Sofia Zara Sheikh – Page 2 – Penn State Graduate Course in SETI

Don’t Talk to Me About a Face on Mars

I couldn’t decide which paper to discuss this week, so I’m talking about both. One made me think, the other made me angry. I suspect that this was the intent of the assignment.

Solar system artifact SETI might be one of the most giggle-inducing subsets of SETI. This seemingly wasn’t always true (throwback to the Martian “canals”), but it suffers from a series of issues. One is that there is a popular misconception that the solar system is a relatively well-explored piece of “territory” and we haven’t found anything yet. So solar system artifact SETI, in that light, seems antiquated. It always surprises me to learn how little we know as I progress through my education, and I think that feeling is relevant here. In addition, solar system artifact SETI makes SETI seem so close to home that the only conceptual guideposts people have are (generally cheesy and terrible) science fiction. Where a remote detection or a long timescale exchange of radio signals would be distant, sterile, and narratively boring, the discovery of an alien probe in the solar system or a city and giant face on Mars feels like fiction, so it’s treated as such, instead of legitimate science.

Now, to the articles!

The Freitas paper very logically stepped through the process of finding an answer to the question “which surveys on which parts of parameter space would have to be performed to disprove the existence of probes in the solar system?”. I take issue to a couple of framing assumptions that Freitas makes. Firstly, I don’t think it’s reasonable to assume that any probes we would find would be made for a neutral-to-discovery purpose (because we would’ve found one already if it wanted to contact us and we’d never see it if it was trying to hide, the logic goes). I can imagine many exceptions to this idea: a probe that was meant for communication but was damaged, a probe that is trying its best to contact us but by a method that we don’t have access to yet (perhaps on purpose, so we only see it at a reasonable point in our technological development), or a probe that was only partly for communication (mostly for another purpose, with only minor energy put into a beacon). The other thing that bothered me is that all of the constraints for the observational probe were constructed under the assumption that the probe wanted to observe Earth. That looking at a habitable planet, and that having the resolution to watch civilization arise on it, were valuable to our hypothetical watchers. I think that’s a bit anthropocentric – it could very well be that our asteroid belt is absolutely fascinating and ugh look at the primitives mucking up that third planet, they’re everywhere in this sector.

All of that said: you can’t do this work without making some assumptions to reduce the scale of the problem, and these were relatively minor ones. I loved the structure of the paper: consider the construction and purpose of the probe, then consider where it could be placed, note previously completed searches and their incompleteness (chock-full of references), then look at detection probabilities with current instruments and reasonable times. This is a methodical and scientific way to go about the stated problem in the paper.

The Carlotto paper, on the other hand, was rage-inducing. It would take a very, very convincing landscape artifact for me to feel comfortable announcing a “non-natural” origin. If Europa was covered in a giant swastika a la Armada (Ernest Cline’s less successful follow-up novel to Ready Player One), that would probably be sufficient. The 3D face is reconstructed from only two relatively low-resolution images, which makes me uncomfortable. The feature has since been imaged from other angles (by, among others, the Mars Global Surveyor) and, spoiler alert, doesn’t actually look like a face.

This is an example of textbook pareidolia: humans have a tendency to see patterns in random data, especially and specifically faces. Being good at recognizing and reading faces is vital for a social creature like a human being, so better to have some false positives than to accidentally mistake one’s significant other for a coat rack. But a base and known brain-stem bias like this should NOT cause us to write horribly misleading papers about the possible existence of an extinct Martian civilization. I don’t know how couth it is to consider the political ramifications of other people’s research, but it’s frustrating to see a vibrant and important sub-field continually shooting itself in the foot with scientifically sketchy bold claims and over-speculation from a few members of the community.

/endrant

Is It a Megastructure? (No)

The G-HAT papers have definitely been dense reading. I think Part IV (the paper I’ll be discussing in this blog post) has been the most accessible one to me so far.

My favourite table/figure in this work is simply Table 1, so I’m going to talk about it a lot.

