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Is SETI dangerous?

Interdisciplinarity in science can be wonderful: combining expertise across disciplines leads to new insights and progress because it’s only when people from those disciplines communicate about a particular problem that progress is made, and that happens much more rarely than communications among members of a single discipline.

It’s important, though, when working across disciplines to actually engage experts in those other fields. There’s a particular kind of arrogance, common among physicists, that a very good scientist can wander into another discipline, learn about it by reading some papers, and start making important contributions right away. xkcd nailed it:

xkcd comic. A physicist is lecturing an annoyed person who has beer working at a blackboard and laptop with notes strewn about. "You're trying to predict the behavior of <complicated system>? Just model it as a <simple object>, and then add some secondary terms to account for <complications I just thought of>. Easy, right? So, why does <your field> need a whole journal, anyway? Caption: Liberal arts majors may be annoying sometimes, but there's nothing more obnoxious than a physicist first encountering a new subject.And my favorite takedown of the type is from SMBC (go read it!)

There’s a new paper about the dangers of SETI out by Kenneth W. Wisian and John W. Traphagan in Space Policy, described here on Centauri Dreams. In it, they describe the worldwide “arms” race, similar to the one in the film Arrival, to communicate with ETIs once contact is established. They say this is an unappreciated aspect of SETI and that SETI facilities should take precautions similar to those at nuclear power plants.  Specifically, they write:

In the vigorous academic debate over the risks of the Search for ExtraTerrestrial Intelligence (SETI) and active Messaging ExtraTerrestrial Intelligence (ETI) (METI), a significant factor has been largely over- looked. Specifically, the risk of merely detecting an alien signal from passive SETI activity is usually considered to be negligible. The history of international relations viewed through the lens of the realpolitik tradition of realist political thought suggests, however, that there is a measurable risk of conflict over the perceived benefit of monopoly access to ETI communication channels. This possibility needs to be considered when analyzing the potential risks and benefits of contact with ETI.

I have major issues with their “realpolitik” analysis, but I’m not an expert in global politics, international affairs, or risk aversion so I’m not going to critique that part here. Instead, I’ll stick to my expertise and point out that the article would be much stronger if the authors had consulted some SETI experts, because it is based on some very dubious assumptions about the nature of contact.

The authors seems to think it is clear that once a signal is identified:

  1. Only around “a dozen” facilities in the world will be able to receive the signal, and that states will be able to somehow restrict this capability from other states. The authors think this covers both laser and radio.
  2. That it will be possible to send a signal to the ETI transmitter, and that this capability will have perceived advantages to states.

While there are some contact scenarios where these assumptions are valid, they are rather narrow.

First, modern radio telescopes are large and expensive because they are general purpose instruments. They can often point in any direction, and have a suite of specialized instrumentation designed to operate over a huge range of frequencies.

But once a signal is discovered, the requirements to pick it up shrink dramatically. Only a single receiver is required, and its bandwidth need be no wider than the signal itself. The telescope need only point at the parts of the sky where the signal comes from, so it need only have a single drive motor. And the size of the dish need not be enormous, unless the signal just happens to be of a strength that large telescopes can decode it but small ones cannot, which is possible but a priori unlikely.

Indeed, there are an enormous number of radio dishes designed to communicate with Earth satellites that could easily be repurposed for such an effort, and can even be combined to achieve sensitivities similar to a single very large telescope, if signal strength is an issue. And there is no shortage of radio engineers and communications experts around the world that can solve the problem quickly and easily. The scale of such a project is probably of order tens of thousands to millions of dollars, depending on the strength and kind of signal involved. The number of actors that could do this worldwide is huge. Also, such efforts would be indistinguishable from normal radio astronomy or satellite communications, so very hard to curtail without ending those industries.

The situation is similar for a laser signal: if it is a laser “flash” then the difficulty is primarily in very fast detectors that can pick it up. Here, the technology is not as mature, and if the flashes are *extremely* fast it is possible that the necessary technology could be controlled but, again, this assumes a very particular kind of laser signal. And, again, there are an enormous number of optical telescopes which will have similar sensitivity to optical flashes as existing optical SETI experiments (which, again, are only expensive because they search a huge fraction of the sky for signals of unknown duration).

Finally, there is the issue of two-way communication: unless the signal is coming from within the solar system or the very closest stars, the “ping time” back and forth is at least a decade, and likely much longer. There is no “conversation” in this case: the first response to our communications would be ten years down the line! So the real dangers are transmitters within the solar system or signals that contain useful information without the need for us to send signals.

In summary, the concerns expressed in this article apply to a narrow range of contact scenarios in which the signal is, somehow, only accessible to those with highly specialized equipment or from a transmitter within the solar system. The first seems highly unlikely; I do not know to evaluate the second, but note that such signals are not searched for routinely in the radio, anyway.

I’d be happy to engage with experts in space law on a paper on the topic, if I know any?

Science is not logical

OK, time for some armchair philosophy of science!

You often hear about how logic and deductive reasoning are at the heart of science, or expressions that science is a formal, logical system for uncovering truth. Many scientists have heard definitions of science that include statements like “science never proves anything, it only disproves things” or “only testable hypotheses are scientific.” But these are not actually reflective of how science is done. They are not even ideals we aspire to!

You might think that logic is the foundation of scientific reasoning, and indeed it plays an essential role. But logic often leads to conclusions at odds with the scientific method.  Take, for instance, the “Raven Paradox”, expertly explained here by Sabine Hossenfelder:

Sabine offers the “Bayesian” solution to the paradox, but also nods to the fact that philosophers of science have managed to punch a bunch of holes into it. Even if you accept that solution, the paradox is still there, insisting that in principle the scientific method allows you to study the color of ravens by examining the color of everything in the universe except ravens.

I think part of the problem is that the statement “All ravens are black” sounds like a scientific statement or hypothesis, but when we actually make a scientific statement like “all ravens are black” we mean it in something closer to the vernacular sense than the logical one. For instance:

  • “Ravens” is not really well defined. Which subspecies? Where is the boundary between past (and future!) species in its evolutionary descent?
  • “Black” is not well defined.  How black? Does very dark blue count?
  • “Are” is not well defined. Ravens’ eyes are not black. Their blood is not black.

Also, logically, “all ravens are black” is strictly true even if no ravens exist! (Because “all non-black things are not ravens” is an equivalent statement and trivially true in that case). Weirdly, “all ravens are red” is strictly true in that case, as well! This is not really consistent with what scientists mean when we say something like “all ravens are black”, which presumes the existence of ravens. We would argue that a statement like that in a universe that contains no ravens is basically meaningless (having no truth value) and actually misleading, not trivially true, as logic insists.

So the logical statement “all ravens are black” is supposed to be very precise, but that is very different from our mental conception of its implications when we hear the sentence, which are squishier. We understand we’re not to take it strictly literally, but that is exactly what logic demands we do!  And if we don’t take it in exactly the strict logical sense, then we cannot apply the rules of formal logic to it. This means that the logical conclusion that observing a blue sock is support for “all ravens is black” does not reflect the actual scientific method.

You might argue that “black” and “raven” are just examples, and that in science we can be more precise about what we mean and recover a logical statement, but really almost everything we do in science is ultimately subject to the same squishiness at some level.

Also, and more damningly:

If we were to see a non-white raven—one that has been painted white, an albino, or one with a fungal infection of its wings— we would not necessarily consider it evidence against “all ravens are black”!  We understand that “all ravens are black” is a general rule with all kinds of technical exceptions. Indeed, a cardinal rule in science is that all laws admit exceptions! Logically, this is very close to the “no true Scotsman fallacy,” but it is actually great strength of science, that we do not reach for universal laws from evidence limited in scope, only trends and general understandings. After all, even GR must fail at the Planck length. 

So even the word “all” does not have the same meaning in science as it does in logic!

More generally, in science we follow inductive reasoning. This means that seeing a black raven supports our hypothesis that all ravens are black. But in logic there is no “support” or “probability,” there is only truth and falsity. On the other hand, in science there are broad, essential classes of statements for which we never have truth, only hypotheses, credence, guesses, and suppositions. Philosophers have struggled for years to put inductive reasoning on firm logical footing, but the Raven Paradox shows how hard it is, and how it leads to counter-intuitive results.

I would go further and argue that strictly logical conclusions like those of the Raven Paradox are inconsistent with the scientific method. I would simply give up and admit: the scientific method is not actually logical!

After all, science is a human endeavor, and humans are not Vulcans. Logic is a tool we use, a model of how we reason about things, and that’s OK: “All models are wrong, but some are useful.”  Modeling the Earth as a sphere (or an oblate spheroid, or higher levels of approximation) is how we do any science that requires knowledge of its shape but it’s not true. Newton’s laws are an incredibly useful model for how all things move in the universe, but they are not true (if nothing else, they fail in the relativistic limit).

Similarly, logic is a very useful and essential model for scientific reasoning, and the philosophy of science is a good way to interrogate how useful it is. But we should not pretend that scientists follow strict adherence to logic or that the scientific method is well defined as a logical enterprise—I’m not even sure that’s possible in principle!

The astrophysical sources of RV jitter

A big day for our understanding of RV jitter!
Penn State graduate student Jacob Luhn has just posted two important papers to the arXiv. You can read his excellent writeup of the first of them here:
It took Jacob a HUGE amount of work to determine the *empirical* RV jitter of hundreds of stars from decades of observations from Keck/HIRES. These are “hand crafted” jitter values, free of planets, containing only the HIRES instrumental jitter plus astrophysical jitter.
(Along the way, we wondered how to put error bars on jitter, which is itself a deviation. What’s the standard deviation of a standard deviation? Jacob found the formula—it’s in the paper if you’d like to see how it’s done (you have to use the kurtosis). )
You may have seen Jacob’s work at various meetings: young stars and evolved have high jitter, so there is a “jitter minimum” where they are quietest.
But this paper has more! It turns out the location of the jitter minimum depends in a predictable way on a star’s mass.
Figure from Jacob's paper illustrating the dependence of jitter on log(g) and mass.
The second paper describes the properties of F stars with low jitter.
But don’t F stars all have high jitter?
Nope. Jacob has found many stars in the “jitter minimum” are F stars with < 5 m/s of RV jitter. This has important implications for following up transiting planets.
My favorite consequence of this work is that we will be able to now *predict* the RV jitter of a star from its mass, R’HK, and log(g) *empirically*, incorporating *all* sources of RV noise . Right now, such predictions are only good to ~factor of 2. Jacob can predict it to <25%!
But predicting RV jitter is a story for another paper, coming soon. For now, enjoy these papers at AJ and on @jacobkluhn’s blog:

Battling the Email Monster

Sometimes when people ask what I do for a living, I tell them I write and answer email.  It certainly is a big part of my day!

