Why is 'x' the unknown? | Terry Moore

Summary

The script explores the origin of the letter 'X' representing the unknown in mathematics and popular culture. It traces back to the Arabic language and its mathematical texts, which were translated into European languages during the 11th and 12th centuries. The Arabic word 'shayun', meaning 'something' or 'unknown thing', was transliterated as 'al-shayun' with the definite article 'al'. Due to the absence of the 'sh' sound in Spanish, medieval scholars used the Greek letter 'Kai' (CK sound), which later became 'X' in Latin translations, influencing mathematical texts for centuries.

Takeaways

• 🔠 The letter 'X' is commonly used to represent the unknown in various fields due to historical linguistic reasons.
• 🌐 The origin of using 'X' for the unknown can be traced back to the Arabic language and its mathematical texts.
• 📚 Arabic was a significant contributor to early Western science, including the development of algebra, which is derived from 'al-jebr'.
• 📖 The Arabic mathematical texts were translated into European languages in the 11th and 12th centuries, leading to the adoption of certain conventions.
• 🗣️ The Arabic letter 'sheen', which sounds like 'sh', was challenging for European languages to pronounce and represent.
• 📝 The word 'shayun' in Arabic, meaning 'something' or an undefined thing, was a term used in early mathematical works.
• 🔄 Medieval Spanish scholars, tasked with translating Arabic texts, used the 'ck' sound from Greek to represent the 'sh' sound, which was not present in Spanish.
• 🔄 The Greek letter 'Kai' was used to represent the 'ck' sound, and later, when translating into Latin, it was replaced with 'X'.
• 📘 Once in Latin, these mathematical works formed the basis for European mathematics textbooks for centuries.
• 😀 The humorous conclusion is that 'X' represents the unknown because the 'sh' sound couldn't be pronounced in Spanish, leading to its adoption in mathematical and cultural contexts.

Q & A

Why is the letter 'X' commonly used to represent the unknown in various contexts?

The letter 'X' represents the unknown because it originated from the Arabic word 'shayun', which means 'something' or an undefined thing, and was used in early mathematical texts. The term was transliterated into European languages and eventually became associated with the unknown in mathematics and other fields.

What is the significance of the Arabic language in the development of Western science and mathematics?

Arabic played a significant role in the development of Western science, mathematics, and engineering, particularly during the first few centuries of the Common Era. Scholars from Persia, Arabia, and Turkey contributed greatly to these fields, including the development of algebra, which is derived from the Arabic word 'al-jebr'.

What does the Arabic word 'al-jebr' mean, and how did it influence European mathematics?

The Arabic word 'al-jebr' means 'the system for reconciling disparate parts'. It was a mathematical system that was eventually translated into Latin as 'algebra', which became the foundation for mathematical textbooks in Europe for centuries.

How did the Arabic texts containing mathematical wisdom reach Europe?

The Arabic texts reached Europe, specifically Spain, in the 11th and 12th centuries, sparking a significant interest in translating this knowledge into European languages.

What challenges did Medieval Spanish scholars face when translating Arabic mathematical texts into Spanish?

Medieval Spanish scholars faced challenges in translating Arabic mathematical texts due to the presence of sounds in Arabic that do not exist in Spanish, such as the 'sh' sound, which is part of the word 'shayun' meaning 'something' or 'unknown'.

Why was the Greek letter 'Kai' used as a substitute for the Arabic 'sheen' in translations?

The Greek letter 'Kai' was used as a substitute for the Arabic 'sheen' because Spanish, like many European languages, lacks the 'sh' sound. The 'ck' sound in Greek was a close approximation, so it was borrowed for the translation.

How did the Latin 'X' come to replace the Greek 'Kai' in mathematical texts?

When the mathematical texts were translated into Latin, the Greek 'Kai' was replaced with the Latin 'X', which was phonetically similar and available in the Latin script.

What is the origin of the term 'algebra' used in mathematics?

