There is no ‘Sustainability Solution’ to the Fermi Paradox

‘Sustainable’ doesn’t imply ‘stagnant.’

In The ‘Sustainability Solution’ to the Fermi Paradox (Journal of the British Interplanetary Society 62: 47-51), Haqq-Misra and Baum propose the following counterargument to the Fermi Paradox:

the absence of ETI observation can be explained by the possibility that exponential or other faster-growth is not a sustainable development pattern for intelligent civilizations. Exponential growth is implicit in Fermi’s claim that ETI could quickly expand through the galaxy, an assumption based on observations of human expansion on Earth. However, as we are now learning all too well, our exponential expansion frequently proves unsustainable as we reach the limits of available resources. Likewise, because all civilizations throughout the universe may have limited resources, it is possible that all civilizations face similar issues of sustainability. In other words, unsustainably growing civilizations may inevitably collapse. This possibility is the essence of the Sustainability Solution.

However, this argument fails to take into account the critical fact that the resource base available to a civilization as it expands in area or volume also expands. Just as nothing precludes a sustainable civilization expanding from a single geographical location to an entire planet, there is nothing to suggest that a sustainable civilization cannot expand from a single planet to the entire galaxy. In fact, if a mechanism like Von Neumann probes were used, the amount of resources dedicated to exploration would be bounded and independent of the final explored volume (in the simplest case, a civilization only needs to build and launch one successful probe).

In a way, that was an encouraging mistake to make. The default assumption of growing resources can be very damaging to a civilization, particularly one that is already exploiting the entire planet. But resource-bound civilizations can expand to the limit of their feasible transportation technology—-after all, ours did—- and although so far we have done so in an unsustainable way, that needs not be the case, neither for an Earth-wide civilization nor for one colonizing the galaxy.