That said, I have a pretty good relationship with email. I have a well-managed inbox and occasionally even hit inbox zero, despite getting a lot of emails every day and juggling a lot of responsibilities.

There are a lot of guides out there about how to do this, including this nice Harvard Business Review article on how to have an efficient email session, the “touch it once” philosophy that apparently got its start in the pre-email days, and the original “inbox zero” philosophy that leverages a lot of Gmail features.  My own philosophy borrows a lot from all of these, especially the idea that when you encounter an email you should dispose of it quickly in a way that either gets it off of your desk or puts it where it needs to be for you to act on it.

I know many people with tens of thousands of unread emails, and it’s probably not practical for them to go through and dispose of them all.  For them, I might recommend email bankruptcy: file everything away, start from an empty inbox, and this time don’t let it build up.

I got to this state by building up a lot of good email habits including, counterintuitively, sending myself lots of emails.  Here they are, in case you’d like to try it:

  1. Get GMail. It has good filtering, enough storage space for all of your email, a snooze feature, and (and this is key): such good search capabilities that you don’t have to file anything. It has good support for mobile devices, you can configure it for offline use, and the cloud storage means you don’t have to worry too much about backups.
  2. Use hotkeys. They save a second per email which really adds up. Have one for archiving, one for spam, one for responding, and one for responding to all.
  3. Think of your inbox as your to-do list.  If it’s in your inbox, it’s a short- to medium-term action item. Every email is an item. If you’re not going to do something with it soon, it should not be in your inbox. Keep your list of big and/or long-term projects you’re working on somewhere else.
  4. Archive emails immediately after dealing with them. This is how you cross the item off of your to-do list. GMail is also spooky good at giving “nudges” about emails you sent that never got answered, helping you to not lose track of important threads when they leave your inbox.
  5. Use snooze a lot. If you don’t need to work on it soon, snooze it until you do need to work on it. That final report due in December? Snooze until late November.  That speaker you need to arrange visits for? Snooze the “yes I can host” email you sent until the week before they arrive. That thing you’re going to buy this weekend? Snooze until Friday afternoon. Don’t have things in your inbox that aren’t potential action items today or very soon.
  6. Battle the email monster often and efficiently. I “weed” my inbox many times per day. It’s a constant triage, with every email getting one of three dispositions every time I see it:

    1) deal with it and archive it forever,
    snooze it for later, or
    decide you’ll deal with it very soon.
    It’s a good way to spend those odd bits of time between meetings or on a bus where you don’t have time to dig into a big project.

  7. Send yourself emails. If you have an ongoing thing that you need to have on your to-do list (i.e. in your inbox) and there is no associated email for the next short-term task, make one by sending yourself an email with the task as the subject.
  8. Get used to saying “send me an email”. If I’m in a conversation and we generate an action item for me, I make sure there is an email to go with it. You might send it to yourself, you might summarize the conversation at the end in an email to them and you, or (if appropriate) just ask them to send you an email asking for that thing. Now it’s on your to-do list.
  9. Expect that you will archive everything. Plan that every single email will eventually get stored away, the sooner the better. It’s not gone; you’ll find it again because you have Google search. If it’s not on your to-do list, archive it.
    [If you really really can’t not file things because you need that level of organization in your mail: use a label+archive hotkey.  Choose a small number of labels (they’re like folders) and file the emails you’re worried you’ll lose appropriately as you archive them. But: you don’t have to label everything.]
  10. Learn to use the GMail search bar. You can find emails very quickly if you know how to search on sender, dates, and other nifty keywords. This is key: you need to always be able to find any email without spending a lot of time filing them.
  11. Unsubscribe aggressively.  Spam is not to be immediately deleted! Each one is an action item: unsubscribe (if it’s true spam and not just normal marketing you can hit GMail’s “spam” button and better train the AI to keep these out of your inbox in the first place).  Between unsubscribing aggressively and GMail’s spam filter I get very little unwanted mail, which is essential for a well-managed inbox.
  12. Filter out the noise. There are emails you need to have and maybe want to read in batches but don’t really need to read every time they arrive. You can filter them to archive and get a label before they ever hit your inbox. When you want to catch up, go to the label and read them at your leisure, but don’t waste a tiny part of each day acting on them. If you’re worried you’ll never get around to reading them if they’re out of sight, send yourself an email to read them! Now they’re just a single line in your inbox, not many.
  13. Keep it on the first page. If your inbox exceeds your first page (50 or so) you need to sit down and deal with it. This will make you more productive and help with the feeling of doom that comes from having too many emails. Find what is not important to do this week and snooze it. Archive the stuff you just aren’t ever going to get to (maybe send a “sorry I won’t get to this” email first).  Be realistic about what you’re going to do. Don’t guilt pack emails in your inbox!

That’s how it works for me. I know it’s not for everybody, but hopefully there are some nuggets in there you can use.

Technosignatures White Papers

Here, in one place, are the white papers submitted last year to the Astronomy & Astrophysics decadal survey panels:

  1. “Searching for Technosignatures: Implications of Detection and Non-Detection” Haqq-Misra et al. (pdf, ADS)
  2. “The Promise of Data Science for the Technosignatures Field” Berea et al. (pdf, ADS)
  3. “A Technosignature Carrying a Message Will Likely Inform us of Crucial Biological Details of Life Outside our Solar System” Lesyna (pdf, ADS)
  4. “The radio search for technosignatures in the decade 2020—2030” Margot et al. (pdf, ADS)
  5. ” Technosignatures in Transit” Wright et al. (pdf, ADS)
  6. “Technosignatures in the Thermal Infrared” Wright et al. (pdf, ADS)
  7. “Searches for Technosignatures in Astronomy and Astrophysics” Wright  (pdf, ADS)
  8. “Observing the Earth as a Communicating Exoplanet” DeMarines et al. (pdf, ADS)
  9. ” Searches for Technosignatures: The State of the Profession” Wright et al. (pdf, ADS)

And, because it’s relevant and salient: the Houston Workshop report to NASA by the technosignatures community:

“NASA and the Search for Technosignatures: A Report from the NASA Technosignatures Workshop” (Gelino & Wright, eds.)  (pdf, arXiv)

On Watching the Sound of Music as an Adult

As a child, I watched the first two hours of The Sound of Music countless times. We had recorded it off of TV on a VHS top set to short-play mode, and so we only caught the first two hours.  For me, the movie ends with the von Trapps pushing their car away from the house to begin their escape from the Nazis.  I’ve only seen the rest of the movie a few times, as an adult.

As kids, we loved most of the music, we loved the scenes with the kids, we loved “Uncle Max,” and of course we loved Maria.  We generally skipped past the “boring parts” where the adults were talking and “Climb Every Mountain.”  We wanted to see “Do Re Mi” and “Lonely Goatherd”.

My kids have seen it a few times now (2-day rental at the public library) and they love it, too, for the same reasons I did.  But now I love it for different reasons—it’s a rich and brilliant film with lots to offer, much of it contradictory to the reasons I loved it as a child.

Some observations from an adult perspective:

    1. The movie downplays the evil of Nazism.
      As a kid, the Nazis are bad because Georg doesn’t like them and they want him to go to Berlin. In real life, the Nazis were evil because they were genocidal. It’s great to teach kids that “Nazis are bad” but watching as an adult you can’t help but think that the the von Trapps’ troubles are trivial compared to what was actually going on.
    2. “Climb Every Mountain” is great.
      The abbess his some pipes.
    3. Christopher Plummer was a dish.
      We understand Maria’s attraction to him because of the way the camera treats him as a sex object (for instance using soft focus) in a way modern movies usually reserve for women.
    4. Uncle Max is not a good man.
      He makes it clear he’s perfectly happy to collaborate with the Nazis, especially if he’ll make money doing it. The children (in the movie and those watching) love him because he’s so gregarious, but it is only his love for the von Trapps, their money, and Georg’s shaming that makes him help them escape. He doesn’t really deserve the hero status the movie gives him.
    5. Baroness Schraeder is not a villain.
      As kids we see only see her as an antagonist because she stands in between Georg and Maria’s love, and we dislike her because we see her scheming with Max about money, because she doesn’t like to play ball, and because she dreams of of putting the kids in boarding school.But as an adult I find her to be a sympathetic character, remarkable for her strength and maturity.

      A widow, she finds love in Georg, a good and handsome man who loves her for who she is, not for her money. She is desperate for him to marry her, but this is hardly a character flaw for a single, rich, middle-aged European woman in the 1930s. Georg promises the safety, stability, and love we all seek in life.

      She schemes to get Maria out of the house, yes, but wouldn’t we all in her position? And her schemes are all honest: at end of Act I she truthfully tells Maria Georg is falling in love with her, and Maria follows her calling and leaves the house to pursue her vows. It’s what Maria thinks she wants!

      And when it all falls apart and Georg is clearly conflicted, she doesn’t fight to the end. She knows when she’s been beaten, and she saves face by ending the relationship before he can say anything, telling him to follow his heart. Georg’s smile as she breaks it off is one of admiration, respect, appreciation, and love. It’s a brilliantly done scene, and as an adult that has loved and lost I find it remarkably moving.
      Richard Dreyfuss GIF

    6. Julie Andrews is brilliant.
      Especially thinking about the range revealed by her later roles as mature, stern characters, her innocent, effervescent Maria is just a delight to behold.

