What’s the smallest thing in the universe? - Jonathan Butterworth

翻译人员: Ziyan Fan 校对人员: Lipeng Chen

If you were to take any everyday object, say a coffee cup, and break it in half,

如果拿一个日常的物品， 比如一个咖啡杯，把它切成两半，

then in half again, and keep carrying on, where would you end up?

然后再切成一半，之后继续切， 什么时候才会结束？

Could you keep on going forever?

你会一直继续下去吗？

Or would you find a set of indivisible building blocks

你会不会找到一套 不可以被分割的“积木块”，

out of which everything is made?

万事万物都可由其组成？

Physicists have found the latter- that matter is made of fundamental particles,

物理学家们已经发现了后者—— 物质是由基础的粒子组成，

the smallest things in the universe.

这些粒子是宇宙里最微小的东西。

Particles interact with each other according to a theory called the “Standard Model”.

这些粒子在被称为“标准模型“的 理论下互相作用。

The Standard Model is a remarkably elegant encapsulation

标准模型是对不可分割的、

of the strange quantum world of indivisible, infinitely small particles.

无限小的粒子的量子世界的提炼。

It also covers the forces that govern how particles move,

它也包含了力如何指导粒子运动，

interact, and bind together to give shape to the world around us.

相互作用，以及结合在一起 形成世间万物。

So how does it work?

那么它是怎么工作的呢？

Zooming in on the fragments of the cup,

放大杯子上的碎片，

we see molecules, made of atoms bound up together.

我们看到原子聚集在一起形成分子。

A molecule is the smallest unit of any chemical compound.

一个分子是任何化合物中的最小组成单元。

An atom is the smallest unit of any element in the periodic table.

一个原子是任何元素周期表中 元素的最小组成单元。

But the atom is not the smallest unit of matter.

但是原子不是物质最小的组成单元。

Experiments found that each atom has a tiny, dense nucleus,

实验发现每一个原子都有微小的、 密实的原子核，

surrounded by a cloud of even tinier electrons.

原子核被极小的电子云包围着。

The electron is, as far as we know,

正如我们所知，电子是

one of the fundamental, indivisible building blocks of the universe.

宇宙中基础的、 不可分割的基础材料之一。

It was the first Standard Model particle ever discovered.

它是第一个被发现的标准模型粒子。

Electrons are bound to an atom’s nucleus by electromagnetism.

电子通过电磁场聚集在原子核周围。

They attract each other by exchanging particles called photons,

它们通过交换一种叫做 光子的粒子来互相吸引，

which are quanta of light that carry the electromagnetic force,

光子是带着电磁场力的光量子，

one of the fundamental forces of the Standard Model.

电磁场力是标准模型的基础力。

The nucleus has more secrets to reveal, as it contains protons and neutrons.

原子核有更多的秘密需要被发现， 它包含了光子和中子。

Though once thought to be fundamental particles on their own, in 1968

虽然它曾被认为是最基础的粒子，

physicists found that protons and neutrons are actually made of quarks,

但是在1968年物理学家发现 光子和中子是由夸克组成，

which are indivisible.

而夸克是不可分割的。

A proton contains two “up” quarks and one “down” quark.

一个光子包含两个上夸克 和一个下夸克。

A neutron contains two down quarks and one up.

一个中子包含两个上夸克 和一个下夸克。

The nucleus is held together by the strong force,

原子核被很强的力凝聚在一起，

another fundamental force of the Standard Model.

这是标准模型的另一个基础力。

Just as photons carry the electromagnetic force,

正如光子带着电磁场力，

particles called gluons carry the strong force.

一个叫胶子的粒子带着很强的力。

Electrons, together with up and down quarks,

似乎电子与上下夸克一起

seem to be all we need to build atoms and therefore describe normal matter.

