Benoit Mandelbrot: Fractals and the art of roughness

TED
6 Jul 201021:19
EducationalLearning
32 Likes 10 Comments

TLDRThe speaker explores the concept of roughness and its surprising order, introducing the audience to the fractal geometry that underlies natural and artificial complexities. From the intricacies of a cauliflower's surface to the branching patterns of the lungs, the talk delves into how simple mathematical rules can describe complex phenomena. The Mandelbrot set, a key discovery, exemplifies how beauty and complexity emerge from simple iterative formulas, challenging the traditional separation between mathematics and reality.

Takeaways
  • 📚 The speaker discusses the concept of roughness and its significance in understanding complexity in nature and human-made objects.
  • 🌾 The cauliflower is used as an example to illustrate self-similarity, where parts of the object resemble the whole but on a smaller scale.
  • 🔍 The speaker introduces the idea of measuring roughness with numerical values, indicating a level of order within seemingly chaotic structures.
  • 🎨 The concept of roughness is applied to artificial landscapes used in cinema, demonstrating the practical applications of this mathematical understanding.
  • 🫁 The speaker explains how mathematical models have helped in understanding the complex structures of biological systems like the human lung.
  • 🌐 The geometry of nature, which was once poorly understood, is now being explored through the lens of fractal mathematics.
  • 🌧️ Clouds, despite their complexity and variability, can be represented using simple rules, showcasing the power of fractal geometry.
  • 🤔 The speaker reflects on the historical separation of mathematics from reality, and how his work has bridged this gap by applying mathematical concepts to describe natural phenomena.
  • 🏆 The importance of recognizing and understanding discontinuities in data, such as stock market prices, is highlighted as a key to mastering the subject matter.
  • 🌀 The Mandelbrot set, a key discovery of the speaker, is presented as an example of bottomless wonders emerging from simple, repeated mathematical rules.
  • 🎨 The use of color in visualizing complex mathematical shapes is emphasized to help make sense of the intricate patterns and structures.
Q & A
  • What is the main topic discussed in the transcript?

    -The main topic discussed is the concept of roughness and its measurement, particularly in natural and artificial objects. The speaker explores how roughness can be quantified and its significance in various fields.

  • Why does the speaker prefer the term 'roughness' over 'irregularity'?

    -The speaker prefers 'roughness' because 'irregularity' implies the opposite of regularity, which is not accurate. Regularity is the opposite of roughness, and the basic aspect of the world is very rough.

  • What is the significance of the cauliflower example in the transcript?

    -The cauliflower is used to illustrate the concept of self-similarity, where each part of the cauliflower resembles the whole but on a smaller scale, highlighting the complexity and simplicity inherent in natural objects.

  • How did the speaker initially get involved in studying roughness?

    -The speaker got involved in studying roughness by a complete fluke many years ago and was amazed to find strong traces of order within the roughness.

  • What is the roughness number and how is it used?

    -The roughness number is a numerical value that quantifies the roughness of a surface. It is used to measure and compare the roughness of different objects, both natural and artificial.

  • How does the speaker describe the concept of measuring coastline length?

    -The speaker describes the concept as a fallacy because the closer you measure, the longer the coastline appears to be. This challenges the traditional notion of a fixed coastline length.

  • What role do artificial landscapes play in cinema?

    -Artificial landscapes, which can be generated using mathematical formulas, are used in cinema to create realistic backgrounds, such as distant mountains, without the need for physical sets.

  • How does the speaker's work on roughness relate to the study of lungs and other branching systems?

    -The speaker's mathematical models of roughness have been helpful in understanding the structure of lungs and other branching systems, aiding surgeons and researchers in studying related illnesses.

  • What is the significance of the Brownian motion example in the transcript?

    -The Brownian motion example demonstrates how complex patterns can emerge from simple rules, and how the roughness number can be used to measure and understand these patterns.

  • What is the Mandelbrot set and why is it significant?

