# Dissolving the Fermi Paradox (Applied Bayesianism)

• My sum­mary:

Pos­si­ble solu­tion to the Fermi para­dox: there is no para­dox. The nor­mal ap­proaches find that there should be a very large num­ber of civ­i­liza­tions by plug­ging point es­ti­mates into the Drake Equa­tion, but mul­ti­ply­ing point es­ti­mates (as op­posed to prob­a­bil­ity dis­tri­bu­tions) with each other gives you mis­lead­ing re­sults.

As a toy ex­am­ple, if you mul­ti­ply nine fac­tors to­gether to get a prob­a­bil­ity of life per star, each of the fac­tors a ran­dom real num­ber drawn uniformly from [0, 0.2] and the point es­ti­mate for each be­ing 0.1, then the product of the point es­ti­mates is 1 in a billion. This would trans­late to an ex­pected 100 life-bear­ing stars, given 100 billion stars. But if you in­stead com­bine the prob­a­bil­ity dis­tri­bu­tions, you get a me­dian num­ber of 8.7 life-bear­ing stars (the mean is still 100).

Go­ing through the liter­a­ture to es­ti­mate rea­son­able prior dis­tri­bu­tions for differ­ent val­ues in the Drake Equa­tion, you get much more pes­simistic es­ti­mates for the prob­a­bil­ity of life in the uni­verse; the pri­ors cho­sen by the au­thors sug­gest a 40% a pri­ori chance for life only emerg­ing once. We re­ally might just be alone.

• Could we gen­er­al­ise this ap­proach?

EY wrote that mul­ti­ply­ing point es­ti­mates are not cor­rect for es­ti­mat­ing the prob­a­bil­ity of suc­cess of cry­on­ics. https://​​www.jefftk.com/​​p/​​mul­ti­ple-stage-fal­lacy How­ever, it looks like his con­clu­sion is that the to­tal prob­a­bil­ity of suc­cess should be higher than im­plied by mul­ti­pli­ca­tion, not lower as in case of San­ders’ pre­sen­ta­tion. This may be be­cause in his case most prob­a­bil­ities are above 0.5, so in fact mul­ti­pli­ca­tion of the failure prob­a­bil­ities would give lower es­ti­mate. That is the prob­a­bil­ity of cry­onic failure is smaller than pre­dicted by mul­ti­pli­ca­tion of prob­a­bil­ities of failure on each step.

• Nice idea, but I don’t think the cases aren’t math­e­mat­i­cally analo­gous. Eliezer is just talk­ing about mul­ti­ply­ing prob­a­bil­ities, not es­ti­mates of any­thing. And he’s say­ing that that won’t pro­duce the right an­swer be­cause of hu­man bi­ases, not be­cause it’s math­e­mat­i­cally in­valid. Whereas in the Drake equa­tion we are mul­ti­ply­ing prob­a­bil­ity dis­tri­bu­tions for cer­tain pa­ram­e­ters (the fre­quen­cies at which the var­i­ous con­di­tions for life oc­cur) and it’s a math­e­mat­i­cal fact that the me­dian of the product isn’t the product of the me­di­ans.

• I agree with the con­clu­sion that the Great Filter is more likely be­hind us than ahead of us. Some ex­pla­na­tions of the Fermi Para­dox, such as AI dis­asters or ad­vanced civ­i­liza­tions re­treat­ing into vir­tual wor­lds, do not seem to fully ex­plain the Fermi Para­dox. For AI dis­asters, for in­stance, even if an ar­tifi­cial su­per­in­tel­li­gence de­stroyed the species that cre­ated it, the ar­tifi­cial su­per­in­tel­li­gence would likely colonize the uni­verse it­self. If some civ­i­liza­tions be­come suffi­ciently ad­vanced but choose not to colonize for what­ever rea­son, there would likely be at least some civ­i­liza­tions that would.

