Is There Life on Earth?

Hello, friends!

Let’s imagine some space aliens are cruising by our Solar System.  They turn their scanners on our planet and see… what?

Among other things, they’d notice that Earth’s landmasses are partially covered with a strange, green-colored substance.  Of course, you and I know what that green substance is.  It’s chlorophyll.  But would those extraterrestrial observers, who have no prior knowledge of our planet, be able to figure that out?  Even if they did, would they realize what chlorophyll is used for?  Maybe.  Probably not, though.

Which brings me to my all-time favorite scientific paper: “A search for life on Earth from the Galileo spacecraft,” by Carl Sagan et al.  I love this paper in part because it’s so clearly and concisely written, with jargon kept to a minimum.  Sagan was, after all, a talented science communicator.  But I also love this paper because its conclusions are so shocking, so eye-opening.

In 1990, NASA’s Galileo spacecraft turned all its high-tech instruments toward Earth and detected… not much, actually.  Galileo did pick up radio broadcasts emanating from the planet’s surface.  Aside from that, though, Galileo’s data offered highly suggestive (but also highly circumstantial) evidence on Earthly life.  The lesson: finding life on other planets is hard.  Even using our very best equipment, it was hard for NASA to detect signs of life right here on Earth!

At least that’s what I got out of reading Sagan’s Galileo experiment paper.  And based on various commentaries I’ve read or heard about this paper, that seems to be the lesson other people got out of it too.  So I was surprised to hear Sagan himself, approximately seven-and-a-half minutes into this interview, saying the exact opposite.

We’ve flown by some sixty worlds.  We claim that we haven’t found life anywhere, and that that is a significant result.  That is, that we would have found life had it been there.  But this has never been calibrated.  We’ve never flown by the Earth with a modern interplanetary spacecraft, all instruments on, and detected life here.  And so Galileo, because of this peculiar gravity assist VEEGA trajectory, permits us to do that.  And as I’ll describe tomorrow, we find life five or six different ways, including intelligent life.  And this then means that the negative results that we find elsewhere are, in fact, significant.

I’ve been puzzled by this for a while now, but I think I’ve finally figured out why Sagan would say this.  It’s politics.

On the one hand, scientists need to understand the challenges they’ll face (including the limitations of their own equipment) in searching for life on other worlds.  That really is, I think, the purpose of the Galileo experiment paper.  On the other hand, it would not do to say on public television, to cantankerous taxpayers and the listening ears of Congress, that NASA spends millions of dollars on space probes that are not even capable of detecting life right here on Earth.

Space exploration is expensive.  And like all expensive types of research, sooner or later the researchers involved have to learn how to play politics.

No Gospel Truth in Science

Hello, friends!

So there’s this notion in the popular press that when a new scientific paper comes out, that paper should be taken as the final definitive word on an issue.  Science has spoken.  This is a scientific fact now.  But that is not how science works.

When new research is published, you should expect there will be followup research, and then that followup research will be followed up by even more research.  A new scientific paper really shouldn’t be seen as a proclamation of fact but rather as the beginning of a dialogue among scientists, or perhaps as the continuation of a dialogue that’s already in progress.

The recent detection of phosphine in the atmosphere of Venus has turned out to be a fantastic example of this ongoing dialogue in action.  The initial research was published in two separate papers (click here or here).  Basically, astronomers found the spectral signature of phosphine (PH3) in the Venusian atmosphere, and they were at a loss to explain where all that phosphine could be coming from.

Based on everything we currently know about Venus, those two papers tried to rule out several possible explanations.  Such a large quantity of phosphine could not be created by Venus’s atmospheric chemistry.  It could not be spewing out of volcanoes on Venus’s surface.  It could not be delivered to Venus by asteroids or comets.  One very intriguing possibility that could not be ruled out: maybe there’s life on Venus.  On Earth, phosphine is produced almost exclusively by living things.

But those two papers were not the definitive final word on the matter.  A dialogue had begun.  Soon, followup research came out suggesting that phosphine could be spewing out of volcanoes after all.  It would still be pretty shocking to discover that Venus has enough active volcanoes to produce that much atmospheric phosphine—but it be nowhere near as shocking as discovering Venus has life.

