The Order of Time

The third part of the book is the most difficult, but also the most vital and the one that most closely involves us. In a world without time, there must still be something that gives rise to the time that we are accustomed to, with its order, with its past that is different from the future, with its smooth flowing. Somehow, our time must emerge around us, at least for us and at our scale.³

This is the return journey, back toward the time lost in the first part of the book when pursuing the elementary grammar of the world. As in a crime novel, we are now going in search of a guilty party: the culprit who has created time. One by one, we discover the constituent parts of the time that is familiar to us—not, now, as elementary structures of reality, but rather as useful approximations for the clumsy and bungling mortal creatures we are: aspects of our perspective, and aspects, too, perhaps, that are decisive in determining what we are. Because the mystery of time is ultimately, perhaps, more about ourselves than about the cosmos. Perhaps, as in the first and greatest of all detective novels, Sophocles’ Oedipus Rex, the culprit turns out to be the detective.

Here, the book becomes a fiery magma of ideas, sometimes illuminating, sometimes confusing. If you decide to follow me, I will take you to where I believe our knowledge of time has reached: up to the brink of that vast nocturnal and star-studded ocean of all that we still don’t know.

PART 1 THE CRUMBLING OF TIME

1 LOSS OF UNITY

Dances of love intertwine

such graceful girls

lit by the moon

on these clear nights. (I, 4)

THE SLOWING DOWN OF TIME

Let’s begin with a simple fact: time passes faster in the mountains than it does at sea level.

The difference is small but can be measured with precision timepieces that can be bought today on the internet for a few thousand dollars. With practice, anyone can witness the slowing down of time. With the timepieces of specialized laboratories, this slowing down of time can be detected between levels just a few centimeters apart: a clock placed on the floor runs a little more slowly than one on a table.

It is not just the clocks that slow down: lower down, all processes are slower. Two friends separate, with one of them living in the plains and the other going to live in the mountains. They meet up again years later: the one who has stayed down has lived less, aged less, the mechanism of his cuckoo clock has oscillated fewer times. He has had less time to do things, his plants have grown less, his thoughts have had less time to unfold. . . . Lower down, there is simply less time than at altitude.

Is this surprising? Perhaps it is. But this is how the world works. Time passes more slowly in some places, more rapidly in others.

The surprising thing, perhaps, is that someone understood this slowing down of time a century before we had clocks precise enough to measure it. His name, of course, was Albert Einstein.

The ability to understand something before it’s observed is at the heart of scientific thinking. In antiquity, Anaximander understood that the sky continues beneath our feet long before ships had circumnavigated the Earth. At the beginning of the modern era, Copernicus understood that the Earth turns long before astronauts had seen it do so from the moon. In a similar way, Einstein understood that time does not pass uniformly everywhere before the development of clocks accurate enough to measure the different speeds at which it passes.

In the course of making such strides, we learn that the things that seemed self-evident to us were really no more than prejudices. It seemed obvious that the sky was above us and not below; otherwise, the Earth would fall down. It seemed self-evident that the Earth did not move; otherwise, it would cause everything to crash. That time passed at the same speed everywhere seemed equally obvious to us. . . . Children grow up and discover that the world is not as it seemed from within the four walls of their homes. Humankind as a whole does the same.

Einstein asked himself a question that has perhaps puzzled many of us when studying the force of gravity: how can the sun and the Earth “attract” each other without touching and without utilizing anything between them?

He looked for a plausible explanation and found one by imagining that the sun and the Earth do not attract each other directly but that each of the two gradually acts on that which is between them. And since what lies between them is only space and time, he imagined that the sun and the Earth each modified the space and time that surrounded them, just as a body immersed in water displaces the water around it. This modification of the structure of time influences in turn the movement of bodies, causing them to “fall” toward each other.⁴

What does it mean, this “modification of the structure of time”? It means precisely the slowing down of time described above: a mass slows down time around itself. The Earth is a large mass and slows down time in its vicinity. It does so more in the plains and less in the mountains, because the plains are closer to it. This is why the friend who stays at sea level ages more slowly.

If things fall, it is due to this slowing down of time. Where time passes uniformly, in interplanetary space, things do not fall. They float, without falling. Here on the surface of our planet, on the other hand, the movement of things inclines naturally toward where time passes more slowly, as when we run down the beach into the sea and the resistance of the water on our legs makes us fall headfirst into the waves. Things fall downward because, down there, time is slowed by the Earth.⁵

Hence, even though we cannot easily observe it, the slowing down of time nevertheless has crucial effects: things fall because of it, and it allows us to keep our feet firmly on the ground. If our feet adhere to the pavement, it is because our whole body inclines naturally to where time runs more slowly—and time passes more slowly for your feet than it does for your head.

Does this seem strange? It is like when, watching the sun going down gloriously at sunset, disappearing slowly behind distant clouds, we suddenly remember that it’s not the sun that’s moving but the Earth that’s spinning, and we see with the unhinged eye of the mind our entire planet—and ourselves with it—rotating backward, away from the sun. We are seeing with “mad” eyes, like those of Paul McCartney’s Fool on the Hilclass="underline" the crazed vision that sometimes sees further than our bleary, customary eyesight.

TEN THOUSAND DANCING SHIVAS

I have an enduring passion for Anaximander, the Greek philosopher who lived twenty-six centuries ago and understood that the Earth floats in space, supported by nothing.⁶ We know of Anaximander’s thought from other writers. Only one small original fragment of his writings has survived—just one:

Things are transformed one into another according to necessity,

and render justice to one another

according to the order of time.

“According to the order of time” (κατὰ τὴν τοῦ χρόνου τάξιν). From one of the crucial, initial moments of natural science there remains nothing but these obscure, arcanely resonant words, this appeal to the “order of time.”

Astronomy and physics have since developed by following this seminal lead given by Anaximander: by understanding how phenomena occur according to the order of time. In antiquity, astronomy described the movements of stars in time. The equations of physics describe how things change in time. From the equations of Newton, which establish the foundations of mechanics, to those of Maxwell for electromagnetic phenomena; from Schrödinger’s equation describing how quantum phenomena evolve, to those of quantum field theory for the dynamics of subatomic particles: the whole of our physics, and science in general, is about how things develop “according to the order of time.”