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moridinamael comments on Open Thread, September 1-15, 2012 - Less Wrong
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It has become increasingly clear over the last year or so that planets can in fact form around highly metal poor stars. Example planet. This both increases the total number of planets to expect and increase the chance that planets formed around the very oldest stars. (Younger stars have higher metal content). One argument against Great Filter concerns is that it might be that life cannot arise much younger than it did on Earth because stars much older than our sun would not have high metal content. This seems to seriously undermine this argument.
How much should this do to our estimates for whether to expect heavy Filtration in front of us? My immediate reaction is that it does make future filtration more likely but not by much since even if planets could form, a lack of carbon and other heavier elements would still make formation of life and its evolution into complicated creatures difficult. Is this analysis accurate?
I have a Great Filter related thought which doesn't address your question directly but, hey, it's the Open Thread.
My thesis here is that the presence of abundant fossil energy on earth is the primary thing that has enabled our technological civilization, and abundant fossil energy may be far less common than intelligent life.
On top of all the other qualities of Earth which allowed it to host its profusion of life, I'll point out a few more facts related specifically to fossil energy, which I haven't seen in any discussions of Fermi's Paradox or the Great Filter.
Life on Earth happens to be carbon-based, and carbon-based life, when heated in an anoxic environment, turns into oil, gas and coal.
Earth is roughly 2/3 covered in oceans (this figure has varied over geologic time), a fact with significant consequences to deposition of dead algae, erosion, and sedimentation.
Earth possesses a mass, size, and age such that the temperature a few kilometers below the surface may be hundreds of degrees C, while the surface temperature remains "Goldilocks."
Earth has a conveniently oxidizing atmosphere in which hydrocarbons burn easily, but not so oxidizing that it prevents stable carbon-based life. Quite a narrow window, really.
Life has existed on Earth for billions of years, and thus algae and other life forms have been dying in oceans and swamps and accumulating subsurface hydrocarbon source material, for billions of years.
Put all this together and realize that the formation of oil, gas, and coal happens only in rare and specific circumstances even on Earth. We seem to have a lot of these resources today, but it took billions of years for them to accumulate in the quantities we now find.
If any one of the above facts were not true, we would not have fossil energy - coal, oil, gas, plastics, lubricants - we would not have an industrial revolution, and we would not have a technological civilization.
Many of the facts on the above list have to be true simply to enable fire, as in, wood fire, imagine what human history would look like if the oxygen content of Earth's atmosphere was too low to sustain wood fire?
Anyways, maybe people have discussed this before, but I wasn't able to Google anything up.
Frankly, I'm wondering if the whole idea of exponential growth is just short cultural time horizons applied to the implications of fossil fuels for energy production, which touched off the Industrial Revolution. The Hubbert Peak holds, although coming out the other side of it resembles a gradual stepping-downward with its own local spikes and valleys (much as there are spikes and valleys in growth and use now, despite a steady upward trend). Fossil fuels still supply over three quarters of the world's energy demand; there hasn't been a nuclear renaissance so far and as much as someone always wants to boost pebble bed, travelling-wave or thorium reactors, innovation and growth for nuclear both seem quite limited on the balance. That might not seem like a big deal now (surely it could happen, right?) but what if that situation does not change appreciably, and world civilization starts transiting down the other side of of the curve, taking a few centuries to do it? What if we never do figure out FAI, or MNT, or fusion, or whatnot? What if that's because the noise of society, geopolitics and history-in-general just don't allow for them to come to pass?
What if the the answer to Fermi's paradox is simply "You'd have to mistake the infrastructural equivalent of a blood sugar rush for an inexorable trend in technological development to even wonder why nobody's zipping around in relativistic spacecraft or building Dyson spheres?" What if the problem is just short time horizons and poor understanding of context?
This. I've been searching for a way to articulate this idea for quite some time, and this is the best way I've seen it stated.
The last few centuries are potentially extremely atypical in human history. We have three generations of economists raised on exponentiation to think it is normal, and a series of technological advances that almost all require highly concentrated energy in ways that are seldom appreciated. When you think about it too, it would appear that something like an oil well is the most concentrated source of easily captured energy in the solar system - where else do you get such a huge amount of highly reduced matter next to such highly oxidized gas? With the interface between them requiring something as simple as a drill and furnace? Per unit of infrastructure and effort that is an incredible resource that I honestly doubt you can really improve upon. I have long suspected that reversion towards (through perhaps not all the way to) the mean is far more likely in our future.
