Thought experiment shows how we might be at the mercy of quantum jerks from another universe

Thought experiment shows how we might be at the mercy of quantum jerks from another universe
Credit: Nicole Gray

Artificial intelligence researcher and US Air Force Captain Eric Halloway recently published a fun thought experiment showing how simple it would be to prove we live in one of multiple universes. His theory relies on inventing a quantum coin-flipper and using a ray gun to vaporize an unknowable number of people across the entire spectrum of the multiverse. Basically, it’s the plot of Avengers: Endgame.

Here’s the gist:

Quantum physics tells us that quantum particles exist in a state called superposition until they’re measured. If you imagine a quantum particle as a coin, it’s neither heads nor tails and both heads and tails until such time as a measurement is performed (you flip it, wait for it to come to a stop, and decide whether it’s heads or tails). If a quantum particle isn’t measured, it should remain in superposition.

Some quantum physicists believe that this is possible because quantum reality is comprised of more than one universe. In other words, the reason a quantum particle can be both heads and tails until it’s measured or observed, is because it exists in more than one universe at a time.

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Using Halloway’s quantum coin-flipper we can extrapolate theoretical evidence for the multiverse. Here’s a passage from their article:

Using our quantum coin flipper, we flip our quantum coin one thousand times. Every single possible sequence must exist in some universe according to quantum multiverse theory. In that case, in one of the universes, our quantum coin flipper has flipped a thousand heads in a row. The odds of flipping a thousands heads in a row are so small as to be impossible. Therefore, the only way we can ever observe our quantum coin flipper flip a thousand heads in a row is if the multiverse is true.

Well, now we’re getting somewhere. Except we’d have to be the people in the universe where it happened 1,000 times in a row for this to be helpful right?

Halloway writes:

Remember, we, as observers, are guaranteed to be in all the universes with all the possible sequences, and thus we are also in the universe with a thousand heads. And thus we achieve our test of the multiverse: if we ever observe our quantum coin flipper flip a thousand heads in a row, we can be almost certain the multiverse theory is true.

Now here’s the problem: We observers are not only in the thousand heads universe but also in all the other universes with arbitrary mixtures of heads and tails. To get a definitive result, we need to eliminate ourselves in all universes except the universe with a thousand heads. And so we give our quantum coin flipper a disintegration ray gun.

I volunteer to be the quantum coin flipper.

Halloway concludes:

To guarantee that we observers are only in the universe with a thousand heads, our quantum coin flipper delivers a ray blast to the observers any time it flips tails. Because we will have ceased to exist in all universes with any tails, we must only exist in the universe with a thousand heads. Additionally, this universe with a thousand heads is guaranteed to exist, so we are guaranteed to survive this gruesome experiment.

So, gun to your head: Do you believe in quantum mechanics? The ramifications of this experiment are mind-boggling. There’s a conversation about the existence of God to be had here – Halloway eludes to this at the end of his article with a comment about intelligent design – but we’re more interested in the technology side of things.

Let’s say we do develop a disintegration ray and a quantum coin-flipper. Since we know particles manifest as something a bit more important than just ones and zeros like the sides of a coin, namely reality, we can assume the ability to eliminate specific observers should give us the powers of a deity.

Control over superposition would seemingly be like having a trick coin that always comes up heads in a world where everything was decided by coin toss and you always got to pick first.

On the one hand, this means we could theoretically figure out a way to stack the odds in our favor and exploit the underlying framework of the quantum universe to our advantage. If certain sequences of quantum events result in say, ensuring the Earth was perpetually perfect, wouldn’t it make sense to consider it?

Problem is, it seems like doing so wouldn’t be consequence-free. At the bedrock of our physics beliefs lies the simple truth embedded in Newton’s laws: energy isn’t free. The balance of those missing “tails” flips has to come from somewhere.

So on the other hand, it stands to reason that being the initial observers to figure out how to exploit superposition across the quantum multiverse is the only good position to be in. As Ricky Bobby, the fictional star of Talladega Nights, would say: you’re either first or you’re last. And whoever’s in first would have an absolutely perfect universe.

And that leads us to one simple conclusion: the perfect universe wouldn’t have the kind of 2020 we’re having. If there’s a multiverse, we’re not the ones with the ray guns.

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