Firstly, I think it encapsulates the fundamental challenges in artifact SETI: 1) the artifact has to exist and 2) we have to be able to tell that there’s an artifact. This sounds simple, but I think is a useful comparison to the fundamental challenges in communication SETI: 1) the (intentional!) signal has to exist and 2) we have to be able to tell that it’s a signal.

Secondly, it’s good to keep perspective in SETI research: not every anomaly is ETI. In fact, all of them so far are not. The table illustrates that for every megastructure-y looking object, there are reasonable (and plausible) “natural confounders”. This makes sense; though we’re trying to wring as much information out of a single lightcurve as we can (and we’re quite good at it – we can even tell the full 3D stellar rotation and planetary orbit geometry) it’s still just a lightcurve, and there are many inputs that produce the same output. Perspective is vital, especially in a paper that is ~hunting for alien megastructures~

Thirdly, I just love lists, as you can probably tell by the way I write my blog posts. The section following the table goes through the six physical “Distinguishing Features of Megastructures” (ex. anomalous masses, aspects, or orbits). The section after that talks about the nine physical “Confounding Natural Sources of Megastructure Signatures” (ex. starspots, ring systems, or non-transited stars in the field of view aka. “blends”). I’m italicizing the word physical to illustrate exactly what it is that I like about the structure of this section: it shows what distinguishing properties of the systems being observed would be visible to an observer within the system. But we are not within the system – we’re working from lightcurves. And that’s where Table 1 comes in: showing exactly which of the physical properties discussed in (perhaps agonizing) detail would cause which of the 10 lightcurve anomalies in the Table.

I will now briefly summarize the rest of the paper, which I found generally less interesting to me. The next section talks about a few objects in particular that show some of the transit anomalies discussed in the previous section. The section after that discusses how to distinguish a signal beacon from a constant source from an information-rich signal by doing statistical analyses in both the frequency and time domains. The authors quantify it with a “normalized information content statistic”. I’ll admit that the methods in this section were mostly over my head, but I think (hypothetically) that the uniform application of them to future SETI studies would be a fruitful pursuit.

I’m Conflicted About Artifact SETI

I’m going to frame this blog post into “pros” and “cons” of artifact SETI, with a lot of references to three specific papers we read about searching for extremely advanced ETIs(Annis (1999), Carrigan 2009, and Wright et al. 2014b).

Pros:

No dealing with Schelling points!
No making assumptions about xenopsychology and alien motivations!
No need to even consider a METI approach!
This is actual, performable, observational astronomy.
Huge budgets aren’t needed. Carrigan (2009) used IRAS sources which had already been catalogued.
Actual constraints can be placed. Annis (1999) made a (perhaps arbitrary) statement that no galaxy out of his ~130 galaxy survey had a Type III civilization harvesting 75% or more of the available stellar energy.
Interesting objects can (and will) be found during the search for outliers, which is far less likely in communication SETI. Carrigan (2009) found 16 objects which were (weak) Dyson sphere “candidates”, which mostly indicated an unusual IR signature.

The Con:

We can only look for extremely advanced civilizations, because we need the artifacts themselves to be detectable by our technology at interstellar and even intergalactic distances. The three papers we read for this week were all focused on Kardashev Type II or Type III civilizations. The sheer enormity of lengths of time involved versus (assumed) civilizational lifetimes means that we’re way more likely to come into contact with a civilization more advanced than we are than one at about the same age. But the idea of searching for them makes me a little squeamish.

Any astronomer can tell you that the distance scales of space are not really built for/intuitive to humans. I personally find that there’s a sort of intellectual harmony in the thought that interstellar travel is just hard and not worth it (not quite in a Hart sense of “physical explanations”). Though the swan songs of “free” energy, FTL travel, and the use of dark energy are tempting, and the excuse of poorly understood current physics convenient (as discussed in Wright et al. 2014b), that doesn’t mean they’re necessarily rational fallbacks. Much of our ideas about how galactic settlement would work are based more on the ideas of settlement from Earth’s history, and though it feels tempting to just zoom out and apply the same metaphors, there are fundamental differences that to me* feel insurmountable.