• I would be also in­ter­ested in an­thropic up­dates and util­ity up­dates of Fermi para­dox.

An­thropic up­dates: 1) Ac­cord­ing to Katja Grace, SIA makes more prob­a­ble that we live in a uni­verse with the later filter. https://​​www.academia.edu/​​475444/​​An­thropic_Rea­son­ing_in_the_Great_Filter

2) If the early filter is true, part of it may be still ac­tive, like the higher in­ten­sity of gamma ray bursts, as­ter­oid im­pacts, or tem­per­a­ture in­sta­bil­ity of at­mo­sphere. If this is true, we live in the more frag­ile world, and global warm­ing is higher risk.

3) If any new civil­i­sa­tion is ex­pand­ing with al­most speed of light and is de­stroy­ing ev­ery­thing on its way, which is the most ex­pected out­come of Alien pa­per­clip max­imiser, we could ex­ist only in the re­gions of the uni­verse, where such event didn’t hap­pen yet. How­ever, if it were very of­ten, we should find our­self sur­pris­ingly early. But we are not. Sun is some­where in the me­dian of all stars which will ever ap­pear. But if we look on the timescale, and ex­pect that the uni­verse will ex­ist trillions of years (no Big Rip), then we are sur­pris­ingly early.

Utility con­sid­er­a­tions:

1. If Rare Earth is true, METI and SETI is use­less and thus safe ac­tivity. For a long time I wrote that SETI is much more dan­ger­ous ac­tivity than METI, as we could find alien AI. https://​​www.academia.edu/​​30029491/​​The_Risks_Con­nected_with_Pos­si­bil­ity_of_Find­ing_Alien_AI_Code_Dur­ing_SETI

2. But even smaller prob­a­bil­ity that Rare Earth is not true has higher con­se­quences be­cause if visi­ble aliens ex­ist, it could have enor­mous con­se­quences for us, as it means ei­ther later filter, or a pos­si­bil­ity of the con­tact.

• This anal­y­sis re­mains pred­i­cated on the as­sump­tion that a long-last­ing in­tel­li­gent sys­tem is eas­ily visi­ble over cos­molog­i­cal or galac­tic dis­tances with the sorts of in­ves­ti­ga­tions that have already been performed by us.

EDIT—BTW, there’s a lot of in­ter­est­ing ev­i­dence com­ing out for the ease of abio­ge­n­e­sis, and that think­ing of earth’s bio­sphere evolu­tion in terms of ‘it took 4 gi­gayears to get to get X, what if thats just rare’ is the wrong way of think­ing about things—that you need to talk about geo­chem­i­cal phase tran­si­tions rather than ac­cre­tion of in­no­va­tions, af­ter which you get ex­plo­sive changes.

• you need to talk about geo­chem­i­cal phase tran­si­tions rather than ac­cre­tion of in­no­va­tions, af­ter which you get ex­plo­sive changes.

That’s what they talk about on the abio­ge­n­e­sis slides, right?

• I was talk­ing more about things like the great ox­i­da­tion (re­duced at­mo­sphere and iron in the wa­ter to a very lit­tle oxy­gen in the air and hy­dro­gen sulfide in the wa­ter) and the pro­tero­zoic/​phanaerozic tran­si­tion (low-phos­phate oceans with some hy­dro­gen sulfide and low oxy­gen lev­els to oxic, high-phos­phate very pro­duc­tive oceans and lots of at­mo­spheric oxy­gen that sup­ports an ozone layer).

The great ox­i­da­tion is look­ing like it al­most cer­tainly was NOT due to the re­cent in­ven­tion of oxy­genic pho­to­syn­the­sis, but was in­stead a geo­chem­i­cal tip­ping point that came when the slow­ing ge­ol­ogy of the earth and the steady ox­i­da­tion of crustal sinks could no longer ab­sorb all the bio­genic oxy­gen and the very-small-com­pared-to-the-crust at­mo­sphere whipped into a new state long af­ter the oxy­genic pho­to­syn­the­sizer drivers that ul­ti­mately caused it were in place, trig­ger­ing mas­sive bio­chem­i­cal shifts across the bio­sphere in a short time.

