百科知識視頻之煎蛋小學堂12 愛因斯坦引力論

In 1907 a young Albert Einstein was looking for a way to extend his special theory of relativity to include acceleration.It took him eight years to come up with the mathematical solution that we know as the General theory of relativity.

1907年，年輕的愛因斯坦在尋找一個可以將狹義相對論推廣到包括加速參考系的理論。他花了長達八年時間想出了一個數(shù)學上的解釋，也就是我們現(xiàn)在熟知的廣義相對論。

It tells us that we all live in a 4-dimensional spacetime.We can move up and down,left and right,backwards and forwards,That's three physical dimensions,but we also move in time-in the direction of the future,That's dimension number four.

廣義相對論認為 我們都生活在一個四維時空中,我們可以上下 左右 前后的運動,這是三維實體空間，但我們還能在時間維度上朝著未來前進。這就是第四個維度。

One consequence of Einstein's theory is that space-time can be stretched,a bit like a rubber sheet,He found out that mass,or energy,tells the 4 dimensional space-time how to deform,and vice versa,that deformation tells matter How to move.

愛因斯坦理論的結(jié)論之一就是：時空有點像橡膠，可以扭曲。他發(fā)現(xiàn)質(zhì)量或者能量可以令四維空間形變，反之，形了變的空間又能影響物質(zhì)的運動。

It's way easier to think about if we consider less dimensions,Let's cut one out and limit ourselves to two spatial dimension,When we put in the Earth,its mass curves the space-time and our apple falls towards it,And this is what we call gravity.We can make it even simpler still,and remove another spatial dimension.

在低維度上思考會簡單很多，我們可以剪出一個維度，并把自己限制在這個兩維度空間里，然后把地球放上去，它的質(zhì)量會彎曲時空并且令蘋果滾向它，這就是我們所說的重力。我們可以讓繼續(xù)簡單地探討一下，再去掉進一個空間維度.

Here we are,you,me,the apple all falling towards Earth,While we can clearly see and feel the attraction from something really massive and nearby,Like the earth,the effect of things that are further away is harder to notice,

看吧!你，我還有蘋果都掉到地球上。盡管我們可以清楚地看到并感受到，來自附近很大質(zhì)量物體的吸引，比如地球，但遠處物體的影響就很難察覺了。

For example,the influence we feel from the moon is pretty weak,And the main effect we can observe is when parts of the ocean fall into the space-time curvature.That the moon causes,Most people like to call this effect tides.It's the gravity of the sun that holds our planet in its orbit,but we can barely feel this effect at all.This is because the gravitational force decreases with the square of the distance,So it becomes weak really quickly the further away you go.

例如，月球引力帶給我們的感覺就很微弱，我們所能觀察到的現(xiàn)象就是：受時空彎曲影響而跌宕的海水，這就是由月球造成的。大部分人稱之為潮汐，太陽的引力將地球困在其軌道中運轉(zhuǎn)，但我們幾乎感覺不到這種力，這是因為引力會隨距離的增大按其平方值遞減，所以隨著距離增加，力會迅速地減小。

In the end gravity may be a weak force,but while electric charges cancel each other out in large objects,that can't happen with gravity,Over large distances gravity always wins and will even allow us to perceive the universein a completely new way.While all modern astronomy sees the Universe,Einstein's general relativity predicts that: We can also hear the Universe with Gravitational waves.

最終 引力也許會變成一個很小的力，大物體里面的電荷會互相抵消，但引力不會在大尺度上，引力總是勝利的，它讓我們以一種全新的方式認識宇宙，雖然所有的現(xiàn)代天文學都在觀察宇宙，但愛因斯坦的廣義相對論預言說：我們還能通過引力波聆聽宇宙的聲音.

These ripples in space-time are the sound of the universe and travel at the speed of light,They are emitted by the most extreme objects and are detectable from really really far away.This is pretty awesome,because soon the effects of gravity might be more to us than just the means by which stuff sticks to the ground.It will also provide us with a whole new way of observing our Universe and all the incredible objects that is contains.

這些在時空中以光速傳播的漣漪就是宇宙之聲，它們是由最極端的物體產(chǎn)生的 可以在極遠處被接受到，這真的非常神奇，因為不久之后，引力的影響，將不僅意味著東西會被吸到地面上。它將讓我們一種完全新的方式來觀察這個宇宙和宇宙中所有不可思議的物體。