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  • General

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  • 广义相对论

    An image of a galaxy with X-ray emissions detected by Chandra Observatory, showing bright central area.

    The mission of NASA's Chandra X-ray Observatory is to detect X-ray emission from the hottest regions of the Universe such as the high-  gas swirling around a  black hole .
    ::美国航天局Chandra X射线天文台的任务是探测宇宙最热的地区产生的X射线排放,例如黑洞周围的高气波。

    The General Theory of Relativity
    ::《一般相对论论论》

    In 1905, Albert Einstein published the  theory of special relativity , a  theory  about space and time. In the following years, Einstein worked on the fact that   produced the same effect as gravitation. For example, if you were in an accelerating spaceship, or just an elevator, you could not tell if the force on you was from   or gravitation. While Newton's  Law  of Universal Gravitation works well for ordinary gravitational fields, it is inaccurate when the gravitational intensity is high. Albert Einstein formulated the  theory of general relativity  in 1914 as a new way to explain gravity.
    ::1905年,艾伯特·爱因斯坦发表了特殊的相对论,即关于空间和时间的理论。在随后的几年里,爱因斯坦致力于研究产生与引力同样效果的事实。例如,如果你在加速的宇宙飞船中,或者只是升降机中,你无法判断你身上的力是来自还是引力。纽顿的《世界引力法》对普通引力场效果良好,但当引力强度高时,它并不准确。艾伯特·爱因斯坦于1914年提出了一般相对论,作为解释引力的新方法。

    The classical explanation of gravity is that a force of attraction acts at a   between two objects and the magnitude of the force is directly proportional to each of the masses and inversely proportional to the square of the distance between the objects. The objects move toward each other due to this force of attraction. Einstein’s new concept of gravity states that matter (mass) causes the space around the matter to curve and also distorts time. A straight line through this curved space would also be curved in order to be a straight line.
    ::对重力的经典解释是,在两个对象之间和力量的大小之间,吸引力的力量直接与每个质量成正比,与物体之间的距离平方成反比。由于这种吸引力,物体相互向上。爱因斯坦新的重力概念指出物质(质量)使物质周围的空间曲线并扭曲时间。穿过这个曲线空间的直线也会弯曲,成为一条直线。

    Suppose we take a model of the earth in the shape of a globe and draw a straight line on the globe that travels from Kodiak Island, Alaska to the southern tip of Greenland. This straight line passes northward of Hudson’s Bay, missing it entirely.
    ::假设我们以地球为模范,从阿拉斯加的科迪亚克岛到格陵兰的南端,在地球上划一条直线。 这条直线从哈德逊湾北向,完全忽略了这条直线。

    Map of Canada illustrating the straight line from Kodiak Island to Greenland, highlighting Hudson's Bay.

    Now suppose we take a map of Canada that has been flattened to exist in two dimensions and once again, draw a straight line from Kodiak Island, Alaska to the southern tip off Greenland.
    ::现在假设我们拿一张加拿大的地图, 已经平定为存在两个维度, 再一次,划一条直线 从阿拉斯加的科迪亚克岛 到格陵兰的南端。

    This time, the straight line cuts right through the middle of Hudson’s Bay.
    ::这一次,直线直穿哈德逊湾。

    Map of Canada showing a straight line through Hudson's Bay, illustrating geometric differences in projections.

    Why the difference? The actual space occupied by the earth is three dimensional and spherical. When that space is altered in order to fit it onto a two-dimensional sheet of paper, the actual geometry of the surface is altered. A straight line on a curved surface does not mean the same thing as a straight line on a flat surface. When an object travels through curved space, it must follow the curvature of the space in order to move in a straight line.
    ::为何不同? 地球所占据的实际空间是三维和球体。 当该空间被改变以适应于两维纸面时, 表面的实际几何会改变。 曲线表面的直线与平面的直线并不相同。 当一个物体穿过曲线空间时, 它必须跟随空间的曲线才能移动直线 。

    When there is no mass in a volume of space, the space is not curved. An object passing through such space would follow a straight line in our normal way of thinking of a straight line.
    ::当空间体积没有质量时,空间就不会弯曲,通过这种空间的物体会以我们正常的直线思维方式沿着直线走。

    Graphic illustrating curvature of space-time, related to the General Theory of Relativity.

