Weird question: could we see distant aliens?

ETA: Con­test is closed.

Sup­pose there was a large alien civ­i­liza­tion halfway across the ob­serv­able uni­verse, us­ing a galaxy’s re­sources to try to get our at­ten­tion. Would we have no­ticed? What if they were us­ing 0.1% of a galaxy’s re­sources, or 1000 galax­ies’ re­sources?

I’ve ar­gued re­cently that such an alien civ­i­liza­tion is (a) not that un­likely a pri­ori, even given that there aren’t any closer aliens, (b) po­ten­tially re­ally im­por­tant to no­tice.

I be­lieve the an­swer to my ques­tion is prob­a­bly “definitely.” But I can’t tell with any con­fi­dence, so while it’s prob­a­bly definitely it might be maybe and could be prob­a­bly not. I’d like to know the an­swer, but space isn’t my thing.

I’m offer­ing a prize for any­one who an­swers this ques­tion. To be a bit more pre­cise:

  • Your goal is to con­struct a strat­egy that a tech­nolog­i­cally ma­ture civ­i­liza­tion could use to get our at­ten­tion, even if they were halfway across the ob­serv­able uni­verse.

  • The strat­egy is al­lowed to use the re­sources of an av­er­age galaxy. Note that they don’t know when they are look­ing, so they need to run the strat­egy for a few billion years. And they have no idea what di­rec­tion we are in, so it needs to be visi­ble from any di­rec­tion (no lasers).

  • By “get our at­ten­tion” I mean: be in­ter­est­ing enough that we would already have no­ticed it and de­voted some telescope time to look­ing in more de­tail at that part of the sky. (Once they have our at­ten­tion it seems sig­nifi­cantly cheaper to send a mes­sage.)

  • Alter­na­tively, you can also win by pro­vid­ing an ar­gu­ment for why this isn’t likely to be pos­si­ble. Ba­si­cally just say­ing any­thing that con­vinces me that the ques­tion is no longer open.

  • The sec­ond and third parts of the ques­tion are the same as the first half, but for 1000x and 1/​1000th of an av­er­age galaxy’s re­sources.

A sim­ple ex­am­ple of a strat­egy is to cre­ate a re­ally bright bea­con some­where far away from any galaxy, which looks weird in some way. I ex­pect (based mostly on su­per in­for­mal dis­cus­sions with An­ders Sand­berg and Jared Ka­plan) that this strat­egy is good enough, i.e. that 0.1% of a galaxy’s power is plenty to make a bea­con that would be re­ally ob­vi­ous to us from halfway across the uni­verse. But I’m definitely not sure. The bea­con can have a weird spec­trum, or flicker in a strange way, or only be ac­tive 1% of the time (but be 100x brighter), or what­ever.

Note that an an­swer needs to make refer­ence to the as­tro­nom­i­cal ob­ser­va­tions hu­man­ity has ac­tu­ally made, e.g. how long telescopes of a par­tic­u­lar strength have spent look­ing at any par­tic­u­lar part of the sky, and what kinds of pat­terns would have been no­ticed.

With re­spect to the ca­pa­bil­ities of the alien civ­i­liza­tion, I’m an un­apolo­getic techno-op­ti­mist. If it’s within the en­ergy bud­get, I’m prob­a­bly will­ing to be­lieve they can make it hap­pen un­less it sounds su­per crazy. For 1x and 1000x ques­tions, it’s fine if they want to grossly dis­figure a galaxy if that would be the best way to be no­ticed. For the 1/​1000 ques­tion, grossly dis­figur­ing a galaxy isn’t al­lowed un­less we can be pretty con­fi­dent it doesn’t re­duce the use­ful­ness of that galaxy by >0.1%.

I’m also ba­si­cally happy to as­sume that they know ex­actly what our civ­i­liza­tion is look­ing for and so can op­ti­mize their solu­tion to be no­tice­able to us. (After all, they’ve run a billion billion simu­la­tions of civ­i­liza­tions like ours, they know the dis­tri­bu­tion, they can spend 5x as much en­ergy to cover the whole thing.)

I don’t care about whether we’d no­tice “things the aliens would want to do any­way,” be­cause I have no idea what aliens would want to do and have limited con­fi­dence in our abil­ity to make pre­dic­tion. In par­tic­u­lar, it seems plau­si­ble that they would blend in with the back­ground by de­fault (e.g. maybe some­thing like aes­ti­va­tion hy­poth­e­sis is true). I’m much more in­ter­ested in an­a­lyz­ing de­liber­ate at­tempts to be ob­served, since those al­low us to ar­gue “If there ex­ists a cheap way to be no­ticed, and they want to be no­ticed, they’ll do it.”


Note: prize is no longer available.

I’m offer­ing a prize for a con­vinc­ing an­swer to this ques­tion.

Ini­tially the prize is $100. It in­creases by 10%/​day, un­til cap­ping out at $10,000 in 49 days.

Sub­mit by writ­ing a com­ment on this post.

The prize starts out low be­cause I think this might be a re­ally easy ques­tion. Feel free to try to be strate­gic if you want. If you get scooped be­cause you are wait­ing for the prize to grow, I have zero sym­pa­thy.

The crite­rion is “Paul is con­vinced.” Ci­ta­tions and clear ex­pla­na­tions are prob­a­bly helpful. In gen­eral sources don’t have to be su­per au­thor­i­ta­tive; if you cite Wikipe­dia I’d pre­fer a cita­tion to a his­tor­i­cal ver­sion of a page be­fore the con­test started, just to rule out hijinks.

You are al­lowed to just link to an ex­ist­ing anal­y­sis that cov­ers this ques­tion, or link with a small amount of ex­tra work, if that’s con­vinc­ing. As­sum­ing the linked ex­pla­na­tion was writ­ten be­fore my blog post, you’ll get the prize, not the au­thor of the linked post. The pur­pose of this prize is to buy in­for­ma­tion, it’s not like the al­ign­ment prize.

I ex­pect that win­ning sub­mis­sions will be rel­a­tively short, prob­a­bly just a few para­graphs with some links and calcu­la­tions. You can take longer if you want, but I as­sume no re­spon­si­bil­ity for the harm thereby done to the world.

I re­serve the right to be ar­bi­trary in eval­u­at­ing sub­mis­sions. I am not go­ing to feel guilty about it. If your will­ing­ness to par­ti­ci­pate de­pends on me feel­ing guilty about peo­ple who spent a bunch of time but who I un­fairly re­jected, then please don’t par­ti­ci­pate.

I may give par­tial credit if some­thing seems like a use­ful con­tri­bu­tion but doesn’t re­solve the ques­tion com­pletely (even if it’s just a short com­ment with a poin­ter to a use­ful re­source).

I may give feed­back in the com­ments.

If you think this isn’t the best thing for me to do with my time and are wor­ry­ing about my life de­ci­sions—it was ei­ther this or spend my own hours look­ing into the ques­tion. Don’t worry too much, this shouldn’t take long.

Note: prize is no longer available.