Space and Time(second chapter )
Day. 4
Vocabulary
1，at rest.
①(technical )not moving
Eg. At rest the insect looks like a deaf leaf.
②dead and therefore free from trouble or anxiety, people say "at rest "to aviod say"dead "
Eg He now lies at rest in the churchyard.
2,equivalent.
①(Of /to sth )a thing, amount, word, etc. That is equivalent to sth else
Eg. Send $200 or the equivalent in your own currency.
②(To sth )equal in value, amount, meaning, importance, etc.
Eg. Eight kilometers is roughly equivalent to five miles.
3,slope,
①the amount by which sth slopes
Eg. A gentle /steep slope
②to go somewhere quietly, especially in order to aviod sth /sb
Eg. They got bored waiting for hin and sloped off.
4,ellitical.
①With a word or words left out of a sentence deliberately.
Eg .an elliptical remark.
②(geometry )connected with or in the form of an ellipse.
Eg. There are some objects which is elliptical.
5.spiral
①a shape or design, consisting of a continuous curved line that winds around a central point, with which curve further away from the centre.
Eg. The birds circled in a slow spiral above the house.
②a continuous harmful increase or decrease in sth,that gradually gets faster and faster.
Eg. The destructive spiral of violence in the inner.
6.rotation
①the action of an object moving in a circle around a central fixed point.
Eg. The daily rotation of the earth on its axis.
②once complete movement in a circle around a fixed point
Eg. The switch controls the number of rotation per minute.
③the act of regularly changing the thing that is being used in a particular situation, or of changing the person who does a particular job
Eg. The committee is chaired by all the members in rotation.
7,echo
①the reflecting of sound off a wall or inside a confined space so that a noise appears to be repeated ；a sound that is reflected back in this way
Eg. There was an echo on the line and I couldn 't hear clearly.
②the fact of an idea, event, etc. Being like another and reminding you of it; sth that reminds you of sth else.
Eg. Yesterday 's crash has grim echoes of previous disasters.
③an opinion or attitude that agrees with or repeats one already expressed or thought
Eg. His words were an echo of what she had heard many times before.
④torepeat what sb else has just said, especially because you find it surprising
Eg." He's gone! "Viv echoed.
8.ether
①ether is a colourless liquid that burns easily. It is used in industry and in medicine as an anaesthetic.
Eg. A sweetish smell of ether and iodine.
②The air sometimes referred to as the ether, usually when talking about sounds being communicate or broadcast through it.
Her words disappeared into the ether.
9,Finite
①having a definite limit or fixed size
Eg. A finite number of possibilities
10.postulate
①to suggest or accept that sth is truw so that it can be used as the basis for a theory, etc.
Eg. They postulated a 500-year lifespan for a plastic container.
11.propagate
①ifpeoplepropagate an idea or piece of information, they spread it and try to make people believe it or support it.
Eg. They propagated political doctrines which promised to tear apart the fabric of British society.
②if you propagate plants, you grow more of them from the original ones
Eg. The easiest way to propagate a vine is to take hardwood cuttings.
12,comparatively
13,irrational
14,ripple
15,infrared
16,hitherto
17,cone
18,ionics
19,notion
20,emit
Day. 5
先科普一下:
下文的文字是节选自Space and Time 的一部分.
data back to ，追溯，从…开始，
spread out伸展，延长，分散，
There are some sentence I like:
Only events in the future of P can be affected by what happens at P because nothing can travel faster than light.
Only then would events on earth lie in the future light cone of the event at which the sun went out.
Thus, when we look at the universe, we are seeing it was in the past.
Compared with Annie's, I found there are some details I should notice. Firstly,I lost some points about this essay. secondly, I haven't refined the article. Last but not least, from the misunderstanding of some sentence, I can't totally assimilate this article.
