The Great Filter – Fossil Fuels

As noted before, the Great Filter, if there is one, may be contemporaneous with our species or in our near future, after we solve today’s pressing problems.  We might even be living through one right now. 

Great Filter catalogs have a large number of examples from biology, ranging from the initiation of self-replicating anythings to the evolution of smart anythings.  After that are examples from technology and sociology, and their interactions, like environmental destruction of the planet or nuclear annihilation.  There is one possibility that originates back in the first, biological, portion of that, the early Earth days, but doesn’t hit us until the early technology days, like a century ago.  Spanning these eons is one particular item that plays a supreme role in our technology development: fossil fuels. 

We all learn that there are three fossil fuels, coal, oil and natural gas, corresponding to the three states of matter, solid, liquid and gas; we also know there are more states of matter, and that fossil fuels also come in ooze, which is a technical term meaning liquids with almost enough viscosity to be solid.  The predominant theory of the origins of fossil fuels is embodied in their name.  Ancient organic fossils were laid down, and then covered over by dust, dirt and other matter.  As time went on, the vegetation became one of the three or four types of fossil fuels, and it patiently waited underground for us to find it.  Another theory is that it is abiotic in origins, and comes from chemical transformations of the carbon in rocks.  No matter what the origin, it takes a long time to build up.

Tar, the ooze form of fossil fuels, has been known for perhaps the length of civilization, and was put to a few uses.  But it was coal, which started to be mined in the last part of the sixteenth century, that started off the industrial revolution.  It is a concentrated energy source, and was used everywhere energy was needed.  It provided the ability to create higher temperatures for metallurgy.  It provided more energy per pound and improved the ability to build engines, both for propulsion and for mechanization.  Oil did the same, but also became an important feedstock for the manufacture of countless products.  Gas also produced the same benefits.  Without them, the industrial revolution would not have happened.  Without the industrial revolution, we would not have the technology we have today, which is a necessary stepping stone to star voyaging. 

So, if there had been processes which prevented the formation of fossil fuels, it would certainly have prevented stellar tourism as well as most of everything else new and clever today.  There doesn’t seem to be any alternative that could have replaced fossil fuels that is not facilitated by the pre-existing use of fossil fuels to make it.  No alternative path to higher technology without fossil fuels means it is a Great Filter, provided that it is not present on other planets.  Its importance makes it a candidate for a Great Filter, but our lack of knowledge of whether other planets have any keeps us from promoting it from a mere candidate to a strong possibility for answering the question of why there are no aliens in our backyards.

To be useful to alien civilizations, in their struggle to get beyond sailboats and wood fires, there must be a large quantity of it, and moderately accessible as well.   Having an alien planet with some trace amounts of hydrocarbons buried underground is not going to propel them over the hurdle of initial technology development and put them in the running for nuclear power. 

What could be the mechanism for a planet with life forms not developing fossil fuels?  If the vegetation on the planet, assuming it has some, is sparse, like a desert here on Earth, there would not be enough to accumulate.  Most likely there would have to be forests that grow unimpeded and build up under them layers and layers of dead vegetation.  Since the fossil fuels were laid down hundreds of millions of years ago, this means dinosaur era forests had to continue to build up carbon containing deposits that will later get buried deeper and deeper.  After long enough to accumulate, and after the heat that comes with depth of accumulation and burial does its work, we have fossil fuels of one type or another.  Liquid and gas types would emerge onto the surface unless there were impermeable rock strata.   Sometimes the impermeable strata are made of salt.  It is not hard to imagine how a strata of salt forms – a sea with dissolved salt dries up, maybe periodically, and leaves successive layers of salt, which eventually become thick enough to hold back a large basin of oil or gas.  Non-salt strata may form similarly, either from blown dust onto a dry area, or sediment precipitating out of a body of water. 

By thinking through the necessary precursors to large fossil fuel deposits on Earth, it becomes clear that it is a combination of vegetation being right, tectonic movement of continents forming seas or depressed areas, climate changes turning wet areas in to dry ones or the inverse, and probably some weather requirements, such as winds not being too strong to allow large plant objects to grow.  A lack of rapid decay of deposited vegetation might also be necessary, which is an indication of the microbes present and how they behave. 

Going back a bit further, perhaps the tectonic shifts and the weather and climate changes are affected by the Earth’s orbit or the presence of the moon, and how these changed over millions of years.  The evolution of decay process microbes could be a factor.  The structure of the earth, both its crust and the mantle that drives the motion of the crust could be major factors.  At this point in our scientific knowledge, we cannot say which of these are major factors and which had to be just right for some millions of years to have the conditions needed for the production of the deposits of fossil fuel which we have so easily discovered.  But it is clearly a reasonable speculation that one or more of these might be rarities, and if one or more are, we would be correct in assessing that fossil fuels are the Great Filter.

Since we have these fossil fuels and have used them to push ourselves up the rungs of technology development, we may be the lucky ones in the galaxy.  It means that if we get to star-traveling, we are going to find a lot of worlds with really swift sailboats and horse buggies but no carbon dioxide polluting their atmosphere.  It was a tradeoff we made.