  1. Julie Andrews and Christopher Plummer’s onscreen chemistry is fantastic

  1. Except for Leisl, the kids aren’t actually in this movie much
    They hardly get any actual lines, and are mostly just caricatures. The exception is Leisl’s hard lesson in love with Rolf, which is really well done.

  1. “I am Sixteen Going on Seventeen” doesn’t hold up.
    It’s a great song, and a beautifully choreographed sequence that wonderfully captures the unstable mix of love and lust that saturates teenagers, but the sexual politics are so retrograde it’s painful to watch.

  1. Mrs. von Trapp looms over the movie
    The children’s mother is rarely mentioned and we learn almost nothing about her except that she loved music and sang to the children with Georg (“I remember, father,” says Leisl, with aching innocence to the pain Georg is in at those words.).

    As adults and parents we are fascinated: Georg’s retreat into a stern taskmaster is clearly a defense against the pain of his loss; Maria’s music and exuberance clearly reminds him of her. We would understand Georg so much better if we could meet her; instead we barely know of her.

  2. Georg is a remarkable man, perfectly portrayed by Plummer
    His fierce morality, unshakable patriotism, strength, and sensitivity shine through the screen. I first saw the “Eidelwiess” scene as an adult, and Plummer nails it, with Georg unable to finish the song until Maria, his children, and the people of Salzburg give him the strength. For me, it’s a highlight of the movie.

The Little Principle

It it ethical to be good to your family?

Since the Renaissance, ethics has been a core subject in the humanities, but it has fallen out of the usual core curriculum at liberal arts schools, but Penn State is reviving the tradition. Many faculty at Penn State have taken ethics training via Penn State’s Rock Ethics Institute, which provides a week-long crash course in the basics and helps us integrate ethics into the curriculum.  The aspiration is that all faculty will be trained and all courses will have an ethics component. I think it’s a great project.

This means that I have just enough training in formal ethics to think about the topic as a sort of educated layperson or hobbyist. I find ethics to be a great way to think through problems and interrogate our motives, but not necessarily a way to arrive at the “right” answer to a dilemma: different ethical frameworks can yield different conclusions, as can bringing different values to the problem (but when all frameworks point to the same conclusion, you know you’ve got a robust answer). Some ethical reasoning is also about justifying our guts’ impulses formally, codifying, explaining, and refining peoples’ collective moral compass.

One paradox I struggle with is between our deep, instinctual tendency to treat our friends and loved ones better than others, and the bedrock principles of fairness that underlie most ethical frameworks. Put simply: there are things I would do for my family I would not do for a stranger, and things I’d do for a stranger I would not do for an enemy. How does that fit in with ethical analysis?

When thinking about this, I call it “The Little Principle,” and I consider it axiomatic. Here it is:

It is appropriate to treat some people better than others. Specifically, one should prioritize those to whom one has an emotional bond over others.

or, more simply: “Je suis responsable de ma rose.”

The name comes from The Little Prince, the classic children’s(?) book by Antoine Saint-Exupéry. It is a primary theme of the book, and is captured best in the lesson the fox teaches the little prince:

So the little prince tamed the fox. And when the hour of his departure drew near—

“Ah,” said the fox, “I shall cry.”

“It is your own fault,” said the little prince. “I never wished you any sort of harm; but you wanted me to tame you…”

“Yes, that is so,” said the fox.

“But now you are going to cry!” said the little prince.

“Yes, that is so,” said the fox.

“Then it has done you no good at all!”

“It has done me good,” said the fox, “because of the color of the wheat fields.” And then he added:

“Go and look again at the roses. You will understand now that yours is unique in all the world. Then come back to say goodbye to me, and I will make you a present of a secret.”

The little prince went away, to look again at the roses.

“You are not at all like my rose,” he said. “As yet you are nothing. No one has tamed you, and you have tamed no one. You are like my fox when I first knew him. He was only a fox like a hundred thousand other foxes. But I have made him my friend, and now he is unique in all the world.”

And the roses were very much embarrassed.

“You are beautiful, but you are empty,” he went on. “One could not die for you. To be sure, an ordinary passerby would think that my rose looked just like you—the rose that belongs to me. But in herself alone she is more important than all the hundreds of you other roses: because it is she that I have watered; because it is she that I have put under the glass globe; because it is she that I have sheltered behind the screen; because it is for her that I have killed the caterpillars (except the two or three that we saved to become butterflies); because it is she that I have listened to, when she grumbled, or boasted, or even sometimes when she said nothing. Because she is my rose.

And he went back to meet the fox.

“Goodbye,” he said.

“Goodbye,” said the fox. “And now here is my secret, a very simple secret: It is only with the heart that one can see rightly; what is essential is invisible to the eye.”

“What is essential is invisible to the eye,” the little prince repeated, so that he would be sure to remember.

“It is the time you have wasted for your rose that makes your rose so important.”

“It is the time I have wasted for my rose—” said the little prince, so that he would be sure to remember.

“Men have forgotten this truth,” said the fox. “But you must not forget it. You become responsible, forever, for what you have tamed. You are responsible for your rose…”

“I am responsible for my rose,” the little prince repeated, so that he would be sure to remember.

The book is elliptical and has some odd moral dimensions, but with this theme it nails something important on the head, something both profound and trivial: you treat those you care about better than those you have never met.

It’s easy to get carried away with individual ethical principles, to take your morality to extremes. I’ve written before about the great evil that comes from following your ideas to their logical conclusions (and also about the importance of radicalism to positive political change). Clearly, taking The Little Principle to its extreme leads to a sort of puerile selfishness, where all of our actions are centered around helping ourselves and those in our in-group, at whatever expense to others. Depending on whom we identify with, this can lead to great evils like genocide, and is contrary to the egalitarian principles of law and democracy. The Little Principle needs to sit next to another principle that all humans (and, I’d argue, much life) is entitled to a minimum level of moral standing. The Little Principle is not license to treat others badly.

But the other extreme—that we owe nothing special to our friends and loved ones—is fundamentally contrary to who we are as humans. Indeed, we don’t even restrict this instinct to other people, but it extends to our pets, our environment, and even whole classes of beings we’ve never met (“Save the Whales!”). The Little Principle states that any useful moral framework acknowledges that individuals can prioritize which others they help and care for.

I think one way to thread the needle is to acknowledge that this prioritization is personal, not universal. I treat my children better than yours, but I also expect you to treat yours better than mine. We do have universal moral responsibilities, but we also have relative ones that depend on who we care about. We can build universal legal and moral structures that themselves eschew the Little Principle, while enshrining it at the individual level. We are “a nation of laws, not of men.” A court will impartially defend the rights of any parent to care for their own children.

It’s an interesting and nuanced issue!

Background to the 2019 Nobel Prize in Physics

Fifty percent of the 2019 Nobel Prize in Physics goes to Michel Mayor and Didier Queloz for the discovery of 51 Pegasi b!  I had a tweet thread on the topic go viral, so I thought I’d formalize it here (and correct some of the goofs I made in the original).

A hearty congratulations to Michel Mayor & Didier Queloz, for kickstarting the field that I’ve built my career in! Their discovery of 51 Peg b happened in my senior year of high school, and I started working in exoplanets in 2000, when ~20 were known.

A thread:

The Nobels serve a funny place in science: they are wonderful public outreach tools, and a chance for us all to reflect on the discoveries that shape science. The discussions they engender are, IMO, priceless.

They also have their flaws: because they are only be awarded to 3 at a time, they inevitably celebrate the people instead of the discovery.

(This technically a requirement from Alfred Nobel’s will, but there are other requirements, like that the discovery be in the past year, that the committee ignores. Also, the Peace Prize is regularly awarded to teams, but the science prizes have never followed suit.)

Anyway, many of the discoveries awarded Nobels are from those who saw farther because they “stood on the shoulders of giants.” The “pre-history” of exoplanets is a hobby of mine, so below is a thread explaining the caveats to 51 Peg b being the “first” exoplanet discovered.

The first exoplanet discovered was HD 114762b by David Latham et al. (where “al.” includes Mayor!) in 1989. It is a super-Jupiter orbiting a late F dwarf (so, a “sun like star” for my money), published in Nature:

Dave is a conservative and careful scientist. At the time there were no known exoplanets *or* brown dwarfs, and they only knew the *minimum* mass of the object, so there was a *tiny* chance it could have been a star. He hedged in the title, calling it “a probable brown dwarf”.

I wonder: if Dave had been more cavalier and declared it a planet, would *that* have kickstarted the exoplanet revolution? Would he be going to Stockholm in a few months?

Meanwhile, Gordon Walker, Bruce Campbell, and Stephenson Yang were using a hydrogen fluoride cell to calibrate their spectrograph. In 1988 they published the detection of gamma Cephei Ab, a giant planet around a red giant star:…331..902C/abstract

They were also very careful. At least four of the other signals reported there turned out to be spurious. They did not claim they had discovered any planets, just noted the intriguing signals. In follow up papers they decided the gamma Cep signal was spurious. Turns out it was actually correct!

Again, what if they had trumpeted these weak signals as planets and parlayed that into more funding to continue their work? Would they have confirmed them and moved on to stars with stronger signals? Would they be headed to Stockholm?

Moving on: in 1993 Artie Hatzes and Bill Cochran announced a signal indicative of a giant planet around the giant star beta Gem (aka Pollux, one of the twin stars in Gemini).

Like gamma Cep A, the signal was weak. Like Campbell Walker & Yang, they hedged about its reality. But again, it turns out it’s real!…413..339H/abstract

Then, in 1991 Matthew Bailes and Andrew Lyne announced they had discovered an 10 Earth-mass planet around a *pulsar*. This was big news! Totally unexpected! What was going on!? They planned to discuss in more detail in a talk at the AAS that January.

But when the big moment came, Bailes retracted: they had made a mistake in their calculation of the Earth’s motion. There was no planet, after all. That made more sense. He got a standing ovation for his candor.

But in the VERY NEXT TALK Alex Wolszczan got up and announced that he and Dale Frail had discovered *two* Earth-massed planets around a different pulsar! They would later announce a third, and that remains the lowest mass planet known.

