关于“光” 你不知道的17件事

1.God commanded, “Let there be light,” but it didn’t happen for nearly half a million years. That’s how long after the Big Bang the universe took to expand enough to allow photons (light particles) to travel freely.

神说：“要有光。”但是光直到50万年之后才出现——大爆炸之后50万年，宇宙终于膨胀到足够大，可以让光子在其中自由穿行。

2.Those photons are still running loose, detectable as the cosmic microwave background, a microwave glow from all parts of the sky.

这时光子的运动仍然是无规则的，以宇宙背景辐射的形式存在——就是从宇宙的各个部分发出的微波。

3.Light moves along at full “light speed”—186,282.4 miles per second—only in a vacuum. In the dense matrix of a diamond, it slows to just 77,500 miles per second.

光只有在真空中才以“光速”，即186,282.4英里/秒（299,792,458米/秒）运动，在钻石这样的高密度物质中，光速会下降到77,500英里/秒（124,724,160米/秒）。

4.Diamonds are the Afghan­istan of gemstones: Any entering photon quickly gets bogged down. It takes a lot of pinging back and forth in a thicket of carbon atoms to find an exit. This action is what gives diamonds their dazzling sparkle.

钻石是宝石中的阿富汗：任何进入其中的光子都会被迫放慢速度。光子要在错综复杂的碳原子间反复冲撞才能找到出路。而这就是钻石闪耀着令人眩目的光辉的原因。

5.Eyeglasses can correct vision because light changes speed when it passes from air to a glass or plastic lens; this causes the rays to bend.

眼镜可以校正视力是因为光从空气射入玻璃或塑料的镜片时速度会改变，于是光线就发生了弯折。

6.Plato fancied that we see by shooting light rays from our eyes.

柏拉图认为，我们之所以看得见，是因为我们的眼睛会发射光线。

7.The Greek philosopher was not completely wrong. Like all living things, humans are bio­luminescent: We glow. We are brightest during the afternoon, around our lips and cheeks. The cause may be chemical reactions involving molecular fragments known as free radicals.

古希腊哲学家的看法并非完全错误。人类和所有其他生物一样，都有着“生物发光现象”，也就是说人体确实会发光。我们在下午最明亮，最明亮的部位则是嘴唇和脸颊。这一现象的原因可能是名为“自由基”的分子片段参与化学反应造成的。

8.Bioluminescence is the largest source of light in the oceans; 90 percent of all creatures who live below about 1,500 feet are luminous.

生物发光是海洋中的最大光源：生活在距海平面1500英尺以下的生物有90%都会发光。

9.World War II aviators used to spot ships by the bio­luminescence in their wakes.

二战中的飞行员曾通过船只尾流中的生物发光现象来定位船只。

10.Incandescent bulbs convert only 10 percent of the energy they draw into light, which is why Europe will outlaw them by 2017. Most of the electricity turns into unwanted heat.

白炽灯只能将通过自身的电能的10%转化为光能，而大部分电能都转化成热能浪费掉了。因此欧洲将在2017年禁用白炽灯。

11.In the confined space of an Easy-Bake oven, a 100-watt bulb can create a temperature of 325 degrees Fahrenheit.

在一个封闭空间——比如Easy-Bake玩具烤炉里，一个100瓦的白炽灯泡可以达到华氏325度（约163摄氏度）的高温。

12.Visible light makes up less than one ten-billionth of the electromagnetic spectrum, which stretches from radio waves to gamma rays.

在覆盖了从无线电波到伽马射线的电磁光谱中，可见光只占不到百亿分之一的比例。

13.Goldfish can see infrared radiation that is invisible to us. Bees, birds, and lizards have eyes that pick up ultraviolet.

金鱼可以看见我们看不见的红外线。蜜蜂，鸟类和蜥蜴则有着可以看见紫外线的眼睛。

14.Photography means “writing with light.” English astronomer John Herschel, whose father discovered infrared, coined the term.

摄影其实就是“用光来书写”。这个说法是英国宇航员John Herschel（他的父亲发现了红外线）创造的。

15.Shoot now: The “golden hour,” just after sunrise and before sunset, produces the prettiest shadows and colors for photographs.

摄影的“黄金时间”是日落后和日出前的短暂时间，此时能拍出光影和色彩都堪称完美的照片。

16.Auroras light up the night sky when solar wind particles excite atoms in the upper atmosphere. Oxygen mostly shines green; nitrogen contributes blue and red.

当太阳风激发了高层大气中的原子，就会产生极光。氧气产生的极光多半是绿色的，氮气这是蓝色和红色。

17.But to the Inuits, auroras are spirits of the dead kicking around the head of a walrus.

17.但是对于居住在北极地区的因纽特人来说，极光是死者的灵魂在把海象头当球踢……