All of that to say: I don’t find it very intellectually fulfilling to do artifact SETI for Type II and Type III civilizations, Type III civilizations especially. It’s too much speculation. So while Annis makes conclusions about the frequency of Type III civilizations, I don’t find his results particularly compelling or surprising.

*at this point in my education, perhaps I’ll look back on this and laugh

3 Types, 3 Questions

This week, I wanted to talk about Kardashev (1964) because I naturally started doing a lot of follow-up as I read. The famous idea that was first proposed in this paper was the classification of civilizations by the amount of energy they consume, as summarized below:

Type I: Earth-level, consuming 4 * 10^19 erg/s

Type II: Full-star usage (a la Dyson spheres), consuming 4 * 10^33 erg/s

Type III: Full-galaxy usage, consuming 4 * 10^44 erg/s

I had three questions that popped up over the course of reading the paper.

Has the definition of Type I always been the same over time?
Did we keep up with Kardashev’s energy growth rate predictions?
Whatever became of CTA-21 and CTA-102?

I’ll tackle these one at a time.

In my memory, when I’ve heard about the Kardashev scale before, humanity was said to be at a Kardashev 0.7 or so, which is a pretty long way from a Kardashev I (because the scale is not linear). The argument that I read (I believe in the book Physics of the Impossible by Michio Kaku*) is that a Kardashev I civilization uses an amount of energy equal to the amount of starlight falling on the planet’s surface. A quick glance at the Wikipedia page confirms that interpretation. But, as I mentioned above, Kardashev defined it as being the amount of power that Earth was using in 1964, at the time the paper was written. So when did the flip in definition happen? Turns out this shift was the fault of the ever-present Carl Sagan. His standardization of the scale with a logarithmic power formula allows values other than I, II, and III and allows a more generalizable formulation (versus Kardavshev’s Earth-centric standards). It’s amazing to me that a redefinition happening a decade after the original paper has caught hold so strongly.
Since it has been over 50 years since this paper was written, I was curious to see if we had kept up to Kardashev’s proposed growth rate of 3-4% a year, starting at 4 * 10^19 erg/s. After a long 10 minutes of trying to figure out why my simple exponential growth rate equations were wrong (ergs/second not ergs/year, past-Me), I got an answer of ~6.5 * 10^27 to ~1.3 * 10^28 erg using his values (using 3% and 4% growth respectively). The actual current value is 3.9 * 10^27 erg, so while Kardashev’s predictions were optimistic by a factor of 2-3, they weren’t really that far off. That’s honestly pretty impressive, at least to me (perhaps an economist would say that this is an easy problem, but it isn’t quite intuitive to me). Will it continue at this rate, or will we level off in some logistic-like function? That’s the question, isn’t it? But at least so far, we’re on track with Kardashev’s prediction.
After some research on CTA-21 and CTA-102, it looks like (predictably) they were both false alarms. CTA-102, according to a quick Wikipedia, is identified as a very-variable quasar with extremely luminous “blazar states”. This is a great example of how objects of interest to SETI (at least in the context of artifact SETI) are going to invariably be interesting to the rest of astronomy, and should be valued for that reason. Meanwhile, both objects had an entire article in the NYT written on them by none other than Isaac Asimov. A quick scan on Google Scholar suggests that it too is just a quasar, though a less extreme example than CTA-102.

*This book was my “eureka” moment about wanting to be a physicist/astronomer. I picked it up on a whim when my seventh grade book club got to go to the local book store for a mini-field trip. After finishing it, I decided that I wanted to go into physics, and I haven’t looked back since.

The Beastly Biases from the Planet Earth!

I was originally conflicted about Wright and Oman-Reagan (2017).

