# “e” is Just as Important as Pi fact

## Is Euler’s Number the New Pi?

We all have heard of the famous mathematical constant Pi, but did you know there is another constant that is just as important called “e”? Often referred to as Euler’s number, after the Swiss mathematician Leonhard Euler, “e” is approximately equal to 2.71828 and is deeply ingrained in the fabric of mathematics. Discovered in the context of compound interest, “e” has since proven its significance across various domains of mathematics and natural phenomena, akin to the constancy of pi in circular calculations.^{[1]}^{[2]}

While pi is celebrated for its relationship to the circle, “e” is the base rate of growth shared by all continually growing processes. It appears in the rhythm of life’s ups and downs, not just in the abstract realms of mathematics but in everyday financial, biological, and physical systems. The story of “e” began with a curiosity about how things grow and compounded over time, leading to its uncovering in the 17th century, which has since changed how we calculate and understand the nature of growth.

## Common Beliefs and Applications of Pi and “e”

While Pi garners acclaim for its geometric applications, such as calculating the circumference and area of circles—a principle essential for fields ranging from architecture to engineering—”e” holds its ground in dynamic systems that change continuously.

The contrast in public recognition between Pi and “e” may be attributed to Pi’s tangible connection to everyday geometry; we see its applications in wheels, clocks, and pie charts. In contrast, “e” operates behind the scenes, driving both theoretical explorations and practical processes.

For instance, “e” is critical in finance for determining continuously compounded interest, profoundly affecting savings and loan economics. The formula “FV = PV x e^(i x t)” illustrates how investments grow over time in a way that a simple interest calculation using Pi cannot capture. This same principle of growth extends to biology, where “e” models population dynamics and the spread of diseases, influencing public health policies and treatments.

In technology, “e” informs the decay algorithms that predict how long a smartphone battery will last or how quickly a hot drink will cool, applications that Pi’s geometric focus doesn’t address. Meanwhile, “e” also describes the rate of atmospheric pollutant degradation, a vital component of environmental science.

Both constants are foundational, yet their applications are distinct: Pi is the go-to for static geometric calculations, while “e” excels in modeling growth and decay, processes that are inherently dynamic and temporal. Together, they form the backbone of mathematical constants that describe the universe, with “e” deserving as much recognition as Pi for its diverse and critical applications in our ever-changing world.^{[3]}

## Who Was Leonhard Euler?

Getting a deeper understanding “e” and why it is important also means delving into the life of Leonhard Euler.^{[4]}

Euler was Born in 1707 in Basel, Switzerland, and later mentored by Johann Bernoulli (see Bernoulli numbers). Although famous for the constant, contributions extend well beyond his establishment of “e” and include geometry, calculus, trigonometry, algebra, fluid dynamics, and astronomy.

Euler’s intellectual journey was marked by an extraordinary breadth of research and an ability to solve problems that had baffled his predecessors. His prolific output includes the introduction of much of modern mathematical terminology and notation, such as the concept of a mathematical function and the notation “f(x)”.

Notably, Euler’s formula in complex analysis, eix=cos(x)+isin(x), where “i” is the imaginary unit, is hailed as one of the most beautiful theorems in mathematics because it establishes a deep relationship between the exponential function and trigonometric functions. This formula is a special case of Euler’s identity, often cited as the most remarkable formula in mathematics, for it links five fundamental mathematical constants: 0, 1, π, e, and i.

Euler’s work on the number “e” helped develop the logarithms field, which revolutionized computation. He also made significant contributions to number theory and was instrumental in the development of the Euler–Maclaurin formula, which connects discrete sums and continuous integrals.

In addition to his mathematical genius, Euler possessed remarkable perseverance. Illustrated in the continuation of his work despite losing his eyesight later in life. This did not hinder his productivity; in fact, some of his most significant work was done during this period of his life.

Euler’s legacy is celebrated not only in the numerous theorems named after him but also in the way his work laid the foundation for much of contemporary mathematics and physics. His enduring influence is a testament to the power of human curiosity and intellect, and his name, inseparably linked with “e,” continues to inspire mathematicians and scientists around the world.

## “E” in Everyday Life

The mathematical constant “e” surfaces in many aspects of our daily experiences, often in ways we might not immediately recognize. For instance, the exponential growth of finances that “e” models is not just a concept for bankers and investors. When a population of bacteria grows in a petri dish, or when a viral video’s view count increases rapidly, they follow patterns describable by “e.”

