Where are all the Aliens?

Thinking about SETI, the search for extraterrestrial intelligence, is a fascinating exercise in thinking about about civilization. This link is inevitable because any rational search strategy forces you to consider what civilizations do, how they evolve and, most importantly, how long they last. Back when nuclear war was our biggest worry the question of civilizations' endurance always seemed to hing on its bellicosity. Our new found recognition of climate change and the limits to growth changes that perspective. Now we have to ask if there is something fundamental to the very agent which makes civilization seem possible which can, in turn, threaten it - technology.

To that end I want to share with you a paper I have been reading that I found on the astrophysics preprint server. The paper is called THE SUSTAINABILITY SOLUTION TO THE FERMI PARADOX and its authors Haqq-Misra & Baum have been remarkably creative in merging SETI with our new concerns. The Fermi paradox is an old conundrum (which may not have really started with Fermi) that asks, essentially "If ETs exist, why aren't they here already?" The idea is that if one assumes an exponential expansion of a star-faring civilization then unless things just got started everywhere in the galaxy civilization-wise, we should already have been overrun by little green friends.

Haqq-Misra & Baum have an answer for this that comes from our new understanding about limits to growth. Here is their abstract.

No present observations suggest a technologically advanced extraterrestrial intelligence (ETI) has spread through the galaxy. However, under commonplace assumptions about galactic civilization formation and expansion, this absence of observation is highly unlikely. This improbability is the heart of the Fermi Paradox. The Fermi Paradox leads some to conclude that humans have the only advanced civilization in this galaxy, either because civilization formation is very rare or because intelligent civilizations inevitably destroy themselves. In this paper, we argue that this conclusion is premature by introducing the “Sustainability Solution” to the Fermi Paradox, which questions the Paradox’s assumption of faster (e.g. exponential) civilization growth. Drawing on insights from the sustainability of human civilization on Earth, we propose that faster-growth may not be sustainable on the galactic scale. If this is the case, then there may exist ETI that have not expanded throughout the galaxy or have done so but collapsed. These possibilities have implications for both searches for ETI and for human civilization management

I will let you read the rest for yourself and see what you think.