# 17 Equations That Changed The World

Author : Somasundaram R Mathematics is everywhere, a small equation you studied in your childhood become a big reason for many changes in engineering and technology around the world. In 2013, famous author Ian Stewart published a book 17 Equations That Changed The World. This book elaborately explains each equation and how it molded engineering to human accessible day to day technologies, which is really inspired me to write this. In this article, we are going to see the summery of that 17 Equations and its applications.

## 1. Pythagoras’s Theorem

The Pythagorean Theorem is a statement in geometry that shows the relationship between the lengths of the sides of a right triangle – a triangle with one 90-degree angle​​.  ### Applications of Pythagoras’s Theorem

The Pythagorean Theorem widely used in Architecture and Construction, Laying Out Square Angles, Surveying, and  Navigation.

## 2. Logarithms

A logarithm is the power to which a number must be raised in order to get some other number .​  ### Applications of Logarithms

Logarithms widely used to measure Earthquake intensity measurement, Acid measurement of solutions(pH Value), Sound intensity measurements, and express larger value.

## 3.Calculus

Calculus is a form of mathematics which was developed from algebra and geometry. It is made up of two interconnected topics, differential calculus, and integral calculus. ​ ### Applications of Calculus

Calculus is widely used for engineers, scientists, and economists. The contribution of these professionals has a huge impact on our daily life – from your microwaves, cell phones, TV, and car to medicine, economy, and national defense.

## 4. Law of Gravity

Every object in the Universe attracts every other object with a force directed along the line of centers for the two objects that is proportional to the product of their masses and inversely proportional to the square of the separation between the two objects. ### The significance of Gravitational Laws:

Gravitational laws are used in many ways from small bicycle manufacturing to the aerodynamics of a Rocket.

## 5. The Square Root of Minus One

Imaginary number is a complex number that can be written as a real number multiplied by the imaginary unit i, which is defined by its property i2 = −1. ### The significance of the Imaginary number

When we get the square root of -1, we replace it with the shortcut i, which is called the "imaginary" number because negative square roots don't actually exist (and it's much easier to keep writing i than to write out the square root every time). That way, we keep the "imaginary" number just in case we will make the number useful again later in another equation by squaring it or multiplying it by a different imaginary number or something. And it turns out, in EE, this happens all the time.

## 6. Euler’s Formula for Polyhedra A (convex) polyhedron is called a regular convex polyhedron if all its faces are congruent to a regular polygon, and all its vertices are surrounded alike. Plain experimentation with sticks will allow you to easily construct 5 regular polyhedra: tetrahedron, cube, octahedron, icosahedron, and dodecahedron.

## 7. Normal Distribution

The normal distribution, also known as the Gaussian distribution, is a probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean.​​ ## 8. Wave Equation

The wave equation is an important second-order linear partial differential equation for the description of waves—as they occur in classical physics—such as mechanical waves (e.g. water waves, sound waves and seismic waves) or light waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics. pulse traveling through a string with fixed endpoints as modeled by the wave equation. Spherical waves coming from a point source. A solution to the 2D wave equation ## 9.Fourier Transform

The Fourier transform (FT) decomposes a function of time (a signal) into the frequencies that make it up, in a way similar to how a musical chord can be expressed as the frequencies (or pitches) of its constituent notes. ## 10.Navier – Stokes Equation

This equations arise from applying Isaac Newton's second law to fluid motion, together with the assumption that the stress in the fluid is the sum of a diffusing viscousterm (proportional to the gradient of velocity) and a pressure term hence describing viscous flow Navier Stokes equation is used to describe the flow characteristics of a Newtonian fluid. A fluid in which relation between stress and rate of strain is linear. In other words, a fluid obeys Newton law of viscosity. Honey, Benzene, Water, Kerosene oil, are just a few examples of a Newtonian fluid.

## 11.Maxwell’s Equations

Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, and electric circuits. The equations provide a mathematical model for electric, optical and radio technologies, such as power generation, electric motors, wireless communication, lenses, radar etc. Maxwell's equations often involve calculus, there are simplified versions of the equations. These versions only work in certain circumstances, but can be useful and save a lot of trouble.

## 12. Second Law of Thermodynamics L. Boltzmann, 1874

## 13. Relativity

The increased relativistic mass (m) of body times the speed of light squared (c2) is equal to the kinetic energy (E) of that body. E = mcProof of Albert Einstein's special-relativity equation E = mc2. ## 14. Schrodinger’s Equation

Schrödinger equation is a mathematical equation that describes the changes over time of a physical system in which quantum effects, such as wave particle duality, are significant. The Schrodinger equation is used to find the allowed energy levels of quantum mechanical systems (such as atoms, or transistors). The associated wavefunction gives the probability of finding the particle at a certain position. The solution to this equation is a wave that describes the quantum aspects of a system.

## 15. Information Theory

Information entropy (Entropy) is the average rate at which information is produced by a stochastic source of data. The measure of information entropy associated with each possible data value is the negative logarithm of the probability mass function  ​ ## 16. Chaos Theory

The Chaos theory is a study in mathematics to understand the dynamic behavior of nature. The butterfly effect is the best example of chaos theory, small wings flapping in one state can cause big effects at a later stage. Chaos Theory deals with nonlinear things that are effectively impossible to predict or control. it also called the deterministic behavior of the system. Newtonian laws are completely deterministic one.

### Principles of Chaos

• The Butterfly Effect: “Small changes in the initial conditions lead to drastic changes in the results”
• Fractals: “Fractal is a pattern. They are complex and created by simple repeating process”
• Unpredictability: “Difficult to predict the ultimate effect of a complex system”
• Feedback: “When feedback is given to the systems, it will get disordered” ## 17. Black – Scholes Equation

Black–Scholes–Merton model is a mathematical model for the dynamics of a financial market containing derivative investment instruments. Applications of Black – Scholes Equation:

• ### Investment

References

Real Life Uses of the Pythagorean Theorem

How is Calculus Used in Everyday Life?

Maxwell's Equations: Definition & Application

Normal Distribution

Wave equation

Fourier transform