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 improbable event, while others nearby are unscathed.

But if MWI is true, additional thoughts present themselves. If the lightning was caused by a cosmic ray as described above, then you were struck by lightning in only a tiny proportion of the resulting histories.

And according to MWI, the other worlds in which you’re completely unscathed, and which dwarf your own world in their quantum weights, are as real as your own.

How ought you to feel about this?

Personal loss

An initial response might be that you’ll feel worse. The sense of unfairness you feel in being subject to an improbable event, may be compounded by reflecting on the actual existence of numerous additional people (your multiverse counterparts) who did not get struck in exactly the same circumstances.

But on further reflection you might be consoled by the fact that these ‘additional’ people are actually versions of you.

As we saw in the previous post, there are thorny questions of personal identity here. But whether or not it is technically you or not, it’s a person with an identical history and stream of consciousness up to the point that the two worlds diverge, and someone who is presumably enjoying exactly the same experience you would have had, if you hadn’t been struck.

Suppose the lightning strike leaves you paralysed, and you need to adjust your life plans accordingly. A key part of the distress you’d most likely feel would be the sense of loss or frustration about those parts of your previous life plans that can no longer be realised.

But according to MWI, there are numerous worlds in which those plans are still on track. So a large part of the value assigned to those plans still exists.

The impact you’d have had on the world around you will still be felt in those other worlds. Even the conscious experience of living exactly the life you would otherwise have had, with all its unique joys and achievements, will be realised in those worlds.

It’s true that they won’t happen in this world, and you can reasonably feel sad about this. But those impacts, those joys and achievements are not lost from the universe. Some relief from your sadness seems justified.

Why me?

There’s an extent to which we all want the things that we value to be realised, independently of which physical location or stream of consciousness they are realised in.

To this same extent, you should also gain some relief from the sense of unfairness at being ‘picked out’ for misfortune. Your multiversal self was not unfairly picked out for disaster, since only a fraction of your multiverse instances was actually struck by lightning.

Looking across all those instances, there was no ‘bad luck’ involved: only probabilistic processes taking their natural course according to the laws of physics. The improbable event of being struck by lightning happened to your multiversal self in proportion to its natural (im)probability.

We should acknowledge that it’s not always easy to take this multiversal perspective, just as it’s not easy in general to be a good person.

It’s also a matter of degree. It requires practice and experience to develop the ‘virtue’ that is the disposition to adopt this perspective fully.

Your ‘default’ attitude might be to care mostly about your this-worldly instance, and only a little, or only sometimes about your counterparts in other branches.

But a sustained practice of contemplating the nature of these quantum counterparts, combined with meditation on your values and desires, might gradually result in adopting this perspective more easily, more frequently or more strongly.

Losing those we love

What if it’s not you, but someone you love who is struck by the lightning? Let’s suppose for simplicity that in this case the strike is fatal.

It hurts, of course. You will miss them and mourn them.

In part you will miss what they did for you: that they enlivened your days, gave you companionship, joy and laughter. In this respect it is a personal loss to you no different in essence to being struck by the lightning yourself.

But in part you will miss them in their own right. You will be sad that they - their specific human qualities and experiences - no longer exist.

However if MWI is true they do still exist - in the sense that those specific qualities and experiences still exist - in the vast majority of other branches.

Again it’s true that they don’t exist in this world, and you can reasonably feel sad about that. But those qualities and experiences are not lost from the universe. Again some relief from your sadness seems justified.

The Quantum Afterlife

And in this case we can draw a clear similarity between the many-worlds perspective and religious beliefs about personal survival after death.

People subscribing to Christian, Islamic, or Ancient Egyptian or Greek religions, for instance, have felt consoled by the thought that their loved ones continue their personal existence after death in a different realm.

Such people are sad when their loved ones are no longer with them in ‘this’ world. But they're comforted by the thought that they continue on in a different realm, in such a way that their personality and memories remain intact.

And they're comforted by these thoughts even though that other realm (like other multiverse branches) is inaccessible to them from within this world.

It is true that in the religious imagination, the afterlife is given some comforting features not shared by multiverse branches.

For instance, in Christianity and Islam the afterlife is imagined as being more suited to personal happiness (heaven) than life before death. And it’s also imagined as a place where you can eventually hope to be reunited with your loved ones, after your own death.

But multiverse branches also have some comforting features not shared with the religious afterlife.

For example they allow your loved one to continue to realise their existing life goals, without the radical rupture of transport to a very different realm. A realm, moreover, which is not as much fun as it's made out to be.

So the many-worlds view plausibly offers approximately the same level of comfort as the religious view of heaven - with the advantage, of course, of being based in good science.

Improbable timelines

We often think of important historical events, like the fall of a political leader, as governed by random forces - though we don’t often consider the quantum-mechanical roots of this randomness.

But political leaders are not immune to lightning strikes: ergo if lightning strikes can be quantum events, so can regime changes^[3].

This means there is a world-historical analogue of the previous examples. Instead of finding yourself or a loved one being struck by lightning, suppose that you find yourself - due to a lightning strike or similar quantum event - in an improbable, and very bad timeline.

A difference in this case is that it’s harder to tell whether the current global timeline is bad relative to other physically possible timelines.

There are plenty of reasons to think that our current timeline is bad (AI doom, environmental catastrophe, global conflicts etc). But it’s harder to judge where it sits in the spectrum of physically possible timelines to date.

In an alternative timeline, could an inspiring leader or cultural shift have already led us to be better prepared for AI risk, or a more environmentally sustainable economy?

The answers to such questions depend on speculations on the basic forces of human history, and the balance of power between long-term, emergent trends and random, chaotic events.

Nevertheless we do make such judgements, implicitly or explicitly. We sometimes feel that our timeline is not as good as it could or should be.