     

    Visual representation of the principles of general relativity, illustrating curved space and gravity.

    When a large mass is placed in the space, however, the space is curved due to the presence of the mass. In this case, an object passing through the space must follow the curvature of the space in order to follow a straight line. Thus the path of the object bends toward the mass. The change in the direction the object appears to be exactly the same as it would have been following Newton’s law of gravity.
    ::然而,当一个大质量被放置在空间时,空间会因质量的存在而曲线。 在这种情况下,通过空间的物体必须跟随空间的弯曲以遵循直线。因此,物体的路径会向质量弯曲。 物体方向的改变似乎与牛顿的引力法则完全相同。

    In the general theory of relativity, objects move toward each other not because of a force that acts at a distance but because they are following curved space. The mathematical expressions describing the properties of a gravitational field around a mass are given in a set of formulas called the  Einstein Field Equations . These formulas are a highly complex system of partial differential equations, which are beyond the scope of our material. Under normal levels of gravitational field strength, however, the relativistic mathematics for gravity reduce to Newton’s mathematics for gravity. When gravitational field strength is extremely high, however, the correct movement of objects can only be calculated with Einstein’s relativistic gravity. Mass tells space how to curve and space tells mass how to move.
    ::在一般相对论理论中,物体彼此相向并不是因为在距离上起作用的力量,而是因为它们正在跟随曲线空间。描述质量周围引力场特性的数学表达式是在一套称为爱因斯坦田地方程式的公式中给出的。这些公式是一个非常复杂的局部差异方程式系统,它超出了我们物质的范围。然而,在正常的引力场强度水平下,重力相对数学减少了牛顿的数学重力。然而,当引力场强度极高时,只能用爱因斯坦相对引力来计算物体的正确移动。质量告诉空间如何曲线和空间如何告诉质量如何移动。

    Experimental tests to garner support for the general theory of relativity were not easy to find. The first involved the orbit of the planet Mercury. The orbit of Mercury (the closest planet to the sun) exhibits perturbations and a precession that could not be fully explained by Newton’s Law of Universal Gravitation. The motion of Mercury was in much greater agreement with the predictions from the equations of general relativity. The acceptance of the theory of general relativity increased greatly after it was shown to correctly predict the orbit of Mercury.
    ::获得对相对论普遍理论的支持的实验性试验并非易事。 第一项试验涉及行星“汞”的轨道。 水星(离太阳最近的行星)的轨道出现了扰动和分裂,牛顿的《普遍引力法》无法充分解释这一点。 水星运动与一般相对论等式的预测意见更加一致。 在显示对水星轨道的正确预测之后,对一般相对论的接受程度大大提高了。

    Both Newton’s theory of universal gravity and the theory of general relativity predict that light can be deflected by gravity. The calculation of the amount of deflection predicted by Einstein’s theory was approximately double that predicted by Newton’s theory. The deflection of light by gravity was tested in 1919, five years after general relativity was proposed.
    ::牛顿的宇宙引力理论和一般相对论理论都预测光能被引力偏转。 爱因斯坦理论所预测的偏转量的计算大约是牛顿理论所预测的两倍。 引力偏转于引力的测试于1919年,也就是在提出一般相对论五年之后的1919年。

    Two British groups took photographs of a region of the sky centered on the sun during the May 1919 total solar eclipse and compared the positions of the photographed stars with those of the same stars photographed from the same locations in July 1919 when the sun was far from that region of the sky.
    ::两组英国人拍摄了1919年5月日全日食期间以太阳为中心的一个天空区域的照片,并将拍摄到的恒星的位置与1919年7月在同一地点拍摄到的同一恒星的位置作了比较,当时太阳远离天空区域。

    Curved Space Around A Mass, Showing Object Paths Influenced By Gravity.