Add note.& Annie FM
①霍金只是演示了某人如何测量某事件发生的时间以及离开他的距离。每个惯性系都有自己的space-time比如火车上的乘客和站台上的人 如果火车上的人往桌上扔乒乓球并且弹回手中 他认为的小球轨迹是直上直下 站台上人看小球就不是，会认为小球运动的距离更长这就是space的不同 如果把小球换成光子，运动速度为光速，对于两人来说光子运动距离不同，速度一样，那么所花的时间也不一样；就是说同一个事件对于不同人的time不同[图片] A: 对，这里霍金的思维有点跳跃，突然提到利用光速和时间差来测量距离，这当然也可能是一个对时间空间维度等价的展示。凡是空间上的距离都可以转化为时间的距离。（但是反过来就不好操作了，像我们昨晚讨论的一样。回到过去就无法用改变空间距离来实行）你这个解释很好，也就是我昨天挣扎着试图解释的时间膨胀概念，我总想彻底抛弃经典物理学角度但是忘了惯性坐标系还是成立的只是时间测量上不再是绝对的了。这个小球其实就是原子钟里面的脉冲波，每一秒大概是9亿个脉冲的样子，每个脉冲都在近光速经过的观察者看来经过了比在钟旁边的人看到的更长的距离，所以钟对于这个飞船上的观察者来说自然就走的更慢。有关那个乒乓球的例子，如果你不仔细看，还以为这是完全会被相对论推翻的，这也是我自己昨天迷惑了很久的例子，因为爱因斯坦自己的文章里都说这个例子不再适用于光速运动坐标系了。但这里的不适用是指速度不能因为相对运动而叠加，但是距离还是可以的。如果你以光速离开地球，地球上的光速并不是双倍，这个叠加是无效的。但是你以光速离开地球，地球上的光速（原子钟里的脉冲譬如说）在你看来是经过了更长的距离，于是就经过了更长的时间（速度恒定）
② Q:What happens at suchevents can neither affect nor be affected by what happens at P.这句话怎么理解呢A:这些事件（包括它们的时空坐标）无法影响P点发生的事，也无法被其影响
③Q: stub one's toe on the stone是什么意思呢A:Stub是断了的意思，就是说踢石头却反伤了自己的脚趾，形容那种愤恨的心情
④Q: For instance,one can say that a point in a room isseven feet from one wall, three feet from another, and five feet above thefloor请问这个到底指什么呢A:长宽高是三维物体的描述方面，三个。这里是指离一面墙7英尺，距另一面3，高于地面5。而精确定义是点的坐标向量是三，那么就是三维空间
⑤ Q: if a pulse of light is sent from one place toanother，differentobservers would agree on the time that the journey took，but will not always agreeon how far the light traveled.这句话怎么理解呢？如果距离不一样，时间为什么会一样呢？A:经典物理学依据默认概念是绝对时间，也就是时间的长度对任何状态下的观察者都是一样的，这是牛顿体系下的科学家的默认前提，而运动距离是相对的，譬如5小时内火车上一个人对旁边的人来说运动距离是0，然而地面上的人觉得这个人运动距离是300英里。然后速度就是相对的。再把观察对象这个人换成光线，就是新物理学相对论范围里的事儿了，用经典力学的思维来看就会得出光速相对于观察者速度这样的结论来，然而已经被实验证伪了（就是那个Edward Morley实验）
⑥ Q: The bigdifference between the ideas of Aristotle and those of Galileo and Newton isthat Aristotle believed in a preferred state of rest, which any body would takeup if it were not driven by some force Or impulse这里面的preferred state of rest和take up怎么理解好呀，好像有点懂但是又说不清楚A:preferredstate of rest,最倾向的状态。Take up采取，物体在没有外力作用下总是倾向于采取静止状态
⑦Q:怎么理解时间是相对的呢A:如果我无法和你实时对手表，那我和你的时间就不是一回事，Eg:如果我想祝你20岁生日快乐，却在你22岁时才收到了谢谢,这样子是夸大，但是这么说换个参考的标准光速也就不那么快了，导致宇宙没有了绝对时间这个概念
⑧Q:我们所接受的光，是已经过去的时间吗A:是太阳的过去，世界上最远的距离就是我说我爱你太阳的同时，他说我爱你地球，然而它八年前就说了，于是我充满幸福感的等了八年，等到了一片黑暗，原来太阳八年前熄灭了。Hhh科学文艺的爱情爱因斯坦说，我们是无法飞回过去的，就算逆着飞，飞到的也是别的星球的过去而非自己星球的。虽说时间的距离和空间的距离是等价，但是空间的距离可以逆转，时间的距离似乎不行，在同一个地点，时间轴的移动是单向的
Q:那就是说我们永远无法回到过去吗A:是啊，但是有可能你飞到别的星球，看到唐朝的光线投射到几百光年外的一个星球上的片段，海市蜃楼一样，你看到了过去的事件、任务，但是却无法改变历史，因为处在不同的时空中。时间上只能往前
Q:时间轴空间轴等价怎么理解呢？A：我觉得所谓时间轴和空间轴等价就是说，空间距离就意味着时间距离。所谓的我在这里你在这里我们同心合意那都是对上帝而言有可能是真实，但是对需要光线来判断时间进展的人类，是无意义的。如果光速无限大，那我们就有绝对时间啦，北斗星上发生的事瞬时就可以收到了......但是光速无限大的情况就是光能无限大，那么从太阳逃逸出来的光线可能太多了，人类就会被热死了，所以有很多假设听上去很安全，实际上不符合物理世界的现存规律
Day 7
Through the essay, I learned a lot about Space and Time. I spent about 7hours to finish the Mind map of it,there are much concepts that I can't understand in the short time.Once I know what it said,I found it so intersting to read it .The history of Newtown 's law, Relativity and the debate of absolute time and position ...
In fact, It sacred me when I saw the total pages of 101,then I know the real length of the passage. During this period, I felt tired but enjoyed. Igave up the retell class, cuz I haven't enough time to learn two class. Carefully reading needs lots of time, I am trying to balancing my major and reading.
Reading is a meaningful thing, ,I am so gald to have this opportunity to attend this class. It broaden my horizon, and it also train my logical thinking.
modified logical picture