And then even more followup research came out with this paper, which points out possible errors in the original research and suggests that we may be dealing with a false positive detection.  Venus might not have phosphine after all, or maybe it doesn’t have as much as originally believed.

And the dialogue continues.  More research will come.  More responses will be published, and then there will be responses to those responses, and so forth until the scientific community reaches some sort of consensus about this Venusian phosphine business.  And even then, that scientific consensus still might not be the 100% final word on the matter.

Based on the way the popular press reports science news, you could easily get the impression that scientific papers should be treated as gospel truth.  You would be understandably confused, then, when one scientific paper comes out refuting the findings of another.  Subsequently, you may come to the conclusion (as a great many people apparently have) that science must not know anything at all.  Science just keeps contradicting itself, it seems.

But scientific papers are not meant to be taken as gospel truth.  They’re part of an ongoing back-and-forth dialogue.  So the next time you hear about some new scientific discovery on the news, remember that scientific papers are not intended to be bold proclamations of fact.  And when you hear about some new paper refuting older research, you’ll understand what’s going on.

Daily Life with Dinosaurs

Hello, friends!

There’s an important science fact that I wish more people were aware of.  Birds are not merely the descendants of dinosaurs.  According to a taxonomic system called cladistics (also known as phylogenetic systematics), birds are dinosaurs.  To quote this article from DinoBuzz:

Using proper terminology, birds are avian dinosaurs; other dinosaurs are non-avian dinosaurs, and (strange as it may sound) birds are technically considered reptiles.  Overly technical?  Just semantics?  Perhaps, but still good science.

So with that in mind, the following statements are 100% true:

  • I often wake up to the sound of noisy dinosaurs outside my window.
  • I sometimes see dinosaurs swimming in the river near my house.
  • I hate it when dinosaurs poop on my car.
  • I enjoy eating dinosaur meat.  Sometimes I put dinosaur meat on sandwiches or in salads.

Anyway, what sort of experiences have you had with dinosaurs in your daily life?  Please share in the comments!

P.S.: Have you seen those dinosaur-shaped chicken nuggets in the grocery store? They’re cute.  I’m just not convinced that they’re made from 100% real dinosaur meat.

Science is Wrong About Everything

Hello, friends!  So one day when I was a little kid, I got into a huge argument with another kid in school.  I’d said something about how Earth is a sphere, like all the other planets.  The other kid told me (firstly) that Star Trek isn’t real and (secondly) that the earth is flat.

As evidence, the other kid told me to just look around.  It’s obvious that the world is flat.  If I needed more proof, I could look at a map.  More kids soon jumped into this argument.  They all agreed: the earth is flat, and also I’m a huge nerd for watching so much Star Trek.  I was outnumbered, and being outnumbered was further proof that I must be wrong.

I went home so mad that day.  How could those other kids be so stupid?  I was right.  Everybody else was wrong.  I’m tempted to turn this into a metaphor for Internet culture, but that’s not the point I want to make today.

Yes, when those other kids said the Earth is flat, they were wrong.  But when I said the Earth is a sphere, I was wrong too.  Less wrong, obviously.  But still, I was wrong.

Isaac Asimov’s essay “The Relativity of Wrong” is a brilliant summation of how science works.  It should be required reading for every human being (click here to read it).  As Asimov explains:

[…] when people thought the earth was flat, they were wrong.  When people thought the earth was spherical, they were wrong.  But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together.

As Asimov goes on to explain, there was a time, long ago, when educated people really did believe the world was flat, and they had good reasons for thinking it to be so.  But then discoveries were made.  New knowledge was learned, and people came to think of the world was a sphere.  Then more discoveries were made, and people started to think of the world as an oblate spheroid (round, but slightly bulgy at the equator).  And then still more discoveries were made, and even the oblate spheroid model turned out to be slightly inaccurate.

People (including people on the Internet) will gleefully point out that science has been wrong about stuff in the past; therefore, science could be wrong about stuff today—stuff like evolution, climate change, general relativity—also stuff like vaccinations and COVID-19.  When science is wrong so much, why pay attention to science at all?

