Name: Testing the limits of human vision
Uploaded: 2018-06-20T08:38:49.000Z
Duration: 5 min 34 s

- [William] You have seen this eye chart before.

It's at the DMV, it's at the optometrist,

是在車管所，是在驗光師那裡。

it's in doctor's offices all over the place.

它是在醫生的辦公室 所有的地方。

You probably know that font as the eye chart font.

你可能知道那個字體是眼圖字體。

而且，你肯定知道那個巨大的E。

This thing is a dead simple tool for testing eyesight

這東西是測試視力的簡單工具。

and it's helped millions of people see better.

- But, as simple as it is, there's some very precise math

- 但是，雖然簡單，但也有一些非常精確的數學知識

It doesn't just tell you if you need glasses,

它不只是告訴你是否需要眼鏡。

it tells you something about the fundamental limits

- And, we wanted to put that math to the test

- 而且，我們想把這個數學的測試。

The eye chart we all know and love was created back

我們所熟知和喜愛的眼形圖，早在上世紀90年代就被創造出來了。

in 1862 by a Dutch ophthalmologist named Herman Snellen.

1862年，由一位名叫赫爾曼-斯奈倫的荷蘭眼科醫生。

His early prototypes used abstract shapes,

他的早期原型使用了抽象的形狀。

And the designed hasn't changed much since then.

The chart is designed to measure one very particular aspect

該圖表的設計是為了衡量一個非常特殊的方面

或者說我們能夠看到非常精細的細節。

It's basically the resolution of the eye.

Now here resolution isn't measured in pixels,

現在這裡的分辨率不是以像素來衡量的。

it's measured in degrees, like of an angle.

它是以度來衡量的，就像一個角度。

- [Rachel] Say you're looking at two lights shining

- 假設你看到的是兩盞燈在閃耀

at you from a distance, you can tell them apart

because the light from each source is traveling

through your eye and hitting a different set

of light sensitive sells, called photoreceptors.

的光敏感賣點，稱為光感受器。

Especially because, as the light travels through the eye,

特別是因為，當光線穿過眼睛時。

Eventually, the two lights will blend together

and your brain will start to interpret them as one.

你的大腦會開始把它們解釋為一個整體。

That angle, between the two paths of light right

那個角度，在兩條光路之間的權利。

as you lose the ability to pick them apart,

因為你失去了把它們挑開的能力。

對於健康的成年人來說，它的規模

of just 1/60 of a degree, also known as one arcminute.

它是建立在一個五乘五的網格上。

so that's the black lines and white spaces

are all the same width, about a 16th of an inch.

都是一樣的寬度，大約16英寸。

If you stand 20 feet away and look at that little E,

如果你站在20英尺外，看著那個小E。

If you can read most of the letters in that row

如果你能讀懂這一行的大部分字母的話

Meaning, at 20 feet, the patterns of white and black

意思是說，在20英尺處，白色和黑色的花紋

are just at the limit of your eye's resolving power.

只是在你眼睛的解析力的極限。

Now, you might be able to read a row or two beneath 20/20,

現在，你也許能讀懂20/20下面的一兩行字。

In fact, 20/20 was never defined as perfect or even average,

事實上，20/20從來沒有被定義為完美甚至是平均。

it's just a baseline to measure everything against.

也就是說，如果你有20/20的敏銳度。

you'd have to walk forward five feet to see it clearly.

在敏銳度上從一個人到另一個人。

Partly, because we have similar densities

Compare that with other animals like eagles,

which have a very different optical setup than we do,

它有一個非常不同的光學設置與我們做。

他們的眼睛是經過優化的相機傳感器

- 不管你的分辨率極限是多少。

you can use it to calculate your own acuity

你可以用它來計算你自己的敏銳度。

Based on the Snellen chart, Rachel's acuity

根據Snellen圖表，Rachel的敏銳度為：

her maximum resolution just under one arcminute.

她的最大分辨率只有不到一弧分。

of this window right here, and we're gonna

這個窗口的權利在這裡，而我們要去

go out there and show you some very large E's,

去那裡給你看一些非常大的E的。

and all you have to do is tell us if you can identify the E.

而你要做的就是告訴我們，如果你能識別E。

than one arcminute, she should comfortable see an E

比一弧分，她應該舒適地看到一個E。

and you tell me if it's facing the right way,

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Testing the limits of human vision

eventually

ridiculous

aspect

slightly