There’s this idea, called the great filter, that is used to explain why we haven’t found alien civilizations yet. The basics are this: The universe has existed long enough for any early-developing intelligent species to have populated the galaxy by now, even with slower than light technology.

Basically, we could almost do it with our level of tech, and can see the engineering challenges that would be needed to make it practical. It’d take thousands of years, but that’s nothing on the galactic scale.

It’s doable.

There’s also this idea that we’re kind of late to develop in the galactic time scale, so someone should have beaten us to it. The fact that no one apparently has suggests that there’s a ‘great filter’ an insurmountable problem that any growing civilization must face and can not overcome. (This video gives a good overview)

There have been many candidates put forward as to what that great filter could be – the technology to build nuclear weapons, pandemics gaining access to whole populations thanks to transportation efficiencies, some kind of genetic lethargy, even the Internet’s ability to destroy logical/scientific progress.

Here’s a candidate that I’ve been thinking about a lot lately. Maybe the great filter is the absence or abuse of fossil fuels. Fossil fuels are a limited resource. Technically they are renewable, but not on our time scale. To have fossil fuels, a planet has to be of a certain age, sustained multiple periods of life and had the geological process necessary to develop them.

Perhaps early Civilizations were too early and there weren’t fossil fuels available for them to use to industrialize. Perhaps, like us, these Civilizations squandered their fossil fuels on immediate needs instead of thinking long term for the greater good of their species.

What role does fossil fuel have on the development of an interplanetary civilization? Our industrial revolution was driven by the use and adaptation of fossil fuels to industrial production. Coal, the first fossil fuel utilized on a massive scale, launched the revolution, with oil and gas coming along soon after to make even better energy sources for the production of fidget spinners and other much needed plastics (sarcasm kids). Prior to that, transport had to be done in slower and smaller ships, reducing the capability of factories to produce goods, thus slowing the growth of economies, and reducing economies of scale. Things were more expensive and innovation was slower.

Oil, along with natural gas and the various industries that can produce oil-based products added not only greater speed to the whole economic cycle, but allowed for greater possibilities -air transport became feasible, space travel became achievable. But what happens when the fossil fuels are gone?

That’s my idea of the great filter. Civilizations as a whole discover and use up their fossil fuels before they achieve interstellar travel. Not that fossil fuels would take them there, but that fossil fuels are a step on the path, a step that many civilizations either don’t have access to or fall off of.

To use an analogy that might be too on point, think of civilization as a rocket ship. Before fossil fuels, we could build the ship, but only dream of launching it. With fossil fuels applied, our economy can now lift off and make orbit. But to get to greater heights, we need something better than fossil fuels. We may not discover that answer before fossil fuels run out, plummeting us back to the ground and breaking us for a long time if not permanently.