Thank you. It's still a bit indistinct to me as yet -- I haven't seen many other people talking about it in these terms, except Karl Schroeder (who explores it a bit in his science fiction writing), but I knew something seemed a little funny when the Rare Earth Hypothesis and its pop-sci cousins started growing in popularity among the transhumanist set. It seems like an awful lot of the background ideas about the Fermi Paradox and its implications for anthropics in the core cluster that LW shares go back to an intellectual movement that came to prominence at a time before we'd discovered more than a tiny handful of exoplanets. Now we know there's at least one Earth-sized world around Alpha bloody Centauri and even Tau Ceti of all stars is being proposed as rich in worlds; at this rate I personally expect to learn about the probable existence of another biosphere around a star within 100 ly, within my natural lifetime (though, for the reasons expressed in my comment, I'm doubtful we'd be able to reliably notice another civilization unless they signalled semi-deliberately or we got staggeringly lucky and they have a recognizably-similar fossil fuel "spike" within a similar window, meaning we can catch the light of cities on the night side assuming Sufficiently Powerful Telescopes).
nod I suspect the future probably looks rather weird to LWian eyes, in this regard -- neither a reversion to the 10th or 17th century for the rest of human existence, nor much like the most common conceptions of it here (namely: UFAI-driven apocalypse vs FAI-driven technorapture). It's hard to tease out the threads that seem most relevant to my budding picture of things, but they look something like: increasing efficiency where it's possible, a gradual net reduction in the stuff economists have been watching grow for the last few generations, some decidedly weirdtopian adaptations in lifestyle that I can only guess at... we've learned so much about automation, efficiency, logistics and soforth and it seems like there's plenty of time to learn a great deal more, such that my brain tries to conjure up visions of a low-energy but surprisingly smart future infrastructure where the world is big again.
I think the jury is still out on this... on the one hand we are finding huge numbers of planets, and it is likely that our sampling biases are what push us towards finding all these big "super-earths" close to their parent stars (I take issue with that terminology, calling something something of ~5 earth masses 'potentially habitable' or even 'terrestrial' is problematic because we have no experience with planets of that size range in our system and you can't confidently state that most things with that mass would actually necessarily have a surface resembling a rock-to-liquid/gas transition). On the other hand we are finding so many systems that look nothing like ours with compact orbits and arrangements that probably could not have formed that way and thus went through a period of destructive chaos, suggesting that the stability of our system could be an anomaly. I'm waiting on the full several years of Kepler data that should actually be able to detect earth-radius planets at a full AU or so from a star, until then there seem to be too many variables.
I mostly agree. I actually find the 'great silence' not particularly puzzling - the only things we have reliably excluded are things like star system scale engineering, and massive radio beacons that either put out large percentages of a planet's solar input out in the form of omnidirectional radio or ping millions of nearby stars with directional beams on a regular basis. When you consider the vast space of options where such grand things don't happen, for reasons other than annihilation, you get a different picture. We couldn't detect our own omnidirectional radiation more than a fraction of a light-year away, and new technologies are actually decreasing it of late. And how many directional messages have we sent out explicitly aimed at other star systems? A dozen? And they would need directional antennas to be picked up. What are the odds that two points in space that don't know of each other's existence would first have one point their message in the right direction, and then have the second one look in the correct direction at the right time? Even if you assume there are many thousands of sources in our galaxy (which I think could be a wild overestimate filter or no given the history of terrestrial life), that puts the nearest one hundreds of light years away in a volume containing millions of stars. Even if they have an order of magnitude or three more effort being put out into sending messages, that still isn't much given the sheer volume. A full galaxy just wouldn't look different from an empty one to beings like us that have been looking less than a century, if the proposed grand destiny of intelligent life proves to be a 'sugar rush' even in the absence of reversion to the mean. (Such a reversion would pretty well certainly still include radio in our toolkit or the toolkit of whoever else was smart enough to figure out electrodynamics, so such a civilization could still be detectable - although what a reversion could lack is the concentrated wealth to build and maintain lots of fifty meter dishes and use them for, effectively, stargazing.)
I would say what it is most likely to resemble is, simply, history. Civilizations rise and fall over centuries (not overnight!) and ours is probably no exception, even if the endpoint might not be as low as past troughs. There are eras of prosperity and eras of destitution, different in different parts of the world as power structures and ecologies shift. Technologies appear, some of them stick around essentialy forever after they are invented and others, like steam heat and clockwork and factories exporting across an entire continent in ancient Rome, get lost when the context that produced them changes. Most eras produce something new that they can pass on usefully to the future, though what they produce that can be perpetuated in a different context would often be unexpected to those in that era.
