Deep life, oxygen, and false positives

In the last couple of days we connoisseurs of all things extraterrestrial received some good news and some bad news.

Let's start with the bad news first.

One of the ways astronomers have suggested we might detect life on other planets is the presence of oxygen in the atmosphere, which could be detected spectroscopically.  Oxygen is highly reactive -- it is, unsurprisingly, a strong oxidizer -- meaning that it will tend to react chemically with whatever's around and get bound up into a compound of some sort.  Therefore, the logic went, if there's oxygen in the atmosphere, something must be releasing it faster than it's being removed by ordinary chemical reactions.

Ergo, a living thing (probably doing some variation on photosynthesis).

A piece of research published this week in Earth and Space Chemistry called, "Gas Phase Chemistry of Cool Exoplanet Atmospheres: Insight from Laboratory Simulations," written by a team of scientists from seven different research institutions, came to a startling conclusion -- that atmospheric oxygen might not be a signature of life but a result of photochemistry (chemical reactions triggered by sunlight).

What the researchers did was to expose various mixtures of gases thought to be common components of exoplanet atmospheres to a variety of temperatures (from 25 C to 370 C) and light intensities and spectra, and they found that in many conditions, the energy from the heat and light was sufficient to break down oxidized gases (such as carbon dioxide) and release molecular oxygen.

"People used to suggest that oxygen and organics being present together indicates life, but we produced them abiotically in multiple simulations," said Chao He of Johns Hopkins University's department of Earth and Planetary Science.  "This suggests that even the co-presence of commonly accepted biosignatures could be a false positive for life."

Now, this doesn't mean that if oxygen is found in an exoplanet's atmosphere, it is a false positive; it's just that the He et al. research shows that the finding would not be the slam-dunk astronomers thought it was.  Which is unfortunate.  Given that it's likely that most of the planets hosting life do not have life forms advanced enough to communicate across interstellar space, it'd be nice to have a way to find out they're out there without leaving Earth.  And one of the better possibilities for that has just been shown to be unreliable.

News from the Deep Carbon Observatory, a project that is the collective effort of over a thousand geologists, chemists, and biologists, is more encouraging.  Most of us have the idea that life is only possible on the thin skin of the Earth, and that if you go very deep into the Earth's crust conditions become quickly hot enough and pressurized enough that nothing could live.

Well, that's not true.

The DCO released research last week showing that the amount of life in the "deep biosphere" might amount to as much as twenty billion tons, meaning it would outweigh all of humanity put together by a factor of twenty.  The DCO team drilled three miles deep into the seafloor, and investigated the deepest gold and diamond mines ever created, and everywhere they looked, they found life.

Lots of it.

They found life flourishing at a temperature of 122 C -- twenty-two degrees above the boiling point of water.  They found it in pitch darkness, where there's nothing around to eat except for rocks.  They found it at crushing pressures in the deepest trenches in the ocean.

Sounds like we might have to redefine what we mean by "conditions hospitable for life."

And, germane to the topic of today's post, it will broaden what conditions lie in the "Goldilocks Zone" -- the region surrounding a star where its planets would experience temperatures that are neither too warm nor too cold, but "just right."  Apparently "just right" has a broader range than we ever dreamed, which means that a great many more planets out there might host life than we ever expected.

However, it bears mention that the denizens of the deep biosphere are all simple.  Nothing much more complex than a nematode (roundworm) has been found down there.  So if you were hoping for running across the Morlocks, so far that's a no.

But it's a pretty exciting finding nonetheless, and supports a contention I've had for years -- that life is common in the universe.  Or, as Ellie Arroway put it in Contact, "If not, it'd be an awful waste of space."  Now it's on the chemists and atmospheric scientists to find us a better way to tell that it's there, since the oxygen idea just got shot down.

We'll see what they come up with.  Because I'm certain that it's only a matter of time before we prove beyond any doubt that we're not alone in the universe.

********************************

This week's Skeptophilia book recommendation is Michio Kaku's The Physics of the Impossible.  Kaku takes a look at the science and technology that is usually considered to be in the realm of science fiction -- things like invisibility cloaks, replicators, matter transporters, faster-than-light travel, medical devices like Star Trek's "tricorders" -- and considers whether they're possible given what we know of scientific law, and if so, what it would take to develop them.  In his signature lucid, humorous style, Kaku differentiates between what's merely a matter of figuring out the technology (such as invisibility) and what's probably impossible in a a real and final sense (such as, sadly, faster-than-light travel).  It's a wonderful excursion into the power of the human imagination -- and the power to make at least some of it happen.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

Chemtrail survey

One of the problems with scientists being understood by laypeople is that they don't speak the same language.

