Our Moral Obligations for Parallel Universes are Unclear, Says Expert Paul Sutter

Paul Sutter explains how there could be multiple versions of you in the multiverse, and why it's tricky to know what the ethics are for parallel universes.

By Paul M. Sutter
Apr 3, 2024 2:00 PMApr 3, 2024 1:55 PM
Person flipping a coin
(Credit: New Africa/Shutterstock)


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When talking about parallel universes, physics is usually the main subject. But what about the ethics behind the multiverse? Paul Sutter, a theoretical cosmologist, award-winning science communicator, NASA advisor, U.S. Cultural Ambassador, and a globally recognized leader in the intersection of art and science, helps us question the ethics behind parallel universes.

What are the Ethics Behind Parallel Universes?

This is a good one! If we do live in a multiverse, are we forced to reconfigure our concepts of ethics and morals? If all possibilities aren’t merely allowed, but actually happen, then what meaning should we attach to wrong actions? How should we treat death? For every unethical act, there is a universe where the moral path is being followed. For every tragic death, there is a universe with a narrow escape.

I’m going to argue that the multiverse doesn’t lead to a breakdown of ethics, but first let me set up the physics.

The Physics Behind the Multiverse

There are two kinds of multiverse in modern physics. One is based on interpretations of quantum mechanics and says that every time a subatomic particle does something random, the universe branches off, with each universe containing one of the possible results.

The other is based on cosmology and is a hypothesis that the universe outside of our observable limit is expanding at a super-fast rate, seeding other bubble universes in the process.

Both ideas of the multiverse lead to a staggering multiplicity of universes, and the very real possibility that we are not alone. More specifically, the possibility that you are not alone. Let’s look at the quantum version of multiverse to see what this means.

Read More: Is A Subatomic World Possible And What Would It Look Like?

What Is the Quantum Version of the Multiverse?

Let’s say you flip a coin and it comes up heads. There were innumerable quantum interactions that lead to that result, and the result really was random; it just as easily could have come up tails. According to some interpretations of quantum mechanics, our universe contains you (plus a heads-up coin), and there is another “branch” of the universe that contains a you (plus a tails-up coin).

There are now two copies of you, living independent lives in their own quantum realities. If you repeat this thought experiment, you quickly realize that there are an almost infinite number of you’s copied throughout the multiverse.

Instead of innocent coins, let’s take a more gruesome example and attach a deadly poison to the coin flip. When you flip the coin, there are now two copies of you, but one universe contains a living you and the other universe contains a dead one. But since you’ll only ever experience living, the only “you” with any awareness is the living one – from your perspective, you survive the deadly coin flip.

Some physicists and philosophers have taken this line of thinking to extreme lengths, arguing for a sort of quantum immortality. As long as there is a chance, however slim, that you survive any interaction, you will keep living, your thread of conscious awareness unbroken.

That includes the slim chance that humanity discovers how to stop aging, allowing you to live forever, and includes every possibility where you don’t get sick, don’t get cancer, don’t get in an accident, and so on. One of “you” is always living on some branch of the multiverse.

Read More: 3 Ways You Use Quantum Physics Every Day

What Is the Cosmology-Based Multiverse?

The cosmology-based multiverse works in a different way, but the result is the same. Instead of branching off from every quantum possibility, this multiverse just generates all the possibilities on its own. In our coin flip example, in our universe the coin lands heads. But there is also a universe out there where the exact same scenario played out, except the coin landed tails.

This also allows for a sort of immortality. There is a version of you existing in some universe that has the exact same experiences, exact same life, exact same tastes and memories and heartaches and dreams, that simply gets to live forever.

So if I do something to cause you harm, does it really count? In one universe I may be distracted by my phone and crash my car into yours. But there’s another universe where that didn’t happen. How can I be punished if all possibilities are realized throughout the multiverse?

The most straightforward answer is for us to decide that we don’t care about the multiverse. In other words, we care about the actions that occur in this universe and this universe alone. We can never observe or interact with the other universes of the multiverse, so this is the only one we’ve got and the only one we’re allowed to care about. Besides, the multiverse is merely hypothetical; we don’t even know if these ideas are right.

Read More: Is the Multiverse Theory Science Fiction or Science Fact?

Our Moral Agency

Another response is to argue that if we believe that we have moral agency (which is another subject) then we must still be held responsible for our actions. It’s one thing to talk about coin flips and random chance. It’s another to talk about deliberate human choices.

Perhaps there is no universe where I was paying attention and avoided the crash, and it’s unavoidable: in every universe with that exact same setup, I get distracted. Without proof of what my other me’s are up to, we can only act based on the information right in front of us.

Lastly, we can take this logic and flip it around. If you’re concerned that there might be universes where I didn’t cause a harmful act, and therefore I shouldn’t be punished, then rest assured that there are also universes where I did cause a harmful act but managed to get away scot-free.

Read More: How Does Multiverse Theory Relate to Time Travel?

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