呵呵，分步 => 分布：）

Motivations for Detecting Gravitational Waves

探测引力波的动机

Why Bother Looking for Gravitational Waves?

为什么要寻找引力波？

LIGO and GEO are complex experiments that need a lot of money and time to run, as demonstrated by the need for Einstein@Home. However, if gravitational ways are detected, they will show the universe in a completely new light.

就像Einstein@Home所展现的，LIGO和GEO都是需要花费大量资金和时间来维持运行的复杂实验。但如果真探测到引力波，我们将获得一种全新的方法以观测宇宙。

Most of the things we know about the universe we learned from studying it with light. Light is the only source of information we have, for instance, from distant objects in space such as galaxies. Gravitational waves would be an additional source of information from distant objects. They would give us information on objects that don’t emit light, like black holes, and on how massive objects are moving and colliding.

目前对于宇宙的了解大都是通过光学途径获取的。光是我们观测太空中比如银河系深处天体的唯一方法，而引力波有可能成为了解这些遥远天体的新手段，它将帮助我们获取如黑洞等不发光的天体的信息、了解超重天体的运行及碰撞情况。

One way to visualize the importance of detecting gravitational waves is to think of the universe as a movie and gravity waves as sound. By studying the movie with light, we can see what happens. By studying the movie with sound, we can hear what happens. Although each of these methods gives us some information on the storyline, we can only really understand what is happening when we can see and hear the movie at the same time. This is why scientists are so excited about being able to study the universe with gravitational waves and light waves.

关于探测引力波的重要性，打个形象的比方，可将宇宙看作一部电影，而引力波是电影的声音。只通过光来研究电影，我们可以看到正在发生什么；通过声音来研究电影，我们能听到正在发生什么。虽然这两种手段都让我们对电影的故事情节有所了解，但只有同时看和听，我们才能真正了解这部电影。这就是这什么能同时利用引力波和光波来研究宇宙会让科学家们如此激动的原因。

Scientists have some idea what they might hear while listening to gravitational waves, but they are also excited about the possibility of hearing things they never thought to listen for. Join Einstein@Home today and be a part of this important investigation!

科学家们对于将可能从引力波中听到的信息已有所设想，但他们仍然非常激动于能够听到人类之前从末听到的声音！现在就加入到Einstein@Home中并成为这次伟大探索的一份子吧！

好像主要的页面就剩http://boinc.equn.com/einstein/gwaves/sources/index.htm了
建议这页右上角的“相关主题”改为“本页内容”，毕竟只是页内的跳转

[ Last edited by Youth on 2005-11-11 at 12:23 ]

Gravitational Wave Sources

引力波源

Binary Systems
Supernova
Neutron Stars
Black Holes
Cosmic Gravitational Wave Background

双星系统
超新星
中子星
黑洞
宇宙引力波背景

Gravitational waves are produced when there is a change in the curvature of spacetime. Since the shape of spacetime depends only on how mass is distributed, events that change the distribution of mass cause gravitational waves. It takes events with a lot of energy to make gravitational waves that we can detect because spacetime is not very elastic. Remember the bowling ball analogy? Space-time is like a stiff trampoline, one that only sinks when you put something very heavy on it.

当时空结构的曲率发生变化的时候就会产生引力波。既然时空结构的形状仅取决于质量的分布，能够改变质量分布的事件就能够导致引力波的产生。因为时空结构并不是富有弹性的，要产生我们能探测到的引力波将需要相当多的能量。还记得保龄球的比喻吗？时空结构就像一张僵硬的蹦床，你只有将相当重的物体放在上面蹦床才会下陷。

Like ripples on a pond, gravitational waves lose strength as they move farther from where they started. This is why they are so difficult to detect on earth – we need heavy objects moving at speeds near the speed of light to create gravitational waves large enough to detect, but all of those objects are also far from the earth. The gravitational waves that scientists think we can detect with LIGO and GEO 600 are from things like binary neutron stars, supernovae, and colliding black holes.

就像池塘中的水波，引力波在产生后的传播过程中也会损失能量。这就是在地球上难以探测到它们的原因 - 必须是以接近光速的速度运行的超重天体，才能产生足够强的引力波供我们探测，然而这些天体往往都离地球相当远。科学家们认为通过LIGO和GEO我们也许能探测到来自中子星、超新星和碰撞黑洞的引力波。

Binary Systems

双星系统

The Butterfly Nebula, binary stars at center.
Image courtesy of NASA.