    -The Mandelbrot set is a set of complex numbers that, when plotted, form a complex and beautiful fractal pattern. It is significant because it shows that bottomless wonders can spring from simple rules that are repeated without end.

  • How did the speaker's early work on stock market prices influence his later research?

    -The speaker's early work on stock market prices led him to develop theories about financial price increments, which later influenced his approach to studying roughness and complexity in natural and artificial systems.

Outlines
00:00
🌿 The Discovery of Order in Roughness

The speaker begins by acknowledging their age and thanks the audience. They introduce the topic of roughness, a seemingly chaotic and complex aspect of life that has been historically difficult to control or understand. The speaker recounts their unexpected involvement in studying this form of complexity and their astonishing discovery of underlying order within it. They prefer the term 'roughness' over 'irregularity' to describe the fundamental rough nature of the world. Using the example of a cauliflower, the speaker illustrates the concept of self-similarity, where parts of an object resemble the whole but on a smaller scale. They then discuss their findings on measuring roughness quantitatively and the implications of this for artificial landscapes in cinema and for understanding natural phenomena like lung and kidney structures.

05:01
🌐 Mathematics and the Geometry of Nature

The speaker delves into the complexity and simplicity of natural structures like the lung, which despite its small volume, has a surprisingly large surface area that was historically difficult to measure due to its ill-defined nature. They discuss how their mathematical work has aided medical professionals in understanding such branching systems. The speaker also touches on the creation of artificial landscapes and the historical shift in mathematics from reality-based to pure invention, exemplified by the introduction of plane-filling curves. They highlight the use of the Hausdorff dimension as a measure of roughness, which was initially dismissed by mathematicians but found practical applications in art and nature, including the study of clouds and algae depicted in paintings by Hokusai.

10:02
🔍 The Unraveling of Brownian Motion and Fractal Geometry

The speaker recounts their mid-career exploration of Brownian motion, a random process that led to a surprising discovery when made to return to its origin, revealing an island-like shape. This discovery led to the measurement of roughness in such patterns, specifically a roughness number of 1.33 for Brownian motion. The speaker also reflects on their diverse background as a mechanical engineer, geographer, mathematician, and physicist, which all contributed to their unique perspective. They discuss the initial skepticism and eventual acceptance of their theories on stock market prices, emphasizing the importance of understanding large discontinuities in price movements rather than focusing on minor fluctuations.

15:04
🎨 The Mandelbrot Set and the Beauty of Infinite Complexity

In the final paragraph, the speaker describes their most significant discovery, the Mandelbrot set, which emerged from an exploration of complex numbers and simple iterative formulas. They marvel at the intricate, harmonious, and beautiful shapes that result from this formula, which are self-similar at different scales, resembling the whole when zoomed in on a part. The speaker also humorously recounts an incident where a shape resembling the Mandelbrot set was mistaken for an extraterrestrial artifact, highlighting the set's unexpected appearances in nature. They conclude by emphasizing the profound wonders that arise from repeating simple rules, a concept central to the Mandelbrot set and a theme reflective of their life's work.

