Day4 -5-6 SPACE AND TIME

NEW WORDS

1. (For example, the acceleration is twice as great if the force is

twice as great.) The acceleration is also smaller the greater the mass (or quantity of matter) of the body.

acceleration  

D: 1.the act of accelerating; increase of speed or velocity.

     2.a change in velocity. 

e,g,This leaves room for someaccelerationof the pace of withdrawals, an option the White House is reported to be considering.

velocity  /vəˈlɒsəti/

 D: 1. rapidity of motion or operation; swiftness; speed:

eg.a high wind velocity.

2.Mechanics.the time rate of change of position of a body in a specified direction.

3. the rate of speed with which something happens; rapidity of action or reaction.

eg.But Galston says what made the difference for Reagan was also the velocity of the change.

If the law were that the gravitational attraction of a star went down faster or increased more rapidly with distance, the orbits of the planets would not be elliptical, they would either spiral in to the sun or escape from the sun.

elliptical 

D: pertaining to or having the form of an ellipse.

eg. The same goes for theellipticalmachine hunger strike, which also comes off as tonally deficient, to say the least.

Nevertheless, Roemer’s achievement, in not only proving that light travels at a finite speed, but also in measuring that speed, was remarkable – coming as it did eleven years before Newton’s publication ofPrincipia Mathematica.A proper theory of the propagation of light didn’t come until 1865, when the British physicist James Clerk Maxwell succeeded in unifying the partial theories that up to then had been used to describe the forces of electricity and magnetism. Maxwell’s equations predicted that there could be wavelike disturbances in the combined electromagnetic field, and that these would travel at a fixed speed, like ripples on a pond.

equation

D: 1.the act ofequatingor making equal; equalization:

the symbolic equation of darkness with death.

2. equally balanced state; equilibrium.

3. Mathematics.an expression or a proposition, often algebraic, asserting the equality of two quantities.

4. Also calledchemical equation.Chemistry.a symbolic representation showing the kind and amount of the starting materials and products of a reaction.

eg. They provide the one real opportunity during a campaign for candidates to signficantly change theequationand move the numbers

electromagnetic

D. of or relating to electromagnetism or electromagnetic fields

Contemporary Examples

Theelectromagneticforce between the electrons lets you pick up the cup, counteracting gravity in the process.

实在不行了今天，未完待续

A proper theory of the propagation of light didn’t come until 1865, when the British physicist James Clerk Maxwell succeeded in unifying the partial theories that up to then had been used to describe the forces of electricity and magnetism.

propagation  noun

1.the act of propagating.

2.the fact of beingpropagated.

3.multiplication by natural reproduction.

4.transmission or dissemination.

propagate 

D: to spread (a report, doctrine, practice, etc.) from person to person; disseminate. 

EG. Anti-abortion organizations tend to tend to propagatethe idea that the procedure is dangerous and unproven.

He was stern but never oppressive – we knew abuse of power and would notpropagateit in our personal lives.

stern

adjective,sterner,sternest.

1.firm, strict, or uncompromising:

stern discipline.

2.hard, harsh, or severe:

a stern reprimand.

3.rigorous or austere; of an unpleasantly serious character:

stern times.

4.grim or forbidding in aspect:

a stern face.

Maxwell’s equations predicted that there could be wavelike disturbances in the combined electromagnetic field, and that these would travel at a fixed speed, like ripples on a pond. If the wavelength of these waves (the distance between one wave crest and the next) is a meter or more, they are what we now call radio waves. Shorter wavelengths are known as microwaves (a few centimeters) or infrared (more than a ten-thousandth of a centimeter). Visible light has a wavelength of between only forty and eighty millionths of a centimeter. Even shorter wavelengths are known as ultraviolet, X rays, and gamma rays.

disturbance  noun

Synonyms  perturbation, confusion. See agitation.5.confusion, tumult, riot.

1. the act ofdisturbing.

2. the state of beingdisturbed.

3. an instance of this; commotion.

4. something thatdisturbs.

5. an outbreak of disorder; a breach of public peace:

Political disturbances shook the city.

6. Meteorology.any cyclonic storm or low-pressure area, usually a small one.

7. Geology.a crustal movement of moderate intensity, somewhat restricted in area.

EG..And they are writing a tell-all story or causing some kind ofdisturbance, be it legal or whatever else to get attention.

The man was a member of the Los Angeles police force investigating adisturbanceat such-and-such and address.

one wave crest

noun

1. the highest part of a hill or mountain range; summit.

2. the head or top of anything.

3. a ridge or ridgelike formation.

4. the foamy top of a wave.

