Summary: The Many-Worlds interpretation of quantum mechanics can help us feel better about improbable bad events, since the things we value remain unaffected in most other worlds.

I’ve previously suggested that when we think about the ethical implications of the many-worlds interpretation (MWI) of quantum mechanics, the kinds of implications we should expect are ones about how to feel in certain situations, and what kinds of character traits or ‘virtues’ we should try to develop.

And I’ve also explored what those implications are in the case of mutually exclusive life choices.

I’m now going to consider the implications of MWI for how we should think and feel about a different range of scenarios, namely improbable, bad events in one’s life, or world history.

Lightning strikes

Being struck by lightning is a classic example of an improbable event with harsh consequences.

It’s also plausibly an example of a quantum event.

As David Deutsch points out, even a single cosmic-ray particle, travelling towards earth from deep space, may have a quantum wave function with a spatial spread larger than earth’s diameter.

Consequently its interaction with the atoms of the earth’s atmosphere constitutes a ‘natural quantum measurement’ of its location, and therefore a source of multiple decoherent histories or ‘worlds’.

Deutsch writes^[1]:

In each such history there is an autonomous instance of the cosmic-ray particle, which will dissipate its energy in creating a ‘cosmic-ray shower’ of electrically charged particles. Thus in different histories, such a shower will occur at different locations. In some, that shower will provide a conducting path down which a lightning bolt will travel. Every atom on the surface of the Earth will be struck by such lightning in some history.

The detailed mechanisms of lightning formation are still not well understood, but let’s suppose Deutsch is right.

If you were struck by lightning today^[2] and were seriously injured but not killed, what implications would MWI have for how you should think and feel about that event?

There are of course some thoughts and feelings you would have whether or not MWI is true. You would be in severe physical pain, and probably emotional distress too as you consider the ramifications for your future plans. And you may also rightly feel some sense of unfairness in being subject to such an improbab...

Meaning in the Multiverse