Mathematicians Use Numbers Differently From The Rest of Us

Veritasium
6 Jun 202333:05
EducationalLearning
32 Likes 10 Comments

TLDRThe video script explores the concept of p-adic numbers, a system of numbers that diverges from traditional base 10 arithmetic and includes infinite digits to the left of the decimal point. It explains how these numbers can solve problems that are intractable with real numbers, such as Fermat's Last Theorem, and how they are used in advanced research areas like number theory and algebraic geometry. The script also discusses the unique properties of p-adic numbers, including their ability to represent fractions and negative numbers without special symbols and the challenges they pose to traditional mathematical tools. The video uses examples of squaring numbers and multiplying 10-adic numbers to illustrate these concepts, highlighting the transition from base 10 to prime bases to avoid certain mathematical issues.

Takeaways
  • 🧠 The concept of 10-adic numbers is introduced, which are infinite digit numbers in base 10 that follow specific multiplication and addition rules.
  • πŸ”’ 10-adic numbers can be squared infinitely, with each squaring increasing the number of matching digits at the end of the number.
  • πŸ€” The video challenges the conventional understanding of numbers by exploring numbers with infinite digits to the left of the decimal point.
  • πŸ“ˆ 10-adic numbers can represent rational numbers, such as fractions, without using traditional symbols like the division bar.
  • 🌟 The video discusses the application of 10-adic numbers in advanced fields like number theory and algebraic geometry.
  • πŸ”„ A pattern is observed where multiplying 10-adic numbers results in self-referential numbers, breaking traditional algebraic rules.
  • 🌐 The issue with 10-adic numbers is that they allow for non-trivial solutions to the equation n^2 - 1 = 0, which is problematic for mathematicians.
  • πŸ’‘ The solution is to use p-adic numbers, where p is a prime number, which avoids the issues encountered with 10-adic numbers.
  • πŸ“š The video references historical mathematicians Diophantus, Fermat, and Hensel, and their contributions to the development of number theory.
  • πŸ† P-adic numbers have been instrumental in solving renowned math problems, including Fermat's Last Theorem.
  • 🌌 The geometry of p-adic numbers is fundamentally different from real numbers, visualized as an infinite, triply branching tree structure.
Q & A
  • What pattern does the script describe when squaring numbers?

    -The script describes a pattern where the square of a number ends in the same digits as the original number. For example, 5 squared ends in 5, 25 squared ends in 25, and 625 squared ends in 625. This pattern extends to larger numbers, with the last few digits matching.

  • What are 10-adic numbers and how are they written?

    -10-adic numbers are a number system written in base 10, where digits extend infinitely to the left of the decimal point. They can represent rational numbers, including fractions and negative numbers, without using additional symbols like the divided by symbol.

  • How can you multiply two 10-adic numbers?

    -To multiply two 10-adic numbers, you can multiply them out digit by digit from right to left, just like in ordinary multiplication. Each digit of the result depends only on the corresponding digits of the 10-adic numbers being multiplied.

  • What is the significance of the number that is its own square in the 10-adic system?

    -The existence of a number that is its own square in the 10-adic system is significant because it breaks the usual mathematical property that the product of several numbers can only be zero if one of the numbers is zero. This poses a problem for solving equations in the 10-adic system.

  • Why do mathematicians prefer using p-adic numbers with a prime base?

    -Mathematicians prefer using p-adic numbers with a prime base because they restore the useful property that the product of several numbers will only be zero if one of the numbers is itself zero. This is not the case with 10-adic numbers, which can have non-zero products that are zero due to the composite nature of 10.

  • How does the concept of negative numbers work in the 10-adic system?

    -In the 10-adic system, negative numbers are represented by a string of 9s. To find the negative of any 10-adic number, you can multiply it by all 9s or perform two steps: take the 9s complement (the difference between each digit and 9) and then add 1.

  • What is Fermat's Last Theorem and why was it significant?

    -Fermat's Last Theorem, proposed by Pierre de Fermat in 1637, states that the equation x^n + y^n = z^n has no integer solutions for any n greater than 2. It was significant because it remained unproven for 358 years and its proof required the invention of new mathematical concepts, including p-adic numbers.

  • How did the concept of p-adic numbers contribute to solving Fermat's Last Theorem?

    -The concept of p-adic numbers provided a systematic method for solving problems in Diophantus' 'Arithmetica', which were crucial to proving Fermat's Last Theorem. The proof involved using p-adic numbers with different prime bases, such as 3 and 5, to overcome obstacles encountered during the proof process.

  • What is the geometric interpretation of 3-adic numbers?

    -The geometric interpretation of 3-adic numbers can be visualized as an infinite triply branching tree, where each level of the tree represents a different power of 3. Each 3-adic number is represented as a stack of infinite cylinders that get shorter and narrower as they go up, reflecting the relative contributions of each successive cylinder to the value of the 3-adic number.

  • How does the concept of distance or absolute value work in the p-adic system?