Well, it’s true.  In absolutist (this-or-that-ist) terms, science is wrong.  Science is always wrong, about everything, all the time.  Science is full of educated guesses and close approximations of observed reality.  It’s not perfect.  It will never be perfect.  But with each new discovery, science is a little less wrong today than it was yesterday.  And you can trust science to keep being less and less wrong, even if it will never be 100% right.

And that process of constant refinement and improvement, that process of getting closer and closer to the truth—that’s something worth paying attention to, something worth taking seriously, don’t you think?

P.S.: I’ll concede that those kids in school were right about one thing.  I was, and still am, a huge Star Trek nerd.

Galactic Census Report: How Many Civilizations Are in Our Galaxy?

Hello, friends!  Have you heard the news?  Scientists have determined that there should be at least thirty-six alien civilizations in our galaxy right now.

Here’s the actual research paper from The Astrophysical Journal (warning: paywall).  As you might imagine, this research is based on some key assumptions.  And the authors do make it clear that they are making assumptions.  Reasonable assumptions, they argue, but still… ASSUMPTIONS!!!

The first major assumption is this: any Earth-like planet with an Earth-like chemical composition that happens to have an Earth-like orbit (i.e.: habitable zone) and has been around for an Earth-like period of time (approximately 4.5 billion years) has a reasonably good chance of developing Earth-like intelligent life.

The second major assumption is this: once a civilization advances to the point that it can start broadcasting its presence to the rest of the universe, that civilization will also have advanced to the point of being able to destroy itself.  Earth-like intelligent life has a tendency, the authors argue, for self-destruction.  Maybe it’ll be nuclear weapons, or maybe a climate catastrophe of some kind.  Or, I don’t know, maybe an increasingly globalized society will make itself more vulnerable to some sort of global pandemic.

Obviously the authors make other assumptions as well, but those two are the big ones.  When plugging numbers into a modified version of the Drake Equation, the most pessimistic assumptions yield an estimate of 36 civilizations in our galaxy (with a margin of error that could push that number all the way down to 4).  The most optimistic assumptions yield an estimate of 928 civilizations (with a margin of error that could push the number all the way up to 2908).

As I’ve said before, scientific papers should never be taken as proclamations of absolute fact.  That’s especially true for papers like this one.  Scientific papers are part of an ongoing back-and-forth conversation in the scientific community.  What do we currently know?  How much do we still have to learn, and what should our expectations realistically be?  That’s what this paper from The Astrophysical Journal is really about: setting expectations for SETI research.

So what should our expectations be, based on those two key assumptions the authors made?  Well, even under the most optimistic scenarios, our nearest neighbors are predicted to be hundreds (if not thousands) of lightyears away—far enough away that they’d be very, very, very difficult to find using our current technology, and establishing two way communications would be virtually impossible.

So maybe we’re not alone in the universe, but we may as well be.

Sciency Words: Null Hypothesis

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we look at the meaning and origins of scientific terms.  Today on Sciency Words, we’re talking about:


Whenever there’s a big scientific discovery in the news, my first question is always: should I take this seriously?  The answer is usually no.  The popular press may say one thing, but when you dig into the actual science, you often find the facts do not support the hype.

So when I started reading about a second possible planet in the Proxima Centauri system, I wanted to know: should I take this seriously?  In this article from Scientific American, the astronomers who discovered this possible planet are quoted as saying:

Since the very first time we saw this [potential planetary] signal, we tried to be its worst enemy.

The astronomers are then quoted saying:

We tried different tools to prove ourselves wrong, but failed.  However, we have to keep the doors open to all possible doubt and skepticism.

For me, this is the most reassuring thing any scientist could say.  Too often in popular culture, scientists are portrayed a certain way.

For a multitude of reasons, this is not a real scientist.

But no, good scientists are not out to prove to the world that they’re right.  They’re trying as hard as possible to prove to themselves that they’re wrong.  Which brings me to the null hypothesis.

According to the Oxford English Dictionary and other sources (like this one), the term “null hypothesis” can be traced back to British statistician Ronald Fisher.  Fisher first wrote about the null hypothesis in 1935, in a book titled The Design of Experiments.

As a way of introducing the concept, Fisher tells us the story of a woman who claimed to have an oddly specific talent.

