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

譯者: Lilian Chiu 審譯者: Helen Chang

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

如果拿一樣日常物品，比如咖啡杯，

把它劈成兩半，再劈成兩半，

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

不斷重覆，結果會是什麼？

Could you keep on going forever?

能無止境重覆嗎？

Or would you find a set of indivisible building blocks

還是能找到一組 不能再更細分的基礎元素，

out of which everything is made?

是萬物的組成呢？

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

物理學家的答案是後者： 物質由基礎粒子組成，

the smallest things in the universe.

粒子是宇宙中最小的東西。

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

粒子的彼此互動 根據「標準模型」這個理論。

The Standard Model is a remarkably elegant encapsulation

標準模型

出色、優雅地概括描述

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

無法更細分粒子的奇特量子世界；

It also covers the forces that govern how particles move,

它也涵蓋粒子的移動力、

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

互動力、結合力，

形塑我們周遭的世界。

So how does it work?

它是如何運作的？

Zooming in on the fragments of the cup,

放大細看杯子的碎片，

we see molecules, made of atoms bound up together.

我們看到分子，由原子結合而成。

A molecule is the smallest unit of any chemical compound.

分子是所有化合物的最小單位。

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

元素週期表中所有元素的 最小單位則是原子。

But the atom is not the smallest unit of matter.

但原子並不是物質的最小單位。

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

實驗發現原子全都有個 小而緊密的核，

surrounded by a cloud of even tinier electrons.

被一群更小的電子包圍著。

電子是我們所知

The electron is, as far as we know,

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

無法再分割的宇宙基礎元素之一。

It was the first Standard Model particle ever discovered.

它是最早被發現的標準模型粒子。

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

原子核透過電磁作用限制電子，

They attract each other by exchanging particles called photons,

二者透由交換光子來彼此互吸，

which are quanta of light that carry the electromagnetic force,

而光子就是光的量子，帶著電磁力，

那是標準模型基本力之一。

one of the fundamental forces of the Standard Model.

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

原子核還可以揭露更多的秘密，

因為它包含了光子和中子。

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

雖然一度被認為是基本的粒子，

但在 1968 年，物理學家發現

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

光子和中子其實是由

不可分割的夸克組成。

which are indivisible.

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

光子含有兩個「上」夸克 和一個「下」夸克。

A neutron contains two down quarks and one up.

中子含有兩個下夸克 和一個上夸克。

The nucleus is held together by the strong force,

原子核由一股強力維繫住，

another fundamental force of the Standard Model.

是標準模型的另一種基本力。

Just as photons carry the electromagnetic force,

正如光子帶著電磁力，

particles called gluons carry the strong force.

名為膠子的粒子則帶著這股強力。

Electrons, together with up and down quarks,

電子與「上」、「下」夸克，

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

似乎就夠用來建構原子，

因而能用來描述一般的物質。

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

然而高能實驗發現 其實有六種夸克——

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

下與上、奇與魅、底與頂——

- and they come in a wide range of masses.

它們的質量相異甚大。

The same was found for electrons,

情況類似重一點的電子的兄弟，

which have heavier siblings called the muon and the tau.

叫做渺子和濤子。

Why are there three (and only three) different versions

何以這些粒子都恰好有

三種不同的版本

of each of these particles?

This remains a mystery.

仍是個謎。

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

這些很重的粒子 存在的瞬間極為短暫，

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

由高能撞擊產生，非日常所能見。

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

這是因為它們 急速衰退成較輕的粒子。

Such decays involve the exchange of force-carrying particles,

這種衰退涉及交換 稱為 W 和 Z 的載力粒子，

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

它們與光子不同，具有質量，

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

它們攜帶的弱力 是標準模型的最後一種力。

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

這種弱力能讓光子和中子互換，

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

乃是太陽融合作用中的重要部分。

To observe the W and Z directly,

為要直接觀察 W 和 Z，

we needed the high energy collisions provided by particle accelerators.

我們用粒子加速器做高能撞擊。

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

另一種標準模型粒子稱為微中子。

These only interact with other particles through the weak force.

它們只會透過弱力和其他粒子互動。

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

有數以兆計由太陽產生的微中子

分分秒秒穿透我們。

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

測量弱互動

發現有不同類的微中子

associated with the electron, muon, and tau.

分別和電子、渺子、濤子有關。

All these particles also have antimatter versions,

這些粒子都有反物質的版本，

which have the opposite charge but are otherwise identical.

除了電荷相反，其他都一樣。

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

高能撞擊會產生 成對的物質和反物質粒子。

and they annihilate each other when they meet.

它們相遇時會互相抵銷。

The final particle of the Standard Model is the Higgs boson

最後一種標準模型粒子 是希格斯玻色子，

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

是宇宙的背景能量場中的量子漣漪。

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

所有的基本物質粒子透由 與能量場互動而取得質量，

according to the Standard Model.

這是標準模型的說法。

The ATLAS Experiment on the Large Hadron Collider

大型強子對撞機的超環面儀器實驗

is studying the Standard Model in-depth.

深入研究標準模型。

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

透由精確量測形成宇宙的粒子和力，

ATLAS physicists can look for answers to mysteries

超環面儀器的物理學家

嘗試破解標準模型無法解釋的謎題。

not explained by the Standard Model.

For example, how does gravity fit in?

比如，重力在這裡的角色是什麼？

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

載力粒子和物質粒子間的 真正關係是什麼？

How can we describe “Dark Matter”,

我們要如何描述「暗物質」？

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

大部分宇宙物質由暗物質組成，

但暗物質卻沒被解釋。

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

雖然標準模型漂亮地解釋 我們周遭的世界，

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

有海量的宇宙謎題仍待我們去探索。