For example, if you shake a stick back and forth in water: water waves.

例如，如果你在水中來回晃動一根棍子：水波。

Vibrate a piece of metal back and forth really fast: air pressure waves.

快速地來回振動一塊金屬：氣壓波。

Shake some electrons back and forth really fast: radio waves.

將一些電子快速地來回晃動：無線電波。

And yes, shake a planet or star back and forth really fast: gravitational waves.

是的，快速地來回晃動行星或恆星：引力波。

Gravitational waves happen because the effects of gravity don't travel outwards at infinite

引力波的發生是因為重力的影響不會以無限的速度向外傳播

speed – so if the sun were to suddenly jump a few hundred thousand kilometers to the side,

速度--所以如果太陽突然跳到幾十萬公里外的一邊。

the changed gravitational field would take time to pulse outwards.

改變後的引力場將需要時間向外脈衝。

And if the sun shook back and forth and back and forth, instead of a single pulse, you'd

而如果太陽來回搖晃，而不是單一的脈衝，你會

get continuous gravitational waves.

得到連續的引力波。

So what's doing the "waving"?

那麼是什麼在做 "揮手 "呢？

In the case of water, the height of the water increases and decreases at any particular

在水的情況下，水的高度在任何特定的時候都會增加和減少。

location as the waves travel past.

波浪經過時的位置。

In the case of sound, the pressure of the air increases and decreases at any particular

在聲音的情況下，空氣的壓力在任何特定的時間都會增加和減少。

location as the waves travel past.

波浪經過時的位置。

In the case of radio or cell phone signals or any other electromagnetic waves, the electric

在無線電或手機信號或任何其他電磁波的情況下，電

and magnetic fields get stronger and weaker at any particular location as the waves travel

在任何特定的位置，隨著波的傳播，磁場會變強和變弱。

past.

過去。

And in the case of gravitational waves, the gravitational field gets slightly stronger

而在引力波的情況下，引力場會變得稍微強一些

or weaker as the waves travel past.

或在波浪經過時變弱。

You can tell a wave has passed by looking at how nearby particles behave – a bobber

你可以通過觀察附近的粒子的行為來判斷一個波是否已經過去--搖擺器

on the water rises up and down, the electrons in a radio antenna move back and forth because

水面上的電子來回移動，無線電天線中的電子也來回移動，因為

of the changing electric field, and free-floating people or planets or cats move back and forth

變化的電場，而自由漂浮的人或行星或貓來回移動

because of the changing gravitational field – though in this last case, the peculiarities

因為引力場的變化--儘管在最後一種情況下，其特殊性

of gravity mean that the free-floating things actually experiencing the gravitational wave

意味著自由漂浮的東西實際經歷了引力波的影響

don't feel like they're moving.

不覺得他們在移動。

But if you measure the space between them by sending a pulse of laser light and measuring

但如果你通過發送一個脈衝光脈衝來測量它們之間的空間，並測量

the time it takes for it to come back, you'll find that the distance between them increases

的時間，你會發現它們之間的距離會增加。

and decreases.

和減少。

In practice, physicists don't actually measure gravitational waves with free-floating cats

在實踐中，物理學家實際上並沒有用自由漂浮的貓來測量引力波

– they use very very fancy expensive mirrors which are effectively free-floating because

- 他們使用非常非常花哨昂貴的鏡子，這些鏡子實際上是自由漂浮的，因為

they're hung on pendulums suspended on isolation tables suspended on isolation tables, or which

他們被掛在懸掛在隔離臺上的鐘擺上，懸掛在隔離臺上，或者哪些

are _actually_ free-floating because they're attached to satellites floating in space – though

實際上是自由漂浮的，因為它們與漂浮在太空中的衛星相連 - 儘管

this hasn't been done yet.

這一點還沒有做到。

The reason physicists need fancy floating mirrors to detect gravitational waves is that

物理學家需要花哨的浮動鏡來探測引力波的原因是

the waves are very, very weak.

波浪非常、非常弱。

For example, the electrons that vibrate back and forth in a radio antenna to make electromagnetic

例如，在無線電天線中來回振動的電子，使電磁

waves ALSO make gravitational waves; electrons _are_ matter moving back and forth after all.

波也會產生引力波；畢竟電子_是來回運動的物質。

But the waves they make are super weak: a 200 watt radio transmitter gives off something

但它們發出的波是超級弱的：一個200瓦的無線電發射器發出的東西

like a quadrillionth of a quintillionth of a quintillionth of a quintillionth of that

像四億分之一的五億分之一的五億分之一的五億分之一的五億分之一。

power as gravitational radiation.

功率作為引力輻射。

And that's why here on earth we can only detect the biggest baddest astronomical events – like

這就是為什麼在地球上，我們只能檢測到最大的最壞的天文事件--如

superfast spinning neutron stars or merging black holes or the big bang.

超高速旋轉的中子星或合併的黑洞或大爆炸。

Though so far, we've only detected black hole collisions.

儘管到目前為止，我們只探測到黑洞碰撞。