A lady declares that by tasting a cup of tea made with milk she can discriminate whether the milk or the tea infusion was first added to the cup.

The Design of Experiments, by Ronald Fisher

Fisher then describes an experiment to test this woman’s claim.  She’s given eight cups of tea, four with the milk added first, and four with the milk added afterward.

In the context of this experiment, the null hypothesis predicts that the woman will not be able to tell which tea is which—she’s only guessing.  Or to put that in sciencier language, the null hypothesis asserts that there will be no statistically significant relationship between the way this woman’s tea was prepared and the way she believes her tea was prepared. As Fisher explains:

[…] it should be noted that the null hypothesis is never proved or established, but is possibly disproved, in the course of experimentation.  Every experiment may be said to exist only in order to give the facts a chance of disproving the null hypothesis.

The Design of Experiments, by Ronald Fisher

A null hypothesis is usually paired with an “alternative hypothesis,” which asserts that a statistically significant relationship does exist.  In Fisher’s tea tasting example, the alternative hypothesis would be that the woman really can tell which tea is which.  You can never really prove that either the null hypothesis or the alternative hypothesis is true, but a well designed experiment should be able to prove that one hypothesis or the other is false.

Going back to that possible planet in the Proxima Centauri system, the article from Scientific American does not explicitly mention the null hypothesis; however, the spirit of the null hypothesis is clearly in play.  Astronomers are trying their best to prove that that planet does not exist, and so far they can’t do it.  And that’s enough to convince me that I should take this new planet seriously (at least for now).

Next time on Planet Pailly, we’ll find out what this not-yet-disproven planet might look like.

The Peril of Being Self Educated

Hello, friends!

As many of you already know, I blog about science, but I am first and foremost a science fiction writer (fingers crossed, soon to be a published science fiction writer!).

Back in 2010, I started this blog as a way to force myself to do the kind of research that I, as an aspiring Sci-Fi author, thought that I ought to be doing.  In the beginning, I really didn’t know much about science, except for some stuff I remembered learning in school.  And most of that stuff I remembered from school turned out to be wrong or, at best, only half true.

That’s one of the reasons I love being self educated.  Writing this blog has given me an opportunity to discover and correct many of the misconceptions I once had about science.  And my Sci-Fi writing has improved as a result.  I was recently looking over one of my old manuscripts.  So many silly misconceptions are on full display in that text.  Thank God that story never got published!

Another reason I love being self educated: doing deep dives on topics that I find interesting or that I think could be useful in my stories—topics like lithium mining, Troodon intelligence, or Venus’s unknown absorber.  The kinds of topics that never seem to get covered in school or that rarely get attention from the popular press.

I have, on occasion, surprised professional scientists with just how much I know about some weirdly specific topics.  And then I’ve surprised those same scientists with how much I don’t know about more ordinary, more generalized things.  That’s the peril of being self educated.  Your knowledge is splotchy, inconsistent.  You end up with these weird gaps in your knowledge, gaps that someone with a more traditional science education would not have.

And that’s why I keep blogging: because there’s still a whole lot I don’t know, and I’m sure I still have a lot of misconceptions in my head about science, and about other things too.  One thing I didn’t anticipate when I started this blog was how valuable a resource you, dear reader, would be.  You’ve asked me questions.  You’ve challenged me.  Some of you have pointed out my mistakes and suggested new avenues of research.

For that, I just want to say thank you, and please keep it up!

Next time on Planet Pailly, what if I told you Earth is not the perfect planet for life?

Something Worth Knowing

Hello, friends!

Today I’d like to share a very old video I found on YouTube.  It’s a series of man (and woman) on the street interviews where people are asked if they think we’ll find life on other planets.

According to the video description, this was filmed in 1962.  It’s interesting to me to hear people talk about the possibility of finding “vegetable” and/or “animal” life on Venus.  At that time, the Soviet Union’s Venera 1 spacecraft would have already visited Venus; however, due to a technical glitch, Venera 1 failed to transmit any data about Venus back to Earth.  So surface conditions on Venus were still unknown to us Earthlings.