Initial Feeling 1: I think interdisciplinary work benefits all fields involved, and it isn’t performed enough. We are all too familiar with our own literatures (and thinking that we’re pretty up-to-date because of that); meanwhile another literature is examining the same problem from a different angle or (worse) just solving the same problem in parallel. And I’m not just talking about related fields (astronomy/geosciences, astronomy/engineering, etc.). I attended the Global Hands-On Universe Conference in 2016, which works at the intersection of science, art, and education, and found the experience and the motivation behind the conference to be extremely useful. My takeaway was that astronomers don’t pay nearly enough attention to education research and the benefits of art as a means of public communication and outreach.

Initial Feeling 2: I am an astronomer. I need to be hired by and funded by astronomers, and I need work to be done in my field to advance my understanding of it and to guide my own research interests and strategies. I need my peers to take my research as seriously as any other sub-field. And I think that papers that are too speculative will water down the field and make all of those goals harder to accomplish. Some of these claim to be astronomy papers (and have some good points) but are still filled with wild imaginings, others (this work included) are clearly outside the scope of a typical scientific paper as an astronomer would think of it and thus might be prone to the ‘giggle factor’.

Initial Resolution: I think the resolution of these two points of view is to place value on interdisciplinary work that tackles and tries to provide answers to problems in SETI – the literature needs work that strives to improve the search, regardless of discipline (such as this paper by Nathalie Cabrol). The other reading for this week was, to be fair, a popular science article, but I don’t believe that it’s a particularly useful piece as far as the search itself goes. If our SETI efforts are ever successful, then we’ll need scores of papers that consider how we might meet and receive extraterrestrial intelligences. Until then, the scientific discipline should focus on the search.

This paper is both necessary and useful as far as the search goes, even though it might seem on the surface to not be directly related (by way of Schelling points or search suggestions etc.). Improving public perception of the search is important: SETI needs to prove its place as a worthy discipline so that people know why it should receive funding. Improving the flux of a diverse crew of scientists into the field is important: this is always true, but especially in a field such as SETI, where we need the broadest perspectives and most open minds to try to get past a thousand insidious layers of anthropocentrism. Keeping an eye on how biases brought about through language and culture can affect the way SETI is performed is important: science does not exist in a vacuum, and scientists are sometimes loathe to admit that fact.

After attending the first Decoding Alien Intelligence workshop at the SETI Institute this year, my perspective on this issue has developed further. A conversation I had with Michael Oman-Reagan opened my eyes to some strong biases that the astrobiology community has come to accept as fact. Why did we start SETI with radio astronomy? Some solid engineering reasons, but also maybe because radio astronomy was in vogue in the 1960s. Why is Europa considered an extremely strong candidate for astrobiology? Maybe because it’s really cool and has promising features, but maybe (as David Grinspoon suggests) just because we’ve heard it repeated so much. Why are we suddenly sure that any life we find will be post-biological? Maybe more because the idea of AI is rooted in our culture right now and less because “it’s inevitable”. Why is machine learning the best technique for SETI research today? Maybe because it’s all the rage in Silicon Valley, where most SETI efforts are geographically located. Why do the aliens always watch I Love Lucy, for goodness’ sakes! The biases are everywhere, ahhhhh!

Hmmm, maybe there’s a paper in here somewhere…

As a final (somewhat unrelated) point on the topic of biases, I find it interesting to characterize METI as prideful/dominion-focused/arrogant and SETI as submissive/cautious. The language in the paper made me think of the two methods, for the first time, as somewhat tied to cultural ideas of masculinity and femininity. This made me realize that in SETI more than anything else, having a base of practitioners that are neither diverse nor aware of their own implicit biases is crazily dangerous. It would be a little ironic if the systematic biases that humanity has always fostered led to our planetary downfall, but I’d prefer not to laugh at that particular irony.

METI: What Percentage “Bark”, What Percentage “Bite”?

Ah, METI.

Short for “messaging to extraterrestrial intelligences”, it’s nothing if not extremely enticing.

“Enough of this waiting around! What if everyone is just listening? We’re too afraid of taking risks. If we were trying to find someone here on Earth, we would obviously send signals to them while we look. If we’re really serious about learning the frequency of intelligent life in the galaxy, we’d do the same thing!”