The limiting oxygen concentration for most woods is between 14% and 18%. The Earth oxygen concentration is a little over 20% so it does look close. But this is slightly misleading: All that oxygen showed up because carbon based life was releasing it from water and carbon dioxide in photosynthesis. Oxygen using life only showed up after there were dangerously high levels of oxygen. And if the oxygen levels get very high then the photosynthesizers will start to get poisoned and the percentage will go down. So it isn't really likely to have an atmosphere with so much oxygen that it is a problem for carbon life.
But yes, certainly an equilibrium with less oxygen is plausible in which case fire would be close to impossible even if the percentage dropped by only a small amount.
The oxidizing atmosphere is not due to chance. It was created by early life that exhaled oxygen, and killed off its neighbors that couldn't handle it. Hence, I don't think the goldilocks oxygen levels speak much to great filter questions.
Early in civilization, we used wood and charcoal as energy sources. Blacksmithing and cast iron were originally done with wood charcoal. Cast iron is a very important tool in our history of machine tools and hence the industrial revolution. It's possible that we could have carried on without coal, instead using large-scale forestry management or other biomass as our energy source. In the early 1700s there were already environmental concerns about deforestation. They were more related to continued supply of wood for charcoal and hunting grounds than "ecological" concerns, but there were still laws and regulations enacted to deal with the problem.
How many people do we need to support a high-tech civilization? I suspect fewer than we tried it with. It's quite possible that biofuel sources would have produced a high tech civilization, just slower and with fewer people.
Also, note that biofuels can produce all the lubricants and plastics you need just fine. The Fischer-Tropsch process has been implemented on a large scale before.
I think that given all this, you could get the modern metal lathe and the steam engine without fossil fuels. We already harnessed basic water and wind power without fossil fuels. I suspect with modern machine tools you get to electricity and large-scale water and wind power generation, even without fossil fuels. Again, more slowly, and possibly without so many people, but I think you can get there.
Actually, the neighbors that couldn't handle oxygen got forced underground. They live in the mud under the deep sea, in digestive tracts, etc.
Well, some of their descendants are still alive, yes. But I believe that there was a lot of dying involved in that process. More than I think is implied by the phrase "forced underground".
These are all good points and I don't disagree with you. It probably is worth pointing out that ever since about 1800 our civilization has had "the pedal to the metal" in terms of accelerating our demand for energy, i.e. an exponential rise in energy demand, and that demand has been consistently met and often exceeded - this is why we can afford to fill our personal cars with this precious fuel on a regular basis.
I think that a sufficiently forward-thinking civilization probably could base its energy production around biofuels, but a gallon of gasoline-equivalent would probably cost about a thousand dollars-equivalent. Building a skyscraper would be a project akin to manned space flight. Manned space flight would be completely out of the realm of possibility.
The more important question would be how hard it would be to get nuclear energy.
I find this doubtful, being as ethanol (25 MJ/L) is nowhere near that expensive to create, and is fairly near the energy density of gasoline (35 MJ/L).
Consider the entire economy, though. Let's not assume that ethanol could ever replace fossil fuels at the scale needed for explosive technological growth. the reason pure ethanol is cheap in the modern world is because we have enormous economies of scale producing the necessary feedstocks which rely on trucks and trains and fertilizers, hell, even the energy used to distill the ethanol is typically from fossil fuel.
It's about supply-demand. If, tomorrow, there were no gasoline anymore, the price of ethanol would be astronomical.
Note, though, that we are talking about much smaller population - so you could spend quite a lot of land per capita on growing both ethanol source and fuel.
Current size of humankind is clearly unsustainable in this mode, of course.
With a much smaller population you start losing all sorts of other advantages, especially economies of scale and comparative advantage.
Careful. Economies of scale for quantity million parts don't show up until probably the 20th century. Prior to that, the effect of reduced population size might just be reduced variety. Do you have any idea how many manufacturers of engine lathes there were at the end of the 19th century, for instance? (Hint: more than a couple.)
Well, one point is that supposedly there were a lot of societal factors that also had to be in place for the industrial revolution to take place. (Apparently if you lived anywhere but Britain, if you were doing anything cool, the ruling monarch would come along and just take it.) So it's not necessarily just tech.
Another point is that Earth appears to have periodic ice ages, and many/most human civilizations seem to collapse after a while. So sustaining progress over long periods is nontrivial.
Environmental ones too. Britain had to be so short of wood and charcoal to burn that using coal in home stoves, even with its nasty byproducts, was preferably to most people going without any source of burnable fuel. The widespread proliferation of coal that followed to meet the demand meant there was plenty of it about to turn to other purposes.