What is reality, really? Brian Cox's 'Horizons' tour probes the mysteries of the universe

Brian Cox as seen during a speaking event in May 2022.
Brian Cox as seen during a speaking event in May 2022. (Image credit: Tristan Fewings/Getty Images)

Brian Cox would like you to consider the very nature of the space-time continuum and our place within it.

That might seem like a big lift, so the world-renowned physicist is here to walk you through it. Cox is currently touring the U.S., bringing audiences a dazzling show filled with not only stunning images of the universe and simulated black holes but also big questions: Why are we here? How did life evolve? Are space and time really as fundamental as we perceive them to be?

In the show, called "Horizons: A 21st Century Space Odyssey," Cox asks these questions and leads audiences on a journey in answering them, from past discoveries by Albert Einstein to current research that's changing our very understanding of reality.

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In the field of theoretical physics, Cox told Space.com, "We are being led now, in the last few years, to a theory which suggests that space and time are not fundamental — that there's some deeper structure."

This concept, known as "emergent space-time," is the idea that space and time are not fixed, unchanging things but rather made up of constituent parts, like how the atom comprises neutrons, protons and electrons (and those particles are made up of even more particles). The theory suggests that there are even more layers of the universe to peel back.

One way scientists are studying the idea of emergent space-time is through black holes, Cox said. Black holes pose many conundrums, such as "these things from which nothing can escape apparently have a temperature and glow and evaporate and radiate away," Cox said.

One question plaguing physicists right now seems simple enough: "Do black holes destroy information?" Cox said. But actually thinking about the question is not simple at all. The problem deals with the idea of Hawking radiation. This theory, first described by Stephen Hawking in the 1970s, suggests that black holes have a measurable temperature. Where does this temperature come from? Basically, imagine two particles that share information between them; one falls into the black hole, and one does not. The particle that falls into the black hole is destroyed with a burst of radiation.

However, these two particles are entangled, according to quantum entanglement theory; two particles share information even if they're millions of light-years apart. So, if one particle is destroyed, what happens to its twin? In the quantum world, information cannot be destroyed. So we're left with a paradox.

And that's just one of the many mysteries about the universe and our place within it. Cox wants audiences to walk away with a sense of awe — at the complexities of the universe, the discoveries humans have made since we first turned our eyes to the sky and how humanity fits into it all.

"The more we learn about biology and the evolutionary history of life on Earth, the more it starts to look like, whilst microbes might be all over the place, things like [civilizations] might be very rare indeed," he said.

In other words, we might be the only beings in our galaxy — or at least our corner of it — who have the ability to think about the big questions like the nature of reality, and we shouldn't take that for granted.

"Science has both relegated us from the center of the universe for the last 300 or 400 years, and also, perhaps, placed us in an extremely important position," Cox said.

Interested in probing these universal mysteries further? Check out the North American tour schedule for "Horizons : A 21st Century Space Odyssey, which runs through late June.

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JoAnna Wendel
Space.com contributor

JoAnna Wendel is a freelance science writer living in Portland, Oregon. She mainly covers Earth and planetary science but also loves the ocean, invertebrates, lichen and moss. JoAnna's work has appeared in Eos, Smithsonian Magazine, Knowable Magazine, Popular Science and more. JoAnna is also a science cartoonist and has published comics with Gizmodo, NASA, Science News for Students and more. She graduated from the University of Oregon with a degree in general sciences because she couldn't decide on her favorite area of science. In her spare time, JoAnna likes to hike, read, paint, do crossword puzzles and hang out with her cat, Pancake.