Some wondered: Was this one really right? Had they done their barycentric correction properly? It held up. The first rocky exoplanets ever discovered, and the last to be discovered for *20 years*.

And there would be more. In 1993 Stein Sigurdsson and Don Backer interpreted the anomalous period second derivative of binary millisecond pulsar PSR 1620-26 as being due to a giant planet. This, too held up.…415L..43S/abstract

Meanwhile, in a famous “near miss”, Marcy & Butler were slogging through their iodine work. They actually had the data of multiple exoplanets on disk when Mayor & Queloz announced 51 Peg b, but not the computing power to analyze it.

If you’re interested in more detail, you can read this “pre-history” in section 4 of my review article with Scott Gaudi here:

None of this, BTW, is meant to detract from Michel & Didier’s big day. 51 Peg b was the first exoplanet with the right combination of minimum mass, strength of detection, and host star characteristics to electrify the entire astronomy community and mark the exoplanet epoch. As I wrote above, they kickstarted the exoplanet revolution. It makes sense that Mayor & Queloz got the prize!

This is to make sure that the Nobel serves its best purpose: educating, and promoting and celebrating scientific discovery.

Happening to See You Again

[This year is the 20th anniversary of Cape Cod Light by Michael Hattersley. The other parts of this series are here.]

Michael survived the AIDS epidemic without infection and died on his own terms, by his chosen vices of cigarettes and alcohol, but the toll the disease on him was inescapable. As with most gay men of his generation, Michael lived with the regular trauma of bad news, of old friends that had learned they were infected, of seeing the obituaries and funerals of friends new and old. And, of course, he lived with and helped manage David’s HIV+ status for around 8 years.

Michael and David on the beach, I would guess Key West in the ’80’s.

Harvey Milk wrote “If a bullet should enter my brain, let that bullet destroy every closet door in the country,” understanding the role tragedy played in gay liberation. AIDS had an analogous effect, forcing hundreds of thousands of gay men to reveal themselves to friends and family: soon people in every demographic group in America knew someone close to them was suffering the trauma of the disease. It was an important part of the sudden and profound shift in American attitudes towards LGBTQ people. The collective sorrow and mass outing of gay men across the country created a fraternity of common experience and grief, and an ever-shrinking group of men who had lived through it all.

The twenty-seventh poem in Cape Cod Light is Happening to See You Again, about meeting an old, pre-crisis acquaintance after many years. The title is much lighter than the content of the poem; indeed it is facetious: this man has sought Michael out for closure of traumas past, not randomly bumped into him.

Michael once told me that he got a phone call from a fan of his poem, which first appeared as Occasion for Poetry in Bay Windows (now The Rainbow Times). Michael had a long discussion about why it resonated so much with the caller. Michael was disappointed when he realized that the caller was under the misimpression that Michael was describing reconnecting with an former lover, when the poem is clearly about an old acquaintance for whom Michael had very little respect, both in their youth and upon “happening” to see them again.

The poem reminds me of a scene (which I probably misremember) in Single Lives, a play by Michael’s friend Sinan Ünel, in which an elderly gay man recounts visiting his decades-estranged wife to get her signature on divorce papers so he can marry his longtime partner. She had expected to be angry upon seeing him; to confront him with all of her grievances and to wield her power over him to have some revenge or closure for his wrongs. But instead she realizes he is not the angry, closeted man she remembers, but a completely different person: the decades have changed them both so much that the old arguments might as well be someone else’s. She signs the papers without incident, having achieved a different peace than she had imagined she would.

Happening to See You Again

When I saw you last night
The guilt fell away
For all the things I didn’t do to you twenty years ago.
So much that’s remembered never happened.
What sticks in the mind are the doubts about ourselves
We attribute to others.
As you clutched me, reaching though the layers of alcohol and Xanax,
As you knelt, weeping, between the urinals,
As you recalled the imagined treason all about you,
And pounded the tiles for justice, I remembered the same days
Gaudy with the first tastes of physical love,
Decked with lazy afternoons, and long nights festive at the bars.
Now you spend your hours washing the bodies of the dying
And dream of a world without disease on the beaches of California.
I know why you seek me out.
How many of us from those days are left alive?
Everything must be made right within the narrowing circle
As if the imagined slights happened yesterday.
How many times will you be condemned again to live,
To make sure a lover is firmly in the nest so you can betray him
Proving, once again, the world desires you,
Carefully scabbing the scars of future tears?

The next poem is here.

Measuring Rocky Exoplanet Compositions with Webb

Back in June 2016 I advertised a postdoctoral position between me and Steve Desch at ASU for someone to work on the problem of exoplanet interior compositions.

Normally, the way we determine the interior composition of exoplanets is a combination of inference, measurement, and guesswork.  In the Solar System we can study the surface compositions of planets directly, get the bulk density by dividing masses by radii cubed, and a sense of internal structure by looking at how the surfaces have changed or what a body’s gravitational field says about the interior mass distribution. It’s amazing how much we can determine about, say, the interior of Europa!

Evidence from NASA’s Galileo mission suggested that there might be a liquid water ocean underneath Europa’s icy crust. Image credit: NASA/JPL

On Earth we can also use seismology to directly probe the density and composition of the Earth’s interior.  Some things we still don’t know to great precision (the water content of Earth’s mantle is still pretty uncertain, though it’s small) but in general we have a good sense of what’s down there, despite having a very limited set of actual samples from far below the surface (from volcanos, mostly).

Based on this we have a good sense of how the planets formed, and so we can make good inferences and guesses about the parts we don’t know about yet. For instance, we suspect that Jupiter formed around a rocky core of about ten times the mass of the Earth; one of the purposes of Juno is to see if we can better determine Jupiter’s inner composition and perhaps check this model prediction.

This artist’s concept shows the pole-to-pole orbits of the NASA’s Juno spacecraft at Jupiter. Image credit: NASA/JPL-Caltech/SwRI

Exoplanets are much harder.  We generally can measure their masses from radial velocities and radii if they transit, and for planets for which we have both we have bulk densities. By analogy with Solar System planets we can then guess that they have similar compositions to those, and from the compositions of their host stars we can make inferences about how they might differ. But getting anything like a mantle or surface sample seems impossible.


There is a whole class of planet recently discovered by Kepler (Saul Rappaport and Roberto Sanchis Ojeda did a lot of the pioneering work here) that appears to be evaporating. The transit signatures of these things is amazing; they vary in depth (sometimes disappearing entirely!) and don’t have the usual shape of transiting planets. Apparently, these are small rocky bodies  (which have orbital periods of less than a day and which are too small to see transit at all) have gigantic, variable tails of rock that is condensing from a plume of surface material evaporated by the intense heat of their parent star.

Screen shot 2013-03-09 at 5.24.42 PM.png
Transits of KIC 12557548, from Fig. 2 of Rappaport et al. 2012
Here’s an artist’s impression:

Exoplanet KIC 1255b orbits its parent star followed by a comet-like dust tail. Image credit: Maciej Szyszko.

So by now maybe you’ve spotted the opportunity: that background star is a great lamp to pass light through that material so we can figure out what it’s made of!  Is it mantle material? Is it core material?  It it hydrated?

Studies of white dwarf “pollution” can measure the bulk, relative elemental abundances of material from presumably rocky planets that have crashed into the white dwarf, but here we have the opportunity to study chemical composition of one particular layer of a distant rocky exoplanet—we can’t even do this for the Earth!

But will it work? Are the transits deep enough? Can we distinguish different minerals with spectroscopy? Are there any stars bright enough for this?

Yes to all.  ASU/NExSS postdoc Eva Bodman has all the details in her latest paper. It’s an exciting time!

Eppur si muove

We sometimes read in the history of astronomy that it was Bessel that finally proved the Earth moves around the sun with the measurement of the parallax of 61 Cygni, one of the brightest and closest stars to Earth in the Northern Hemisphere.

This is because people early on realized that if the stars are different brightnesses because they are at different distances, and if the Earth really does move around the Sun, then we should see the nearby ones appear to move with respect to the background ones annually as our light of sight towards them changes.  The effect is quite small, and it was challenging for 18th and 19th century astronomers to measure the tiny effect using only their eyes to make measurements (the biggest parallaxes are like a part in a million).

And so astronomers put a lot of effort into this, and indeed eventually Bessel pulled it off. But the clinching observational proof actually came about 100 years earlier, based on those same observations!

Astronomers were expecting to see a “reflex” motion: when the Earth moved in one direction the nearby stars would appear to slightly move in the opposite direction, so when the Earth was at one extreme of its orbit they would appear to be a bit closer to the center of Earth’s orbit (i.e. the Sun) than they should be.  Instead, astronomers kept measuring a much larger than expected motion (around 20 arcseconds instead of less than 1 arcsecond) in the wrong direction: the stars seemed to move towards a point about 90 degrees away from the Sun, towards the ecliptic.

This is what was actually happening, but it was actually pretty confusing at the time.  One way they were measuring positions was by using the zenith as an absolute direction (you can use a plumb or a liquid to determine which direction is straight up) and a telescope to see how close stars got to the zenith as they passed overhead.  So they could only measure one component of the star’s motion, so all they knew is that it was large and had the wrong phase (90 degrees from what was expected).

What was actually going on is that the stars were suffering from aberration. Imagine you have a trash can an you want to collect as much rain as possible.  If there is no wind, you should just keep the can vertical.  But, if you are on the bed of a pickup truck moving at 10 mph, then some of the rain that would have fallen into the can will hit the side instead.  To maximize rain collection, you have to tip the bucket towards the front of the truck (i.e. in the direction of the truck’s motion) to get the rain to go straight down into the can.

Wikicommons illustration of the aberration of starlight. Original here. By Brews ohare, CC BY-SA 3.0.

Similarly with telescopes: to get starlight to go straight down the optical axis of the telescope, you actually have to “lead” the motion of the Earth slightly by pointing in the direction of Earth’s motion.  This effect is equal in radians to the speed of the Earth’s orbit divided by the speed of light, or about 20″.  This is what was being observed, and this is what Bradley finally figured out in 1727.