    -In the p-adic system, the concept of distance or absolute value is based on the lowest level of the tower where two numbers disagree. The distance between two numbers is determined by the p-adic place at which they differ. This means that the further away from the decimal point the disagreement occurs, the smaller the distance between the two numbers.

  • What is the role of p-adic numbers in modern mathematics and technology?

    -P-adic numbers play a crucial role in modern mathematics and technology by providing a different perspective on number systems and problem-solving. They have been used in cutting-edge research in number theory, algebraic geometry, and other fields, and have been instrumental in solving some of the most challenging mathematical problems, such as Fermat's Last Theorem.

Outlines
00:00
πŸ”’ Exploring Infinite Digit Patterns and 10-Adic Numbers

This paragraph delves into the intriguing world of number patterns and introduces 10-adic numbers, a number system based on base 10. It starts with a pattern of squaring numbers and observing the endings, leading to the discovery that certain numbers have infinite digits that repeat a specific pattern when squared. The explanation continues with the concept of 10-adic numbers, which can be added, multiplied, and even contain fractions and negative numbers without the need for additional symbols. The paragraph aims to convince the audience that these unconventional numbers are not only meaningful but also essential in advanced research areas like number theory and algebraic geometry.

05:01
πŸ€” Understanding 10-Adic Numbers and Their Properties

This section builds upon the previous one by further exploring the properties of 10-adic numbers. It explains how the number system works, including addition and multiplication, and how it can represent rational numbers and negative numbers. The paragraph also discusses the unique aspect of 10-adic numbers where a number can be its own square root, leading to the conclusion that this system breaks one of the fundamental mathematical tools used for solving equations. The explanation highlights the issue with using base 10, a composite number, and suggests the use of prime number bases as an alternative to avoid such problems.

10:04
🌟 Prime Number Bases and the Advantages of P-Adic Numbers

This paragraph shifts focus to prime number bases and their role in p-adic numbers. It explains how using a prime number base simplifies the multiplication of two numbers to zero, restoring the useful mathematical property that a product of several numbers can only be zero if one of the numbers is zero. The section introduces the concept of 3-adic numbers as an example and shows how they can be used to solve Diophantus' equations. The explanation highlights the advantages of p-adic numbers, including their ability to avoid finding non-trivial solutions that are not integers or fractions, which is a significant benefit in number theory and other mathematical fields.

15:06
πŸ“š Historical Context: Fermat's Last Theorem and P-Adic Numbers

This segment provides historical context by discussing Fermat's Last Theorem and its connection to p-adic numbers. It mentions the work of Pierre de Fermat and the infamous statement that led to the theorem, which remained unproven for centuries. The paragraph explains how the invention of p-adic numbers played a crucial role in finally solving the theorem, as demonstrated by Andrew Wiles' and Richard Taylor's work. The discussion emphasizes the importance of p-adic numbers in modern mathematics and their application in solving complex mathematical problems.

20:08
🌐 The Geometry of P-Adic Numbers and Their Visualization

This paragraph delves into the geometry of p-adic numbers and how they differ from real numbers. It introduces a visual representation of p-adic numbers as an infinite triply branching tree, which helps in understanding the concept of distance or separation between numbers in this number system. The explanation highlights the unique properties of p-adic numbers, such as their absolute values and the triangle inequality, and how these properties make p-adic numbers more manageable for finding rational solutions to equations compared to the real numbers.

25:10
πŸš€ Practical Applications and the Future of P-Adic Numbers

The final paragraph discusses the practical applications of p-adic numbers and their significance in various fields. It emphasizes the breakthrough in proving Fermat's Last Theorem using p-adic numbers and how this discovery has opened up new avenues for research and innovation. The paragraph also touches on the educational resources available for those interested in exploring the history and concepts of mathematics further, particularly through Brilliant's online courses. The conclusion encourages viewers to embrace the vast potential of mathematical exploration and the endless possibilities for discovery.