In class last week, we did an Earth-centric exercise about finding a group you know nothing about. Both of our in-class groups immediately jumped to METI as our main strategy. After that exercise, I definitely wished that we could just do METI and see what happens. And, under one condition, I would.

The character Coil from the legendarily long* superhero web-fiction Worm has the power to split the world into two timelines, see how they play out, and collapse the one he doesn’t like as much (he uses this power for evil, of course).

If I were Coil, I would 100% try METI, just to see what happens.

http://worm.wikia.com/wiki/Coil — If I were this guy, METI wouldn’t scare me

Because I am not Coil, I can’t just collapse a timeline in which humanity accidentally attracts the attention of something far up the feeding chain (as we expect almost all concurrent intelligences would be). I would prefer not being personally responsible for the extinction of our species, or even (less dramatically) the complete alteration of our future. As a global collective of governments (an idea which seems almost as silly as contacting ETI), perhaps authority could be taken if a decision was reached together. But even so, it’s a decision that has the potential to impact all of humanity, even echoing through generations. So can we ethically make that step, even with a global consensus?

Let me take a step back here: I am talking about a “perfect” METI. An isotropic METI signal that is guaranteed to be detected by any intelligent species that it encounters. It’s a philosophical question about an action that will be able to change humanity. As Gertz (2016) argues very sharply, the METI that has been done so far is decidedly not that. Modern METI is more of a publicity stunt with minimal methodology. The focus is often more on the taboo of messaging and the content of the message than on any reasonable way of tackling the problem (not sending a repeat of the signal some time later, for the purpose of scientific reproducibility, and having no plans to listen for a return message are smoking guns for me). One of the more recent communications was a series of songs sent by METI International. The songs weren’t even that good.

I am afraid of “perfect” METI. I am not afraid of current METI. But I think that over time, as technology advances and older technology gets cheaper, “perfect” METI will get closer and closer to being a reality. Some preemptive thought toward the issue is probably justified.

I wanted to get the opinion of one of my friends, who decided to stay anonymous. My friend is a research analyst at the Open Philanthropy Project and spends a lot of time thinking about how to quantify ethical quandaries and how to maximize the amount of “good” that can be created by given amounts of resources and actions. They shared their ideas about METI with me over text, so their responses have been edited for clarity.

“My instincts lean towards [METI] sounding risky if we don’t see any evidence of other civilizations intentionally doing the same. […] I would want to make SETI much better first and wait until we’ve explored a decent chunk of the sky. If, after we do that, it seems like we’re hearing nothing that seems like intentional loud messaging from other places I would think that’s strong evidence that either a) no one’s around, so METI wouldn’t be useful or b) somehow everyone [simultaneously] decided not to, so maybe it’s dangerous.”

I also asked them if they thought that it was possible to construct a cost-benefit calculation to decide if METI was a good idea or not.

“I think there probably would be a way to do that but I’m not sure I have enough context to do the analysis. [Naively], the main benefit is how much it speeds up our search for intelligence and the main cost is risk to Earth.”

This was interesting to me, because it seems like it might be possible to try this analysis without falling back on infinite goods and bads. That’s an idea, at least! Any treatment of it could probably produce results on a huge sliding scale a la the Drake equation because of the uncertainties involved, but it would be interesting to at least try to isolate the factors involved.

*it’s the length of A Song of Ice and Fire

A Review Paper and a Beach of Multicolored Rocks

This forty-page paper is a doozy, but so, so important. I only wish that we had an equivalent paper written in 2018 (Caleb and Will were brave enough to tackle this project – check out their work!)

[Warning: this post is also a doozy]

Tarter (2001) is a comprehensive review of the state of SETI as a field: where it came from, where it is, and where it’s going. This is important in a field with so many proposed projects and so few performed projects. I think it’s safe to say that most people assume that we’ve searched far more than we actually have, such that the Fermi Paradox seems very sharp. But unless you’re a proponent of very, very obvious, ubiquitous von Neumann machines in the Solar System, this paper makes it pretty obvious that we’ve barely scratched the surface of searching.