EG..His black hair sweeps back from thecrestof his high forehead and laps at the nape of his neck; his lips are pursed.

foam noun

1. a collection of minute bubbles formed on the surface of a liquid by agitation, fermentation, etc.:

foam on a glass of beer.

foamy adj

infrared

noun 

D: the part of the invisible spectrum that is contiguous to the red end of the visible spectrum and that comprises electromagnetic radiation of wavelengths from 800 nm to 1 mm.

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I

牛顿第一定律：the real effect of a force is always to change the speed of a body rather than just to set it moving, whenever a body is not acted on by any force, it will keep on moving in a straight line at the same speed. 力的真正效应总是改变物体的速度，而不是仅仅使之运动，只要一个物体没有收到外力，它就会以相同的速度保持直线运动。

牛顿第一运动定律，简称牛顿第一定律。又称惯性定律、惰性定律。常见的完整表述：任何物体都要保持匀速直线运动或静止状态，直到外力迫使它改变运动状态为止。

牛顿第二定律：the body will accelerate at a rate that is proportional to the force 物体被加速，其改变率与所受外力成正比。

牛顿第二运动定律的常见表述是：物体加速度的大小跟作用力成正比，跟物体的质量成反比，且与物体质量的倒数成正比；加速度的方向跟作用力的方向相同。

引力定律：every body attracts every other body with a force that is proportional to the mass of each body 任何两个物体都相互吸引，其引力大小与每个物体的质量成正比。

the farther apart the bodies, the smaller the force 物体之间的距离越远，则引力越小

牛顿的普适的万有引力定律表示如下：任意两个质点有通过连心线方向上的力相互吸引。该引力大小与它们质量的乘积成正比与它们距离的平方成反比，与两物体的化学组成和其间介质种类无关。

没有绝对的静止，静止是相对的概念，因而人们无法确认在不同时间发生的两个事件是否发生在空间的同一位置。

Generally, people think time was completely separate from and independent of space.

Although our apparently commonsense notions work well when dealing with things like apples, or planets that travel comparatively slowly, they don’t work at all for things moving at or near the speed of light.

通常人们认为时间相对于空间是完全分开并且独立的。经典力学中的其中一个假定是时间和空间是绝对的，长度和时间间隔的测量与观测者的运动无关，物质间相互作用的传递是瞬时到达的，由此可知，经典力学实际上只适用于与光速相比低速运动的情况。在高速运动情况下，时间和长度不能再认为与观测者的运动无关。

麦克斯韦方程预言

① there could be wavelike disturbances in the combined electromagnetic field, and that these would travel at a fixed speed, like ripples on a pond.在合并的磁场中可以存在波动的微扰，它们以固定的速度，如同池塘水面上的涟漪那样运动。

②radio or light waves should travel at a certain fixed speed 无线电波或光波应该以某一固定的速度运动。

既然摆脱了绝对静止的概念，也就是说固定的速度必须要有一个参照物才能测量出来，声波在空气中传播，所以人们认为光在真空中应该也是通过一种物体传播，将之命名为以太。但迈克尔逊－莫雷实验否定了以太的存在。爱因斯坦提出抛开绝对时间观念的话，整个以太的观念则是多余的。

the laws of science should be the same for all freely moving observers, no matter what their speed.

相对论的基本假设：不管观察者以任何速度做自由运动，相对于他们而言，科学定律都应该是一样的。将这个观念扩展到马克斯韦理论和光速中，即为不管观察者运动多快，他们测量出的光速应该都是一样的。

As an object approaches the speed of light, its mass rises ever more quickly, so it takes more and more energy to speed it up further. It can in fact never reach the speed of light, because by then its mass would have become infinite, and by the equivalence of mass and energy, it would have taken an infinite amount of energy to get it there. For this reason, any normal object is forever confined by relativity to move at speeds slower than the speed of light.

当一个物体接近光速的时候，它的质量上升的越来越快，所以需要越来越多的能量才能进一步加速。事实上，它永远都不可能达到光速，因为那时候质量会变成无限大，根据质量能量等价原理，所需要的能量也就无限大。所以相对论限制任何正常物体永远以低于光速的速度运动。

speed= distance/time

在牛顿理论中，时间是绝对的，空间不是绝对的（time is absolute,space is not absolute）, 所以不同的观察者就会测量出不同的光速，所以相对论终结了（put an end to）绝对时间的概念（absolute time）。

Each observer could use radar to say where and when an event took place by sending out a pulse of light or radio waves.

准确测量距离的方法，记录发出脉冲和接受脉冲之间的时间t，所要测定的对象的距离为 t/2 乘以光速。

The theory of relativity does, however, force us to change fundamentally our ideas of space and time. We must accept that time is not completely separate from and independent of space, but is combined with it to form an object called space-time

相对论使我们从根本上改变了对时间和空间的观念：时间不能完全脱离和独立于空间，而必须和空间结合在一起形成所谓的时空。