The Real Physics Behind Dark Matter's Interdimensional Travel - CNET

Blake Crouch isn't a scientist, but that didn't stop him from including real scientific theories in his bestselling novel Dark Matter and the Apple TV Plus sci-fi thriller based on it. And one theory that really stuck with him was that of alternate universes.

Dark Matter was originally published in 2016.

"I got really turned on by the idea of multiple realities and more so the science behind it," Crouch told me in an interview. "I [thought] it would be really cool to write a novel about quantum physics." 

However, Crouch said he didn't take any science or math courses in college. So to incorporate quantum physics into the book and show, Crouch worked with Clifford Johnson, a physics professor at the University of California, Santa Barbara. I talked with Johnson about the physics behind the fiction. 

"It really is a compelling story all about the choices we make in our lives," Johnson said. "It's a real pleasure to see that much science upfront, and so I helped [Crouch] develop a lot of the ideas."

The main theory Dark Matter explores is that of the multiverse -- the theory that there are infinite other universes beyond our own. And in order to explore this theory, the show uses an interdimensional travel device called "the box." 

The box is a hefty contraption that might not be as visually appealing as similar devices in other works of science fiction, like Back to the Future's DeLorean or Dr. Who's Tardis, but there are real theories behind how it might work. And who knows, maybe these theories will lead to breakthroughs in the world of physics, or maybe they already have in another universe.

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How does the box work in Dark Matter?

Dark Matter's box is an example of an interdimensional travel device. According to TV Tropes, these kinds of devices allow a person or group of people to travel to another universe. And that journey starts with the box.

In Dark Matter, characters enter the box -- which blocks out everything from the outside -- and take a mind-altering drug. Our characters then imagine the reality they want before exiting the box to a different universe. Johnson explained that the box is a way to visualize all possible outcomes for a superposed quantum state. 

OK, explain it to me like I'm five, please

It's no DeLorean, but the box will still get you to another universe.

An easier way to understand this, and superposed quantum states, is by using the famous Schrödinger's cat thought experiment. 

The gist of the experiment is you put a cat in a sealed box that you can't see into, along with something that can kill it, like poison or radioactive material. Then, because you can't interact with what's inside the box or see whether the item in the box killed the cat or not, you can't observe whether the cat is dead or alive at any given moment. Therefore the cat is both at the same time -- it's in a superposition of both dead and alive. Only after you've opened the box and observed the cat can you report on the cat's state.

Johnson said that the cat in the experiment has two possible outcomes -- alive or dead -- but when a person enters the box in Dark Matter, they have many outcomes they can choose from. Dark Matter's box is in essence the inverse of Schrödinger's cat. Instead of an observer not being able to see or interact with a small portion of reality, the observer can't see or interact with anything outside of a small portion of reality (the box). 

So, the way the Dark Matter's box works is a person enters it, imagines the reality they want to be in with the help of a drug, and then the person exits the box to the reality they constructed with their mind. While the person is in the box, they put themselves in a state of superposition among all the different realities, and the one they focus on becomes real once they observe it by leaving the box.

Could the box really work?

Maybe we'll invent a device like the box one day.

Maybe, but we may never know. Some people have posited theories on reality similar to those posed in Dark Matter. 

"The guys who won the Nobel Prize for physics in ['22] were talking about nonlocality and the idea that objective reality doesn't exist," Crouch said. "There's no independent reality that is just hanging out out there without conscious, biocentric beings observing it."

Others have said similar things. Robert Lanza, an adjunct professor at Wake Forest University School of Medicine, developed a theory of biocentrism that argues that consciousness is the driving force behind reality and the universe, not the other way around.

"Nothing has existence unless you, I, or some living creature perceives it," Lanza wrote in the American Scholar in 2007. "The images you see are a construction by the brain. Everything you are experiencing right now … is being actively generated in your mind."

However, the biggest obstacle to proving these theories is building a device like the box. Crouch and Johnson both said designing the box was a challenge since it had to block out everything -- and I truly mean everything -- in order for a person to be in superposition.

"Things like temperature, anything above absolute zero," Crouch said. "Or neutrinos flying through our atmosphere, constantly flying through our bodies … Variations in wind, temperature, all these things…"

Any shifts in these variables would cause the box to simply be a hunk of metal since those shifts would act on the person inside the box, taking them out of a superposed state. 

"We've never built anything like that and it's not clear that we really can," Johnson said. "But it's fun to imagine what that might look like if you could."

Are there any other ways to get to alternate universes if they exist?

If entering a state of superposition to enter into another reality seems a little too far out there, perhaps a black hole can help. This might sound as fantastical as Dark Matter's box, but renowned physicist Stephen Hawking entertained the idea. Hawking theorized that a black hole could function as a passage to somewhere else, including another universe.

"They are not the eternal prisons they were once thought," Hawking said in a 2008 lecture. "Things can get out of a black hole, both to the outside, and possibly, to another universe. So if you feel you are in a black hole, don't give up. There's a way out."

We don't know for certain what would happen if a person fell into a black hole, but Gaurav Khanna, a physics professor at the University of Massachusetts Dartmouth, told me in an interview that a person might be able to survive the encounter. 

Sagittarius A*, the supermassive black hole at the center of the Milky Way.

Khanna and a team of researchers found that if a person, or spacecraft, fell into a supermassive black hole, like Gargantua in the film Interstellar or Sagittarius A* in our own solar system, it might be a smooth and steady ride. 

"While we don't know what the other side of a black hole connects to," Khanna said, "If we make a leap of faith and envision that the other side of a black hole connects to another part of our universe, or perhaps another dimension, then you could smoothly, without much discomfort, go from one to the other."

However, Khanna said that a black hole must meet three criteria in order for it to possibly function as a portal: it has to be considered supermassive, it has to be old, and it must be rotating. If a black hole doesn't meet those requirements, like it's too small, well…

"The smaller [the black hole], the worse it's going to be," Khanna said. "Even if you go to a black hole the size of our sun, I don't think there's any hope of surviving."

So we could travel to other universes with the right conditions?

"This is not a blueprint on how to travel to other worlds," Crouch said. "This is a speculative idea that says, 'Oh if we had a few things, a few advances in these certain areas of technology, then perhaps we can start having a conversation about how macroscopic objects exist in a state of superposition.'"

And if traveling to another universe by getting a person into a state of superposition like in Dark Matter proves unreliable, a supermassive black hole might do the trick. 

"The door's open a little bit," Khanna said. "We have some understanding, experimentally, that this could actually work."

You can watch Dark Matter now on Apple TV Plus, which costs $10 a month. You can also check out how February was the warmest February on record and what to know about the Great Pacific Garbage Patch.

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