Mindmap
Keywords
💡Roughness
Roughness, in the context of the video, refers to the irregular, complex, and seemingly chaotic nature of certain natural and artificial surfaces or phenomena. It is a central theme as the speaker discusses finding 'order in that roughness'. For example, the speaker mentions the roughness of a cauliflower's surface and the concept of measuring roughness with a numerical value.
💡Fractal
A fractal is a mathematical concept that represents rough or fragmented shapes at all scales, which can be found in nature and art. The video discusses the fractal nature of objects like cauliflowers, clouds, and even financial data, illustrating how simple mathematical formulas can generate complex, self-similar patterns.
💡Self-similarity
Self-similarity is the property of an object where it is similar to a smaller copy of itself. The video uses the example of a cauliflower to explain this concept, where cutting a floret from a cauliflower and looking at it separately, it resembles a smaller version of the whole cauliflower.
💡Complexity
Complexity in the video refers to the intricate and multifaceted nature of certain phenomena that may initially appear disordered. The speaker explores the idea that within this complexity, there can be underlying patterns and order, as seen in the study of roughness and fractals.
💡Mandelbrot Set
The Mandelbrot Set is a set of complex numbers that, when iterated through a simple mathematical formula, do not diverge. It is named after the speaker, who discovered its significance in the study of fractals. The video describes the Mandelbrot Set as an example of bottomless wonders emerging from simple rules.
💡Brownian Motion
Brownian motion is the random movement of particles suspended in a fluid as they are bombarded by molecules. The speaker discusses modifying the concept of Brownian motion to return to the origin, resulting in a shape resembling an island, which has a roughness number of two.
💡Roughness Number
The roughness number is a numerical value used to quantify the roughness or complexity of a surface or pattern. In the video, the speaker describes how this number can be used to measure the roughness of various surfaces, including artificial ones generated by computer algorithms.
💡Peano Curve
A Peano curve is a space-filling curve, a mathematical concept where a continuous curve is used to fill a two-dimensional space. The video mentions Peano as an example of a mathematician who created shapes that did not previously exist in nature, challenging the traditional separation between mathematics and reality.
💡Hausdorff Dimension
The Hausdorff Dimension is a mathematical measure that characterizes the 'roughness' or 'complexity' of a shape. The speaker found that this dimension, initially considered a mathematical joke, was a good measurement for the roughness of surfaces and patterns.
💡Coastline Paradox
The coastline paradox is a concept where the measured length of a coastline increases as the measurement scale decreases, suggesting that the concept of coastline length is not well-defined. The video uses this to illustrate the complexity and variability in measuring natural forms.
💡Julia Set
A Julia Set is a collection of complex numbers that, when iterated through a specific mathematical formula, do not tend to infinity. The video describes the speaker's work on Julia Sets, which resulted in the discovery of intricate and beautiful shapes from simple equations.
Highlights

The speaker discusses the concept of roughness as an ancient and uncontrollable aspect of complexity.

Involvement in a study of roughness led to the surprising discovery of order within it.

The preference for the term 'roughness' over 'irregularity' to describe the basic aspect of the world.

The cauliflower as an example of a naturally occurring fractal, demonstrating self-similarity at different scales.

The ability to measure roughness with a numerical value, indicating a new way to quantify complexity.

The creation of artificial landscapes using computer algorithms based on the input of roughness values.

The concept of coastline length as an example of a measure that changes with the scale of observation.

The practical application of measuring roughness in fields such as cinema for creating artificial landscapes.

The anatomical implications of fractal geometry in understanding the structure of lungs and other branching systems.

The development of a new geometry for complex natural forms that were previously ill-defined.

The simplicity of the rules behind complex natural phenomena, such as clouds, despite their apparent chaos.

The historical shift in mathematics from reality-based shapes to the invention of non-existent forms.

The reintroduction of reality-based mathematical objects to describe aspects of natural complexity.

The introduction and significance of the Hausdorff number as a measure of roughness, initially dismissed by mathematicians.

The artistic representation of fractals in paintings, predating the mathematical understanding of fractals.

The exploration of Brownian motion and its fractal properties, leading to a deeper understanding of its roughness.

The personal journey from studying stock market prices to discovering the complex patterns in financial data.

The impact of discontinuities in financial data, challenging the traditional approach to modeling price variations.

The discovery of the Mandelbrot set and its profound implications for understanding the complexity of simple mathematical formulas.

The visual representation of the Mandelbrot set, emphasizing the harmony and beauty emerging from simple rules.

The unexpected appearance of the Mandelbrot set in a crop circle, highlighting the set's cultural impact.

The overarching theme of the talk: the endless wonders that arise from repeating simple rules in mathematics and nature.

Transcripts
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