Take the cooling of your morning coffee, for example. The rate at which it cools down and loses heat to the surrounding air can be modeled using natural logarithms based on “e”. Similarly, when you charge your smartphone, the rate at which the battery reaches full capacity follows a logarithmic curve that eventually plateaus as the charge completes, which is an application of “e” in the charging algorithm.

In nature, “e” is observable in the way leaves are arranged on a stem or the way a population of animals grows within an ecosystem. These are not linear processes but follow patterns that can be modeled using equations involving “e”, showing exponential growth under ideal conditions. For instance, the number of fish in a steadily reproducing population or the way a forest expands can be estimated using “e” if we assume unlimited resources and no predation.

Even in the vastness of space, “e” helps astronomers understand the luminosity and growth of certain types of stars, as well as the distribution of galaxies in the universe. This distribution often follows a Poisson process, which is deeply linked to “e”.^{[5]}

Moreover, “e” governs the decay processes as well. For instance, the decay of radioactive substances, an essential concept in both medicine and archaeology, follows a pattern described by “e”. Radiocarbon dating, which allows us to estimate the age of archaeological finds, is based on the exponential decay equation involving “e”.

These examples show that “e” is a silent contributor to many natural phenomena and technologies that we interact with and benefit from daily. It is a thread woven into the fabric of life, as omnipresent and fundamental as the more widely recognized constant, Pi.

## The Story of Pi and “e”

Pi and “e” represent fundamental constants that have shaped the understanding of our world through mathematics. Pi’s story is well-known, tracing back to ancient civilizations that recognized its significance in circular measurements. For example, the Great Pyramid at Giza, with its perimeter-to-height ratio approximating 2π, suggests that the ancient Egyptians may have had an understanding of this constant.

On the other hand, “e” made a later entrance with the work of John Napier on logarithms, which was a breakthrough in simplifying complex calculations. Euler’s identification of “e” as a constant and its subsequent use in calculating compound interest, modeling population growth, and defining the nature of logarithms mark just a few of the ways “e” has been pivotal in the advancement of mathematics alongside Pi.

## Understanding “e” Without a Math Degree

“Euler’s number,” or “e,” is not just for mathematicians—it’s a concept with real-world implications that can be grasped through everyday experiences. For instance, when we talk about the interest rates on a loan, we’re discussing concepts that hinge on the principles of “e.” If you’re tracking the performance of your retirement fund, the projections are likely using “e” to model growth over time. This constant also describes natural phenomena such as the rate at which a rumor spreads through a population or how a viral video gains popularity online—processes that can be understood in terms of exponential functions and “e.”

## The Irrational Beauty of “e”

The infinite and non-repeating nature of “e” makes it a fascinating subject not just in mathematics, but also in the broader context of understanding patterns and growth in the natural world. Its presence is felt in the spiraling patterns of shells and galaxies, which can be described by logarithmic spirals involving “e.” In the arts, the concept of the “golden ratio,” often associated with aesthetic beauty, is closely related to the Fibonacci sequence, which, as it progresses, approaches an exponential curve defined by “e.” The irrationality of “e” thus transcends mathematics, influencing art, design, and our general quest for patterns in life and the universe.

## Why “e” Deserves More Fame

In the realm of mathematics and beyond, “e” emerges not just as a number but as a cornerstone of natural laws and human comprehension. Its mathematical elegance and profound utility are woven into the very fabric of the world we experience. From the exponential growth of our investments to the decay of radioactive materials, from the spread of a forest to the reach of a viral online post, “e” is a silent yet ubiquitous force.

It’s in the growth curves of our economies and the spiraling of galaxies that we witness the subtle but pervasive influence of “e”. The constant’s ability to encapsulate change—be it growth or decay—makes it a powerful tool for understanding and navigating the complexities of our world. Its applications are as boundless as those of pi, deserving equal billing for its role in our equations and models.

“E” deserves more fame because it helps unlock the mysteries of both the universe and everyday phenomena. It is as essential as pi in describing the circles of a planet’s orbit as it is in predicting the growth of a population or the interest on a loan. For its omnipresence in processes that are fundamental to life, technology, and the universe itself, “e” warrants a place of honor alongside pi. This recognition is not just for the sake of mathematical completeness, but for the enrichment of our understanding of the patterns that underpin our existence.

- e is everywhere. Nature.com.
- e (mathematical constant). Wikipedia.org.
- Radiocarbon Dating. Wikipedia.org.
- Leonhard Euler. Wikipedia.org.
- The Expanding Search for Homogeneity. Caltech.edu.