At that point in time, only 99 projects had ever been documented. I tried to see the comprehensive list, but unfortunately, the link to the supplementary material (it seems to be via seti.org) is broken. Hence, I can’t actually back up this statement, but I would guess that many of these were single/few target observations like Project Ozma.

It’s absolutely amazing to me that a paper written within my conscious memory can look so different from the scientific lessons and landscape that I’ve experienced less than two decades later (not that I was aware of the publication of this paper at six years old, but my point stands). Kepler was competing for selection, Huygens hadn’t happened yet, and Tarter’s plot of known exoplanets looks frighteningly sparse compared to the plots I generated effortlessly on exoplanets.org for Dr. Bekki Dawson’s graduate class on the subject. Tarter’s discussion of exoplanet finding techniques, however, and her thoughts on how the revolution would progress were incredibly prescient.

Things I Learned: I liked her explanation of the uncertainty principle argument to justify the search for signals that were unnaturally short in time or frequency. I had always thought of narrowband searches as the most obvious SETI search method (with much bias), but this is the best argument I’ve read for pulsed optical SETI having equal footing. Interesting sidenote: Charles Townes himself talked about how his invention could be used for interstellar communication.

I also did not know that there were distance-dependent effects that happen in both the optical (dust extinction) and the radio (minimum frequency resolution you care about because of broadening through the ionized ISM). I did not appreciate how interstellar scintillation could, frequency-dependently, affect the signal amplitude. This is a good reason to search for combs – I’d be curious to see if anyone has ever run a comb search, because if so, I’ve never heard about it.

There’s so much to say about this content-dense paper, but I’ll leave it off on a final point starting with the following mediocre metaphor I just came up with.

Mediocre metaphor: the search space is a beach of multi-colored rocks. We know we’re looking for something that looks out of place, but that’s all the information we have. If we only look for, say, paths in the black rocks, we might walk right by a conspicuous grouping of green ones, or an artificial stack of large ones. But add two more pieces of information: 1) there’s a particular kind of basalt on this beach which isn’t found elsewhere 2) geologists love to study it. Now there’s a very obvious reason for our unknown signalers to add something weird into the basalt – maybe they shape a column of basalt into a triskaidecagon (it usually forms hexagonal columns). Even if we (as the searchers) don’t know where to look and don’t see anything, the granite experts will notice that something is up.

This is the rationale behind looking for “impossible objects” (an intentional variant of the idea of “nature plus”): making a signal that almost looks like an astronomical object that would be studied in the normal course of a civilization’s scientific advancement… but with something weird about it. Pulsars that don’t follow physical rules, stars with weird emission lines, supernovae going off in the Fibonacci sequence. This eliminates a lot of the Schelling Point philosophizing (frequency/target/bandwidth/time/etc./etc./etc.) involved in guessing what a transmitting civilization would do, which I am very much in favour of, personally.

Galactic Peace Sounds Pretty Nice

As a matter of course, any astronomer has an intellectual understanding that Carl Sagan was the face of popular astronomy for many years. But as someone who was born the year before his death, I never got to experience that era first-hand. Now, reading his writing, I’m struck by the gorgeous simplicity of his arguments and the philosophical grace of his writing, and I understand more readily the “legacy” (if you will) of his name.

All of this to say: I absolutely adore the first paragraph of his 1982 paper with William Newman, “The Solipsist Approach to Extraterrestrial Intelligence”. I wrote a similar paragraph to kick off my undergraduate honor’s thesis, but this was the poetic distillation of the argument that I was aiming toward (and definitely didn’t reach).

Anyway.

The main argument of the paper is a contradiction to Tipler’s “solipsistic” argument that if there were other intelligent beings in the universe, we would’ve seen von Neumann machines in our own solar system; we haven’t so there aren’t. Sagan and Newman correct some of the more optimistic values in Tipler’s order of magnitude calculation. This originally made me very happy, as I felt rather uncomfortable with Tipler’s isotropically expanding, quickly replicating, unsupervised von Neumann machine argument in the paper we read for Tuesday.

