In this episode of the podcast we talk about Existential Risks and the future of humanity. But first, we start off with an analysis of the recent film "Don't Look Up" and what it says about our present moment and our ability to come together to mitigate existential catastrophes.

In Part 1, we'll be looking mostly at naturally occurring existential risks. In Part 2, being released next week, we'll look more in-depth at human-caused existential risks.

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  • 0:00 - Introduction, Don't Look Up
  • 4:53 - Analysis of Don't Look Up (spoiler warning)
  • 30:53 - Orientation to what an Existential Risk is
  • 45:05 - Asteroid or comet impact
  • 54:44 - Eruption of a supervolcano
  • 1:02:35 - Interstellar object disturbing our solar system
  • 1:10:23 - Supernovas and Gamma-Ray Bursts
  • 1:13:58 - Increasing solar radiation
  • 1:18:43 - Sun enters its red giant phase
  • 1:19:41 - End of the Universe
  • 1:23:56 - Outro, about the Companion Podcast

Food for Thought:

I'd love to read your responses to these questions in the comments below.

  1. Are there any naturally occurring existential risks that you're particularly concerned about or wish I would have covered?
  2. Do you think the long-term vision of humanity colonizing the cosmos is possible, or is it only a Science Fiction fantasy?


  • We kick things off with a discussion and analysis of the film Don't Look Up (spoiler alert!). The film does a great job showing how our modern society is essentially broken, and how anything that can be politicized inevitably becomes politicized (the film is even a commentary on itself here, ironically).
  • We define what an existential risk is: an event that results in the extinction of humanity; either by killing every human being in short order, or by causing human civilization to collapse to a point from which it might never recover.
  • What's at stake here is the long-term future of humanity. If we don't go extinct and we do end up colonizing the stars, this could mean that humans go on to survive for millions, billions or perhaps even trillions of years into the future. Assuming human population increases with every new planet we colonize, and the availability of potentially habitable planets is in the billions in our solar system alone (which is just one of hundreds of billions of solar systems that may be available to us), this could result in an inconceivably large number of humans existing in the future—but only if we avoid extinction in the near term.
  • We examine seven naturally occurring existential risks in detail:
  1. An asteroid or comet impact. This is the one existential risk we've actually put the most effort into solving and mitigating, and ultimately our risk of going extinct as a result of an asteroid or comet impact is quite low (and continues to be reduced each year as more powerful surveillance telescopes come online).
  2. A supervolcano eruption. Our species may have had a close brush with a supervolcano about ~75,000 years ago in the Toba super eruption; the population of humans is thought to have dropped as low as a few thousand breeding individuals. The risk here is that we could experience a prolonged volcanic winter that shuts down photosynthesis and causes widespread mass extinctions throughout our biosphere. We also have no capability of predicting or mitigating a future super eruption, should one occur (they're estimated to occur approximately once per 50,000 years, and the last one was ~75,000 years ago).
  3. An interstellar object disrupting our solar system or the Oort cloud. Something like 100 billion comets orbit the outer reaches of the solar system in a region known as the Oort cloud. It's possible that a wandering rogue planet, brown dwarf, star, or even a primordial black hole could come close enough to our solar system to disrupt the Oort cloud and send comets raining into the inner solar system. It's also possible that a closer encounter could be even more catastrophic: if a large object were to enter our solar system, it could conceivably disrupt planetary orbits and perhaps even eject Earth out into deep space, detached from our star.
  4. A supernova or gamma-ray burst from within our galaxy. Estimates are that a supernova within 30-50 light years could cause a mass extinction event on Earth by devastating our atmosphere and the Ozone layer. Or, a gamma-ray burst within about 25,000 light years could do the same. These are rare events, estimated to occur perhaps once every 1 billion years or 130 million years, respectively.
  5. Increasing solar radiation. This is less of a risk and more of an inevitability. Or a milestone, even. Within a few hundred million years, our sun's increasing luminosity will have eroded most of the carbon in our atmosphere, which will lead to a breakdown of photosynthesis. There will come a point where plants can no longer photosynthesize due to a lack of bioavailable carbon (a bit ironic given our current problem of too much anthropogenic carbon), which will cause a mass extinction from the bottom of the food chain. So within the next billion years or so, Earth is going to become a lot less habitable for life;  we best have moved on to other planets by then.
  6. The sun's red giant phase. Another inevitability, which is likely to happen about 5 billion years from now. When the sun has burnt up all of its hydrogen and starts burning heavier elements (such as helium), it will expand in size significantly—perhaps even further than Earth's current orbit. This means the Earth will either be scorched or swallowed by our own sun. At this point it might be possible to survive in the outer solar system, but the instability of this phase of the sun's life means we'd be better off evacuating to another star system.
  7. Finally, the eventual end of the universe. If we make it this far, we should give ourselves a pat on the back. This won't be happening for an inconceivably long time, but there will likely come a point where survival in the universe is no longer physically possible—either due to a big freeze or a big crunch. Nothing will survive this event, not even black holes.
  • Next week, in part 2, we examine human-caused existential risks, which are estimated by philosopher Toby Ord to be 1,000 times more likely to cause us to go extinct over the next century than naturally occurring ones. [5]

Additional Content:

Works Cited:

  1. Nick Bostrom and Milan M. Cirkovic, Global Catastrophic Risks. Oxford University Press 2008.
  2. Peter Brannen, The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth's Past Mass Extinctions. Harper Collins 2017.
  3. Phil Torres, Morality, Foresigh, and Human Flourishing: An Introduction to Existential Risks. Pitchstone Publishing 2017
  4. Derek Parfitt, Reasons and Persons. Oxford University Press 1984.
  5. Toby Ord, The Precipice. Hatchette Books 2020.