream when I was a kid, sitting out in my parents' yard with my little telescope, that as I looked at the stars there was some little alien boy in his parents' yard looking back at me through his telescope, may one day prove to be within hailing distance of reality.

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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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Unknown unknowns

One of my college physics professors made a statement to his class that was mind-boggling in its inaccuracy.  We'd been learning about the subatomic particles, and he was telling us about the smallest pieces of matter known: quarks.  Physicists had given the different types of quarks fanciful names -- up, down, top, bottom, charmed, strange.  His commentary was something of a sneer: "When scientists spend their times giving ridiculous names to physical phenomena, you know there must not be much in the way of new things waiting to be studied."

Even at the time -- I was about twenty -- it seemed humorless and mean-spirited to claim that just because scientists are having a little fun with naming stuff, they're wasting their time playing around rather than engaging in actual science.  Much later, I ran into Lord Kelvin's statement along the same line, that "There is nothing new to be discovered in physics now.  All that remains is more and more precise measurement."  

The problem was that Kelvin said this in 1900 -- immediately before Einstein and Schrödinger turned all of physics on its head with the theories of relativity and quantum mechanics, respectively.

So saying "there's nothing left to study" is not only arrogant, it's entirely inaccurate.  The preposterous implication is that right now we have a good idea of how much is left that we don't know.  It reminds me of Donald Rumsfeld's much-ridiculed statement about "known knowns, known unknowns, and unknown unknowns."  Yeah, he could have phrased it a little better, but honestly, he had a point.  There isn't any way to estimate the extent of what we're not even aware that we don't know.  The only thing we can go by is the history of science -- which pretty clearly shows that every time we think we have everything explained, the universe steps in a with a well-aimed dope slap.

I started thinking about all this because of a press release in Science Alert about a mysterious radio source near the center of the Milky Way that has astrophysicists scratching their heads.  To quell the immediate reaction a lot of folks are having, no one at this point is saying anything about aliens, or at least no one with any credibility.  But the behavior of the source is odd enough even without bringing in the Daleks or the Andorians or the Stenza or whoever your favorite extraterrestrial bad guys are.

The radio source is euphoniously named ASKAP J173608.2-321635.  (I wonder if my long-ago physics professor would have approved of that name as sufficiently serious.)  The radio emissions from ASKAP-etc. are odd in a variety of respects.  The source emits radio waves for weeks, then will suddenly "turn off" for a while before just as suddenly beginning to shine again.  The electromagnetic radiation from it is highly polarized -- the waves line up, all vibrating in the same direction, like a bunch of people creating waves in long springs, and everyone oscillating the springs up-and-down rather than each spring moving in some randomly-chosen plane of vibration.

The source was discovered through a collaboration between the Australian Square Kilometre Array Pathfinder (that's where "ASKAP" comes from) and the  MeerKAT radio telescope, near Cape Town, South Africa (speaking of whimsical names; the "KAT" part of the name stands for "Karoo Array Telescope;" "meer" is Afrikaans for "more."  It also, of course, riffs on the name of the comical little African mammal of the same name).  This isn't the first time this combo has found something strange.  Earlier this year, they found another yet-to-be-explained interstellar object, the aptly-named "Odd Radio Circles" that have bright edges and dimmer interiors, like giant gossamer soap bubbles.

A MeerKAT image of the center of the Milky Way, as viewed in radio wavelengths

Astrophysicists have considered a number of explanations for these strange objects, and so far, none of them have panned out.  "Possible identifications [include] a low-mass star/substellar object with extremely low infrared luminosity, a pulsar with scatter-broadened pulses, a transient magnetar, or a Galactic Center Radio Transient," the research team writes, "[but] none of these fully explains the observations, which suggests that ASKAP J173608.2-321635 may represent part of a new class of objects being discovered through radio imaging surveys."

So once again, we're confronted with how little we know.  We've come a long way, there's no doubt about that; our scientific achievements as a species are pretty damn impressive, especially considering that serious research has only been going on for a couple of centuries of the tens of thousands of years humans have been at least somewhat technological.  But there will always be more mysteries to solve, more puzzles to put together, more questions to ask.

I'll end with a quote from astrophysicist John Bahcall, whose research into the behavior and properties of neutrinos in the 1960s gave us a new window into why stars shine:

I do not personally want to believe that we already know the equations that determine the evolution and fate of the universe; it would make life too dull for me as a scientist…  I hope, and believe, that the Space Telescope might make the Big Bang cosmology appear incorrect to future generations, perhaps somewhat analogous to the way that Galileo’s telescope showed that the earth-centered, Ptolemaic system was inadequate...  Every time we get slapped down, we should thank Mother Nature -- because we're about to learn something important.

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London in the nineteenth century was a seriously disgusting place to live, especially for the lower classes.  Sewage was dumped into gutters along the street; it then ran down into the ground -- the same ground from which residents pumped their drinking water.  The smell can only be imagined, but the prevalence of infectious water-borne diseases is a matter of record.

In 1854 there was a horrible epidemic of cholera hit central London, ultimately killing over six hundred people.  Because the most obvious unsanitary thing about the place was the smell, the leading thinkers of the time thought that cholera came from bad air -- the "miasmal model" of contagion.  But a doctor named John Snow thought it was water-borne, and through his tireless work, he was able to trace the entire epidemic to one hand-pumped well.  Finally, after weeks and months of argument, the city planners agreed to remove the handle of the well, and the epidemic ended only a few days afterward.

