How cosmic rays help us understand the universe - Veronica Bindi

宇宙射線如何幫助我們了解宇宙？——薇若妮卡．賓狄

譯者: Yesbydefault 倪文娟 審譯者: Adrienne Lin

How much can we really know about the universe beyond our galaxy?

我們究竟能了解 自己銀河系以外的宇宙多少？

The Hubble Telescope has enabled us to see

哈伯望遠鏡可以幫助我們

objects in space as far 13,000,000,000 light years away.

看到太空中距離130億光年的物體

But this still doesn't give us the answers to all our questions,

但仍無法解答所有的問題

questions like, "What is the universe made of?"

像是，宇宙是由什麼構成？

"Which elements are the most abundant?"

哪些元素最多？

"Does space contain undiscovered forms of matter?"

太空有沒有尚未發現的物質型態？

"Could there be antimatter stars or galaxies?"

有沒有「反恆星」或「反星系」？

有些問題無法單靠影像揭曉

Some of these questions cannot be answered solely from visual images,

but what if we had messengers bringing us physical data

但是，如果能有某種「太空使者」

帶來宇宙遠處的物理資料

from distant parts of the cosmos,

beyond the reach of explorers or satellites?

遠超出太空梭和衛星所及呢？

In a way, we do, and these "space messengers" are called cosmic rays.

其實有，這些太空使者叫做「宇宙射線」

Cosmic rays were first discovered in 1912 by Victor Hess

這是在1912年，由維克托·赫斯首度發現

when he set out to explore variations in the atmosphere's level of radiation,

他想探索大氣層的輻射程度變化

which had been thought to emanate from the Earth's crust.

當時輻射被認為是由地殼發出

By taking measurements on board a flying balloon during an eclipse,

他趁著日蝕，搭乘氣球升上高空測量

結果發現高空的輻射強度增加

Hess demonstrated both that the radiation actually increased

at greater altitudes and that the sun could not be its source.

並且不是來自太陽

The startling conclusion was that it wasn't coming from anywhere

驚人的結論是

這高幅射並非來自大氣層以下

within the Earth's atmosphere but from outer space.

而是來自外太空

Our universe is composed of many astronomical objects.

我們的宇宙是由許多天體所組成

BIllions of stars of all sizes, black holes, active galactic nuclei,

包括無數的恆星、黑洞、活躍星河系、

astroids, planets and more.

小行星、行星和更多的天體

During violent disturbances, such as a large star exploding into a supernova,

發生劇烈騷動時 如大型恆星爆炸成超新星

billions of particles are emitted into space.

會產生無數個粒子，瞬間噴射到太空中

Although they are called rays,

雖然宇宙射線被稱做「射線」

cosmic rays consist of these high energy particles

其實是由這些噴發的高能量粒子所構成

rather than the photons that make up light rays.

不是構成光線的光子

爆炸產生的光是以直線行進

While the light from an explosion travels in a straight line

at its famous constant speed,

並且等速

the particles are trapped in extraordinary loops

宇宙射線粒子的運行則是沿著超常的迴路

by magnetic shockwaves generated by the explosion.

受制於爆炸所產生的磁波

Crossing back and forth through these magnetic field lines

沿著這些磁場線來回繞行

accelerates them to almost the speed of light before they escape.

粒子會被加速到接近光速 然後脫離軌道

太空中充滿無數的宇宙射線

There are lots of cosmic rays in space, and some of these particles have traveled

有些粒子運行了幾十億年 才到達地球

for billions of years before reaching Earth.

When they enter our atmosphere, they collide with the molecules there,

當宇宙射線射進地球大氣層 會擦撞大氣層的分子

generating secondary cosmic rays,

生成炸裂的二次宇宙射線

lighter particles with less energy than the original.

質量較輕，能量減弱

Most of these are absorbed into the atmosphere,

且多數會被大氣層吸收

but some are able to reach the ground, even passing through our bodies.

但是有些粒子會射到地表 甚至穿透人體

At sea level, this radiation is fairly low.

在海平面，這種輻射是相當低的

But people who spend a lot of time at higher altitudes,

但是有些人長時間在高空中

such as airline crews, are exposed to much more.

例如機師、空服員 則會暴露於較高輻射量

What makes cosmic rays useful as messengers

為什麼宇宙射線有助我們了解太空？

is that they carry the traces of their origins.

因為它們帶來發源處的訊息

By studying the frequency with which different particles occur,

研究不同粒子發生的頻率

scientists are able to determine the relative abundance of elements,

科學家可以鑑別相當多的元素

such as hydrogen and helium, within the universe.

例如宇宙中的氫和氦

But cosmic rays may provide even more fascinating information

但宇宙射線可能提供更驚人的資訊

about the fabric of the universe itself.

讓我們認識宇宙本身的構造

An experiment called the Alpha Magnetic Spectrometer, A.M.S.,

有一項實驗「阿爾法磁譜儀」，簡稱 AMS

has recently been installed on board the International Space Station,

近年發射安裝到國際太空站上

containing several detectors that can separately measure

AMS 有好幾台偵測儀器，負責分別偵測

a cosmic ray particle's velocity, trajectory, radiation, mass and energy,

宇宙射線粒子的速度、 軌跡、輻射、質量和能量

as well as whether the particle is matter or antimatter.

並且辨識粒子是物質或反物質

While the two are normally indistinguishable,

雖然這兩者通常難以分辨

their opposite charges enable them to be detected with the help of a magnet.

但它們電荷相反，可藉助磁力偵測辨識出來

The Alpha Magnetic Spectrometer is currently measuring 50 million particles per day

AMS 目前每天測量 5 千萬個粒子

with information about each particle being sent in real time from the space station

並把每個粒子的資訊即時傳回地球

to the A.M.S. control room at CERN.

到歐洲核子研究組織的 AMS 控制室

Over the upcoming months and years,

預期未來幾年內

it's expected to yield both amazing and useful information about antimatter,

將可發現關於反物質的驚奇新知、

the possible existence of dark matter,

暗物質的存在可能性、

and even possible ways to mitigate the effects

甚至找出方法 減低宇宙輻射對太空旅行的影響

of cosmic radiation on space travel.

我們邊等待新發現 不妨抬頭仰望清澈的夜空

As we stay tuned for new discoveries, look to the sky on a clear night,

and you may see the International Space Station,

你可能會看到國際太空站飛過

where the Alpha Magnetic Spectrometer receives the tiny messengers

載著 AMS 不斷接收微粒子

that carry cosmic secrets.

即將為我們揭開宇宙奧祕