Talk at the SETI Institute

SETI means ‘Search for Extraterrestrial Intelligence’. I’m giving a talk at the SETI Institute on Tuesday December 17th, from noon to 1 pm. You can watch it live, watch it later on their YouTube channel, or actually go there and see it. It’s free, and you can just walk in at 189 San Bernardo Avenue in Mountain View, California, but please register if you can.

Life’s Struggle to Survive

When pondering the number of extraterrestrial civilizations, it is worth noting that even after it got started, the success of life on Earth was not a foregone conclusion. We recount some thrilling episodes from the history of our planet, some well-documented but others merely theorized: our collision with the planet Theia, the oxygen catastrophe, the snowball Earth events, the Permian-Triassic mass extinction event, the asteroid that hit Chicxulub, and more, including the global warming episode we are causing now. All of these hold lessons for what may happen on other planets.

If you know interesting things about these or other ‘close calls’, please tell me! I’m still preparing my talk, and there’s room for more fun facts. I’ll make my slides available when they’re ready.

The SETI Institute looks like an interesting place, and my host, Adrian Brown, is an expert on the poles of Mars. I’ve been fascinated about the water there, and I’ll definitely ask him about this paper:

• Adrian J. Brown, Shane Byrne, Livio L. Tornabene and Ted Roush, Louth crater: Evolution of a layered water ice mound, Icarus 196 (2008), 433–445.

Louth Crater is a fascinating place. Here’s a photo:

By the way, I’ll be in Berkeley from December 14th to 21st, except for a day trip down to Mountain View for this talk. I’ll be at the Machine Intelligence Research Institute talking to Eliezer Yudkowsky, Paul Christiano and others at a Workshop on Probability, Logic and Reflection. This invitation arose from my blog post here:

Probability theory and the undefinability of truth.

If you’re in Berkeley and you want to talk, drop me a line. I may be too busy, but I may not.

20 Responses to Talk at the SETI Institute

  1. Prof. Baez, its Julius, don’t forget to talk about the Ordivician-Silurian, Late Devonian, Triassic-Jurassic mass-extinction events (‘close calls’).

  2. William Askew says:

    Could the Lac-l’eau-Claire binary asteroid impact event in northern Quebec have had an influence in the beginning of the P/Tr extinction? It seems to have occurred at a time that life took its first little hit in the beginning of the big die off and possibly close to the time of the Bedout and Wilkes impacts. They aren’t very, large 26 km and 36 km dia. but they are a true binary and not an atmospheric breakup. Could they have been part of a swarm that had earth in their sights?

  3. Saw a news headline some 6 months ago, someone had graphed the number of nucleotide base pairs in an organism, vs. the time when organism appeared on earth. It was on a semi-log graph, time was linear, base-pair complexity was log. The graph was more or less a straight line, with an intersection of about 10K-20K base pairs at 4.5 billion years. Which, of course, strongly suggests extraterrestrial origins of basic life-forms.

    I did not read the paper, but got the impression that most of it was devoted to a technical defense of how to count base-pairs correctly; promptly got far more technical than I could quickly skim. (i.e. that counting incorrectly would, of course, be a quick and easy way to invalidate the conclusion).

      • domenico says:

        I thought some time ago that the first life can be originated in the hydrothermal vent, where there are the right chemical element (dna and rna chemical formula elements), and there a mixing of the chemical elements with the right pressure and temperature, to obtain chemical cracking of the chemical elements (700 °C-900 °C and 100 atmosphere); if this is true the chaotic toroidal trajectories of the fluid, can mix hot and cold water, cooking the mixture, breaking and linking the covalent bond like natural selection (mutations and crossover).
        If the first lives have had a cracking natural selection, then I think that the linear regression in the Moore law is not more valid (cracking mutagens instead of spontaneous mutations in the first part, with a different law).

        • I read a strong argument elsewhere that various rocks can make excellent catalytic converters for the rapid assembly of biomolecules. (precisely, not cata- but ana-) Maybe this one, not sure: Robert M. Hazen1 and Dimitri A. Sverjensky “Mineral Surfaces, Geochemical Complexities, and the Origins of Life” I also vaguely recall the application of the renormalization group to same topic (some Russians had previously done renormalization group work on DNA sequences back in the 1980′s). But this is getting off-topic from John’s post.

        • One last off-topic post, on max-ent principles: Axel Kleidon “Life, hierarchy, and the thermodynamic machinery of planet Earth” looks at thermal gradients that drive geology, weather, biology. Despite the simple-looking math, I didn’t really understand it, but it was definitely entertaining. But very off-topic for SETI. Sorry.

      • John Baez says:

        This is utterly fascinating stuff, so thanks. But I’m skeptical about such grand claims. Why do they extrapolate back to 10-20K base pairs and not further?

        • Oh, they don’t stop at 4.5 billion years: they extrapolate back to 9+/- 2 billion years. :-)

          Its OK to be skeptical. They address a wide swath of concerns more or less squarely; I find the arguments plausible; I’m sure that domain experts could be strongly critical. They have to defend against a dozen or more skeptical attacks on widely different topics in a small amount of space.

          They devote maybe 1/4th to 1/3rd of the paper to primitive biochemistry. They promptly dismiss the idea of having polypeptides, oligonucleotides being present from the very beginning. They review and dismiss some simpler models (hypercycles, the ‘autocatalytic set’, the GARD model).

