Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asking the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and ad-free, plus hours of bonus content,

check out go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

This episode is sponsored by Auduble.

I think we can all agree, 2020 has been a heck of a year.

Hopefully the rest of the century will go smoother, but if it doesn't, how will we survive it?

Nuclear weapons, viruses, artificial intelligence, technological singularities, asteroid impacts,

earthquakes, supervolcanoes, 3D printing, automated factories, gray goo, genetic engineering,

unemployment, virtual reality, deforestation, desertification, changing climates, invasive

species, antibiotic-resistant superbacteria, ultra-addictive designer drugs,

solar storms and flares, designer babies, and uplifted lions and tigers and bears, oh my,

the future is going to be quite a challenge. Welcome to Science and Futurism with Isaac Arthur,

and I am your full-mentioned host, Isaac Arthur. In general, I tend to be known for my optimism about humanity's future, but the point I always

feel obliged to bring up when accused of being optimistic is that it's not optimism that

arises from being unable to see all our problems, but from being able to see a lot of potential

solutions too, and that we can meet and overcome these challenges.

We have a lot of challenges coming up in the next century, many of which could cripple or even

obliterate us, and what we're going to do today is go through those, ask how we can avoid the pitfalls,

and how we can mitigate the damage or recover if we still trip into one of those potentially

cataclysmic scenarios.

Of course, normally the one thing guaranteed about surviving the next century is that you,

...