叶军的原子钟一百五十亿年不差一秒，他拿下了被称为诺奖风向标的沃尔夫物理学奖

If a clock started running at the moment the universe was born and kept going until today, how far off would it be?

The answer: less than a second.

A clock like that really exists.

The man who made it is Jun Ye, a Shanghai-born physicist.

On October 1st, he had just won the 2026 Wolf Prize in Physics.

Let's start with the clock.

Ordinary clocks run on batteries and quartz, and can be off by more than ten seconds a month.

The best older atomic clocks rely on atoms: atoms 'vibrate' at an extremely steady rate, like a metronome that never gets tired.

Count how many times it has vibrated, and you know how much time has passed.

What Jun Ye makes is a newer kind of atomic clock, called an optical atomic clock.

Using lasers, he cools about a hundred thousand strontium atoms to near absolute zero.

Absolute zero is the coldest temperature possible in theory, about minus 273 degrees.

At that cold, the atoms barely move, and their 'ticking' becomes especially clean and precise.

Jun Ye's team has broken records again and again.

America's National Institute of Standards and Technology says their clocks won't gain or lose a second in fifteen billion years.

Fifteen billion years is roughly the age of the universe.

What's the use of such a precise clock?

The most direct use is satellite navigation.

Your phone's map knows where you are because satellites carry atomic clocks.

If the time is off by a billionth of a second, your position could be off by thirty centimeters.

But Jun Ye's clock is precise enough to do something even more amazing: see gravity.

More than a hundred years ago, Einstein put forward the theory of relativity.

One of its ideas is: the stronger gravity is, the slower time runs.

The closer you are to the ground, the stronger the gravity, so the slower time runs; the farther from the ground, the faster.

When you stand, your head is farther from the ground than your feet, so your head ages a tiny bit faster.

How small is this difference?

Over a whole lifetime, it adds up to less than a millionth of a second between head and feet.

In 2022, Jun Ye's team did an experiment.

They stacked atoms in layers, with the top and bottom layers only one millimeter apart.

Sure enough, the clock measured it: the atoms on top 'ticked' slightly faster.

A height of one millimeter, and they measured a difference in time.

It was the first time humans saw what Einstein described over such a tiny distance.

Jun Ye said the most exciting part of the result is that it might link quantum physics and gravity.

Physicists have wanted to connect these two theories for a hundred years.

Back to the prize.

The Wolf Prize has been awarded since 1978, and many call it 'the weathervane of the Nobel Prize.'

A weathervane is something that tells you in advance which way the wind is blowing.

Why call it that?

So far, of the seventy-two Wolf Prize laureates in physics, twenty-six later won a Nobel Prize.

That's about one in three.

Sharing the prize with Jun Ye this year is German physicist Immanuel Bloch, who uses lasers to 'arrange' atoms into grids to simulate complex matter.

Jun Ye is also the second ethnically Chinese scientist to win this physics prize.

The first was Chien-Shiung Wu, winner of the very first prize in 1978.

From Chien-Shiung Wu to Jun Ye, forty-eight years passed.

Jun Ye was born in Shanghai in 1967, graduated from Shanghai Jiao Tong University in 1989, then went to America and earned his PhD at the University of Colorado in 1997.

Over all these years, much of his work has served one goal: making clocks a little more precise, and then a little more.

This year's Nobel Prize in Physics will be announced on October 6th — next Tuesday.

What do you think a clock that won't be off by a second in fifteen billion years should be used for most?