本文文本摘自TED Radio Hour

TED Radio Hour为TED和npr联合播出的节目，围绕一个话题和TED Talks串在一起，并邀请TED演讲者一同讨论。

本文探讨的问题是，数学中的“X”。

建议先听后看文本再听。

GUY RAZ, HOST:But before we go any further trying to solve for X, a more basic question - what is X?

TERRY MOORE: X is the unknown.

RAZ: But why X? Why not another letter? Terry Moore wanted to find out.

MOORE: Yes, exactly.

RAZ: Terry directs an organization that promotes mathematics. And he told the story of why X is X on the TED stage.

(SOUNDBITE OF TED TALK)

MOORE: About six years ago, I decided that I would learn Arabic[阿拉伯语], which turns out to be a supremely[=extremely极其，极度地] logical language[逻辑型语言]. To write a word or a phrase or a sentence in Arabic is like crafting an equation[制作/写方程/等式] because every part is extremely precise and carries a lot of information. That's one of the reasons so much of what we've come to think of as Western science and mathematics and engineering was really worked out in the first few centuries of the Common Era[公元;公历纪元] by the Persians[波斯人] and the Arabs[阿拉伯人] and the Turks[土耳其人]. This includes the little system in Arabic called al-jabra. Al-jabra roughly translates to the system for reconciling disparate parts. Al-jabra finally came into English as algebra[数学;代数]. The Arabic texts containing this mathematical wisdom finally made their way to Europe - which is to say Spain - in the 11th and 12th century. And when they arrived, there was tremendous interest in translating this wisdom into a European language.

RAZ: Ok, so they start translating algebra from Arabic into Spanish. So what's the unknown in Arabic? What's the X?

MOORE: It was originally the word sheiun (ph), which means something.

RAZ: Something.

MOORE: Something - some undefined thing.

(SOUNDBITE OF TED TALK)

MOORE: The problem for the medieval[中世纪的;原始的] Spanish scholars who were tasked[(v.)to give someone a task 派给…任务] with translating this material is that the word sheiun can't be rendered into[译成(某种语言)] Spanish because Spanish doesn't have that S-H - that sh sound. So by convention[按照惯例], they created a rule in which they borrowed[to take and use a word or idea from another language or piece of work 引入,借用(词汇或想法）] the C-K sound - the cuh sound - from the classical Greek[希腊语] in the form of the letter Chi. Later, when this material was translated into a common European language - which is to say Latin - they simply replaced the Greek Chi with the Latin X. And once that happened, once this material was in Latin, it formed the basis for mathematics textbooks for almost 600 years. But now we have the answer to our question. Why is it that X is the unknown? X is the unknown because you can't say shh in Spanish.

(LAUGHTER)

MOORE: And I thought that was worth sharing.

(APPLAUSE)

RAZ: So this was kind of like a big misunderstanding, really. Like, it could've been Y. Or it could've been Q or B.

MOORE: It's certainly possible. And to some degree, it was arbitrary[任意的]. But the origin is that Arabic sheiun, which means something. Had they chosen a different word, we probably would be referring to the unknown quantity by some other letter[倒装].

RAZ: Yeah. What if X was B? Then everything would be B. We'd have like, the B-Men and Malcolm B[Malcolm X马尔科姆艾克斯(美国黑人领袖)] and B-marks-the-spot and the B-Files.

X-marks-the-spot

(idiomatic) You will find what you are looking for under an obvious sign for it.

This is the exact spot.

(Sometimes the speaker will draw an X in the spot while saying this.)

eg:This is where the rock struck my car—X marks the spot.

er: Now, please move that table over here. Yes, right here—X marks the spot.

MOORE: That's right. And Project B.

RAZ: That would ruin everything. Thank the gods it was the X.

MOORE: Well, we're used to that now.

RAZ: Do you like algebra?

MOORE: Yes, I love algebra.

RAZ: Why?

MOORE: Because it's beautiful.

RAZ: How, how? I keep hearing that. I hear mathematicians say it's beautiful. And then, you, like, see these movies about these crazy geniuses and they're scrawling[to write something quickly, without trying to make your writing tidy or easy to read 潦草地写；乱涂] on the chalkboards. It is kind of nice, actually. But I still don't get it.

MOORE: I think that's a matter of temperament[气质,性情,性格;质]. There're some people to whom a mathematical proof appears as a thing of beauty. It speaks of a higher truth. It speaks of a harmony to knowledge. The fact that it works at all - let alone[更不用说] that we can understand it - speaks to a larger category of existence and knowledge.

RAZ: Terry Moore - you can see his full talk - Why Is X The Unknown? - at ted.npr.org.

点击“阅读原文”查看文章来源