[I wrote this for my work lunch group after listening to David Wallace on the many-worlds theory of quantum mechanics and its implications. It seemed like a good first post here after a long time lurking.]

Shrödinger’s cat is the famous thought experiment that illustrates the essential weirdness of quantum mechanics. That an object in a superposition simultaneously exists in multiple states that only resolve when an observer measures the object. The many-worlds interpretation of quantum mechanics bites the bullet of quantum measurement by claiming the world ‘splits’ whenever a quantum state is measured, implying there exists a universe where every physical quantum state exists. In this interpretation there is a universe where Shrödinger’s cat is alive and a separate universe where his cat is dead. This continuous branching can be thought of as just another dimension of expansion, no different from how time and space are continuing toward infinity. The key difference being our awareness of the universe depends on the resolved quantum configuration so we cannot directly observe expansion on this dimension as we can with space and time.

What does it mean for your life if the many-worlds interpretation turned out to be correct?  Imagine a version of Shrödinger’s cat but instead of the cat, 1023 people signed up for a peculiar quantum lottery. Each participant promises their savings and belongings to the sole survivor of the lottery (assume everyone has about the same moderate wealth). As believers of the many-worlds interpretation of quantum mechanics, the lottery participants are happy to enter this lottery where only one of them will survive because of how the drawing mechanism works. On the day of the drawing each participant enters a chamber numbered 0-1024.  The drawing proceeds as follows:

• Ten electrons in superposition are assigned bits 1-10
• The spin of each electron is measured in sequence.
  • If the measurement of an electron results in a spin up state the corresponding bit resolves to 1. 
  • Conversely, a measurement that results in a spin down state resolves to 0.
• The resulting 10 bit number is the winner
  • E.g. ↑↓↑↑↓↑↓↑↓↑ becomes 1011010101, which is 725. Therefore, the winner is the person in chamber #725.
• Every chamber aside from the winner is then filled with nerve gas.
• The winner walks out ~1000X wealthier.

Fortunately, everyone gets to walk out ~1000X wealthier since there is a universe branch where every combination of physical states exist. Unfortunately, everyone is removed from 1024 world branches. How should you feel about this if you are a lottery participant? More fundamentally, who are ‘you’ to feel about anything in a universe that is constantly branching?  A possible answer is you are the chain of conscious experiences that started at your birth. In the branching universe there are a multitude of beings that trace themselves back to the same origin. Some of them are quite different from what you would recognize as yourself. Many are probably reasonably recognizable as a version of ‘you.’ 

Shrödinger’s lottery illustrates what happens when macro decisions are contingent on quantum branching events. Without going to the extreme of signing up for a lottery that features nerve gas, you can make significant decisions dependent on branching events to increase the variety of experiences and outcomes of beings who share your origin. More outcomes doesn’t necessarily translate to increased well-being for your same origin beings (SOBs from here on). An unpleasant method to make sure a variety of outcomes results in increased well-being across all your SOBs would be to commit to pruning yourself from branches that fail to meet some threshold of well-being.  Another method would be to only apply the branching predicate to decisions that have a very low likelihood of leading to an unacceptable outcome. 

Considering the anthropic principle in a multi-world universe reveals some interesting implications. Your ability to have conscious experiences in this physical configuration means the SOB you think of as yourself is at least the longest lived SOB in the multiverse.  Additionally, the branch you currently inhabit is likely to branch into many worlds that include SOBs who have read this and integrated it into their chain of conscious experience. Realizing this along with the vast number of universes means if something akin to immortality is attainable within the remainder of your natural lifespan then you have a high probability of living forever.  It may be the case that all the branches from this point on are dead ends where your set of SOBs never have the opportunity to obtain immortality. The lesson of Shrödinger’s lottery in this case would be to make as many immortality relevant decisions contingent on branching events. For example, should you enroll in a cryogenics program after your death? Which company? Should you invest in brain scanning technology? What about life extension technology? Each of these decisions could increase the likelihood that you have at least one SOB that lives forever. If at least one of your SOBs makes it past the immortality filter then there will be approaching infinite you-SOBs around to watch the heat death of the universe.

Of course, immortality might not be something you value. In the utilitarian ethical philosophy your goal should be to maximize the well-being of as many individuals as possible.  While naive application of utilitarian ethics can lead to some bizarre conclusions at the extremes, like harvesting organs from one healthy person to save the lives of several, most people would be sympathetic to the constrained application of the philosophy.  It is difficult to argue with the idea that using your resources to improve the well-being of hundreds of suffering individuals is objectively better than using those same resources to buy yourself a yacht.  However, what if there is a future with nearly infinite you-SOBs?  What if you knew the individuals whose suffering you would reduce live in many fewer branches than you (e.g. cattle on a factory farm). To ensure the greatest good for the greatest number you may be morally obligated to pursue immortality while maximizing happiness in your current chain of conscious experience.  Alternatively, you may be obligated to devote your resources to an individual who has a reasonable chance at immortality and contribute in any way possible to their well-being.  Both of these strategies would result in a multitude of beings who share a pleasurable chain of conscious experience.