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暗物质是什么?

Minute Physics: What is Dark Matter?

Have you ever had the feeling that there’s
你是否曾感觉世上存在着
something bigger out there, something you can’t see?
某种更加巨大却看不见的东西?
Well there is –
它的确存在
it’s called Dark Matter.
名叫暗物质
Dark matter is spread throughout space,
暗物质遍布太空
engulfing the Milky Way and all other galaxies.
将银河系和其他星系包围了起来
It’s four times more common in the universe than visible matter,
暗物质在宇宙中更为普遍 比可见的物质多出4倍
yet we’ve never seen
但是 我们从来没有看见
or directly observed it!
或者直接观测到过它
So how do we know it’s there?
那我们如何知道暗物质存在呢?
Because of gravity.
是因为引力
A galaxy is like a giant merry-go-round that all the stars are riding.
星系就如同所有恒星乘坐的巨型旋转木马
In order to stay on,
为了继续呆在上面
each star has to hold on tight
每颗恒星都必须抓紧
(that’s where gravity comes in),
引力就在此时发挥作用
otherwise it’ll fly off into space.
否则 恒星会被抛进太空
The problem is, the force of gravity from all the stars we can see
问题是 我们能看见的恒星的引力
isn’t strong enough to hold galaxies together
不足以把星系聚集在一起
– all the stars should be flying off the edge of the merry-go-round! But
所有恒星都应该从旋转木马的边缘被抛出去
they’re not.
结果并非如此
It’s as if some invisible rope is helping them hold on.
就好像正有某种隐形的绳子帮助恒星抓牢
Physicists believe that rope is the gravitational force
物理学家们认为这根“绳子”是引力
from stuff we can’t see –
来自我们看不见的东西
hence, Dark Matter.
因此 叫它暗物质
And how do we know the speeds of stars in distant galaxies?
要如何知道遥远星系中恒星的速度呢?
The doppler effect
多普勒效应
(which is why a police siren shifts to
即为什么当警车通过时
a lower pitch as the car passes)
警笛的音高会降低
also works for light –
该效应对光同样适用
that’s how radar catches you speeding, and how astronomers
雷达以此能捕捉超速行驶的车辆
measure the rotation of galaxies.
天文学家以此能测量星系的转速
So, we use what we can see
所以 利用看见的现象
to tell us about what we can’t.
我们能够得知看不见的情况

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视频概述

暗物质在宇宙中数量较多,但我们却直至今日才发现。这个发现过程比较抽象,让我来介绍一下吧!

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收集自网络

翻译译者

翻译爱好者山人乙

审核员

审核员PH

视频来源

https://www.youtube.com/watch?v=Af0_vWDfJwQ

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