The last part of the paper is a more philosophical argument than a mathematical one. I had never actually considered the “intrinsic instability of societies devoted to an aggressive galactic imperialism”. I always found that the “they blew themselves up” solution to the Fermi paradox felt too convenient: did they ALL blow themselves up??? But considering Sagan and Newman’s reasoning, I actually changed my mind about that line of argument. They contend that aggressive, imperialistic societies, like those of Colonial European times, don’t actually survive to become galactic powers because of the deadly combination of infighting + nuclear weapons. It is possible to survive such a stage, but only if you’re a group that is “pre-adapted to live with other groups in mutual respect” through (essentially) Darwinian means. So the ones that remain will be respectful and probably a little more hesitant to run around randomly colonizing or unleashing hostile von Neumann probes on the galaxy. It’s an interesting idea, though it would probably be dangerous idea to apply as a blanket statement.

Maybe the whole galaxy looks like playing a peaceful civilization in one of my favourite videogames from my youth: Spore

It ends, in Sagan-like fashion, with a caution that the question of ETI can never be resolved without an actual observational program / search, and no philosophical arguments or hypothetical calculations can be a substitute for that real, quantitative effort.

Tipler Needs to Chill

“A Brief History of the Extraterrestrial Intelligence Concept” by Frank Tipler is a meta-paper about (or more appropriately, against) SETI as a funded endeavor. The author assigns three different characteristics to the philosophy of SETI-proponents throughout time: plenitude (the belief that Earth is not a special location: in current parlance, the principle of mediocrity), infinite cosmos, and a lack of a sense of history. It is this last point that he seems to try to prove in the paper, going through the ideas of philosophers for and against SETI from Greek times onwards.

There is certainly a place for a discussion of 2000 years of theology and philosophy about whether we are the only intelligent life in the universe. We can stand on the shoulders of all of this work that has come before us, and not worry about uselessly retreading the same ideological ground. That’s a sound and fair reason to be familiar with the long literature. However, using the existence of the literature itself as a counter-argument seems unfounded and rather mean-spirited.

Of course, as one of the slandered SETI-proponents, I had a pretty strong negative reaction to the paper. I felt that the Hart (1975) paper, equally pessimistic, actually engaged the issue with quantitative calculations and a scientific basis. I know that this paper was assigned to let us see the full spectrum of arguments and beliefs about ETI, positive and negative, and for that, it certainly has value. But I strongly disagree with the line of evidence that Tipler chose.

Tipler claims that those in favor of SETI are “always willing to suspend the physics of their day.” But in his conclusion, he points out that there have been scientific advances in the previous two decades which lend credence to SETI: the nebular hypothesis, the Urey-Miller experiment, the development of radio astronomy, and the steady-state theory of the universe. And then he disregards all of these ideas before really engaging with them, ending his paper by stating that the “philosophical and theological beliefs are the main motivations for the belief in ETI”.

In addition, I would contest that going through the history this way provides both pro-SETI and anti-SETI arguments, the pro-SETI ones being played down in this particular paper. For example, the reoccurrence of the idea of ‘plenitude’ throughout history is interesting and good to be aware of… but calling it a flaw of current SETI practitioners seems a bit silly when, again and again, it’s been correct (we aren’t the center of the universe, or solar system, or galaxy, or universe…). Is that a replacement for evidence? Of course not. But if we’re engaging in a philosophical discourse, it’s a reasonable fact to bring up.

Celestial spheres — 19th century woodcut (colorized) – “Fantastic Depiction of the Solar System” – in which some guy sticks his head out of the sphere of stars surrounding the Earth. Because of course all the stars are just on a celestial sphere surrounding the Earth. Why would they want to be anywhere else?

More politically, and less scientifically, the fact that SETI has been in the (European/Western/white/male*) public consciousness for so long is perhaps a reason to pursue it, instead of an argument against it. We’ve wanted to know the answers for so long, but now we have the tools to do so – does that not bring value of its own, divorced from any scientific results or merit?