Mindmap
Keywords
πŸ’‘10-adic numbers
10-adic numbers are a number system that extends the base 10 system by allowing infinite sequences of digits to the left of the decimal point. In the video, they are used to demonstrate the concept of numbers that can solve problems that are impenetrable with ordinary numbers. The script explains that these numbers can be added, subtracted, and multiplied like conventional numbers, and they contain fractions and negative numbers without additional symbols. The concept is used to illustrate the convergence of certain infinite sequences and to challenge traditional mathematical tools, such as factoring equations.
πŸ’‘p-adic numbers
p-adic numbers are a more general class of numbers that include 10-adic numbers, where 'p' represents a prime number base. They are used in number theory and algebraic geometry to solve problems that conventional numbers cannot. The video explains that p-adic numbers have the property that the product of several numbers will only be 0 if one of those numbers is itself 0, which is a useful property for solving equations. The concept is further illustrated by creating a 3-adic number, which is a base 3 number with infinite digits to the left of the decimal point.
πŸ’‘Fermat's Last Theorem
Fermat's Last Theorem is a famous mathematical statement proposed by Pierre de Fermat in 1637, which states that the equation x^n + y^n = z^n has no integer solutions for any integer value of n greater than 2. The video describes the theorem's history and its unproven status for 358 years until the use of p-adic numbers led to its eventual proof by Andrew Wiles. The theorem is a central theme in the video, highlighting the power of unconventional mathematical tools.
πŸ’‘Diophantus
Diophantus was an ancient Greek mathematician known for his work 'Arithmetica,' which focused on finding integer solutions to polynomial equations. The video discusses Diophantus' interest in geometric problems, such as the Pythagorean theorem, and how modern mathematicians use p-adic numbers to solve problems similar to those Diophantus explored. The video also presents a problem from Diophantus' work involving the sum of squares, which is solved using p-adic numbers.
πŸ’‘modular arithmetic
Modular arithmetic is a system of arithmetic for integers, where numbers 'wrap around' upon reaching a certain value called the modulus. In the context of the video, modular arithmetic is used to solve equations in the form of increasing powers of primes, which is essential for working with p-adic numbers. The script provides an example of converting a number to base 3 using modular arithmetic, which is a key step in solving Diophantus' equation using 3-adic numbers.
πŸ’‘geometric series
A geometric series is a sequence of numbers where each term is found by multiplying the previous term by a fixed, non-zero number called the common ratio. In the video, the geometric series formula is used to find the sum of an infinite series in 3-adic notation, which leads to a rational solution for Diophantus' sum of squares problem. The video emphasizes the surprising convergence of the series, despite the common ratio being greater than 1, which would typically cause the series to diverge.
πŸ’‘absolute value
The absolute value of a number is a measure of its distance from zero on the number line, ignoring its sign. In the context of p-adic numbers, the concept of absolute value is adapted to fit the unconventional geometry of these numbers. The video explains that the p-adic absolute value is defined by properties such as non-negativity, multiplicativity, and the triangle inequality, which are essential for the functioning of the p-adic number system.
πŸ’‘prime numbers
Prime numbers are natural numbers greater than 1 that have no positive divisors other than 1 and themselves. In the video, prime numbers are crucial for the construction of p-adic number systems. The script mentions that any prime number can serve as a base for p-adic numbers, and switching between different prime bases can provide alternative solutions to mathematical problems, as demonstrated in the proof of Fermat's Last Theorem.
πŸ’‘number theory
Number theory is a branch of pure mathematics that deals with the properties and relationships of numbers, particularly integers. The video discusses the application of number theory to the study of p-adic numbers, which are essential tools in modern number theory for solving problems that traditional number theory cannot. The use of p-adic numbers in solving Diophantus' equations and Fermat's Last Theorem is highlighted in the video.
πŸ’‘algebraic geometry
Algebraic geometry is a branch of mathematics that studies solutions of polynomial equations, both in single variables and in several variables. The video mentions that p-adic numbers are fundamental tools in algebraic geometry and other advanced fields of research, as they enable the solving of complex problems that are otherwise impenetrable with conventional mathematical methods.
πŸ’‘Brilliant.org
Brilliant.org is an online learning platform that offers courses in math, science, data programming, and computer science. In the video, it is mentioned as the sponsor of the content, and a specific course on math history is highlighted, which covers the minds behind significant mathematical discoveries and the concepts they pioneered. The platform is used as an example of resources available for those inspired to delve deeper into mathematical concepts and history.
Highlights

The pattern of squaring numbers results in the last digits of the base number repeating infinitely.

The number system explored allows for infinite digits to the left of the decimal point, challenging traditional notions of infinity.

10-adic numbers are introduced as a base 10 number system that can perform addition and multiplication like usual numbers.

Rational numbers, such as fractions, can be represented in 10-adic numbers without using the divided by symbol.

The concept of 10-adic numbers leads to the discovery that some numbers can be their own square root, which breaks traditional mathematical tools.

P-adic numbers, using prime bases, avoid the issue of numbers being their own square and restore the useful property of multiplication.

P-adic numbers have been used by over a dozen Fields Medalists and were crucial in solving legendary math problems.

Fermat's Last Theorem, a famous unsolved problem for centuries, was eventually cracked using p-adic numbers.

The method of solving equations using p-adic numbers involves expanding them into increasing powers of primes and solving them modularly.

An infinite string of 1s in 3-adic notation is used to solve Diophantus' sum of squares problem, leading to a rational solution.

The geometry of p-adics is fundamentally different from real numbers, with a unique notion of size and distance between numbers.

The use of p-adic numbers in mathematics has revealed new connections and tools for problem-solving beyond traditional number systems.

The concept of absolute value in p-adic numbers behaves differently from real numbers, with the 'size' of a number determined by the lowest level of disagreement.

P-adic numbers are more disconnected than real numbers, which can be advantageous for finding rational solutions to equations.

The proof of Fermat's Last Theorem involved a switch from the prime 3 to the prime 5, demonstrating the unique utility of different prime bases in p-adic analysis.

The story of p-adic numbers illustrates the vast unexplored territory in mathematics and inspires further discovery and innovation.

The video concludes by highlighting the importance of exploring new mathematical concepts and the resources available for learning more about mathematical history and concepts.

Transcripts
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