就是我们所需构建原子的东西， 进而来描述一般的物质。

However, high energy experiments reveal that there are actually six quarks–

然而，高能量实验 揭露实际上有六种夸克：

down & up, strange & charm, and bottom & top

上和下，粲和奇，底和顶，

- and they come in a wide range of masses.

它们数量巨大。

The same was found for electrons,

正如我们发现电子，

which have heavier siblings called the muon and the tau.

电子有重同类元素叫介子和钛。

Why are there three (and only three) different versions

为什么对于这些粒子来说，

of each of these particles?

有三种（只有三种）不同的版本？

This remains a mystery.

这仍是一个谜。

These heavy particles are only produced, for very brief moments,

这些重粒子只是在非常短的片刻产生，

in high energy collisions, and are not seen in everyday life.

它们只产生于高能量的碰撞中， 而不出现在日常生活中。

This is because they decay very quickly into the lighter particles.

这是因为它们会非常快地衰减回较轻的粒子。

Such decays involve the exchange of force-carrying particles,

这些衰减包含在力的交换和粒子运载，

called the W and Z, which – unlike the photon – have mass.

它们被称为 W 和 Z ——不像光子——有质量。

They carry the weak force, the final force of the Standard Model.

它们带有弱力， 这是标准模型中的最后的力。

This same force allows protons and neutrons to transform into each other,

相同的力允许光子和中子互相转换，

a vital part of the fusion interactions that drive the Sun.

一个驱动太阳的重要融合反应。

To observe the W and Z directly,

为了直接观察 W 和 Z，

we needed the high energy collisions provided by particle accelerators.

我们需要通过粒子加速度器产生高能量碰撞。

There’s another kind of Standard Model particle, called neutrinos.

有另一种标准模型粒子，称为中微子。

These only interact with other particles through the weak force.

它们只通过弱力互相作用。

Trillions of neutrinos, many generated by the sun, fly through us every second.

通过太阳，产生数万亿的中微子， 每一秒在我们身边飞过。

Measurements of weak interactions found that there are different kinds of neutrinos

我们通过弱力相互作用的方法 发现有不同种类的中微子

associated with the electron, muon, and tau.

它们与电子、介子和钛关联。

All these particles also have antimatter versions,

所有这些粒子都存在相对应的反物质，

which have the opposite charge but are otherwise identical.

这些粒子有相反的极性但是其他方面一样。

Matter and antimatter particles are produced in pairs in high-energy collisions,

物质和反物质是在高能量碰撞中成对产生的，

and they annihilate each other when they meet.

当它们相遇时互相抵消。

The final particle of the Standard Model is the Higgs boson

标准模型中的最后一种粒子是希格斯粒子——

– a quantum ripple in the background energy field of the universe.

一种宇宙中能量域背景的量子波。

Interacting with this field is how all the fundamental matter particles acquire mass,

正如标准模型所说， 这个领域的相互反应就是

according to the Standard Model.

基础物质粒子如何获取质量的。

The ATLAS Experiment on the Large Hadron Collider

大强子对撞机上做的超环面仪器实验

is studying the Standard Model in-depth.

就是在深入学习标准模型。

By taking precise measurements of the particles and forces that make up the universe,

通过精准测度组成宇宙的粒子和力，

ATLAS physicists can look for answers to mysteries

超环面仪器物理学家可以找到 无法用标准模型解释的

not explained by the Standard Model.

未解之谜的答案。

For example, how does gravity fit in?

例如：重力如何嵌入模型？

What is the real relationship between force carriers and matter particles?

什么是承载力和物质粒子之间的真正关系？

How can we describe “Dark Matter”,

我们如何描述组成宇宙中大部分物质

which makes up most of the mass in the universe but remains unaccounted for?

但是仍未被观测到的“黑物质”？

While the Standard Model provides a beautiful explanation for the world around us,

虽然标准模型对我们周围的世界 提供了很好的解释，

there is still a universe’s worth of mysteries left to explore.

宇宙中仍存在众多谜题等待探索。