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evand comments on Open Thread, September 1-15, 2012 - Less Wrong
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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.
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.