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Great thread! This is something I think about a fair amount although I haven't gone off the deep end like the Less Wrong people. I usually end up thinking of it in context of the Fermi Paradox. For those not in the know, the Fermi Paradox, simply stated is: "where are all the aliens??" More complexly stated its the inherent contradiction between the multitudes of habitable worlds in the galaxy (depends on how you calculate it but its at least in the high millions), versus how many sentient species we've seen in the galaxy (so far just the 1). Our planet isn't particularly remarkable and it formed rather "late" in the overall timeline of the Universe. So if we look up in the night sky we should be seeing lots of alien life based on the prevalence of habitable worlds...but we aren't. Why? There's a plethora of answers some very mundane (we just can't detect them), some  (they're already here and are lizard people!) but I want to focus on the much more interesting group: that our assumption is wrong and intelligent life is in fact, much, much rarer than we intuitively think based on the number of habitable systems.This can quickly lead to some deeply uncomfortable places as one of the inevitable solutions you'll arise at is that every intelligent species somehow ends up getting destroyed prior to colonizing the galaxy...tying us back into the discussion of Global Catastrophic Risk. There's 2 areas I'd like to talk about in more detail Suicide Pact Technology One of the potential things I've thought about a lot lately are what are known as "suicide pact" technologies. These are things that, once invented, ensure the doom of the species that invented them. One example of this could be say, nanomachines. They're amazing and great and every species ends up inventing them but if they're ever deployed its inevitable they'll malfunction and turn the world into gray goo, thus dooming the civilization that invented them. Problem is, we don't really have any actual examples of them existing given that we...still exist. And the trick with a suicide pact technology is you don't realize its going to wipe out your civilization until its in the process of doing so. The sort of unbridled "omg I love science (but can't be bothered to think of ethics)" from the Elon Musk types greatly concerns me as I don't think they'd be wise enough to avoid accidentally inventing a suicide pact tech. And I'm not sure how we as a species would be able to stop it, these techs are basically trojan horses and it requires someone to be very diligent and forward-thinking to pick up on the risk. The Doomsday Argument This is another interesting one and arises out of statistics. I'll explain the problem through an analogy I once heard to describe it, go through the example in the original paper and then explain the problem in a larger context. Suppose someone says they're going to conduct an experiment. They'll be putting people in 2 groups: in one group you'll be put in a room numbered 1 to 10 and in another you'll be put in a room numbered 1 to 100. You are given no information and after being placed in a room are asked to guess which group you were in. Seems a little silly, but you play along and just as you're about to state your guess the door flies open and you see a giant 7 written on the door. You know this isn't a trick, you definitely are in room number 7. Given what you know now, which group do you think you're in? If you don't care for that explanation, here's the one from the original paper in the September 1993 issue of Nature by Princeton physicist J. Richard Gott III. Gott visited the Berlin wall with a friend in 1969 and, doing some quick math declared "The Berlin Wall will stand at least 2 and 2/3 more years but no more than 24 more years." He was right, the Berlin Wall ceased to exist 21 years after his visit. How did he figure this out? A simple sketch will help.  The insight Gott had was that the past duration of the wall helps to predict its future existence. For any random person witnessing the Berlin Wall in the shaded portion above (half of the Wall's existence) the prediction that the Wall will exist between 1/3 and 3 times as long as it has already existed would be correct. Gott based his estimate on a 50% confidence interval. If you'd prefer, you can use a 95% CI which gives .2 to 312 years. Much less impressive but still correct at the time Gott made his prediction. So what's all this have to do with existential risk? Let's play the same game with humanity.  Line up every person ever born in a line. Now consider your position in line. You are (approximately) number 100,000,000,000 and it is year 200,000 (approximately) but you want to know how many total humans will ever be born (i.e. when will humanity die out?). Going back to the first example: are you in room #7 from 1-100 (i.e. one of the earliest humans) or are you in room #7 from 1-10 (i.e. one of the last humans). Well according to the math of Gott, and knowing that approximately 130 million people are born every year, there's only a 50% chance humans last another 760 years (i.e. when you get another 100 billion humans born) That's....not great odds for us. Now all that said, there are a lot of arguments against this and I'm still not sure if I've got my head fully wrapped around it yet. The most common/best counter-argument I've heard is that Gott's argument plays a little fast and loose with us not knowing anything about where we currently sit on the human timeline. Another fairly simple counter is as follows: Assume either 1. 200 billion humans will be born in total or 2. 200 trillion humans will be born in total. You can then argue "I'm a random unique human. It's much more likely I'm 1 in 200 trillion than 1 in 200 billion" (analogous to arguing you're in room 1-100 rather than room 1-10). After I heard about the Doomsday Argument I did some searching and ended up finding this video from Isaac Arthur (he came up with the door analogy I believe) that I suspect does a better job of explaining it than I do. https://www.youtube.com/watch?v=NQIB3-EtL1w Curious to hear what others think!
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Jan 26, 2021 03:22
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DrSunshine posted:I want to return to this point and piggyback off of it into something I've pondered about. Here's a possible Fermi paradox-adjacent question that I don't think I've seen stated anywhere else. It has a bit to do with some Anthropic reasoning. As preposterous and geocentric as it sounds on its face, the evidence for "We're First" does appear quite good despite the overall age of the Universe. To clarify, the "We're First" answer basically says that no, habitable planets and intelligent life are not that rare, however conditions only recently became such that intelligent life can form. Its a somewhat unsatisfying answer as it seems highly unlikely we're "special" but there is fairly decent evidence for it. Here's an article going through the details of the Firstborn solution in a bit more depth: https://www.universetoday.com/147591/beyond-fermis-paradox-x-the-firstborn-hypothesis/ In no particular order the conditions you need for intelligent, biological life are: 1) Stellar formation in the right type (main sequence, sun-like stars, which are rarer than you think) 2) Sufficient quantity of higher numbered elements to form planets 3) Low number of cataclysmic, planet sterilizing effects (supernovae, gamma ray bursts, black holes, etc.) 4) Sufficient quantity of phosphorus. Until recently this wasn't seen as something that interesting but it does appear that phosphorus is much rarer in the universe at large than it is on our planet/in our solar system 5) Sufficient quantity of some kind of solvent for life (e.g. water) This is a pretty long list and that's before we get to the habitable zone, tidal effects, etc. I don't recall the exact figures but I believe they've determined that given these constrains the Earth was formed right at the start of the period in which all 5 of these criteria could generally be met.
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Feb 2, 2021 21:29
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