I'm not just talking about technical vocabulary, here, the ability to throw around words like photophosphorylation and anisotropy and eigenstate.  I'm talking about how they each use fairly simple words -- words like theory and hypothesis and proof.

As an example, consider the kerfuffle over the activation of the Large Hadron Collider, instrumental in the search for (and ultimately discovery of) the Higgs boson.  There was concern, mostly on the part of non-scientists, that the energy released by the collisions within the LHC could cause some untoward effects.  Since one of the metaphors used to describe what was happening therein was "recreating the conditions that were present at the Big Bang" (a statement that in any case is incorrect by several orders of magnitude), people wondered if the activation of the machine might generate mini black holes -- or possibly a new universe, which would expand and tear our universe apart from the inside.

So looking for reassurance, the scientists were contacted, and asked if this was possible.  And that's when the trouble started.

Scientists, for the most part, are extremely careful to differentiate between the words "possible" and "likely."  So they said, sure, it's possible.  Given that we haven't ever achieved collision energies this high, lots of things are possible, including some we probably haven't foreseen.  You can't rule out an eventuality that depends on data we don't have yet.

Well, at that point, the media was off to the races.  Headlines saying "Scientists Admit It's Possible the LHC Will Destroy the Universe!" began to appear.  Only after the hue-and-cry began did the scientists say, "Now, wait just one minute.  We didn't say it was likely.  In fact, it's extraordinarily unlikely."  But by that time no one was listening, because most people were too busy wailing about how we were all gonna die and it was the physicists' fault.

I'm happy to say, though, that not only did we not die when the LHC was activated, the scientists are beginning to learn how to talk to the rest of us.  Witness, for example, the rather annoyed-sounding paper that appeared in Environmental Research Letters a few days ago, entitled, "Quantifying Expert Consensus Against the Existence of a Secret, Large-Scale Atmospheric Spraying Program," by Christine Shearer, Mick West, Ken Caldeira, and Steven J. Davis.  If you're thinking, "wait, this can't be about what it sounds like," well, yes, it is:

Nearly 17% of people in an international survey said they believed the existence of a secret large-scale atmospheric program (SLAP) to be true or partly true.  SLAP is commonly referred to as 'chemtrails' or 'covert geoengineering', and has led to a number of websites purported to show evidence of widespread chemical spraying linked to negative impacts on human health and the environment.  To address these claims, we surveyed two groups of experts—atmospheric chemists with expertize in condensation trails and geochemists working on atmospheric deposition of dust and pollution—to scientifically evaluate for the first time the claims of SLAP theorists.  Results show that 76 of the 77 scientists (98.7%) that took part in this study said they had not encountered evidence of a SLAP, and that the data cited as evidence could be explained through other factors, including well-understood physics and chemistry associated with aircraft contrails and atmospheric aerosols.  Our goal is not to sway those already convinced that there is a secret, large-scale spraying program—who often reject counter-evidence as further proof of their theories—but rather to establish a source of objective science that can inform public discourse.

So this brings up a couple of points.  First, these folks are going about this the right way.  None of this pussyfooting around about how "we can't prove it" or "without evidence, we can't say it's impossible;" Shearer et al. are saying, "No, you loons, there are no such things as 'chemtrails.'"

Second, didn't you just love the comment about how conspiracy theorists "often reject counter-evidence as further proof of their theories?"  That, I believe, is what is referred to in scientific circles as a "mic drop moment."

But third, I have to wonder who the 77th atmospheric scientist was, the one who had found evidence of chemtrails.  I'd like to talk to that guy, wouldn't you?

Be that as it may, I think the scientists are figuring out that you can't just assume that everyone gets the way evidence and proof (and disproof) are used in science.  They're becoming bolder about saying things like, "Evolution is a fact," "Anthropogenic climate change is happening," and "Homeopathy is pseudoscientific bullshit."  Unfortunate though it may be, using the more cautious diction that is necessary in a scientific paper just doesn't work when communicating scientific findings to the masses.

Anyhow, that paper cheered me up immensely.  Given that common-sense considerations -- such as the fact that jet contrails would be a really crappy toxin delivery device -- don't seem to dissuade the True Believers, it's time for the scientists to come together and say, "Um... NO."  Not, as they pointed out, that it will convince the True Believers -- but because it will let anyone still on the fence know that there is no discussion about this amongst people who aren't certifiable wackos.