The pro­tero­zoic/​phanero­zoic tran­si­tion is look­ing more and more like it could have been an in­ter­est­ing earth-sys­tem-scale flip that had some­thing to do both with a ma­jor in­crease in ex­posed above-wa­ter land­mass (com­ing from the grow­ing con­ti­nents and steadily thin­ning oceanic crust caus­ing a sud­den shift when the ocean level fell to a level that ex­posed large plains rather than just moun­tains) and an in­trin­sic bista­bil­ity of ocean chem­istry such that there are two sta­ble states, one with low pri­mary pro­duc­tivity/​oxy­gen and one with high, that you can only flip be­tween via some kind of shock. Mul­ti­cel­lu­lar an­i­mals as we know them may sim­ply not be a vi­able strat­egy in the low-pro­duc­tivity low-oxy­gen state, and preda­tors that can drive evolu­tion­ary arms races of the sort that prob­a­bly drove the Cam­biran ex­plo­sion cer­tainly are not. As such, the late emer­gence of mul­ti­cel­lu­lar het­erotrophs on Earth (there is ev­i­dence for mul­ti­cel­lu­lar pho­to­syn­the­siz­ers for over a billion years, last I saw) is not nec­es­sar­ily due to them be­ing HARD, but due to the need for the geo­sphere and the chem­i­cal en­vi­ron­ment to go through some phase tran­si­tions first, some driven by slow buildups of ma­te­rial over time and some pos­si­bly more stochas­tic. They show up re­mark­ably fast af­ter those phase tran­si­tions are com­plete.

EDIT: I don’t un­der­stand the as­ser­tion in the linked slides hav­ing to do with abio­ge­n­e­sis that ge­netic sys­tems that were pre­cur­sors to ours could’ve been more sta­ble than ours. LUCA had our ge­netic sys­tem, full stop, and is cer­tainly older than 3.7 gi­gayears at the VERY least, for all we know it could be back to 4.4 gi­gayears. Our ge­netic code also bears the im­print of an ex­plo­sive pe­riod of waaaaay pre-LUCA evolu­tion in which it was op­ti­mized to be liter­ally one in a mil­lion in terms of re­sis­tance to mu­ta­tional dam­age. What came be­fore LUCA was un­sta­ble and fell into a sta­ble state, not the other way around. Fur­ther­more there could be other sta­ble bio­chemistries, with­out the need to posit go­ing di­rectly here (though I will go out on a limb and say I sus­pect pro­tein will be ev­ery­where there is wa­ter as a solvent and that ge­netic polymers are likely to have phos­phates, hah).

EDIT 2: Okay now I see what you are refer­ring to about tran­si­tions in abio­ge­n­e­sis, treat­ing it as a chem­i­cal event with some odds per unit vol­ume per unit time. A rea­son­able anal­y­sis, bet­ter than most, but ne­glect­ing it as a self-re­in­forc­ing PROCESS rather than a sin­gu­lar event. There are other schools of thought, though. There are oth­ers who, treat­ing liv­ing things as dis­si­pa­tive sys­tems that are a chan­nel through which to discharge per­sis­tent chem­i­cal dis­e­quil­ibrium and our core bio­chem­istry as be­ing able to do so at a re­mark­ably low level of or­ga­ni­za­tion, see abio­ge­n­e­sis as a form of break­down into the preferred state of a planet out of equliibrium and un­der chem­i­cal stress. The idea be­ing that even though the break­down is stochas­tic, it is still the preferred state you are push­ing the sys­tem into via putting a stress on it. See Dr. Eric Smith for a dis­cus­sion of the idea from one di­rec­tion (there is a lot of di­ver­sity in ideas on this front):