You can learn more about this history here. Interestingly, Bradley’s original paper describing the aberration and proving the Earth moves has only one citation in ADS!

So while hunting for the proof of Earth’s motion, astronomers actually discovered a much easier to find proof of Earth’s motion!  But it took decades to understand it.

Today, it’s tricky to repeat these measurements with modern equipment. Finding the zenith to a precision of 1″ is not something most observatories are set up to do; we almost never use high precision, absolute positions with respect the ground in astronomy any more (our instruments tend to change their pointing with temperature, humidity, and other factors, so we calibrate them on actual star positions every now and again to keep our pointing models accurate and precise).

But interestingly, there is a way most college observatories and many amateur ones can find an absolute position: star trails!  By turning off tracking and letting the stars trail, one can identify the center of the trails as the true Celestial Pole.  As the Earth goes around the Sun, one can measure star positions with respect to that and detect the aberration, thus proving the Earth orbits the Sun.

Of course, there are lots of other ways to do this: you could build an R~10,000 spectrograph and feed it light from stars on the ecliptic and measure the Doppler shift caused by Earth’s motion, or you could measure the parallax directly with differential astrometry, like Bessel did. But this is a novel solution that actually doesn’t require special equipment of good seeing, just an ordinary camera.

I was going to try this someday, and even wrote up a whole blog post about it, but finally decided that if I haven’t started by now I probably never will, so I’ve “given the idea away” in the form of a Research Note to the AAS (my sixth!).  One reason I never started is that although the equipment needed isn’t special, there are lots of complications.  One is that the Poles move on their own (due to Earth’s axial precession) so you have to remove that effect first.

As part of my plan to learn Python and Astropy I tried to make a figure showing how the apparent position of the true Celestial North Pole moves with respect to the background stars, showing the precession and the aberration.  It was surprisingly tricky!  Plotting things near coordinate singularities is not something most plotting software does well, so in the end I cheated and just plotted things as a plane chart in ecliptic coordinates and drew the Celestial coordinates in by hand.  I think it came out really well:

Figuring out how to calculate the motion of the Celestial Pole (also affected by nutation) was tricky; it turns out Astropy does not expose those functions to the user so I had to cheat.  In the end, I did it two ways that gave the same answer: I asked for the ICRS (astronomical) coordinates of the zenith at the North Pole of Earth.  Astropy converts from geocentric coordinates to barycentric coordinates by correcting for the orientation of the Earth (the axial motion) and the aberration, so this yields the green curve above.  Almost equivalently, one can ask for the Celestial Pole in CIRS coordinates (the intermediate coordinate system between the Earth and Celestrial Sphere) at many times and then ask Astropy to convert these positions to the ICRS frame.   The latter is faster.

To learn more, you can read my research note describing the experiment here.  And if you try this, please let me know!


A Needle In A Haystack

Where does the old idiom “finding a needle in a haystack” come from?

According to my physical copy of Bartlett’s Familiar Quotations, the phrase originates with Cervantes in Book III Chapter X of Don Quixote, and indeed most searches online state so with authority.

But I just checked my physical copy and the Project Gutenberg version and not only is there no  Book III, the phrase does not appear!

Some sleuthing of other phrases that do appear reveals that “Book III” refers to what is normally called “Part II”, and indeed there in Chapter X of my copy it reads:

…tracking Dulcinea up and down El Toboso will be as bad as looking for a needle in a haystack or for a scholar in Salmanca.

just as promised.  So why isn’t it in the Project Gutenberg version? There it reads:

looking for Dulcinea will be looking for Marica in Ravena, or the bachelor in Salamanca.

which is not the same thing at all. Indeed, the Spanish original seems to read:

buscar a Dulcinea por el Toboso como a Marica por Rávena, o al bachiller en Salamanca.

So the phrase is actually not in the original!  It seems to be due to Cervantes’ English translators who used the phrase as a more familiar [to English ears] version of “to find Maria in Ravena”.  Bez Thomas helped me to figure this out on the Twitters:

So where does the phrase “needle in a haystack” originate?  The OED has two attestations that predate Cervantes:

c1530   T. More Let. Impugnynge J. Fryth in Wks. (1557) 837/2   “To seke out one lyne in all hys bookes wer to go looke a nedle in a medow.”
1592   R. Greene Quip for Vpstart Courtier sig. Ev   “He…gropeth in the dark to find a needle in a bottle of hay.”

Where a “bottle” here means “bundle”.  Apparently the translators were using a 100+ year old phrase!   The “haystack” version is from later:

1779   W. Rogers in J. Sullivan Jrnls. Mil. Exped. (1887) 262   “But agreeably to the old adage it was similar to looking for needles in a hay stack.”

And there you have it.  Even an authority as solid as Bartlett’s occasionally gets things wrong, so it’s good to check!


[Update: Apparently Bartlett’s is full of these errors with respect to Don Quixote: see this article here which details the “haystack” mistake and many more.]

Smooth continuum stars and RNAAS

We can tell what stars are made of by the colors missing from their spectra, but that’s not really true for hot, rapidly rotating stars. These stars lack convective envelopes, so they lack magnetic dynamos, so they do not spin down as they age. As a result of their rapid rotation, the Doppler shift blurs out their lines and its hard to get a precise measurement of their abundances (except hydrogen, whose lines are so deep you can’t miss them, even blurred out).

But one astronomer’s trash is another’s treasure. These rapidly rotating stars make great sources of light for calibrating spectrographs because you can be sure that any spectral features you *do* see are due to your instrument, not the star. And these stars can be very bright, so it’s a quick test.

The problem is that not all hot stars rotate quickly enough to be “good” calibrators. For instance, here’s what a small portion of a rapid rotator looks like:
This star’s spectrum is flat (or slightly sloped) in this small region of the blue.  The overall mountain shape is the response of the spectrograph, which this star lets you model.  The “fuzz” is photon noise—by chance some channels get more photons than others.  The spike in the middle is a “cosmic ray” event—a high energy particle from somewhere in the dome struck the detector and caused a spike.  The only thing here that’s due to the star are some barely perceptible wiggles.

Here’s a “bad” calibrator star, that is not spinning fast enough to be a “good” calibrator:

Not smooth at all!  Those “bites” taken out are due to elements in the star’s atmosphere absorbing certain shades of blue light, and the bowl shape is due to the way different parts of the stellar surface are moving towards and away from us as the star rotates.

So which stars are “good” and which are “bad” for calibrating high resolution spectrographs Published values of their rotation speeds turn out to be an unreliable guide for this, so observers over the years make lists of “good” hot star calibrators.  For instance, when I need a “good” hot star, I ask Howard Isaacson at Berkeley, who has a list carefully compiled by Kelsey Clubb.  At Berkeley, Kelsey Club went through the California Planet Survey’s library of hot star spectra and separated the wheat from the chaff, which is really useful!

This sort of list isn’t usually publishable—it’s not the sort of scientific advance or discovery that usually warrants a peer-reviewed paper.  But it is the sort of thing scientists should share and that Kelsey should get credit for.

Now, thanks to the new AAS journal “Research Notes of the American Astronomical Society”, we have a good way to share the list.  This new journal is not peer reviewed, but it is free, curated, and has a science editor who accepts papers. They can only be 1,000 words, have one figure or table, and they do not have to be new or novel or anything—just interesting.

But why not just put it to the arXiv, and skip the 1,000 word limit thing?  Well, Geoff Bower asked the same thing on the Twitter, and I came up with two big reasons: RNAAS will curate machine-readable tables, which is great, and as a AAS journal, if your result is (unlike this one) newsworthy, it might get picked up by AAS Nova.  Editor Chris Lintott points out a third:

Anyway, as a journal that emphasizes utility and curates tables, it is the perfect place for Kelsey’s list, so that’s where we published it.  You can find it here.

I was actually worried this would happen.  When RNAAS came out, and then when Overleaf linked directly to it for submissions, I got worried I’d like it too much:

and (despite my misspelling of RNAAS) I was right.  I’ve now submitted or supervised five of these. Here are the others:

Tabby’s Star Explanations

‘Oumuamua Is Almost Certainly Interstellar

EPRVIII Instruments

Barycentric Corrections in Python

I may have a problem…

Planets in Clusters

As we study more and more exoplanets, one variable that we have not really gotten a great handle on is age.  There are not many planets orbiting stars with very well constrained ages. We’d like to be able to see how, for instance, young planetary systems differ from old ones to study planet-planet scattering, planetary migration, and other effects.

So there have been many studies of planets orbiting stars in star clusters.  Clusters are great laboratories for stars because the stars formed (mostly) at the same time out of the same stuff. The repurposed Kepler mission K2 was great for this because it looked for planets along the Ecliptic Plane, and by a bizarre coincidence almost every important benchmark cluster is in the ecliptic!

Jason Curtis, NSF postdoctoral fellow a Columbia University

Jason Curtis is a Penn State grad now an NSF postdoctoral fellow at Columbia working on the problem of stellar ages and activity, using the topic of his PhD thesis, the nearby open star cluster Ruprecht 147. He campaigned to get NASA to repoint K2 to make sure it would capture the stars of Ruprecht 147 so we could study its properties (and, you know, maybe find some planets).

And it worked! He has now written up the paper, and you can find it on the arXiv, in particular the new hot Neptune K2-231b.

But even more useful, to my mind, than the 231st K2 planet is that this planet has a well constrained age.  If we get a lot more, we can look for those trends we’d like to study about how systems change with age.  Jason helpfully compiled a list of all known planets in clusters, and there put them together in one big table. I imagine that with TESS we’ll end up with so many you won’t be able to fit them on one page, but for now here they are, with references.  For the full thing with working links, be sure to read the paper!


SETI Jargon

SETI has a jargon problem. This is not news; I think everyone in the field appreciates that we need to be more consistent in the words we use.