    The results showed that light was deflected when the sun was present, and also that this deflection was consistent with general relativity but not with “Newtonian physics”. The subsequent publicity catapulted Einstein to world fame. (To date, he is the only scientist to ever have a ticker-tape parade in New York City.)
    ::结果显示,太阳出现时,光线被偏转,而且这种偏转与一般相对论一致,但与“纽顿物理学”不相符。 随后的宣传活动将爱因斯坦推向世界名声。 (迄今为止,他是纽约市唯一一个有长字游行的科学家。 )

    Gravitational Waves
    ::引力波

    Einstein first hypothesized the existence of gravitational waves in 1916. They were thought to be waves in the fabric of space-time, like ripples in a smooth surface of water. These waves were proposed to carry energy in the form of gravitational radiation, temporarily stretching and compressing matter as they pass through.
    ::爱因斯坦首先假设了1916年引力波的存在。 他们被认为是时空结构中的波,就像平滑水面上的波纹。 提议这些波以引力辐射、临时伸展和压缩物质的形式承载能量。

    On February 11, 2016 (one hundred years after Einstein’s prediction), researchers from the Advanced  Laser  Interferometer Gravitational-Wave Observatory (LIGO) announced the first detection of a gravity wave! The signal, a short, quarter-second blip of sound, is an auditory representation of the ripple felt by the two LIGO observatories on either side of the United States. It was caused by the merging of two black holes 1.3 billion light years away.
    ::2016年2月11日(爱因斯坦预测后100年), 高级激光干涉计引力观测站(LIGO)的研究人员宣布首次检测重力波! 信号是短短四分之一秒的声波, 是两个LIGO观测站在美国两侧所感受到的波纹的听力代表。 其原因是两个黑洞相隔13亿光年的合并。

    Other Predictions of the General Theory of Relativity
    ::对一般相对论的其他预测

    Einstein’s general theory of relativity states that time is a fourth dimension adding to the three dimensions of space. Einstein called this four-dimensional geometry spacetime. The general theory of relativity also predicted light coming from a strong gravitational field would have its   shifted toward longer wavelengths, called a red-shift. The theory also predicted that when gravity becomes great enough, it would produce objects called black holes. Black holes are objects whose gravity is so massive that light cannot escape from the surface at all. Since no light can escape, such objects would appear black. Both gravitational red-shift and black holes were considered possible in the Newtonian theory, but measurements correspond better with Einstein's theory.
    ::爱因斯坦的一般相对论理论指出,时间是空间三个维度的第四个维度。爱因斯坦称之为四维几何空间时。一般相对论还预示着来自强大引力场的光线会转向更长的波长,称为红色变换。 理论还预测当引力变得足够大时,它会产生被称为黑洞的物体。 黑洞是其引力如此巨大,光线根本无法从表面逃逸的物体。 由于光线无法逃脱,这些物体会显得黑色。 牛顿理论认为引力式的红轮和黑洞都是可能的,但测量与爱因斯坦的理论更相符。

    On April 10th, 2019, the   revealed it has successfully captured images that provide the first visual evidence of a supermassive black hole. To learn more, watch the video below:
    ::2019年4月10日,它成功捕捉了图像, 提供了第一个超大质量黑洞的视觉证据。要学习更多,请看下面的视频:

    There are also interesting effects having to do with the “curved time” predicted by the theory of relativity. This effect manifests itself by causing time to go slower near a massive object. The theory suggests that time on the top of a mountain runs faster than it does at sea level. Gravity's slowing down of time also affects the frequency of light waves and therefore their color. Light becomes bluer as it approaches a massive object and redder as it moves away. This effect was first observed in 1960 by Robert Pound and Glen Rebka, who shot   up to the top of a building and measured the change in their color as they got farther away from the Earth.
    ::相对论预测的“ 弯曲时间” 也会产生有趣的效果。 这种效果表现在使时间更慢地接近一个巨大的物体上。 理论表明,山顶上的时间比海平面的速度要快。 重力减慢也会影响光波的频率和颜色。 光在接近一个巨大的物体和随着其移动而变红时会变蓝。 1960年, 罗伯特· 庞德和格伦· 里布卡首次观察到了这种效果, 他射向建筑物顶部,测量了距离地球更远时其颜色的变化。

