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EXPLORING PHYSICS ON YOUR OWN
Young’s Experiment:
Put two pinholes (about the size of a period) one diameter apart in an opaque piece of paper. Hold it very close to your eye and look through them at a distant streetlamp at night. The characteristic parallel fringe pattern will appear on your retina. Rotate the card and the fringe pattern will rotate with it——that’s a good way to check that you’re not hallucinating. Use a razor to cut two slits very close together in a 3×5 index card, or better yet, paint a microscope slide black and scratch two parallel lines through the paint. Put either pair(held vertically) close to your eye and look through them at an ordinary vertical straight-filament display bulb; you’ll see a wonderful fringe pattern.
杨氏实验：
在一张不透明的纸板上打上两个相距它自身一个直径的小孔（大约一个英文句号的大小）。将小孔非常近地靠近你的眼睛，并在晚上通过他们观察远处的路灯。特征性的平行条纹将会出现在你的视网膜上。旋转纸板，条纹将随之转动——这是一个确定你看见的不是幻觉的很好的方法。用一把剃刀在一张3 × 5大小的索引卡上划出两道非常接近的缝隙，或者更好的，将一片载玻片涂黑并在上面划出两条平行线。将其中的任意一对（互相垂直放置）靠近你的眼睛并通过它们来观察一个普通的立式直灯丝灯泡，你会看到一幅美妙的条纹图案。
Diffraction & Seeing You Eye from the Inside
Anyone who has ever walked at night in the rain wearing eyeglasses has probably seen the effect of diffraction. Just put a drop of water on a glass plate, hold it near your eye, and look through it at a distant streetlight,and you’ll see a complex system of bright and dark diffraction fringes. Similarly , the amoeba-like floaters that can be seen within your own eye when you squint at a bright broad source are diffraction patterns of drifting cellular debris cast on your retina. Close on eye and the squint as tight as you can at a light bulb (or the sky, or a computer screen close up) until you see the shadow of your lashes. Relax your focus and you’ll see floaters. The circular dark boundaries on the right and left are the outlines of your own pupil. Cover that eye with a hand, wait a few seconds for your pupil to dilate, and then pull your hand away——what happens to the outline?
衍射&从内部看你的眼睛
任何一个曾经戴着眼镜行走在雨夜中的人都有可能看到过衍射效应。只要将一滴水滴在镜片上，把它靠近你的眼睛，通过它观察一个远处的路灯，你就会看到一个明暗夹杂的复杂的衍射条纹图案。相似地，当你斜视一个明亮的面光源时，你会看到漂浮在你视网膜上的细胞碎片形成类似阿米巴变形虫的衍射图样。闭上一只眼睛，紧紧地斜视一个灯泡（或天空，或一个非常靠近的计算机屏幕）直到你看见你睫毛的影子。放松你的眼睛，你会看到漂浮物。左右两边环状的较暗边界是你瞳孔的轮廓。用手盖住一只眼睛，稍等几秒你的瞳孔会放大，然后将你的手移开——轮廓会发生什么变化呢？
Discussion Questions
问题讨论
1. Put a few drops of liquid soap in a cup with a little water and shake it around, making a great froth of bubbles. After several seconds, the bubbles will begin to show bright rainbow color patterns. Why must you wait before the colors appear?
1、向一杯加有少量水的杯子里滴几滴液体肥皂并使劲摇晃，使它产生泡沫。几秒钟后，泡沫将开始呈现出明亮的彩虹式图案。为什么颜色出现前你要等上一会儿？
2.Take a very close look at a worn surface under direct sunlight. A fingernail, an old coin, or the roof of an old car will all show a very fine granular pattern of tiny colored dots. This phenomenon is the so-called speckle effect. What might be its cause? Notice how it seems to move as you slowly move your head parallel to the surface.
2、在阳光直射下仔细地观察一个磨损的表面。可以是指甲、旧硬币、或旧汽车车顶，它们将显示出微小的彩色颗粒状斑点。这种现象就是所谓的散斑效应。什么可能是它产生的原因？请注意当你慢慢地平行于表面移动你的头的时候斑点是如何移动的。
3.Fog up a piece of glass with your breath and look through the fogged plate in a darkened room at a white-light point source. You will see a system of concentric colored rings. Of what does this remind you, and what do you think is causing the effect?
3、哈气使一片玻璃蒙上一层水雾，并在一个暗间里通过它来观察一个白色点光源。你将看到一个由彩色同心环组成的图像。它能给你什么提醒，而你认为是什么造成了这个现象？
4.Light a long-filament vertical light bulb. If you look at it from several meters away through a vertical slit cut in a 3×5 card, you will see a lovely fringe system. Explain what happening.
4.打开一盏立式长灯丝电灯。如果你在数米以外通过一条划在3 × 5索引卡上的竖直细缝观察它，你会看到一个可爱的图像系统。请解释发生的现象。
（选自Eugene Hecht 著 Physics:Calculus(second edition)英文版。本人英语水平有限，如有翻译错误，请指正，谢谢。）
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狗仔卡
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