One reason this matters is that the search for alien technology is really a very broad endeavor (best thought of, I have argued, as a subfield within astrobiology). It includes not just radio astronomy  but infrared astronomy, optical and NIR instrumentation, exoplanets, Earth system science, game theory, social sciences such as anthropology, galactic astrophysics, stellar astrophysics, time-domain astronomy, computer science, multi-messenger astronomy, planetary science, remote sensing, media and communications, law, and political science.

These fields all have their own jargon, and if we want them to be part of SETI we should avoid misappropriating their jargon.  For instance “civilization” has concrete and jargon meaning in anthropology and archaeology. I imagine anthropologists at our meetings wincing every time we use the term in a very different (vaguer, more generic) way than they do.

Indeed, “intelligence” itself is problematic and not an ideal term. The term is nebulous (is an ostrich intelligent? Is a bee colony?) but also presumes much about how an alien species’ psychology works.

Why shouldn’t we assume aliens will be “intelligent” or have “civilizations”? As many have noted, we should not assume that the first extraterrestrial technological species we discover is anything like us: it might not be a collective of individuals, might not be “conscious” in the way we are, might not organize itself with anything like politics, might not be animal, might not be planet-based, etc. etc. etc. Science fiction is filled with potential SETI signals of things that look nothing like “civilizations”, from Hoyle’s Black Cloud to the Borg to the Monolith.

Even more than being careful in not misusing established terms, many have noted that we use many of our own terms inconsistently (Iván Almár has been particularly persuasive on this point, and I’m certainly guilty on this score.)

So, as part of the SETI Institute’s Decoding Alien Intelligence workshop this month and in response to Nathalie Cabrol’s call for white papers an broadening our conception of SETI, I submitted something about how we think about SETI as a field and the jargon we use.

I couldn’t make it, but Penn State graduate student Sofia Sheikh went and presented the paper for me.

My recommendations:

First of all, the field needs a name. The term SETI has variously been used to refer strictly to radio searches, specific NASA programs, to any search for communication, and broader searches, and has been used both to include and to distinguish from efforts such as searches for artifacts.

I agree with Almár that SETI should be the name of the entire field. One problem is that this it includes “intelligence”, which I have just argued is not a good term, but I feel that “SETI” is such a strong “brand” at this point—such a well-known and widely used term—that I think it is best to use it in a jargon sense of “whatever distinguishes technological species from other species that makes them easier to detect because of their technology”.  A rebranding is very unlikely to be successful (I would support it if everyone agreed to start using a single better term).

Having adopted “SETI” as the name of the field because of something like stare decisis, it follows that the term “ETI” is what we are looking for, again in a jargon sense.

I also like Almár’s definition ““the collective name of a number of activities, based on science, aimed to detect messages, signals or traces” of extraterrestrial intelligence.

I also really like the term technosignatures (whose origin I’ve been trying to track down, see this tweet:)

But again, we use it inconsistently.  I prefer the term to include any technological signature, including communication, both because that is the term’s natural meaning and because the contrast with biosignatures helps identify SETI’s place within astrobiology

I like to divide SETI into several classes, including communication SETI and artifact SETI, being the searches for deliberately transmitted information carriers and the effect of technology on the environment.  Other terms for the latter abound (technomarkers, Dysonian SETI, SETA…) and we should settle on one.

Within artifact SETI then there are lots of ways of searching: waste-heat SETI, probe SETI, Solar System SETI, and so on.

METI or active-SETI would also then constitute a subclass of SETI.

Paul Davies coined the term “nature-plus” which is the best term I’ve seen to describe the idea that alien technology could be so advanced that it will look like a force of nature; this could include contamination of stellar abundances, artificially modulated Cepheid variable stars, or even something like Hoyle’s Black Cloud.  It’s not exactly what Davies intended, but its the best label I could find for this kind of search.

Finally, I think it’s important to define a beacon as a signal or artifact meant to be discovered by strangers. The term has been used in other ways, but this is the term’s most natural meaning, and helps us identify which sorts of signal searches can be informed by the concept of a Schelling point. The latter term has many many names in the filed (“strategy of mutual search”, “convergent search strategies,” “attractor for SETI”, “synchrosignals”) generated as people rediscover Schelling’s insight, but we should honor game theory’s prior art here and recognize the value of needing to think about assumptions of common knowledge that we make when looking for “magic frequencies” and such.

Finally, we should avoid terms like “colonize” and “alien race” because of the social baggage they bring along. (This is not because I think we should be PC, but because we should be precise: if you really do mean to project our notions of colonization and race onto alien species with whom we share no evolutionary descent, much less culture, then by all means use those terms).

So that’s my reasoning and set of preferences for jargon, but I recognize this needs to be a collective decision in the community, and I suspect that the final answer will arise collectively and organically, and not by fiat.  Already we’ve received good feedback (CETI is probably its own category, distinct from METI, as Jill Tarter pointed out; “artificial” is a difficult and probably problematic term we should define better, as Frank Drake has pointed out).

Anyway, I think Sofia’s presentation will be public at some point, and the paper is available here at the conference website, and an updated version with the figure below is on the arXiv here.

SETI as Astrobiology-t593u0

Milton’s Cosmology Leaned Heliocentric

It’s a home day for me with the flu, so to recover from a long day of videoconferencing meetings, and because a headache won’t let me concentrate on important stuff, I played around with an idea I wrote up as a high school English project.

Milton wrote the epic Paradise Lost, in which he presents his own cosmology of Heaven, Hell, and Earth. This was an ambitious task, since Dante’s Divine Comedy had set a pretty high standard here.

The geometry of Creation in the Divine Comedy (not to scale) with Hell inside the Earth and heaven outside the final sphere in a Ptolemaic universe.

Milton actually met Galileo in person—he visited Galileo’s estate as a boy when the astronomer was there in his later years under house arrest.

The visit may have left an impression. Milton avoids any reference to where the center of the Solar System is in his cosmology—it’s pretty nebulous exactly how everything is arranged—but in Book 4 the angel Uriel needs to get back to his station in the Sun from Earth. He slid down to Earth on a sunbeam, but fortunately for him the Sun has now set, so the tip of his sunbeam is now up in the air. He just jumps on and slides down:

 …and Uriel to his charge
Returnd on that bright beam, whose point now rais’d 
Bore him slope downward to the Sun now fall’n
Beneath th’ Azores

but how did the Sun get so low? It is “beneath th’ Azores” far to the West:

whither the prime Orb,
Incredible how swift, had thither rowl’d
Diurnal, or this less volubil Earth
By shorter flight to th’ East, had left him there

The “prime Orb” is Ptolemy’s name for the Sun, which had (“incredible how swift”) there “rowl’d Dirunal”—rolled down there over the course of the day.  But Milton did not choose his words lightly.  “Incredible” literally means “beyond credibility”.  He doesn’t buy that it really goes so fast.

Is there an alternative?  Milton dithers.  “Or” he writes “this less volubil Earth” (meaning “less apt to roll” according to the OED) went a much shorter distance the other way and the Sun just stayed where “he” was.  That’s Copernicus’s model for the days!

So he clearly prefers Copernicus’s model, and offers it as an alternative, but opens with the more familiar and established terminology and cosmology of Ptolemy (and Dante).

It’s interesting he didn’t commit.  Perhaps he didn’t want to tie his work to a model that might be wrong, or perhaps he didn’t want to alienate his Ptolemist readership.

I wonder, though, if heliocentrism had been widely accepted a century before, if Paradise Lost would have had a well defined geometry of the universe, like the Divine Comedy famously does, but with Heaven and Hell having distinct places in a heliocentric Solar System?


Maunder Minimum Analogs

For a long time after sunspots were discovered telescopically by Galileo, there weren’t any to see. John Eddy has a nice paper on the history of sunspot measurements, showing conclusively that there was an 80-year period, now called the “Maunder Minumum”, in which the Sun just didn’t have any sunspots.

Why not? We’d love to know.  The Solar dynamo is a bit of a mystery, and it just apparently turning off for 80 years is kind of important—it may have even had an effect on climate on Earth, although that case is often overstated (it’s not glaringly obvious from the global temperature anomaly record).

Shivani Shah, Penn State undergrad now applying to a graduate program near you!

Finding another star undergoing such a period would be great. We could study its corona and chromosphere it answer questions like: Is it still undergoing its magnetic cycle, just without sunspots? Is it just an extended minimum that lasts many cycle periods? Or did the dynamo turn off entirely? If we had a sample of them we could ask: is this typical behavior of Sun-like stars? All cycling stars? Just stars of the Sun’s age?

For a while, people looked for extremely inactive “sun-like” stars to find “Maunder minimum stars”, but I showed in my thesis that these stars are in fact not Sun-like (they’re subgiants).

People looked in M67, a cluster filled with Sun-like stars, to find extremely inactive stars there, but Jason Curtis showed that these stars were not actually all that inactive (the ISM got in the way).

For a long time Steve Saar has advocated using time series to see a star do what the Sun apparently did: go from a cycling state to a quiet state (or the reverse).  This means using the 50+ year baseline of activity measurements we have of stars to find a cycling star that transitions into or out of a cycling state to a “flat activity state”.  That would make for a pretty convincing candidate, I think.

Well, now we have one! Shivani Shah has written up the strange case of HD 4915, a Sun-like star that seems to have had its cycle peter out to almost nothing.  Here’s the killer plot:

Activity history of HD 4915. Larger “S-Value”s mean (presumably) more starspots. Note that the star came down from a (presumed) maximum, came up to a second, weaker maximum, then had a very slow rise to what seems to be a very weak maximum. Is the magnetic cycle of this star dying out?

It’s cool to see something that looks a lot like what we’ve been expecting to see for a while.  For comparison, here are the “grand magnetic minima” the Sun has experienced, measured with sunspots:

Sunspot number vs. time for three magnetic state transitions on the Sun, from the Hoyt & Schatten 1998 historical reconstructions. Note that we have reversed the x-axis on the bottom panel.


