# Roko Jelavić

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# Za­greb Ra­tion­al­ity Meetup

12 Dec 2018 13:08 UTC
1 point
• Per­haps I should have been more spe­cific, I’m talk­ing about a sce­nario where there is an ac­tual ma­chine (like a time ma­chine but in­stead of trav­el­ling in time you travel be­tween uni­verses) in which you step and press a but­ton, and then you ap­pear in a par­allel uni­verse. In stan­dard prob­a­bil­ity we have a po­ten­tial fu­ture state of “I’m dead” and “I’m al­ive” but you can phys­i­cally travel be­tween those two fu­ture states, ei­ther one hap­pens or the other hap­pens. In the in­ter-uni­verse travel sce­nario you can use the ma­chine to travel to other uni­verses and re­vive the copies (or re­pop­u­late the uni­verses in which hu­man­ity went ex­tinct).

EDIT:

So I think we agree on this part:

Let’s say we have 10 uni­verses which are all iden­ti­cal, they all have you in them, you are tied to the tracks and a trol­ley is ap­proach­ing. You have two but­tons to press. But­ton A in all uni­verses has the same effect but you are not sure which the effect is, there is a 90% of it not do­ing any­thing and 10% of it stop­ping the trol­ley. But­ton B uses a QMRNG and stops the trol­ley in 1 uni­verse while let­ting it run you over in 9 uni­verses. To a util­i­tar­ian the to­tal ex­pected util­ity from press­ing any but­ton is the same. In case A, the ex­pected util­ity for each uni­verse is 0.1 lives saved, so for to­tal we get 10 * 0.1 = 1 life saved. In case B, the to­tal ex­pected util­ity is 1 life saved.

Then comes the prob­le­matic part:

The ex­pected util­ity is the same, ex­cept… if in­ter-uni­verse travel is pos­si­ble and you are an ex­pert sur­geon which can save your copy’s life af­ter it has been run over. In that case you sur­vive in one uni­verse and travel to other uni­verses one by one and save the other copies. Tak­ing the sum of util­ity of all uni­verses for all times, the situ­a­tion when a QMRNG is used looks a lot differ­ent than when not used. When not used, at one point in the fu­ture, the util­ity be­comes zero and stays zero. When used, you can re­cover.

So the one sur­geon sur­vives, steps into the ma­chine, presses a but­ton to go to an­other uni­verse, re­vives the copy, then he goes to the next uni­verse (as­sum­ing the uni­verses are nearly-iden­ti­cal ex­cept for the fact one of them got run over by a trol­ley, so all 10 of the par­allel uni­verses have such ma­chines in them) and re­vives the next copy, and so on. So the ex­pected util­ity of us­ing QMRNG is 10 lives saved.

When ap­ply­ing this to xrisk it doesn’t mat­ter if other uni­verses have such ma­chines in them since the trav­el­ers can use their knowl­edge and en­g­ineer­ing skills to con­struct them. That’s what I meant by ” we can as­sume that in­ter-uni­verse travel con­sumes some re­sources and takes some time”.

• Per­haps I should have been more spe­cific, I’m talk­ing about a sce­nario where there is an ac­tual ma­chine (like a time ma­chine but in­stead of trav­el­ling in time you travel be­tween uni­verses) in which you step and press a but­ton, and then you ap­pear in a par­allel uni­verse. It’s not a ques­tion who claims any­thing, nor it is a ques­tion of ran­dom fluc­tu­a­tions, it’s a ques­tion of whether that kind of ma­chine can be built or not. If it can be built, then in­creas­ing quan­tum di­ver­sifi­ca­tion re­duces xrisk, be­cause then the trav­el­ers can travel around and re­pop­u­late other uni­verses.

It is sim­plest to imag­ine a sce­nario where all 10 uni­verses have such ma­chines and you can only travel from one ma­chine to an­other, so you step into the ma­chine in your uni­verse and you step out of the ma­chine in an­other uni­verse.

There is also no point in talk­ing about the ex­act num­ber of such-and-such uni­verses, all that mat­ters is the pro­por­tion of the uni­verses in which some­thing hap­pens, there is an in­finite num­ber of ev­ery pos­si­ble uni­verse. I talked about 10 of them to sim­plify the prin­ci­ple, which holds for any n of uni­verses.

• Can you please elab­o­rate on your ex­am­ple of re­s­ur­rec­tion, it sounds in­ter­est­ing but I don’t un­der­stand it.

• It changes be­cause with or­di­nary ran­dom­ness you can’t travel be­tween differ­ent branches in the de­ci­sion tree. In the thought ex­per­i­ment with the sur­geon he ac­tu­ally phys­i­cally trav­els to a par­allel uni­verse and saves a life of his copy there. So the ex­pected long term util­ity is not 1 life saved but 10 lives saved.

# On­tolog­i­cal un­cer­tainty and di­ver­sify­ing our quan­tum portfolio

8 Aug 2018 9:19 UTC
3 points