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"Even an optimist like Frank Drake estimates that there would be no more than about in the galaxy, which means that the nearest one is likely to be about 1,000 light years away."
VOA: standard.2010.04.16
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So, we'll take a little bit of a step back after we introduce quantum mechanics, and talk about light as a wave, and the characteristic of waves, and then light as a particle. And one example of this is in the photoelectric effect.
等我们介绍完量子力学后,我们要回过头来讨论下光,作为一种波和它的波动性特征,以及光作为一种粒子,其中的一个粒子就是光电效应。
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And what's interesting about this sun is it has a ray of light coming out of the top.
这幅画的有趣之处在于红日的光线从画面的顶端射了出来。
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You were speaking about light in the end of the table this going to be this going to be the end of the tunnel.
你刚才讲到胜利的曙光,这一切会结束的。
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I mean, there is an emptying out of positive meaning in the very awareness that, after all, the red light could mean "go" I'm about to go on and give more examples.
这就事我们不能主动赋予符号意义,但是是要认识到，红灯也有表示，出发，的意思“,我会用更多例子来说明它。
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And the relationship that he put forth is that the momentum is equal to Planck's constant times nu divided by the speed of light, or it's often more useful for us to think about it in terms of wavelength.
爱因斯坦提出的关系式是,动量等于普朗克常数,乘以υ除以光速，或者用波长来表示,通常更容易让我们想明白。
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You get 2.18 times 10 to the plus 6 meters per second, 1% which is about 1% of the value of the speed of light.
。18*10^6米每秒，得到的速度大概是光速的。
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Suppose, for example, that, the right way to live, in light of the facts about death, is to live life to the fullest.
假设，例如，生活的正确的方式，鉴于关于死亡的事实，是尽情地活。
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He is the intellectual who enjoys bringing, you might say, the harsh and unremitting facts about human nature to light, who enjoys dispelling illusions and pretty beliefs.
他是一位学者，乐于将人性残酷、,不得宽恕的真实面,摊在阳光下来检视，他更乐于为人破解假想及天真的信念。
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So, for example, we were talking about a threshold frequency as in a minimum frequency of light that you need in order to eject an electron from a metal surface.
举个例子来说，我们谈论的临界频率是,光从金属表面逐出一个电子,所需的最小频率。
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It's no use talking about the negative relationship between a red light and a green light and a yellow, white, or blue one because they all have the same value.
讲什么它是红灯，不是绿灯,不是黄灯白灯一点关系都没有,它们所代表的意义都一样。
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It makes me feel even worse that everybody else is stuck dying-- or perhaps we should say dying too soon in light of our discussion about immortality.
所有人都为死而苦恼让我感到更糟糕-,或者我们应该说,按照我们对永生的讨论，是死得太早。
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And sometimes it's a matter of factors that you need to figure out what it is, and maybe it's that there's extra light in the room we don't know about.
而且有时候它是,需要计算的一个因素，有时候这个房间里可能有,我们未知的额外的光。
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And we'll also talk about photon momentum as another example of light behaving up as a particle.
并且我们也会讨论光子动量的问题,这个可以作为光有粒子行为的例子。
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Alright. So, since we have these terms defined, we know the frequency and the wavelength, it turns out we can also think about the speed of the wave, and specifically of a light wave, and speed and is just equal to the distance that's traveled divided by the time the elapsed.
好了，我们已经定义了，这些术语，我们知道了，频率和波长，现在可以来考虑,波的速度了，特别是光波的速度，速度等于它走过的距离,除以所用的时间，因为我们。
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How should we live, in light of the facts about death?
我们该如何活着，鉴于这些关于死亡的事实？
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Now in a stoplight, it only has three, one is tempted to say, variables plainly differing from each other: red, yellow and green we have two ways of thinking about the red light.
交通灯，三种灯，红黄绿，它们的颜色和彼此不能,我们有两种方式认识红灯的意思。
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And Einstein credited de Broglie, which is a fair statement of lifting a corner of the great veil, because really there was this fundamental misunderstanding about what the difference was between matter and light, and the reality is that they can both be like-particles and they can both show characteristics of waves.
并且爱因斯坦相信德布罗意，他做了一个公正的论述,揭开了一个伟大面纱的一角，因为关于物质和光,以前确实存在着,根本性的误解，真实情况是它们同时,具有粒子和波的特性。
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How should one live, in light of the facts about death ? that I've been laying out in the semester up to this point?
一个人应该怎样活着，鉴于我这个学期一直讲到这刻的,关于死亡的事实？
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For example, if we talk about photons, of course, we also just mean light, sometimes we refer to this as electromagnetic radiation, and there's several ways that you might be asked this in a problem or that you might be asked to answer.
举例来说，如果我们讨论光子，当然我们也叫做光，有时候我们看作是电磁辐射，而且这里有几种方式,你可能会在题目中被问到,或者被提问回答。
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So that's the important take-away message from this slide. If we think about these different types of lights, microwave light, if it's absorbed by a molecule, is a sufficient amount of frequency and energy to get those molecules to rotate. That, of course, generates heat, so that's how your microwaves work.
重要的信息，如果我们看看,这些不同种类的光，微波,如果被分子吸收，它的频率和能量可以,使分子转动,这当然的，会产生热量,这就是你们微波炉的工作原理。
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And this is a very fast speed, of course, it's about 700 million miles per hour. So, one way to put that in perspective is to think about how long it takes for a light beam to get from earth to the moon. Does anyone have any guesses? Eight seconds, that sounds good.
当然这是一个非常快的速度，它大约是每小时7亿英里,为了更形象化，我们,看看光从地球到月球,需要多少时间，你们猜猜是多少？,8秒，猜的不错。
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So we talked about what we could see with visible light, we said that's actually the Balmer series.
我们已经说过可见光，它是Balmer系。
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He might be a scientist and know all sorts of things about how light works.
他可能是个科学家,通晓光的原理
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So, now we can talk about it in different terms, Ei for example, talking about e sub i, which is the incident energy or the energy of the light that comes in, or talking about work function here, and that's just another way to say threshold energy.
现在我们可以从不同的方面,来谈论它了，举例来说，它是入射能量或者进来的光的能量,或者谈论这里的功函数，它是另一种描述临界能量的方式。
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And the myth has to do with these sort of pictures I was just describing where we don't actually live on the surface of the Earth of in the light, but rather live in certain hollows in the dark where we're mistaken about the nature of reality.
那个传说与我一直形容的,这个大局有关,我们并不真正生活在地表,生活在阳光里,而是生活在某种暗无天日的黑洞中,一个我们都误解了现实本质的地方
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We can plug this in further when we're talking about the visible part of the light spectrum, because we know that for n final equals 2, then that would mean we plug in 2 squared here, so what we get is 1 over 4.
当我们讨论可见光谱的时候,我们可以把这个代进去,因为我们知道n末是等于2的,这意味着我们可以。
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