    Launch the simulation below to further explore Black Holes. Explore what happens as you approach the event horizon, the area in which light can no longer escape. Try to observe the warping of spacetime that occurs near the event horizon that causes the clock to appear to run slower. Then, change the sliders to also observe how radio signals are stretched to longer wavelengths, resulting in lower frequencies:
    ::启动下面的模拟以进一步探索黑洞。 探索当您接近事件地平线时会发生什么, 光线已无法再逃离的区域 。 尝试观察在事件地平线附近发生的时间扭曲, 使时钟看起来速度更慢 。 然后, 将滑动器更改为观察无线电信号如何被拉长到更长波长, 导致频率降低 :

    Further Reading
    ::继续阅读

    Summary
    ::摘要

    • Masses placed in space cause the space to be curved.
      ::空间中的质量导致空间被弯曲。
    • Curved space causes masses moving in a straight line to follow a curved path.
      ::曲线间距导致质量在直线移动以沿着弯曲路径移动。
    • Curved space also caused time to run more slowly.
      ::曲线空间也造成时间运行缓慢。

    Review
    ::回顾

    1. The general theory of relativity was a new way of understanding
      1. the speed of light.
        ::光速 光速 。
      2. gravity.
        ::重力。
      3. mass.
        ::质量.
      4. force.
        ::力。

      ::相对论的一般理论 是理解光速 重力 质量 力的新方法
    2. Gravity can bend the path of light.
      1. True
        ::真实
      2. False
        ::假假

      ::引力可以弯曲光线的路径。
    3. Strong gravitational fields can alter the rate of time passing.
      1. True
        ::真实
      2. False
        ::假假

      ::强大的引力场可以改变时间流逝的速度。
    4. Under what circumstances will a light beam follow a curved path?
      1. when emitted from a moving source
        ::当从移动源中排放时
      2. when measured from an accelerating space ship
        ::以加速的航天器测量
      3. when measured in the presence of an extreme gravitational field
        ::当以极端引力场为尺度时
      4. NEVER
        ::从未

      ::在什么情况下光束会沿着曲曲曲路径走?当从移动源中排放时,如果从加速的航天器中测量,而从没有在极端引力场中测量,那么从移动源中排放的光束在什么情况下会沿着曲曲曲路径走?
    5. If you are traveling toward the star Sirius at  1.5 × 10 8   m / s , what speed would you measure for the speed of light arriving at your ship from Sirius?
      1. 3.0 × 10 8   m / s
        ::3.0 × 10 8米/秒
      2. 1.5 × 10 8   m / s
        ::1.5×10 8米/秒
      3. 4.5 × 10 8   m / s
        ::4.5×10 8米/秒
      4. 0   m / s
        ::0米/秒

      ::如果你在1.5×10 8米/秒时朝天狼星行驶,那么从天狼星到达你的船时,光速将达到何种速度?3.0×10 8米/秒1.5×10 8米/秒4.5×10 8米/秒0米/秒。

    Explore More
    ::探索更多

    Use this resource to answer the questions that follow.
    ::使用此资源回答下面的问题 。

    1. If you have two objects and one of them is moving and one is standing still, what experiment can you do to determine which object is moving?
      ::如果你有两个对象,其中有一个在移动,一个站着,你能做什么实验来确定哪个物体在移动?
    2. If a person in a spaceship flies by a person on the earth and each person assumes that they are standing still and the other one is moving, which person is correct?
      ::如果在太空船上的一个人乘着一个人在地球上飞翔,而且每个人假定他们站立不动,而另一人在移动,那么,谁是正确的?