蝶状星云，中部即为双星
图片由NASA提供（下同）

When two massive stars or black holes orbit each other, they form a binary system. The two objects gradually spiral inward and lose energy in the form of gravitational waves. As the objects get closer together, the gravitational waves they emit get stronger. When the two objects collide, they create an intense gravitational wave signal.

两个大质量的恒星或黑洞相互绕对方运行，就构成了一个双星系统。当两个星体螺旋状地相互靠近时，它们将以产生引力波的形式损失能量。星体靠得越近，产生的引力波也越强，当两个星体最终相撞，将产生非常强的引力波信号。

Binary systems that emit gravitational waves can be made of stars, black holes, or a combination of the two.

双星系统中的星体可以是恒星、黑洞或两者的组合。

Supernova

超新星

Three Great Eyes on Kepler's Supernova Remnant.

开普勒超新星遗迹中的大三眼

A supernova is a violent explosion that happens to the most massive stars. When a heavy star has burned up all of its fuel, it collapses and the outer layers shoot off into space. If the collapse if not perfectly spherical, the supernova will give off an intense burst of gravitational waves.

超新星是指具有超大质量的恒星所产生的猛烈的爆炸。当一个超重恒星烧尽了它自身的燃料，就会开始蹋缩。如果蹋缩过程不是沿着完美的球形，超新星将在瞬间发出强烈的引力波。

超新星

Neutron Stars

中子星

Hubble sees a neutron star all alone in space.

由哈勃望远镜在太空中观测到的一颗孤单的中子星

A supernova can leave behind a dense, rapidly spinning core made almost completely of neutrons, called a neutron star. A neutron star that is not perfectly spherical and rotates rapidly will cause gravitational waves. Some neutron stars become pulsars, stars that send off pulses of radio waves. These can also cause gravitational waves.

超新星爆发后可能会留下一个极高密度、快速旋转的、几乎完全由中子构成的核心，即中子星。中子星并不是完美的球形，在快速的旋转过程上将产生引力波。一些中子星变成了脉冲星，即发射电磁波的星体，它们也可能会产生引力波。

Black Holes

黑洞

Dust disk around a black hole in galaxy NGC 4261.

银河系4261号星云中的围绕黑洞的一个碟状星尘

If a core continues collapsing beyond the neutron star stage, it may become a black hole. In this case, the gravitational attraction of the core is so strong that nothing can escape; the only information black holes emit is in the form of gravitational waves.

如果中子星再进一步蹋缩，它将可能成为一个黑洞。这时，星体产生的引力是如此之大以到没有任何物体能逃脱它的束缚，黑洞对外界唯一能提供的信息就是通过引力波的形式。

Cosmic Gravitational Wave Background

宇宙引力波背景

Scientists also hope to detect gravitational waves left over from the beginning of the universe. This requires even more detectors because these waves are even weaker than the waves from binary stars and neutron stars.

科学家们也希望能探测到从宇宙起源时就存在的引力波。这将需要更多的探测器，因为与双星和中子星产生的引力波相比，这些引力波还要更弱。

[ Last edited by Youth on 2005-11-11 at 13:48 ]

搞定，有些术语不知道怎么翻译，欢迎大家纠错！

目前所有已经翻译好的页面均已上传，所以提到需要修改的地方均已修改过了，所有已翻译页面的标题、链接等等均已检查无误.....

感谢大家的关注与参与，感谢各位对我们翻译工作的支持！

大仙看看这里：

http://einstein.phys.uwm.edu/international.php

把我们的网站链接告诉他们吧：）

equn 已经发过邮件给官方负责人了，正在等待答复呢....

翻译页面：http://boinc.equn.com/einstein/gwaves/detectors/ligo.html

Laser Interferometer Gravitational Wave Observatory (LIGO)

引力波观测激光干涉仪 (LIGO)

LIGO has two locations in the United States – one in Livingston, Louisiana and the other in Hanford, Washington . Each site has an interferometer with 4-km long arms that are enclosed in 1.2-m diameter vacuum pipes. The Hanford location also has a smaller interferometer with 2-km long arms.

位于美国的 LIGO 观测所拥有两套干涉仪，一套安放在路易斯安娜州的李文斯顿，另一套在华盛顿州的汉福。在李文斯顿的干涉仪有一对封闭在 1.2 米直径的真空管中的 4 公里长的胳膊，而在汉福的干涉仪则稍小，只有一对 2 公里长的胳膊。

The two LIGO interferometers work together as one observatory. This is because changes in laser intensity, mini-earthquakes, and other local disturbances can look like gravitational wave signals. Local signals like these only register in one interferometer, but gravitational wave signals register in both. Therefore, comparing data from the two locations helps scientists figure out which signals are from local noise.

