Dhristi JEE 2022-24

What is a Fractal?

Fractal patterns, like many other concepts of mathematics, are full of paradoxes. A source of creativity and beauty, a fractal structure can also be a powerful tool to analyze and communicate complex ideas.

In mathematics, this property of an object is called self-similarity. Shapes that exhibit self-similarity are known as fractals. Fractal patterns are deemed as the most beautiful and exquisite structures produced by nature and are present all around us. We have an abundance of fractal geometry in nature like hurricanes, trees, mountains, rivers, seashells, coastlines, the edge of a snowflake, and many others.

These images could look very complex at first glance but if you take a closer look, both of these objects of nature follow a rather simple pattern. Each individual part of the plant looks exactly similar to one another and to the entire plant, just smaller in size. The same pattern is repeated all over at smaller scales.

There are many intricate plants and parts in nature like the ones shown below:

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Let us try to demystify fractal geometry in this article where we will understand what are fractals, learn about fractals math, and know types of fractals.

Fractal Definition

The fractal theory could be a little tricky to explain in a precise manner but most fractal patterns are linked by a set of common features:

  • Infinite intricacy

  • Zoom symmetry

  • Fractional dimension

  • Complexity from simplicity

We will now explain each of these features by considering the example of a fern. A fern is a great illustration of all the features of a fractal structure. A fern’s shape is intricately detailed where you would notice that the leaves are shaped like exact copies of branches but smaller in size. In other words, the whole fern is built by repeating the same basic shape over and over at ever smaller scales.

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  1. Infinite intricacies - Polish mathematician Benoit Mandelbrot in his 1977 essay “The Fractal Geometry of Nature” wrote, “Nature exhibits not simply a higher degree but an altogether different level of complexity”. The first fractal was discovered in 1861 which created a massive stir in the mathematical community. A zigzag was constructed by German mathematician Karl Weierstrass which was extremely zagged. Even if you magnified the shape to the highest degree, you could only see a cascade of corners. Until modern computing, this zigzag remained just a glimpse of a completely new shape that was unravelled much later.

  2. Zoom symmetry - Symmetry of an object is defined as an action, when applied to a shape, leaves it looking more or less the same. For example, a square shape has rotational symmetry since when we rotate it by 90 degrees there is no way to tell that the square had been spun. Fractal geometry blossomed into a new branch of mathematics largely due to Benoit Mandelbrot who worked for IBM in the 1960s. He had IBM’s immense computing power at his disposal and gave the most famous fractal structure called the Mandelbrot set. It had a completely new level of symmetry which is not present in ordinary shapes. If you zoom in to a small portion of a fractal, you would be amazed that you are looking at the same shape that you started with.

  3. Complexity from simplicity - Despite the complexity of fractal structures, the shape arises from extremely simple core definitions. A small list of mathematical mappings can capture the shape of a fractal. These mappings tell us exactly how the small copies of a fractal are arranged to give the whole bigger fractal. 

Fractals start with a simple geometrical object and a rule for how to change the object. This finally leads to objects which are very complex and their dimension is not an integer. British mathematician Michale Barnsley, in his 1988 book “Fractals Everywhere” says that “Fractal description of an object is a story about how the object grows” reminding us that science is not just about facts and objectivity. Science does have a narrative component also that we ignore quite often. Fractals remind humans that stories also are important. There is an algorithm in Barnsley’s book called the “Chaos Game” that lets computers generate a fractal quickly from its mappings. With its starting point in space, the chaos game tracks its motion while hopping around. Each of the hops is decided upon by selecting one of the mappings randomly.

  1. Fractional Dimensions - The most striking feature of fractal patterns is that they are somewhere in between the normal one, two, or three-dimensional figures. We can define the dimensions of a shape as a measure of how rough the shape is or its size in one direction or how well the shape fills its surrounding space. To illustrate fractal maths imagine a piece of paper that has 2 dimensions (length and breadth). A solid sphere has 3 dimensions (length, breadth, and height) and it will fill more space than a piece of paper. Now if you crumble the paper into a ball, it will resemble a fractal shape which fills more space than the paper but not as much as the solid sphere. In the same way, the fractal geometry of our lungs allows them to pack a huge surface area (spanning a few tennis courts) into a small volume which is just about a few tennis balls. Since so much of the area is packed into such a small space, we are able to extract enough oxygen to keep us alive.

Any geometric pattern which occurs, again and again, makes a fractal structure. Fractals are everywhere around us in nature like ferns, trees, river networks, forks of lightning, etc. Fractal geometry could not be described by Euclidean geometry as it is an amalgamation of self-similar shapes that follow a simple and recursive definition.

FAQs on Fractal

1.What is the three-quarter power law and how does it apply to human bodies?

Ans: The mysterious and ubiquitous “three-quarter power law” came into existence after fractal geometry was revealed. This power-law model the way one structure relates to another and interacts with it. This law is based on the cube of the fourth root. For example, this three-quarter power law applies to our blood circulation system as well. Our arteries are just 3% of our bodies’ volume but can reach every cell of our body and provide nutrients. In the lungs and kidney, the arteries, veins, and bronchitis are intertwined around a common boundary. The arteries that deliver blood and the veins that take away the blood need to meet at a common interface at the surface of the lungs in order to aerate the blood. Every cell in our bodies is provided nutrients by our arteries by using a minimum amount of blood. Our liver, kidneys, lungs, pancreas, brain are some of our organs whose construction is based on the same fractal law.

2.What are some of the applications of fractals?

Ans: Fractals have applications in many spheres including economic, medical, and geography. 

  • Fractal cities - Fractal cities are those cities that tend to grow in a fractal pattern. A large fractal city that keeps absorbing its neighbouring villages and towns resembles a self-similar structure that might look random at first. But it is a dynamic network that can be more efficient than the modern “pre-planned” cities.

  • Fractal medicine - Many medical diagnoses (even cancer) are based on knowledge of fractals. A healthy human’s blood vessels grow in a typical and orderly fractal pattern while cancerous cells grow in an abnormal pattern. This makes them easier to be detected. A fractal analysis like this makes it simpler to distinguish between a healthy cell and a cell that is of concern.

  • Image compression and resolution - Since we can use little data to convey seemingly complex patterns, FTC (fractal image coding) makes working with image resolutions or even the creation of a 3D model extremely data-efficient.