Black dots above are the parts of the Solar record we are suggesting to be analogous to the HD 4915 time series.  The red points are our projections of its future behavior if the analogy is perfect.  So, if this is analogous to the “Dalton Minimum” (no, not that Dalton Minimum) then the next cycle should be rather strong; if it’s truly going into a Maunder Minimum-like state we may not see any activity for another 80 years! So only time will tell if this is right, but I think it’s the best candidate I’ve seen so far.  I hope that by studying this star we can finally crack the nut of what the Sun was doing without sunspots for all those decades!

The paper is on the arXiv here.  Comments welcome!

SETI is Not About Getting Attention

No, this isn’t a post about METI.  This is about an interesting sociological phenomenon about one of the ways in which SETI is marginalized in astronomy.

SETI tends to get media attention, at an amount disproportionate to the amount of SETI work actually done. There are many reasons for this. One is that it is a topic of genuine interest to much of the lay public.  Another is that it is easily sensationalized and conflated with UFOlogy and science fiction by the yellow press.

I’ve had my share of both sides. Take Ross Andersen’s excellent article on Tabby’s Star (which was a scoop; we did not put out a press release or publish anything that triggered it). This story got huge amounts of global media attention, to the point that it appeared on Saturday Night Live and the Tonight Show. This second wave of stories led to the perception that Tabby herself “jumped to aliens” as an explanation, when in fact her paper and press release made no mention of aliens, and the press release announced “comets” as the cause.

The Daily Mail is a sensationalist rag in the UK that seems to have decided I’m their go-to name for all things alien. Sort of like the way that they find a way to shoehorn Stephen Hawking into the headlines of any article they write about space, but to a much smaller degree, they seem to love to claim I’ve found aliens (or that I think I have) when I write the opposite in a public space.  For instance:

  1. I had a press release titled “Search for Advanced Civilizations Beyond Earth Finds Nothing Obvious“.  The Mail Online’s lede was that I had “found 50 galaxies that may contain intelligent alien races.”
  2. I wrote a paper whose premise was that the question of extraterrestrial life (of any kind) in the Solar System is an “open question”, and in particular that the Solar System apparently lacks any alien artifacts.  The Mail Online article’s subheads claimed that I believe that intelligent “aliens either lived on Earth, Venus or Mars billions of years ago.”
  3. And when I wrote a couple of blog posts about how I didn’t think ‘Oumuamua was a great SETI target (but that it should get us thinking about Solar System SETI), they again reversed my meaning and wrote that I claimed ‘Oumuamua “could be an alien spacecraft with broken engines.”

It’s pretty embarrassing to see your work so brazenly sensationalized in the media, but given the Daily Mail’s reputation I’m not sure there’s anything I could have done to prevent it except not talk about SETI at all where it might be overheard. I’ve developed a thick skin about it, but it still smarts to see my name next to pictures of bug-eyed aliens.  I know that colleagues of mine that don’t know the whole story will think less of me because of these false portrayals of me working on “fringe” science or shouting “aliens” at every astronomical anomaly.

Actual image the Daily Mail used in an article quoting me about an asteroid.

So it’s especially galling when my colleagues accuse me of sensationalizing my work or, worse, only working in SETI at all because I’m after media attention. This attitude is probably widespread, because a few fed-up people have lost their cool and announced it several times in rants online; I can only imagine how many more have kept their cool or only said it where I haven’t noticed.  Some examples (names and links omitted to protect the guilty):

  1. About a short ETI discussion in a longer paper (that did not seek or garner any headlines)
    What does the mention of alien civilizations really add to these topics other than an attempt to grab headlines?
    What’s to be gained by a casual mention in the abstract and end of the paper? … this (along with a growing list of other examples in the literature) is an attempt to grab headlines.
  2. Rebutting an argument that there is nothing wrong with seriously discussing SETI angles of astronomical anomalies on social media:
    All fine, but there is another component of this, which is cynical citation of ETI as a simple way of gaining attention. Your discussion assumes earnest and honest motivations. I’m not sure that that is always true.
  3. Starting a discussion about how SETI astronomers need to stop sensationalizing their work:
    most SETI-related news seems to be interfering with conventional scientific discoveries, stealing the limelight – without following basic rules of science
  4. Piling on to that discussion:
    It’s not just SETI you should be dumping on here, if your overall argument is to stop selling bullshit to the media because it’s fun.

At the risk of making an analogy to an infinitely more serious problem, they’re blaming the victims. Here we are getting misquoted and caricatured in the yellow press, and they’re the ones that are offended and embarrassed at what we have put them through. To them, somehow it’s our fault that the Mail misquotes us, and their attitude is that if we didn’t want to be misquoted, then why were we doing that kind of science in the first place? 

The real bad actors here are the yellow journalists, and that is a problem all of us in science and science communication have to deal with all the time; SETI is just a particularly soft target for them.

So, for the record: this kind of media attention is not “fun,” it’s mortifying, and we are not asking for it when we discuss our work in public. Many of the above accusations were surrounded by claims that the writers respect SETI as science, but you don’t really respect scientists’ work if you think it’s irresponsible of them to talk about it out loud, or if you think the only reason they do it is so that they can get their names in the papers.

SETI astronomers have had to deal with conflation with UFOlogy and fringe psuedoscience for decades; I hope that more of our colleagues will recognize that we share their disdain for sensationalism and are pulling in the same direction on the issue of sober science communication about good science.

And I hope that they won’t cast scorn at every SETI paper or reference to ETIs in the literature (“astro-crap” one astronomer called it on Facebook), and not cast aspersions on the authors for working on an important problem (especially junior researchers, who are both the future lifeblood of the field and the most sensitive to these accusations).

SETI gets enough unjustified grief from Congress, the last thing we need is to have to worry about our colleagues in our flanks piling on.

SETI is Part of Astrobiology

What follows is my submission to the National Academies of Sciences, Engineering, and Medicine ad hoc Committee on Astrobiology Science Strategy for Life in the Universe, 2018. It is available as a PDF here.

Please also see Jill Tarter’s companion white paper here.

I. SETI is Part of Astrobiology

“Traditional SETI is not part of astrobiology” declares the NASA Astrobiology Strategy 2015 document (p. 150). This is incorrect.1

Astrobiology is the study of life in the universe, in particular its “origin, evolution, distribution, and future in the universe.” [emphasis mine] Searches for biosignatures are searches for the results of interactions between life and its environment, and could be sensitive to even primitive life on other worlds.  As such, these searches focus on the origin and evolution of life, using past life on Earth as a guide.

But some of the most obvious ways in which Earth is inhabited today are its technosignatures such as radio transmissions, alterations of its atmosphere by industrial pollutants, and probes throughout the Solar System. It seems clear that the future of life on Earth includes the development of ever more obvious technosignatures. Indeed, the NASA Astrobiology Strategy 2015 document acknowledges “the possibility” that such technosignatures exist, but erroneously declares them to be “not part of contemporary SETI,” and mentions them only to declare that we should “be aware of the possibility” and to “be sure to include [technosignatures] as a possible kind of interpretation we should consider as we begin to get data on the exoplanets.”

In other words, while speculation on the nature of biosignatures and the design of multi-billion dollar missions to find those signatures is consistent with NASA’s vision for astrobiology, speculation on the nature of technosignatures and the design of observations to find them is not. The language of the strategy document implies NASA will, at best, tolerate its astrobiologists considering the possibility that anomalies discovered in the hunt for biosignatures might be of technological origin.

But there is no a priori reason to believe that biosignatures should be easier to detect than technosignatures—indeed, we have had the technology to detect strong extraterrestrial radio signals since the first radio SETI searchers were conducted in 1959, and today the scope of possibly detectable technosignatures is much larger than this. Furthermore, intelligent spacefaring life might spread throughout the Galaxy, and so be far more ubiquitous than new sites of abiogenesis. Life might be much easier to find than the NASA strategy assumes.   

Indeed it has been cynically, but not untruthfully, noted that NASA eagerly spends billions of dollars to search for “stupid” life passively waiting to be found, but will spend almost nothing to look for the intelligent life that might, after all, be trying to get our attention. This is especially strange since the discovery of intelligent life would be a much more profound and important scientific discovery than even, say, signs of photosynthesis on Ross 128b.

Further, since technosignatures might be both obvious and obviously artificial SETI also provides a shortcut to establishing that a purported sign of life is not a false positive, a major and pernicious problem in the hunt for biosignatures. SETI thus provides an alternative and possibly more viable path to the discovery of alien life than is reflected in NASA’s astrobiology roadmap. Indeed, this was recognized explicitly in the panel reports of the Astro2010 decadal survey:

Of course, the most certain sign of extraterrestrial life would be a signal indicative of intelligence. [A radio] facility that devoted some time to the search for extraterrestrial intelligence would provide a valuable complement to the efforts suggested by the PSF report on this question. Detecting such a signal is certainly a long shot, but it may prove to be the only definitive evidence for extraterrestrial life. (p.454, Panel Reports—New Worlds, New Horizons in Astronomy & Astrophysics)

II. Why is SETI Neglected in NASA’s Astrobiology Portfolio?

While it is not completely clear why NASA does not include SETI in its astrobiology portfolio, there are several factors that seem likely to be at play.

The first is the risk of public censure: SETI sometimes suffers from a “giggle factor” that leads some to conflate it with “ufology” or campy science fiction. Indeed, such an attitude likely led to the cancelation of the last NASA SETI efforts in the early 1990’s, after grandstanding by US senators denouncing “Martian hunting season at the taxpayer’s expense” (Garber 1999). Such attitudes harm all of science, and the National Academies should be clear that such a “giggle factor” must not be allowed to influence US science priorities.

The second is the erroneous perception that SETI is an all-or-nothing proposition that yields no scientific progress unless and until it succeeds in detecting unambiguous signs of interstellar communication. On the contrary, even with scant funding, SETI has historically been involved in some of the most important discoveries in astrophysics. Not only have the demands of radio SETI led to breakthroughs in radio instrumentation (see, for instance, the new Breakthrough Listen backend at the Green Bank 100-meter telescope, with bandwidth of up to 10 GHz, an ideal Fast Radio Burst detection device; Gajjar et al. 2017), but some of the most famous SETI false positives have proven to be new classes of astrophysical phenomena, including active galactic nuclei (CTA-21 and CTA-102, Kardashev 1964), pulsars (originally, if somewhat facetiously, dubbed “LGM” for “Little Green Men”), and perhaps the still-not-fully-understood “Tabby’s Star” (KIC 8462852, Boyajian et al. 2016, Wright et al. 2016, Wright & Sigurdsson 2017).