这二套 LIGO 干涉仪在一起工作构成一个观测所。这是因为激光强度的微小变化、微弱地震和其它干扰都可能看起来像引力波信号，如果是此类干扰信号，其记录将只出现在一台干涉仪中，而真正的引力波信号则会被两台干涉仪同时记录。所以，科学家可以对二个地点所记录的数据进行比较得知哪个信号是噪声。

LIGO started collecting data in 2003. The observatory is the largest, most sensitive gravitational wave detector ever built. A planned series of upgrades will increase LIGO’s sensitivity even more.

LIGO 从 2003 年开始收集数据。它是目前全世界最大的、灵敏度最高的引力波探测所。一系列的升级计划将更进一步提高其灵敏度。

For more information, visit the LIGO website.

更多详情，请浏览 LIGO 站点。

Participating Institutions: California Institute of Technology, Massachusetts Institute of Technology

参与研究的机构有：California Institute of Technology, Massachusetts Institute of Technology

胳膊？？
不如用“臂”吧~~~

要不我们用“翼”吧？直接用一个“臂”字读起来恐怕也不好，再商量商量吧.....

感觉还是臂更好些，单独念不好听的话，要不就尽量用臂长之类的词

已改，已上传。大家愿意翻译的继续翻译，愿意挑错的继续挑错啊...

http://boinc.equn.com/einstein/gwaves/predict/index.htm
但是，他最为人知的贡献是发现了重力学定理。爱因斯坦的许多理论，包括对引力波的预言，都是从牛顿引力学理论中得到灵感的。

统一一下比较好~~~

还有页面右边的相关主题没有翻译~~~

[ Last edited by fwjmath on 2005-11-13 at 08:52 ]

http://boinc.equn.com/einstein/gwaves/predict/flaws.html

Flaws in Newton's Theory
牛顿理论中的缺陷

As scientists developed better astronomical tools, they noticed slight differences between their measurements and Newton’s predictions. For example, Newton’s prediction of Mercury’s path around the sun was slightly different from what astronomers observed. Newton’s theory also did not give a satisfactory answer to the question:
随着科学家们发展出更好的天文学工具，他们发现他们的观察结果跟牛顿理论预言的有些微的差别。比如说，牛顿理论对于水星运行轨道的预测与实际观察的结果稍微有些不同。此外，牛顿的理论也不能对如下问题作出一个令人满意的解释：

What would happen if the sun suddenly disappeared?
如果太阳突然消失，将会发生什么事？

According to Newton’s theory, the whole universe would know about the sun’s disappearance immediately. This means that all of the planets revolving around the sun would fly out of orbit right away. However, Einstein reasoned that it should take longer for the planets farthest from the sun to find out what happened, so the closet planets should fly out of orbit first.
根据牛顿的理论，整个宇宙都会立刻觉察到太阳的消失。这就意味着所有环绕太阳的行星都会沿切线方向飞离环绕轨道。可是，爱因斯坦以详细的理由说明离太阳越远的行星会越迟知道太阳消失了，所以较近的行星会先飞离轨道。


Image Courtesy of NASA/JPL-Caltech.
NASA/JPL-Caltech惠赠

The idea that information can travel across the universe instantaneously is called action at a distance. Einstein and many other scientists were troubled by action at a distance because it means that some information can travel faster than light.
信息能瞬时通过宇宙传播的这个思想被称为超距作用。爱因斯坦和其他很多科学家都被超距作用所困扰，因为它意味着信息可以传播得比光还快。

Einstein finally solved the action at a distance problem in 1916. He explained that gravity was not an instantaneous force as Newton assumed, but that it took time to travel. This assumption was one reason why some of Newton’s predictions were not quite right. Before we discuss Einstein’s theory of gravity (called the General Theory of Relativity), however, we need to discuss his Special Theory of Relativity.
爱因斯坦在1916年终于解决了超距作用这个问题。他解释，重力不像牛顿说的那样是瞬时传播的，它的传播需要时间。这就解释了为什么牛顿的一些预言是不正确的。在我们讨论爱因斯坦的引力理论（被称为广义相对论）之前，我们要先讨论一下他的狭义相对论。

[ Last edited by fwjmath on 2005-11-13 at 09:17 ]