But setting aside the Venus stuff in particular, in general people’s opinions about space exploration and extraterrestrial life have not changed much since 1962.  Some people are enthusiastically optimistic, others think it’s all nonsense, and a lot of people don’t seem to care one way or the other.

Then, of course, you get the one guy who swears he’s seen a U.F.O.  And then, of course, you get the guy who’s “working off the theory of the Bible,” where it says God only created life on one planet (F.Y.I., I’ve read the Bible too, and I don’t remember it ever saying that).  So again, not much has changed since 1962.

But my favorite is the woman at 1:40 who says she doesn’t expect we’ll find any life on Venus, but then goes on to say we’ll still find “something worth knowing.”  I’d say she was right on both counts!

Personally, I do think there’s life on other planets, and also on other moons (I’m looking at you, Europa).  But regardless of whether or not we find alien life out there, we should absolutely keep searching and keep exploring.  I suspect we will continue to learn all sorts of things that are worth knowing!

Next time on Planet Pailly, we’ll learn how to dance like binary stars.

Wait, What Do You Mean There’s No “Life” on Mars?

Hello, friends!

The other day, someone wanted to pick a fight with me.  This person said to me in a forceful, almost rude tone, that there is absolutely no chance we will ever discover life on Mars.  If you know me at all, you must surely know: them’s fightin’ words!

Except before this conversation could escalate into a full blown argument, it became apparent (to me, at least) that we were not actually talking about the same thing.  You see when I talk about life on Mars, I mean life of any kind, including microorganisms—especially microorganisms.  This other person was using the word “life” to mean, specifically and exclusively, intelligent life.

No, I do not expect we’ll find intelligent life on Mars.  There are no canals, no cities—none of that stuff Percival Lowell once imagined he saw in his telescope.  Nor do I expect to find non-intelligent animals or any kind of plant life.

The best we can hope for is that there might be Martian microorganisms hiding under a glacier, subsisting off a trickle of meltwater.  And to be honest, I’m not overly optimistic about finding even that much life on Mars.  But to say it is absolutely impossible?  No, I cannot agree with that.

And after explaining what I mean when I talk about life on Mars and what my expectations actually are, this person conceded (grudgingly, perhaps) that I might have a point.  Thus what could have been a bitter and fruitless argument turned into an opportunity to educate someone about the science of astrobiology.  Why?  Because I asked the question “Wait, what do you mean by life?”

Language is not as precise a tool as we often imagine.  People sometimes use the same words to mean very different things, leading to misunderstandings, hurt feelings, and unproductive arguments.  I think a lot of those arguments, both big and small, could be avoided if more people would stop and ask: “Wait, what do you mean by (fill in the blank)?”

Next time on Planet Pailly, am I too judgmental?  We’ll find out in this month’s posting of the Insecure Writer’s Support Group.

Beware Wishful Thinking: A Science Lesson

This may seem like a contradiction. Astrobiologists are actively searching for alien life.  It’s their job.  And yet whenever new evidence of alien life is presented, astrobiologists are the first and most vocal skeptics about it.  If your job is to search for alien life, why would you be so quick to doubt any evidence that alien life actually exists?

This goes back to the famous “extraordinary claims require extraordinary evidence” line from Carl Sagan, or the whole proof beyond a reasonable doubt thing I kept saying during my recent A to Z series on the search for alien life.  Astrobiologists very much do want to find alien life.  They’re eager to find it.  Perhaps a little too eager.

And thus, astrobiologists have to be careful.  They have to be extra skeptical, because they have to be on guard against their own wishful thinking.

And really, this is not only true in the field of astrobiology; it’s true of science in general.  And frankly, it’s a valuable lesson for us all, even if you’re not a scientist.

I can’t tell you how many times I’ve really wanted to believe something.  I’ve really wanted to believe that some girl likes me, or that I’ve put my money in sound investments, or that I’ve voted for the right people.  And when you really want to believe something, you’ll latch onto whatever flimsy evidence you can find to prove to yourself that it’s true.

Astrobiologists know this.  Scientists know this (or at least they’re supposed to).  And I think it’s good advice for us all to live by.  The more you want to believe something, the more you should question and doubt it.  Always, always, always be on guard against your own wishful thinking.