I was reading upon a comic when I found some interesting content concerning the "Many-worlds" interpretation and how it could be used in quite an extreme manner.

Imagine we had a "END" machine. When activated, it does what its name suggests, it brings the said universe to the end. However, it only has the ability to bring its own universe to an END.

From here, I will be using the Schrodinger's cat to explain how this will work.

We start by putting a cat, in a box. Within the box is also a radioactive source and a mechanism designed to kill the cat should it detect any radioactivity.

The moment the source becomes radioactive is considered random. Eventually, though, it will become radioactive and the cat will die.

However, instead of killing a cat, it will activate the "END" machine, spelling the end of the universe as we know it.

However, from the view of an outsider, the universe never dies. Every instance, there is a continuum of universes created, some which will activate the "END", some which won't. To the view of an outsider, who couldn't possibly know what were occurring inside the box, all of the said universes will remain to appear the same. The only difference between each universe is what happens inside of the box, which is unknown.

Every universe in which the "END" is activated is essentially terminated from existence. However, there is still a lot of universes in which the "END" is not activated. In these universes, everything proceeds as it would have.

Being an outsider, you can't actually see any difference between one universe to the next, and since the only observable outcome is a future in which the radioactive source is never sensed, then the only possible outcome is, theoretically, that non-radioactive future.

The comic book takes this and asserts that this is how the ice cream man sells his ice cream for free, he simply connects an ice cream sensor to an "END" machine and activates the "END". If there is ice cream, everyone lives. If there isn't ice cream, that universe "ENDs".

And against all odds, apparently the air inside of the container is converted to ice cream, since it is a possible outcome.

Is this a possible result of the "Many-worlds" interpretation? Isn't it a little bit extreme, forcing results that defy probability?

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    $\begingroup$ I constantly find that the most likely outcome of the MWI is that a lot of people are wasting their time on it. $\endgroup$ – CuriousOne Feb 23 '16 at 0:46
  • $\begingroup$ @CuriousOne I've noticed that you voice this opinion in a myriad amount of places (I did do some reading on related questions) and you are probably right. $\endgroup$ – Simply Beautiful Art Feb 23 '16 at 0:49
  • $\begingroup$ On the other hand... I like that you are churning both ice cream and yarn with it... so it's got that going for it. :-) $\endgroup$ – CuriousOne Feb 23 '16 at 0:51
  • $\begingroup$ @CuriousOne Thank the comic for that, which I thought was a real kick. (spoiler) However, the ice cream man got in trouble... $\endgroup$ – Simply Beautiful Art Feb 23 '16 at 0:52
  • $\begingroup$ Instead of asking the question about many worlds theory, equally one could destroy the world if classically all gas molecules are not at the left side of a container. Then the surviving observer finds that the world still exists (sic), but there is not much to conclude from such results. Except that large numbers are hard for humans. What if the entropy of the universe is not increasing by a change? What if a person tunnels / penetrates the classical thermal barrier though a wall? What if a sword gets forged in metal by thermal fluctuations? $\endgroup$ – Mikael Kuisma Feb 23 '16 at 1:05

It is indeed a somewhat extreme result of the many-worlds interpretation. The formal idea is that you can factor a semiprime N by choosing a prime p, say 15,485,867, then rolling three appropriately sized quantum prime-rolling dice that can roll the factors of N but also p: call them A, B, C. The idea is that you kill yourself if simultaneously: (A does not divide N), (C is not equal to p), (D is not equal to p). If you somehow screwed up the range for N, then C and D save you; otherwise A is a factor of N.

This is called "postselection" in the quantum computing literature. The quantum computing illuminary Scott Aaronson proved that if you add it to the bounded-error polynomial-time quantum computing class BQP (producing PostBQP) then you actually get back a computer which is from a "classical" quantum computing class called PP. See the Wikipedia article on PostBQP for further details.

Of course, the cost that you pay for it is that in most universes, people see you kill yourself. It's worth understanding that we are all subject to it eventually: if this notion of the many worlds interpretation is correct, you probably do not need to develop an explicit quantum algorithm to kill yourself; the forces of nature will have enough quantum uncertainties in them that you will simply live forever in some parallel worlds.

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  • $\begingroup$ Thanks for the interesting information, much appreciated. $\endgroup$ – Simply Beautiful Art Feb 23 '16 at 0:55
  • $\begingroup$ But you could also just be a dream inside a dream inside a dream inside a Boltzmann brain that dreams about Boltzmann brains dreaming about a physicist dreaming that he has invented a quantum computer that can simulate Boltzmann brains that are dreaming about quantum computers simulating a MWI universe in which physicists are using cats in boxes to simulate Boltzmann brains that are completely classical, yet so large that they can dream about simulated quantum computers that are especially powerful because they are running on raccoons with tiny laser guns. It's all there, isn't it? $\endgroup$ – CuriousOne Feb 23 '16 at 1:02
  • $\begingroup$ @CuriousOne pretty much, yeah. $\endgroup$ – Simply Beautiful Art Feb 23 '16 at 22:07

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