Why is murder wrong if Many Worlds Interpretation of Quantum Mechanics is true?

[HappySkeptic]

So, what do you think, is suicide possible? Or do people who try an effective way of doing suicide (jumping off of a building, shooting themselves in the head...) simply wake up in some parallel universe, but with a high probability of being paralyzed?

I think suicide is the end, but I see where you are going with this.  The daughter of Hugh Everett (inventor of the Many Worlds interpretation) had mental health issues, and killed herself a decade after her father died.   She believed she would be reunited with him in another universe.  Of course, she wasn't a physicist.

In Many Worlds, each quantum event leads to a branching of universes.  That means an unfathomable number of realities.  In fact, the quantum wavefunction of the universe would encompass all possible realities.

Now, let's say someone makes the choice of jumping off a building.  For a few femtoseconds (I'm just making that number up) the atoms in that person's brain might be correlated with the brain of a version of him that has chosen not to jump.  However, by the time that choice builds up in the brain to become something concrete and real (and high-level activity like making a choice is on the order of milliseconds, not the short time of most quantum interactions), there is almost no quantum correlation between the two versions of the person.  In fact, there are quintillions of versions of that person created every second, each branching off and having little correlation to each other.

Now, we perceive ourselves to live in a single stream of reality, with a single version of ourselves.  Whatever those other echos of reality are, they are quickly lost to the "self" that we experience.  Why would we expect to do a consciousness swap?

If there is something mystical and magical behind the experience of "self" (something I think neurology and science would dispute), it would be just as likely you get reborn as an Andromedan slug beetle.