The work of John Snow led to a complete change in attitude toward sanitation, sewers, and safe drinking water, and in only a few years completely changed the face of the city of London.  Snow, and the epidemic he halted, are the subject of the fantastic book The Ghost Map: The Story of London's Most Terrifying Epidemic -- and How It Changed Cities, Science, and the Modern World, by science historian Steven Johnson.  The detective work Snow undertook, and his tireless efforts to save the London poor from a horrible disease, make for fascinating reading, and shine a vivid light on what cities were like back when life for all but the wealthy was "solitary, poor, nasty, brutish, and short" (to swipe Edmund Burke's trenchant turn of phrase).

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Requiem for an old friend

My fascination for astronomy started a long time ago.  I started learning the constellations when I was about six, and received a telescope as a Christmas present from my grandmother when I was eight.  Just about any clear night it was a good bet I'd be out in my front yard looking up at the stars, wondering what it was like out there, thinking about what other planets might host life -- and if somewhere there was a little alien boy looking back my way and wondering the same thing.

It was about that time that I found out about the Arecibo Observatory in Puerto Rico.  One of the many astronomy books I had called the three-hundred-meter radio dish "our eye on the sky" -- it was my first introduction both to the idea that not all telescopes looked like the little tube with lenses on a stand that I owned, and that it was possible to "see" the sky using wavelengths of light that were invisible to human eyes.  Also, if you were to view the sky with a radio telescope (or in microwaves, or x-rays, or ultraviolet light, or whatever) you would see a very different set of features than the familiar twinkling points of light set against a black background.

In the microwave region, for example, you'd see light coming from basically all directions at once -- the "three degree microwave background radiation" which Arno Penzias and Robert Wilson discovered -- and which is one of our most persuasive pieces of evidence of the Big Bang.  (This discovery was made not at Arecibo but at the Holmdel Horn Antenna in New Jersey.)  X-ray astronomy is how black holes were discovered, and we know about the terrifyingly powerful Wolf-Rayet stars because of telescopes sensitive to the ultraviolet region of the spectrum.

Arecibo, though, was particularly evocative, not only for its function but because of its site, in a limestone sinkhole in the jungles of northern Puerto Rico.  Add to this its role in searching for signs of extraterrestrial life, and you have a combination sure to capture the imagination.  Because of this it made a number of appearances in science fiction, such as the 1994 episode of The X Files called "Little Green Men," and most notably, the amazing 1997 movie Contact, which remains my number-one favorite movie ever, not only for the story but because of a tour de force performance by Jodie Foster as the indomitable astronomer Ellie Arroway.

[Image is licensed under the Creative Commons Mariordo (Mario Roberto Durán Ortiz), Arecibo radio telescope SJU 06 2019 6144, CC BY-SA 4.0]

So it was with considerable sadness that I found out a couple of weeks ago that Arecibo was being permanently dismantled.  Earlier this year, a pair of cable breaks ripped gashes in the dish, and it seemed like the venerable telescope was unrepairable.  As if to confirm that, just two days ago the nine-hundred-ton equipment platform collapsed, falling almost two hundred meters and destroying the entire center of the telescope.

"When we looked outside the control room, we started to see the eventual downfall of the observatory," observatory director Ángel Vázquez said.  "After the breakage of two cables earlier this year, strands of the remaining three cables had been unraveling in recent days, increasing the strain.  And because two of the support towers maintained tension as the collapse occurred, some of the falling equipment was yanked across the side of the dish rather than falling straight down through its focal point...  This whole process took thirty seconds, and an icon in radio astronomy was done."

Vázquez isn't the only one to feel its loss deeply.  "While life will continue, something powerful and profoundly wonderful is gone," said astronomer Seth Shostak, whose work with SETI (the Search for Extraterrestrial Intelligence) was a good part of the inspiration for Contact.

I understand the sentiment.  The whole thing makes me feel something like grief.  Arecibo has been an inspiration to me since I was a child, and its destruction is like losing an old friend.  I know there are other, and more powerful, telescopes out there, but this one seemed to me to be a symbol of our search for something beyond ourselves, for unraveling the secrets of the universe while still right here, looking up into the skies from our home planet.

So farewell to Arecibo.  There will always be something unique and marvelous about the image of that huge telescopic eye in the Puerto Rican jungle.  As Seth Shostak pointed out, its loss won't stop our yearning for knowledge, but it's hard to imagine finding something as grand and iconic to take its place in our imaginations.

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One of the most compellingly weird objects in the universe is the black hole -- a stellar remnant so dense that it warps space into a closed surface.  Once the edge of that sphere -- the event horizon -- is passed, there's no getting out.  Even light can't escape, which is where they get their name.

Black holes have been a staple of science fiction for years, not only for their potential to destroy whatever comes near them, but because their effects on space-time result in a relativistic slowdown of time (depicted brilliantly in the movie Interstellar).  In this week's Skeptophilia book-of-the-week, The Black Hole Survival Guide, astrophysicist Janna Levin describes for us what it would be like to have a close encounter with one of these things -- using the latest knowledge from science to explain in layperson's terms the experience of an unfortunate astronaut who strayed too close.

It's a fascinating, and often mind-blowing, topic, handled deftly by Levin, where the science itself is so strange that it seems as if it must be fiction.  But no, these things are real, and common; there's a huge one at the center of our own galaxy, and an unknown number of them elsewhere in the Milky Way.  Levin's book will give you a good picture of one of the scariest naturally-occurring objects -- all from the safety of your own home.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]