Indeed, exactly because SETI seeks signals of obviously artificial origin, it must deal with and examine the rare and poorly understood astrophysical phenomena that dominate its false positives. Anomalies discovered during searches for pulsed and continuous laser emission (Howard et al. 2007, Wright et al. 2014, Tellis & Marcy 2015, 2017) broadband radio signals, large artificial structures (Dyson 1960, Griffith et al. 2015, Wright et al. 2016), and other astrophysical exotica push astrophysics in new and unexpected directions. If there is a perception that SETI little more than the narrow search for strong radio carrier waves producing a long string of null results it is because historically there has been essentially no funding available for anything else.

Third, there is the erroneous perception that, since radio SETI has been active for decades, its failure to date means there is nothing to find. On the contrary, the lack of SETI funding means that only a tiny fraction of the search space open to radio SETI has been explored (Tarter et al. 2010). Indeed, Robert Gray has estimated that the total integration time on the location of the Wow! Signal (the most famous and credible SETI candidate signal to date) is less than 24 hours (see, for instance, Gray et al. 2002). That is, if there is a powerful, unambiguous beacon in that direction with a duty cycle of around one pulse per day, we would not have detected a second pulse yet. Other parts of the sky have even less coverage. The truth is, we only begun to seriously survey the sky even for radio beacons, and other search methods have even less completeness.

Fourth, there is the erroneous perception that SETI will proceed on its own without NASA support. Indeed, the 2015 NASA Astrobiology Roadmap claims that “traditional SETI is…currently well-funded by private sources.”  Even setting aside the non sequitur of considering the amount of private philanthropic funding when assessing the merits of the components of astrobiology, this is not a fair description of the state of the field. While it is true that the Breakthrough Listen Initiative has pledged to spend up to $100 million over 10 years, in truth its spending has been far below that level, and it is focused on a small number of mature search technologies. Beyond this initiative, private benefactors have supported the SETI Institute’s Allen Telescope Array, but not at the level necessary to complete the array or fund its operations.

Fifth, there is the erroneous perception that the search for technosignatures is somehow a more speculative or risky endeavor than the search for biosignatures. We note that the entire field of astrobiology once faced a similar stigma. Chyba & Hand rebutted that perception in 2005:

Astro-physicists…spent decades studying and searching for black holes before accumulating today’s compelling evidence that they exist. The same can be said for the search for room-temperature superconductors, proton decay, violations of special relativity, or for that matter the Higgs boson. Indeed, much of the most important and exciting research in astronomy and physics is concerned exactly with the study of objects or phenomena whose existence has not been demonstrated—and that may, in fact, turn out not to exist. In this sense astrobiology merely confronts what is a familiar, even commonplace situation in many of its sister sciences.

Their rebuttal holds just as well as SETI today. Indeed, Wright & Oman-Reagan (2017) have articulated a detailed analogy between SETI and the relatively uncontroversial search for dark matter particles via direct detection. They argue that unlike with dark matter searches, with SETI, at least, we have the advantage that we know that the targets of our search (spacefaring technological species) arise naturally (because we are one).

Finally, there is an erroneous perception that SETI is exclusively a ground-based radio telescope project with little for NASA to offer. On the contrary, SETI is an interdisciplinary field (Cabrol 2016) and even beyond the potential for NASA’s Deep Space Network to play an important role in the radio component of SETI, archival data from NASA assets have played an important role in SETI for decades: from Solar System SETI using interplanetary cameras, to waste heat searches using IRAS (Carrigan 2009) WISE, Spitzer, and GALEX (Griffith et al. 2015), to searches for artifacts with Kepler (Wright et al. 2016) and Swift (Meng et al. 2017). Future ground-based projects like LSST and space-borne projects like JWST and WFIRST will undoubtably provide additional opportunities SETI research both as ancillary output of legacy and archival programs and through independent SETI projects in their own right.

III. Reinvigorating SETI as a Subfield of Astrobiology

One difficulty SETI faces is a negative feedback between funding and advocacy.

As it stands, SETI is essentially shut out of NASA funding. SETI is not mentioned at all in most NASA proposal solicitations, making any SETI proposal submitted to such a call unlikely to satisfy the merit review criteria. Worse, the only mentions of SETI in the entire 2015, 2016, and 2017 ROSES announcements are under “exclusions,” in the Exobiology section (“Proposals aimed at identification and characterization of signals and/or properties of extrasolar planets that may harbor intelligent life are not solicited at this time”) and the Exoplanets section (as “not within the scope of this program.”) In other words, SETI is ignored entirely in NASA proposal solicitations, except for those most relevant to it, in which cases it is explicitly excluded.

Meanwhile, other parts of astrobiology have flourished under NASA’s aegis, which has incubated strategies for the detection of life elsewhere in the universe, and produced scientists who can advocate for mature roadmaps to the detection of life in the universe as part of NASA’s astrobiology program. But now, twenty years after the last major NASA SETI program was cancelled, there are only a handful of SETI practitioners and virtually no pipeline to train more.

Thus there are only a few well-developed strategies to advocate for, and only a few scientists to advocate for them. This will doubtless be reflected in the number of white papers advocating SETI (like this one) versus those advocating other kinds of astrobiology responsive to the current call. This disparity should not be seen as indicating a lack of intrinsic merit of the endeavor of SETI, but as a sign of neglect of SETI by national funding agencies.

Since SETI is, quite obviously, part of astrobiology, SETI practitioners should at the very least be expressly encouraged to compete on a level playing field with practitioners of other subfields for NASA astrobiology resources.

Doing so will uncork pent-up SETI efforts that will result in significant progress over the next 10 years and beyond. As a fully recognized and funded component of astrobiology, SETI practitioners will be able to develop new search strategies, discover new astrophysical phenomena and, critically, train a new generation of SETI researchers to guide NASA’s astrobiology portfolio to vigorously pursue the discovery of all kinds of life in the universe—both “stupid” and intelligent.

And if, as many suspect, technosignatures prove to be closer to our grasp than biosignatures, then including of SETI in NASA’s astrobiology portfolio will ultimately lead to one of the most profound discoveries in human history, and a reinvigoration of and relevance for NASA not seen since the Apollo era. In retrospect, we will wonder why we were so reluctant to succeed.

IV. Bibliography

  • Boyajian, T. S. et al. 2016, MNRAS 457, 3988
  • Carrigan, R. A, Jr., 2009, The Astrophysical Journal 698, 2075
  • Cabrol, N. A. 2016, Astrobiology, 16, 9
  • Chyba, C. F. & Hand, K. P. 2005 Annu. Rev. Astron. Astrophys. 43, 31–74.
  • Domagal-Goldman S. D. & Wright K. E. Astrobiology. August 2016, 16(8): 561-653. 
  • Dyson, F. 1960 Science 131, 1667
  • Gajjar, V., et al. 2017, The Astronomer’s Telegram, 10675
  • Garber, S.J. 1999. J. Br. Interplanet. Soc. 52, 3–12.
  • Gray, R., et al. 2002, The Astrophysical Journal 578, 967
  • Griffith, R. et al. 2015, The Astrophysical Journal Supplement Series 217, 25
  • Howard, A., et al. 2007, Acta Astronautica 61, 78H
  • Kardashev, N. S. 1964, Soviet Astronomy, 8, 217
  • Meng, H., et al., 2017 The Astrophysical Journal 847, 131
  • Reines, A. E., 2002 Publications of the Astronomical Society of the Pacific 114, 416R
  • Tellis, N. K, & Marcy, G. W., 2015 PASP 127, 540T
  • Tarter, J., et al., 2010 SPIE 781902
  • Tellis, N. K, & Marcy, G. W., 2017 The Astronomical Journal 153, 251
  • Wright, S., et al, 2014 SPIE 9147E, 0JW
  • Wright, J. T., et al. 2016, The Astrophysical Journal 816, 17
  • Wright, J. T. & Sigurdsson, S. 2016, The Astrophysical Journal, 829, 3
  • Wright, J. T. & Oman-Reagan, M. P. 2017, Int. Jour. of Astrobiology, arXiv:1708.05318

1 Indeed, broad swaths of the astrobiology community disagree with NASA’s assertion. For instance, SETI was included as a component of astrobiology in The Astrobiology Primer v.2.0 (Domagal-Goldman & Wright 2016), and SETI activities fall under the Carl Sagan Center for astrobiology at the SETI Institute (which, despite the name, conducts a broad range of science, including many sub-fields of astrobiology).

AstroWright Group Science at the 231st AAS Meeting: Thursday

Today it’s stars stars stars! Including a couple of really nifty you-heard-it-here-first results.

10:20 am #303.03 Maryland Ballroom A don’t miss Jacob Luhn talk about jitter in dwarf and subgiant stars. Where does jitter come from in inactive stars? Which stars are least jittery? Jacob has the answers in what we are calling the “amazing jitter plot”.  Don’t miss it!

Poster #349.11: Penn State undergraduate Shivani Shah shows off her thesis work studying magnetic cycles in Sun-like stars.  We were going to look at activity-RV correlations but when we found this star we changed our focus: it appears to be entering a Grand Magnetic Minimum state, similar to the Sun’s Maunder Minimum.  Finding such a star has been a goal of stellar astronomers for decades, and now we think we’ve got a good candidate.  Ask her about it during the 9am and 5:30 poster sessions!  (Oh, and Shivani is applying to graduate school this year, so if you’re on an admissions committee, make sure you talk to her!)

Poster #349.24: AstroWright collaborater Brendan Miller presents his work on Swift X-ray monitoring of the coronae of nearby planet-hosting stars.  X rays are an important consideration in the habitability of planets, and this work helps put things into perspective.