Could we send a mes­sage to the dis­tant fu­ture?

Sup­pose that hu­man­ity wiped it­self out but left be­hind com­plex mul­ti­cel­lu­lar life. I think there is a good chance that space-faring civil­iz­a­tion would emerge again on Earth, and I’ve ar­gued that it might be worth­while to try send­ing them a mes­sage.

(In that post I guess­tim­ate that if all went well you might be able to ef­fect­ively re­duce ex­tinc­tion risk by 1300 by send­ing a mes­sage to the fu­ture; I could ima­gine that cost­ing only ~$10M and lever­aging in­terest from non-EAs, in which case it sounds like a good buy.)

Un­for­tu­nately, send­ing a mes­sage 500 mil­lion years into the fu­ture seems very hard. Most things that aren’t bur­ied will get des­troyed and the land­scape it­self is go­ing to be com­pletely trans­formed (tec­tonic plates will be re­arranged, moun­tains will ap­pear and dis­ap­pear, the world will be covered in forms of life that don’t ex­ist yet...).

H/​T to Dan Kane for cri­ti­ciz­ing my ori­ginal post and cla­ri­fy­ing the ac­tual nature of the prob­lem.

More pre­cisely my ques­tion is whether we can:

  • Spend $10M-$100M.

  • En­code 100MB of in­form­a­tion.

  • Wait 500 mil­lion years.

  • Have it be found with prob­ab­il­ity >25% by a civil­iz­a­tion as soph­ist­ic­ated as hu­man­ity in 1900.

I’d also be in­ter­ested in re­lax­ing any of these con­straints a little bit, e.g. spend­ing 10x more, send­ing 10x less data, only last­ing 100M years, or only be­ing dis­cov­er­able in the 21st cen­tury.

I’m not very wor­ried about pre­serving the in­form­a­tion—I sus­pect that if we are will­ing to bury some­thing, we can pre­serve 100MB pretty cheaply. My biggest con­cern is put­ting the in­form­a­tion some­where that our suc­cessors can find it.

My ini­tial sug­ges­tion, cla­ri­fied/​im­proved/​named by Jess Riedel, was to:

  • Bury a small num­ber of ex­pens­ive “pay­load” mes­sages (maybe ~100)

  • Bury a large num­ber of “map” mes­sages (maybe 10,000 − 100,000).

  • Some­how get people to stumble across a map. Either put a lot of them in places where they might end up be­ing easy to find, or trans­form the land­scape in ways that might re­main vis­ible in 500M years.

  • Use the maps to en­code the loc­a­tion of pay­loads. (With each pay­load also in­clud­ing much more de­tailed maps to all the other pay­loads.)

I now feel like both of these steps are hard:

  • It seems very dif­fi­cult to ac­tu­ally put maps in places where they’ll be found. For ex­ample, my pro­posal of us­ing a gi­ant+out-of-place+slow-to-weather rock is prob­ably very dif­fi­cult given how much the land­scape will change, since the rock will prob­ably be either bur­ied or moved.

  • It seems very dif­fi­cult to re­li­ably point to the loc­a­tion of the pay­load, given how drastic­ally the world map will change. You’d prob­ably need to com­bine (a) a clever way of com­mu­nic­at­ing loc­a­tions, with (b) some form of beacon that would be vis­ible if people were look­ing for roughly ghe right thing in roughly the right place. This is fur­ther com­poun­ded by the dif­fi­culty of telling what we were say­ing.

I’m not sure if either of those dif­fi­culties are ser­i­ous. For ex­ample, I’m not sure that the re­l­at­ive loc­a­tions of nearby items would get scrambled too much, in which case you might be able to use local maps.

Even if those dif­fi­culties are ser­i­ous, there is a huge space of pos­sib­il­it­ies and I sus­pect that there is some­thing that works and is reas­on­ably cheap:

  • We could po­ten­tially store mes­sages in the ru­ins of prom­in­ent cit­ies, if cit­ies have a reas­on­able chance of be­ing bur­ied+pre­served (cit­ies have enough weird ma­ter­i­als in them that I ex­pect they’d leave a really vis­ible mark). This could either be used to make small mes­sages easier to find, a place to put pay­loads (which can po­ten­tially be poin­ted to with a map of the city), or both.

  • If mak­ing pre­served mes­sages (or mes­sages with a reas­on­able shot at fos­sil­iz­a­tion) is ex­tremely cheap, then we could po­ten­tially send very large num­bers of them. This could be used either to send a bunch of pay­loads and rely on re­dund­ancy, or to al­low maps to be very large and ex­press­ive. It could also be used to flood the world with massive num­bers of maps (>>1M), so that they can be eas­ily found without beacons. (Really ex­tens­ive flood­ing sounds more like a last ditch ef­fort once we can see ex­tinc­tion com­ing, rather than some­thing you’d do pree­mpt­ively.)

  • There might be geo­lo­gic­ally in­act­ive loc­a­tions where you can just leave gi­ant+out-of-place+slow-to-weather rocks and they have a reas­on­able prob­ab­il­ity of re­main­ing in­tact. Moun­tain ranges form over much less than 500M years, but it’s not clear to me that the whole world churns since I don’t really know any­thing about geo­logy. To do this, you’d need to find a rock that wouldn’t wear away en­tirely, and you’d need a loc­a­tion where it wouldn’t be dis­turbed too much or end up un­der ground.

  • There were some plaus­ible sug­ges­tions in a Face­book thread on this topic (in­clud­ing put­ting stuff in space, de­fin­ing co­ordin­ates with re­spect to tec­tonic plates)

If we could come up with a really con­vin­cing and reas­on­ably cheap way to send a mes­sage, then I think it’s prob­ably worth ex­plor­ing this idea at least a little bit fur­ther. I think the next step would be more ser­i­ously ana­lyz­ing how much good a mes­sage could po­ten­tially do (which is much more spec­u­lat­ive than this step).

I’m in the mar­ket for cer­ti­fic­ates of im­pact for sig­ni­fic­ant con­tri­bu­tions to this prob­lem (in the $100-$10k price range, de­pend­ing on the size of the con­tri­bu­tion).