radiation : Process by which energy is emitted from a source and propagated through the surrounding medium, or the energy involved in this process. Radiation consists of a flow of atomic or subatomic particles or of waves.

辐射:能量从一来源发射出来，并通过周围的媒质传播的过程，或者指这个过程中所包含的能量。辐射由原子或亚原子粒子流或者由波组成。

属类：自然科学-物理-

Familiar examples are light (a form of electromagnetic radiation)and sound (a form of acoustic radiation). Both electromagnetic and acoustic radiation can be described as waves with a range of frequencies and intensities.

熟悉的例子有光(电磁辐射的一种形式)和声(声子辐射的形式)。电磁辐射和声辐射都可以用一定范围频率和强度的波来描述。

属类：自然科学-物理-

The main processes of radioactivity are alpha decay, beta decay, and gamma decay. In 1934 it was discovered that radioactivity could be induced in ordinary matter by artificial transmutation

放射性的主要过程有α衰变、β衰变和γ衰变。1934年发现通过人工蜕变，普通物质也能诱导出放射性来。

属类：自然科学-物理-

Electromagnetic radiation is also often treated as discrete packets of energy, called photons. All matter is constantly bombarded by radiation from cosmic and terrestrial sources, and radioactive elements emit several types of radiation

电磁辐射也常被处理成分立的能量包，称作光子。所有物质都不断地受到来自宇宙或者地面源的辐射。放射性元素发射几种类型的辐射。

属类：自然科学-物理-

Radioactivity: Property exhibited by certain types of matter of emitting radiation spontaneously. The phenomenon was first reported in 1896 by Henri Becquerel for a uranium salt, and it was soon found that all uranium compounds are radioactive due to the uranium’s radioactivity.

放射性:某些类的物质自发发射辐射的特性。1896年贝克勒耳第一个报告在铀盐中发现了这一现象，不久发现由于铀有放射性，所以所有的铀化合物都是放射性的。

属类：自然科学-物理-

In 1898 Marie Curie and her husband discovered two other naturally occurring, strongly radioactive elements, radium and polonium. The radiation is emitted by unstable atomic nuclei (see nucleus)as they attempt to become more stable..

1898年居里夫人和她的丈夫发现了另外两种天然存在的强放射性元素，镭和钋。不稳定的原子核在试图变得更稳定的过程中发射出辐射。

属类：自然科学-物理-

Relativity : Concept in physics that measurements change when considered by observers in various states of motion. In classical physics, it was assumed that all observers anywhere in the universe would obtain identical measurements of space and time intervals

相对论:物理学概念，处在不同运动状态的观察者考虑的测量结果的变化。在经典物理学中，认为宇宙中任何地方的观察者对空间和时间间隔测量的结果都是一致的。

属类：自然科学-物理-

The special theory of relativity (1905)developed from Einstein’s acceptance that the speed of light is the same in all reference frames, irrespective of their relative motion. It deals with non-accelerating reference frames, and is concerned primarily with electric and magnetic phenomena and their propagation in space and time.

狭义相对论(1905)是从爱因斯坦认为光速在所有参照系中都相同，与参照系之间的相对运动无关这一点发展起来的。它处理的是非加速的参照系，主要关心的是电现象和磁现象以及它们在空间和时间中的传播。

属类：自然科学-物理-

An electric voltage applied to the superconductor causes all Cooper pairs to move, forming an electric current. When the voltage is removed, the current continues to flow because the pairs encounter no opposition.

给超导体加上电压，就会使柯柏对全部动起来，形成电流。电压去掉后，电流会无限期地流下去，因为柯柏对没有遇到任何阻碍。

属类：自然科学-物理-

Scattering : In physics, the change in direction of motion of a particle because of a collision with another particle.

散射:物理学中一个粒子与另一个粒子碰撞时运动方向发生改变的现象。

属类：自然科学-物理-

The collision can occur between two charged particles; it need not involve direct physical contact.

这一碰撞可发生在两个相斥的粒子之间，并不要求接触下产生的撞击。

属类：自然科学-物理-

Experiments show that the trajectory of the scattered particle is a hyperbola and that, as the bombarding particle is aimed more closely toward the scattering centre, the angle of deflection decreases.

实验证明，散落的粒子的轨道呈双曲线，而入射粒子越对准散射中心，偏转角就越大。

属类：自然科学-物理-

Sonar :Technique for detecting and determining the distance and direction of underwater objects by tracking acoustic echoes. Sound waves emitted by or reflected from an object are detected by sonar apparatus and analyzed for information.

声纳:利用声学方法侦测或测定水下物体的距离和方向的技术。声纳设备探测从目标发射或反射的声波，分析其中包含的讯息。

属类：自然科学-物理-

In active sonar a sound wave is generated that spreads outward and is reflected back by a target object. Passive systems consist simply of receiving sensors that pick up the noise produced by the target (such as a submarine or torpedo).

在有源声纳系统中，声发射装置发出的声波向外传播并被目标反射回来。无源声纳系统仅具有接收目标(如舰船、潜艇或水雷)所发噪音的接收传感器。

属类：自然科学-物理-

A third kind of sonar, used in communication systems, requires a projector and receiver at both ends. Sonar was first used to detect submarines in 1916. Modern nonmilitary uses include fish finding, depth sounding, mapping of the ocean floor, Doppler navigation , and searching for wrecks or other objects in the oceans.

第三类声纳设备是声通信系统，它在声道两端各有一个发射装置和接收装置。1916年首次用于探测潜艇。声纳的非军事用途包括鱼群寻找、深度探测、海底制图、都普勒领航、寻找失事船只的残骸等。

属类：自然科学-物理-

Hawking radiation:Radiation theoretically emitted from just outside the event horizon of a black hole.

霍金辐射:理论上，从一个黑洞的视界外放出的辐射。

属类：自然科学-物理-

Stephen W. Hawking proposed in 1974 that subatomic particle pairs (photons, neutrinos, and some massive particles)arising naturally near the event horizon may result in one particle’s escaping the vicinity of the black hole while the other particle, of negative energy, disappears into it.

1974年由霍金提出，他认为在视界附近会自然出现一些亚原子粒子对，可能是因黑洞附近的一个粒子逃逸，而另一个(负能量的)粒子被吸进去。

属类：自然科学-物理-

The flow of particles of negative energy into the black hole reduces its mass until it disappears completely in a final burst of radiation.

负能量的粒子流进入这个黑洞后，会减轻它的质量，直到黑洞发生最后的辐射大爆炸后才完全消失。

属类：自然科学-物理-

Spectroscopy : Branch of analysis devoted to identifying elements and compounds and elucidating atomic and molecular structure by measuring the radiant energy absorbed or emitted by a substance at characteristic wavelengths of the electromagnetic spectrum on excitation by an external energy source.

光谱学:一种分析技术，用于鉴别化学元素和化合物，测量物质在外部能源的激发下，吸收或发射电磁波谱中特征波长的辐射能量，从而阐明其原子和分子结构。

属类：自然科学-物理-

The instruments used are spectroscopes (for direct visual observation)or spectrographs (for recording spectra).

所用的仪器是分光镜(用于直接观察)和摄谱仪(用于记录光谱)。

属类：自然科学-物理-