The foundations of calculus were developed by Isaac Newton and Gottfried Wilhelm Leibniz upon the understanding that creating variables through algebra wasn’t enough to solve problems that studied rates on the infinitesimal scale. To understand physics and optics, Isaac Newton needed to understand how a quantity’s rate of change related to the quantity itself, which led to the publication of Newton’s Method of Fluxions; Newton described fluxions as the rate of change while fluents were the quantity. On the other hand, Gottfried Wilhelm Leibniz focused on infinitesimal quantities which served as his foundation for differential and integral calculus. With both contributions, concepts such as the fundamental theorem of calculus and higher derivatives were invented, ultimately accumulating to the completion of the calculus we know and love today. All of STEM builds on rates, from physics to engineering, the development of mankind can be attributed to understanding how one thing will change in relation to another. Calculus is fundamental to my education as a Rutgers University student in the pursuit of an Astrophysics degree; throughout my education I’ll have to understand the instantaneous changes in orbits or stellar fluctuations to monitor how they’ll affect our planet. Mathematicians such as Katherine G. Johnson needed to understand calculus in order to know the rate of change between Friendship 7’s trajectory over time to understand where the vessel would go and calculate how to bring John Glenn home, all without a calculator. On the opposite scale, calculus has contributed to quantum mechanics through deriving the behavior of quantum systems, finding the energy of an electron, and creating a mathematical representation for quantum phenomena. One of the best examples of calculus in quantum physics was Max Planck’s work with blackbody radiation. Planck used calculus to understand the energy distribution over time and developed his radiation law by observing how that energy is distributed into different wavelengths over a blackbody. On our scale of living, engineers use calculus to understand how the instantaneous rate of stress on a material changes once a certain force is applied, then also use calculus to optimize the amount of material to use within a certain area to minimize cost and maximize effectiveness. Before the age of computer aided design, Nikola Tesla was an expert in visualizing calculus equations in his head to develop effective models for his inventions; specifically, in his pursuit of developing AC systems he was able to create his own calculus equations to optimize his models of generators, transformers, and motors to maximize power output, all while saving on resources using mental mathematics. Overall, whether it’s used to calculate the trajectory of the solar system, optimize the area of house compared to the area of the land, or find the change in wavelength as a photon travels, calculus is used all around us and has laid the foundation for inventions that make us Earth’s smartest species.