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Is Time Real?


We physicists are all romantics. Don't laugh; it's true. In our youth we all fall deeply in love. We fall in love with a beautiful idea: beyond this world of constant change lies another world that is perfect and timeless.

This eternal domain is made not of matter or energy. It's made from perfect, timeless mathematical laws. Finding those exquisite eternal laws — or better yet, a single timeless formula for everything — is the Holy Grail we dedicate our lives to.

Unless we lose faith in that Grail. That's what's happened to physicist Lee Smolin, author of the new book Time Reborn. As he puts it:

For Smolin there is no timeless world and there are no timeless laws. Time, he says, is real and nothing can escape it.

Time, of course, seems real to us. We live in and through time. But to physicists, time's fundamental reality is an illusion.

Ever since Newton, physicists have been developing ever-more exact laws describing the behavior of the world. These laws live outside of time because they don't change.

That means these laws are more real than time.

Now before you say "that's crazy," remember that every modern miracle of physics — from jet planes to GPS — is built using these laws. The drive to identify these timeless laws has been very, very successful for us all.

But, according to Smolin, when it comes to cosmology, the ultimate study of the Universe as a whole, faith in timeless laws has led physicists astray. The idea of timeless laws works fine when it's applied to parts of the Universe, like jet planes and GPS satellites, but Smolin argues, "it falls apart when applied to the Universe as whole."

Cosmologists have, for example, known for a while that lots of Universes with lots of different kinds of conditions could have popped out of the Big Bang. Most of them would be sterile places where life could never have formed. Physicists call this the problem of "fine tuning" — getting the Big Bang's conditions to be exactly right, such that the Universe allows our existence. Fine-tuning demands an explanation. Without that explanation we seem like a highly improbable accident and physicists hate highly improbable accidents.

There had been the hope that the problem of fine tuning would disappear when deeper laws of physics were discovered. These new laws would explain why we ended up with this Universe and no other. Unfortunately it hasn't worked out that way.

One our best hopes — string theory — ends up predicting not the one Universe we observe but an almost-infinite number of possible Universes. Some cosmologists choose to see these Universes as real, hailing them as the "discovery" of a multiverse. Smolin, however, isn't buying that line. For him the multiverse is a fiction, the result of too much faith being placed in the existence of eternal, timeless laws.

Instead, Smolin tells us, understanding the history of the Universe we observe demands taking that history — and time itself — seriously. Making time so real that nothing can escape it leads Smolin to what we might call his greatest heresy. The laws of physics, he says, evolve just like species in an ecosystem.

The laws must live within time like everything else and that means they must change. In essence, Smolin claims, there is no eternal, Platonic realm of ideals and there never has been.

Smolin, however, is careful to show that the rejection of absolute law and the possibility of law's evolution is not a new idea. He quotes American philosopher Charles Pierce who stated the case clearly:

Beyond the evolution of physical laws, Smolin goes to some lengths to show how much can change if we take time as fundamental. From the weirdness of quantum mechanics to the mystery of space and its three dimensions, Smolin argues that many of the stubborn problems in modern foundational physics can be overcome once time is restored to its rightful place as the foundation of reality.

Smolin is, indeed, a rebel and this book is a rebel's yell:

At his best, which is the first half of the book, Smolin offers compelling arguments for why the bias in favor timeless law is baggage that can be tossed aside. The problem, however, is that Smolin doesn't have much to go on in terms of specific alternatives.

At his worst, which occurs in the book's dense later sections, it becomes difficult to distinguish between conjecture and established scientific reasoning.

Still, if you are looking for a bracing alternative vision of physics built from the ground-up, Smolin's Time Reborn will take you to the mountaintop, even if it can't bring you back down.

You can keep up with more of what Adam Frank is thinking on Facebook and on Twitter: @AdamFrank4

Copyright 2023 NPR. To see more, visit https://www.npr.org.

Adam Frank was a contributor to the NPR blog 13.7: Cosmos & Culture. A professor at the University of Rochester, Frank is a theoretical/computational astrophysicist and currently heads a research group developing supercomputer code to study the formation and death of stars. Frank's research has also explored the evolution of newly born planets and the structure of clouds in the interstellar medium. Recently, he has begun work in the fields of astrobiology and network theory/data science. Frank also holds a joint appointment at the Laboratory for Laser Energetics, a Department of Energy fusion lab.