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  • There's a famous scene in the Lord of the Rings where the elf Legolas claims to be able

    魔戒裡有個出名的情景。 精靈勒苟拉斯聲清他

  • to count the exact number of horsemen 5 leagues away, and on top of that can tell that their

    能數五里格外騎兵的精確數量, 他更說騎兵的領袖

  • leader is very tall. But even with the most perfect eyes possible, would anyone be able

    很高大。但是就算有最好的眼睛, 有沒有人可以

  • to see that far?

    看到這麼遠?

  • When we see, we're looking at light that's traveled outwards from a light source, bounced

    當我們看東西,我們看到的是 光從光源走出來,在

  • off an object, passed through the lens in the eye, and been focused into an image on

    在物件上反彈,經過眼睛的 晶狀體,然後影像在

  • the retina. Except... light isn't a particle traveling in perfectly straight lines - it

    視網膜對焦。但是... 光不是一粒 在直線上移動的粒子 - 光

  • is a wave. And therein lies the problem, both for us, and for Legolas.

    是波形的,這就是問題所在,對我們 和勒苟拉斯都一樣。

  • Because any wave - whether water, sound or light - that travels through a small opening

    因為所有波浪都一樣 - 無論是 水,聲音,還是光 - 當經過一個小孔,

  • will become spread out by a process known as diffraction, which for light, essentially

    就會散開,這個現象叫 繞射,當光繞射,

  • blurs the image.

    就會模糊影像。

  • You can see this with a telephoto camera lens where the camera aperture has been made very

    你可以看到這個相機鏡頭 的光圈調節到很小

  • very small - small details in the photograph start to become spread out, blurred, and even

    照片中微小的細節開始 變得模糊,甚至

  • indistinguishable! Or, if you hold the edge of a piece of paper in front of your eye and

    不能辨別。或者,你把一 張紙的角放你眼睛前面,

  • try to read past it, small words will become blurry!

    嘗試閱讀一些文字, 微小的字會變得模糊!

  • The blur that a small point of light spreads out to become is called an Airy disk, and

    穿過一個孔然後散開 的光叫艾里斑,

  • the size of the Airy disk for distant tiny objects depends only on the wavelength of

    微小物體的艾里斑,大小 是根據光的波長

  • light in question and the size of the opening you're looking through. So for visible sunlight

    和它經過的孔的大小,所以, 如果是可見光和

  • and a human-sized pupil, diffraction limits us to at best be able to distinguish objects

    跟人一樣大小的瞳孔,繞射 限制我們只能辨別大過

  • that are bigger than seven one-thousandths of a degree, for example, an object one centimeter

    7千分之一度的東西, 例如一個1厘米大

  • in size a hundred meters away,. Another way of putting this is that everything 100m away

    和一百米的物體,就是 指一百米外和

  • and smaller than 1cm gets blurred so that it appears to be about 1cm in size, no matter

    小過一厘米的東西模糊 得像一厘米大,無論

  • how small it really is - subtle details smaller than 1cm blur away.

    那件東西是多麼小 - 小過一厘米 的細節就會變得模糊。

  • So when Legolas, who has very human-sized pupils, looked at the riders of Rohan 24 km

    當一位有跟人類相似的眼睛的 勒苟拉斯看到24公里外的洛汗騎兵,

  • away, diffraction tells us that everything smaller than 3 METERS would have been blurred

    繞射會使所有小過3米 的東西變得模糊像

  • to about three meters in size - perhaps he could still count the number of horsemen,

    大約3米大 - 他可能可以 點算出騎兵的數量,

  • but he definitely couldn't distinguish their heights to within a few centimeters...

    但他一定不可能分別出 他們相差幾厘米的高度...

  • Unless Legolas could see in ultraviolet. Shorter wavelength light diffracts less, so if he

    除非勒苟拉斯可以看到紫外光,波長較短的 光繞射情況較少,所以如果

  • could see in the extreme UV, then he'd be able to distinguish objects 10 cm in size,

    他能看到極端紫外光,他就 能分辨出10厘米的差別,

  • almost enough to discern the height of a man.

    差不多足夠出辨別人的高度。

  • Except that pretty much any kind of air absorbs extreme UV light - so even if he could see

    可是空氣裡面大部分的氣體吸收 極端紫外光 - 即使他能夠看到

  • UV, Legolas would have been left in the dark. Or maybe it's just... magic.

    紫外光,勒苟拉斯就會困在黑暗裡。 或者,他可能... 擁有魔法。

There's a famous scene in the Lord of the Rings where the elf Legolas claims to be able

魔戒裡有個出名的情景。 精靈勒苟拉斯聲清他

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B1 中級 中文 美國腔 模糊 波長 眼睛 看到 魔戒 精靈

魔戒的『精靈』到底能看多遠? (How Far Can Legolas See?)

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    大菲鴨阿 發佈於 2015 年 01 月 17 日
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