The term 'algebra' comes from the Arabic 'al-jebr', which means 'the system for reconciling disparate parts', and was a method for solving equations that was developed by Persian and Arab mathematicians.

How did the use of 'X' to represent the unknown become a cultural phenomenon?

The use of 'X' to represent the unknown became a cultural phenomenon as it was used in foundational mathematical texts that influenced education and popular culture for centuries, leading to its adoption in various fields such as the X prize, the X-Files, Project X, and TEDx.

Why is the letter 'X' associated with mystery or the unknown in popular culture?

The letter 'X' is associated with mystery or the unknown in popular culture because of its historical use in mathematics to denote unknown variables. This association has been carried over into various cultural references and branding.

Outlines

00:00

🔍 The Origin of 'X' as the Unknown

The speaker, Timothy Covell, explores the cultural prevalence of the letter 'X' as a symbol for the unknown, from math classes to popular culture. He delves into his personal experience learning Arabic, a language he describes as supremely logical and precise, akin to crafting equations. Arabic's influence on Western science, mathematics, and engineering is highlighted, particularly through the concept of 'al-jebra', which translates to 'the system for reconciling disparate parts' and evolved into algebra. The speaker then narrates the historical journey of Arabic mathematical texts to Europe, focusing on the 11th and 12th centuries. He discusses the challenges faced by Medieval Spanish scholars in translating Arabic terms into Spanish, especially the sound 'sh', which does not exist in Spanish. To overcome this, they borrowed the 'ck' sound from Greek, represented by the letter Kai. When these texts were later translated into Latin, the Greek Kai was replaced with the Latin 'X', which became the standard in mathematical texts for centuries. The speaker humorously concludes that 'X' represents the unknown because of a linguistic barrier in pronouncing 'sh' in Spanish.

Keywords

💡X as the Unknown

The letter X is used to represent the unknown in mathematics and culture. The video explains that this usage originated because the Arabic letter 'sheen,' which starts the word 'shayun' meaning 'something,' was difficult to translate into Spanish. As a result, translators replaced it with the Greek letter 'Kai,' and later the Latin 'X,' which then became the standard representation for an unknown variable.

💡Shayun

'Shayun' is an Arabic word meaning 'something' or 'an undefined, unknown thing.' This word is central to the video's explanation of how the letter X came to symbolize the unknown. It illustrates the linguistic challenge faced by Medieval Spanish scholars when translating Arabic mathematical texts into European languages.

💡Al-jebra

'Al-jebra' is an Arabic term that translates to 'the system for reconciling disparate parts,' and it is the origin of the word 'algebra.' The video connects this term to the broader theme of how much of Western science and mathematics was developed by Arabic, Persian, and Turkish scholars during the early centuries of the Common Era.

💡Medieval Spanish Scholars

Medieval Spanish scholars were responsible for translating Arabic mathematical texts into European languages. The video highlights the challenges they faced, particularly in translating sounds and letters that did not exist in European languages. Their workaround for the Arabic letter 'sheen' led to the use of X as the symbol for the unknown.

💡Kai

Kai is the Greek letter used by Medieval Spanish scholars to replace the Arabic letter 'sheen' in mathematical translations. This substitution is a key point in the video's explanation of how X came to represent the unknown in Western culture.

💡Arabic Language

The Arabic language is described in the video as supremely logical, with precise and information-rich words and phrases. The video's narrative emphasizes how the precision of Arabic contributed to the development of Western science and mathematics, particularly through the translation of Arabic texts into European languages.

💡Latin Translation

The Latin translation of Arabic mathematical texts solidified the use of X as the unknown in Western culture. The video explains how the transition from Arabic to Greek to Latin ultimately led to the widespread adoption of X in mathematical textbooks used for centuries.

💡Sound Translation Challenges

Sound translation challenges refer to the difficulties faced by Medieval Spanish scholars when trying to translate Arabic sounds that did not exist in European languages. The video's focus on the letter 'sheen' and its replacement with 'Kai' and later 'X' exemplifies these challenges and their long-lasting impact on mathematical notation.