Being aware of one’s biases is important, especially if you’re doing calculations that will a) later affect actual, observational work and b) can be heavily skewed by coming in with priors (looking at you, Drake Equation). Post-discussion, I am a little more accepting that there is a place for this paper. But only a little.

*someday, I would love to do a review of the history of the idea of extraterrestrial intelligence in other cultures – I’ll add it to the list!

The Groundbreaking Project Ozma

This article was written by Frank Drake (of Drake equation fame) in 1961 and was published in Physics Today. It described the planning and execution of the first completed radio SETI observing program in history, the whimsically named Project Ozma. It also included a good deal of justification for why we might expect to find ETI out there – necessarily so, as this was the first project of its kind. Results? No aliens around Tau Ceti and Epsilon Eridani are broadcasting at the little slice of frequencies that were searched.

The search itself targeted 2 stars with 150 hours of radio observing time at Green Bank (I’ll admit, I’m jealous). They focused on the area around the 21-cm line. Since this paper, the 21-cm line became the most popular Schelling Point in frequency space, with the argument that the spin-flip frequency of hydrogen (the most abundant element in the universe) had to be the simplest universal watering hole. Whether that’s actually true, well, it’s hard to say – we human scientists agree that it seems like a promising place to search, but we’re not looking for human scientists out there.

Grab Bag Thoughts:

Now, of course, we know of thousands of exoplanets, but I appreciate the careful skepticism with which the idea was treated back before we had the instruments and evidence that we have today. Also, it’s amazing to me that the smallest extrasolar objects we’d detected at the time were apparently 10X Jupiter’s mass.
Neither of Drake’s “two helpful points” (a 5 billion year constraint, and a “ecosphere”/habitable zone/liquid water argument) are bad starting places – after all, we only have one data point to go off of. They do, however, seem anthropocentric (or maybe just simplistic) in hindsight. Then again, I suppose I have to keep in mind that the ideas and the search itself were novel at the time – hence the reason this was assigned!
On first read, the idea of a “group of intercommunicating civilizations” seemed a little far-fetched to me – we know nothing about the politics/society/mindsets of potential civilizations, so imagining a ton of independently arising civilizations that are all curious, cheery, and helpful seems a little optimistic. It was interesting how prevalent this idea seemed to be (Cocconi and Morrison imagined that they “look forward patiently to answering signals from the Sun” and Bracewell thought they were “probably already linked together into an existing galaxy-wide chain of communication”). But once I’d read Sagan’s argument from Sagan and Newman 1982 (I’ll talk about it in more depth in a future post), I could see the first justification for the popularity of this idea; in a nutshell, civilizations will be subject to a Darwinian evolution that will only preserve those that are not aggressive and intent upon colonization. Comprehensive explanation? Maybe not. But food for thought.
In light of some of the later papers in the semester, Drake’s rigorous scientific search for intelligent/sentient/communicative life seems very grounded and so much better than the general state of the literature in the decades to come. Is it coincidence that passions seemed to get inflamed about the subject in those following decades during funding struggles (a la Garber 1999) and after those original, perhaps a little too airy, early papers? Searching for sentient life has so many benefits that searching for non-sentient life does not (in the form of unintentional or intentional technosignatures) and I wish we had more evidence yay or nay in the form of searches like this one.

~ Less Relevant Coda – How Poorly Things Age ~

Much of what caught my eye while reading this paper wasn’t directly related to the scientific content but rather some (now) obvious faux pas.

Citations! Where are the citations?! It took me forever to figure out who Calvin was and what he did! Answer: if he was Dr. Melvin Calvin (my best guess) he was part of the Berkeley physics department back in the 1960s (go bears), Director of the Laboratory of Chemical Biodynamics at LBL, and won the 1961 Nobel Prize for Chemistry (according to the LBL website)
The “Harpsichord Maker with a Ph.D. in Physics” job posting is just a goldmine. Prize goes to “Men with appropriate advance degrees, preferably a Ph.D., are invited to…”. Intellectually, I know that’s just how it was back then, but it’s startling to read it now.