The fundamentals of space-time: Part 3 - Andrew Pontzen and Tom Whyntie

时空基本原理: 第三部分- Andrew Pontzen and Tom Whyntie

翻译人员: Qingqing Mao 校对人员: Xiaoou Chen

Gravity. It controls the universe.

引力，它控制着宇宙

Everything attracts everything else.

万物互相吸引。

Ouch!

哎哟！

Including you.

包括你

Ow!

哎哟！

In this final lesson,

在这最后一课里

we'll explore what gravity means for space-time,

我们将探寻引力对于时空意味着什么

or rather what space-time means for gravity.

更准确地说，是时空对于引力意味着什么

Until now, we've been dealing with things moving

目前为止，我们已经处理过了

at constant speeds,

匀速运动的物体

with straight world lines in space-time.

它们的世界线是直线

But once you add gravity,

然而一旦你加入引力

if you measure a speed at one moment,

如果你在某一刻测量某物体的速度

then again a bit later,

稍后再次测量

the speed may have changed.

速度可能会有所变化

In other words, as I discovered,

换句话说，我发现

gravity causes acceleration,

引力造成加速

so we need the world line to look different

因此从某一刻至下一刻

from one moment to the next.

世界线需要看起来有所变化

As we saw in the last lesson,

如我们上一节课所见

the correct way to tilt an object's world line

倾斜一个物体的世界线的正确方法

is using a Lorentz transformation:

是使用洛伦兹变换：

Einstein's stretch and squash trick.

爱因斯坦的拉伸和压缩戏法。

So, to map out what gravity is doing to Tom's motion,

为了弄清引力如何影响汤姆的运动

we need to create a whole load of little patches of space-time,

我们需要制造一大堆小片的时空补丁

each transformed by different amounts.

对每一小片补丁做不同程度的变换

So that my world line is at a different angle in each one.

使得我的世界线在每一小片里都有不同的角度

And then, we're ready to stitch everything together.

随后，我们就可以把所有的小片补丁缝到一起

We assemble a cozy quilt of space-time

我们组成了一条舒适的时空被子

where world lines look curved.

其中的世界线看起来是弯曲的

Where the world lines join, the objects collide.

当世界线相交时，物体发生了碰撞

By making these connections between the patches,

随着我们将这些补丁连接起来

a curvature gets built into space-time itself.

时空本身产生了弯曲

But Einstein's true genius

但是爱因斯坦真正天才的地方在于

was to describe precisely how each patch

他精确描述了每块补丁

is stretched and squashed

是如何根据其附近的质量和能量

according to nearby mass and energy.

而拉伸和压缩的

The mere presence of stuff curves the space-time,

物体的存在就能弯曲时空

and curving space-time moves the stuff around.

而弯曲的时空又会移动物体

This is gravity, according to Einstein.

爱因斯坦认为，这就是引力

Previously, Isaac Newton had explained gravity

早先，艾萨克·牛顿

使用力和加速度的概念来解释引力

using the ideas of force and acceleration,

without any wibbily wobbly space-time,

并不需要扭曲的时空

and that did pretty well.

解释的效果也不错

But Einstein's theory does just slightly better

但是爱因斯坦的理论

在预测物理现象时更好一点点

at predicting, for example,

the orbit of Mercury around the Sun,

比如在预测水星绕太阳的轨道时

or the way that light rays are deflected by massive objects.

或者光如何被大质量物体偏折

More importantly, Einstein's theory predicts things

更重要的是，爱因斯坦的理论预测出了

that simply don't exist in older theories

在时间，空间，引力分离的旧理论中

where space, time and gravity were separate.

不存在的现象

The stitching can leave wrinkles in the space-time material.

缝制的过程可以造成时空的褶皱

These are called gravitational waves,

这些褶皱被称为引力波

which should be detectable as tiny, repetitive,

这应该是可以探测到的

它体现为空间里极小的、重复的、微妙的伸缩

subtle squashes and stretches in space.

So we're building experiments to check if they are there.

我们正在建造实验来验证其的存在

In the meantime, indirect evidence,

与此同时，有间接证据

most recently in the polarization patterns of light

强烈地暗示了它们的存在

left over from the Big Bang,

最近的一个间接证据是

strongly suggest that they are.

大爆炸余晖中的偏振模式

But despite Einstein's successes,

虽然爱因斯坦的理论很成功

when too much stuff gets concentrated

然而当很多东西

in too small a space,

被集中到一个很小的空间里

like in a black hole,

比如一个黑洞

the curvature of space-time becomes so large,

此时时空的曲率是如此之大

that his equations collapse.

以至于爱因斯坦的公式垮了

We need a new picture of space-time

我们需要一个

that incorporates quantum mechanics

加入了量子力学的新的时空理论

to unlock the secret at the heart of black holes.

这样才能解开黑洞中心的秘密

Which means there's plenty more to be discovered

这意味着在将来

about space, time, and space-time in the future.

还有很多关于空间，时间，和时空的东西有待发现