💡Western Science and Mathematics

Western science and mathematics, as discussed in the video, were heavily influenced by Arabic, Persian, and Turkish scholars during the early centuries of the Common Era. The video's main message is that much of what is considered Western knowledge actually has roots in the translations and adaptations of Arabic texts.

💡Cultural Significance of X

The cultural significance of X extends beyond mathematics, as it is now found in various contexts such as 'The X Files,' 'Project X,' and 'TEDx.' The video highlights how the letter X has become a symbol for the unknown and mysterious in popular culture, tracing this back to its mathematical origins.

Highlights

The letter X represents the unknown in many cultural contexts.

The origin of X representing the unknown is rooted in the history of mathematics and language.

Learning Arabic led to the discovery of its logical and precise nature, akin to crafting equations.

Arabic language's contribution to Western science, mathematics, and engineering is significant.

Al-jebra, an Arabic system, translates to 'the system for reconciling disparate parts' and became algebra.

Arabic mathematical texts were translated into European languages in the 11th and 12th centuries.

Translation challenges arose due to the absence of certain Arabic sounds in European languages.

The Arabic letter 'sheen' and the word 'shayun', meaning 'something', could not be directly translated into Spanish.

Medieval Spanish scholars used the 'ck' sound from Greek to represent the 'sh' sound in Arabic.

The Greek letter Kai was replaced with the Latin X when translating into Latin.

The Latin X became the standard in mathematics textbooks for almost 600 years.

The reason X is used for the unknown is because the 'sh' sound doesn't exist in Spanish.

The historical journey of the letter X in mathematics is a fascinating linguistic and cultural tale.

The influence of Arabic on the development of algebra and the use of X as a symbol is profound.

The story of X as the unknown illustrates the interconnectedness of language, culture, and science.

Transcripts

Translator: Timothy Covell Reviewer: Jenny Zurawell

I have the answer to a question that we've all asked.

The question is,

Why is it that the letter X

represents the unknown?

Now I know we learned that in math class,

but now it's everywhere in the culture --

The X prize, the X-Files,

Project X, TEDx.

Where'd that come from?

About six years ago

I decided that I would learn Arabic,

which turns out to be a supremely logical language.

To write a word or a phrase

or a sentence in Arabic

is like crafting an equation,

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

by the Persians and the Arabs and the Turks.

This includes the little system in Arabic

called al-jebra.

And al-jebr roughly translates to

"the system for reconciling disparate parts."

Al-jebr finally came into English as algebra.

One example among many.

The Arabic texts containing this mathematical wisdom

finally made their way to Europe --

which is to say Spain --

in the 11th and 12th centuries.

And when they arrived

there was tremendous interest

in translating this wisdom

into a European language.

But there were problems.

One problem

is there are some sounds in Arabic

that just don't make it through a European voice box

without lots of practice.

Trust me on that one.

Also, those very sounds

tend not to be represented

by the characters that are available in European languages.

Here's one of the culprits.

This is the letter sheen,

and it makes the sound we think of as SH -- "sh."

It's also the very first letter

of the word shayun,

which means "something"

just like the the English word "something" --

some undefined, unknown thing.

Now in Arabic,

we can make this definite

by adding the definite article "al."

So this is al-shayun --

the unknown thing.

And this is a word that appears throughout early mathematics,

such as this 10th-century derivation of roots.

The problem for the Medieval Spanish scholars

who were tasked with translating this material

is that the letter sheen and the word shayun

can't be rendered into Spanish

because Spanish doesn't have that SH,

that "sh" sound.

So by convention,

they created a rule in which

they borrowed the CK sound, "ck" sound,

from the classical Greek

in the form of the letter Kai.

Later when this material was translated

into a common European language,

which is to say Latin,

they simply replaced the Greek Kai

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 "sh" in Spanish.

(Laughter)

And I thought that was worth sharing.

(Applause)