And the judgement of relative badness also gets easier, the worse things get. The moment nuclear war actually breaks out, or hostile AGI gets developed, we can increase our confidence that our timeline is worse - on average - than the physically possible alternatives.

Again MWI offers comfort. We can feel sad that this timeline is bad, while still being consoled with the knowledge that a good chunk of other timelines fares better.

The valued things lost in this timeline, are not lost in others. To the extent that we achieve the multiversal perspective, we transcend the feeling that the events of our timeline were unlucky - for all physically possible timelines occurred.

It could be worse

At this point I expect some readers are thinking - sure there are better timelines or multiverse counterparts out there, but there are also worse branches.

There are timelines in which I get struck by lightning again on the way to the hospital. And global timelines with things worse than nuclear war, such as massive, permanent, AI torture camps.

And doesn’t thinking of these balance out the consolation I’ve outlined above?

I don’t think it does, and here’s why.

There’s a purely quantitative and physical asymmetry between better and worse branches: a larger proportion of relevant multiverse branches is better.

In technical terms, the quantum weight or ‘measure’ assigned to better worlds is greater.

And this is true even if, as I've said previously, it doesn’t make sense to actually count branches. (If branch counting does somehow make sense then the number of better branches is also greater).

The psychological situation is more complex. On the one hand loss aversion creates a sort of asymmetry.

Suppose you’ve acquired the wisdom to take the perspective of your multiverse self. If a unit of loss and pain outweighs a unit of gain or pleasure (due to loss aversion), then a specific measure of worse worlds will count more than the same measure of better worlds.

Unless you are really loss averse, this is unlikely to fundamentally change the situation, though. It just means that the level of improbability assigned to the original bad event, needs to be higher to get the same level of comfort from MWI.

On the other hand we should remember that from the default perspective in which we primarily care about our current branch, becoming aware of the existence of worse branches may actually be a comfort, reinforcing our sense of the relative value of our branch.

To the extent that we transcend this default perspective, though, and embrace the multi-branch context, it is true that the discomfort of worse alternate branches must be weighed against the comfort of better branches.

So relative weights of better and worse branches seems central to the consoling effect of many-worlds theory, if you’re in an improbably bad situation.

Quantum events

To avoid illusory consolation, you'll want to be confident that you've correctly assessed your current branch as quantum-mechanically improbable.

We’ve seen that lightning caused by cosmic rays offers a plausible route for quantum probabilities to impact on human affairs. A similar route, also mentioned by Deutsch, is that cosmic rays could directly impact the cells of the body, potentially causing cancer. But how many others are there?

This is an underexplored area, and of course depends on one’s formulation of MWI. The most detailed account that I’ve found is the treatment by Wallace, which I also referred to in the previous post.

To recap, this account says there are three main scenarios in which splitting occurs.

1. Deliberate human experiments: Schrödinger’s cat, the two-slit experiment, Geiger counters, and the like.

2. ‘Natural quantum measurements’, such as occur when radiation causes cell mutation.

3. ‘Classically chaotic’ processes: that is, processes governed by Hamiltonians whose classical analogues are chaotic.

Cosmic rays causing lightning or cancer are examples of (2).

Category (1) raises the interesting question of whether one should ever intentionally link quantum experiments to human-level outcomes, in a sort of human version of Schrodinger’s cat. This is something I hope to cover in a future post, but, for current purposes, suffice to say that I think this practice is unlikely to become sufficiently widespread to affect the conclusions here.

Category (3) is last, but definitely not least. Chaos theory has been applied to weather patterns, fluid dynamics, earthquakes, volcanic activity, ecosystems, neural activity, epidemiology, orbital dynamics, stock market fluctuations, and social dynamics, among other areas.

Exactly how such chaotic phenomena relate to quantum uncertainty, and whether they fit Wallace’s definition in terms of chaotic Hamiltonians, is again an underexplored area.

We will want to know for example whether chaotic behaviour in emergent systems like ecosystems, markets and social groups can be traced back to chaotic behaviour in the base-level physics underlying such systems.

Given the state of research as just outlined it seems reasonable to give some non-trivial level of credence to the idea that quantum probabilities underpin most events in our lives that we think could have gone differently (within the bounds of physical possibility).

O Fortuna

So it seems the multiversal perspective can console us without illusion. There is virtue and comfort in learning to adopt this perspective in times of apparent misfortune, both personal and societal.

The idea of misfortune striking ‘out of the blue’ derives from Horace’s influential Ode 34:

For lo! the sire of heaven on high,
By whose fierce bolts the clouds are riven,
Today through an unclouded sky
His thundering steeds and car has driven.

Towards the end of the Ode, Horace switches focus from the lightning-bolt wielding king of the gods, to the personification of Fortune who

Plucks the monarch's crown,
And decks therewith some meaner wight

In the stoic philosophy that Horace was schooled in, we learn to reconcile ourselves emotionally to the unpredictability of fortune by recognising that that very unpredictability is part of the natural course of things.

In a similar way, MWI can help teach us to reconcile ourselves emotionally to improbable disasters by throwing light on their place in the natural order of the multiverse.

^{^}
In The Beginning of Infinity, p294
^{^}
You might think this requires you to be doing some specific activity, like running for a bus in a storm, but it is possible to get struck by lightning while sitting on the sofa playing video games.
^{^}
Again, David Deutsch makes this point: “There exist other histories in which the course of a battle, or a war, is changed by such an event, or by a lightning bolt at exactly the right place and time, or by any of countless other unlikely, ‘random’ events. This makes it highly plausible that there exist histories in which events have played out more or less as in alternative-history stories such as Fatherland and Roma Eterna” (TBOF p294)