          They do like something called ‘coenzyme world’ where coenzymes (e.g. ATP, NADH, and CoA) colonize droplets of hydrocarbons in water. (something we might expect to find on Titan, Enceladus) which then catalyze hydrocarbons into fatty acids. They spill some fair amount of verbiage on how this could slowly mutate into cells, e.g. by catalyzing glycerol (needed to make hydrocarbon emulsions stable in water.)

          Next, a description of the invention of ‘digital replication’ viz autocatalytic polypetides, oligonucleotides, which start out by stabilizing lipid membranes. etc. What they write is clearly just a sketch — there’s enough material to be covered that, by golly, you could have dozens of conferences and newly minted PhD’s — and, by golly, judging from the bio-evolution-game-theory-complexity blogosphere, these conferences and PhD’s are showing up at a rapid clip.

          Many of their arguments resonate for me, so I find it plausible.

        • Here’s the SETI-talk relevance: if evolution is as slow as they claim, if it takes 9 billion years to get from chemistry to civilization, then the Drake eqn is wrong: there simply has not been enough time to evolve ETI from bacteria. This ‘solves’ the Fermi paradox.

        • John Baez says:

          Linas wrote:

          They review and dismiss some simpler models (hypercycles, the ‘autocatalytic set’, the GARD model).

          Well, dismissing those is a major challenge for any paper! I’m even more skeptical now—but I should read it.

          Here’s the SETI-talk relevance: if evolution is as slow as they claim, if it takes 9 billion years to get from chemistry to civilization, then the Drake eqn is wrong: there simply has not been enough time to evolve ETI from bacteria. This ‘solves’ the Fermi paradox.

          How does that square with your claim that their calculation “strongly suggests extraterrestrial origins of basic life-forms”?

        • John Baez says:

          I’m glad Sharov and Gordon know about Petri nets:

          The general notion of self-reproduction has been defined using the formalism of Petri nets (Sharov, 1991). In short, a system is self-reproducing if there is a finite sequence of transitions (i.e., reactions) that results in the increase of the numbers of all components within the system. For example, the formose reaction is autocatalytic and makes sugars from formaldehyde (Huskey and Epstein, 1989). Such reactions can propagate in space, which is similar to the growth and expansion of populations of living organisms (Gray and Scott, 1994; Tilman and Kareiva, 1997). Autocatalytic reactions have two alternative steady states: “on” and “off” (the “on” state is stabilized via a limited supply of resources). Thus, they represent the most simple hereditary system or memory unit (Jablonka and Szathmáry, 1995; Lisman and Fallon, 1999). For example,a reverse citric acid cycle, which captures carbon
          dioxide and converts it into sugars, may become self-sustainable, at least theoretically (Morowitz, et al., 2000). Prions are examples of autocatalytic reproduction (Griffith, 1967; Laurent, 1997; Watzky, et al., 2008), and indeed have been invoked in various ways in speculations on theorigin of life (Steele and Baross, 2006; Maury, 2009; Hu, et al. , 2010). However, they cannot support the synthesis of the primary (i.e.,unfolded) polypeptide.

  4. Re: hard to read: I take it back, the arxiv is an easy read, nor is there an arcane defense of technique; I must have been thinking of something else.

  5. Arrow says:

    “collision with the planet Theia, the oxygen catastrophe, the snowball Earth events, the Permian-Triassic mass extinction event, the asteroid that hit Chicxulub, and more, including the global warming episode we are causing now”

    Kinda hilarious to put global warming on that list, if anything you should put homo sapiens and associated habitat loss.

    Apart from that it seems the only close call for life in general would be a collision with a large enough astronomical body to melt all the crust, otherwise the life would surely survive in some form. Half the genera dying off might seem extreme to us but from the perspective of life in general succeeding it’s completely insignificant.

    As for SETI, aliens radio silence has probably much more to do with apathy then anything else. The lack of purpose to life is a natural barrier to any intelligent life. There’s only so much intelligence you can have and still maintain a positive enough outlook on life to want to reproduce…

    • John Baez says:

      I wrote that abstract half a year ago. I’m more inclined these days to lump in global warming as part of a bigger situation, the Anthropocene. That’s what I did in my talk on ‘What is Climate Change?’ a couple months ago. So, that’s the tack I’ll take now.

      What matters when pondering the search for intelligent life is not whether the Anthropocene will kill off life on Earth: obviously it won’t. What matters is whether it will prevent our civilization from spreading across the galaxy, or putting resources into sending signals to other planets. And the reason it matters is that what happens, or could happen, to our civilization is one of the few clues we have about what happens to other civilizations. I’ll argue that ‘tragedy of the commons / prisoner’s dilemma’ situations can arise in the course of the development of intelligent life, which have the potential to knock down civilizations. These can also happen before intelligence arises. The oxygen catastrophe is a good example of how life can survive these ‘tragedy of the commons’ situations if they happen slowly enough for evolution to find a way out. Perhaps on some planets situations arise where evolution doesn’t find a way out.

  6. ahhaha says:

    If one professes to be a scientist, one is obliged to see all sides of an argument, else, foolhardiness isn’t checked by the recognition of error.

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