The Development of Quantum Physics: The History of the Physicists Who Revolutionized the Modern Theories of Matter and Energy

Albert Einstein’s greatest and most famous theory is the theory of relativity, which fundamentally changed the understanding of physics and astronomy during the 20th century. When first published, relativity superseded a 200-year-old theory of mechanics put forth by Isaac Newton. The theory of relativity overturned the concept of motion from Newton's day, into all motion is relative. Time was no longer uniform and absolute. Therefore, physics is no longer understood as space by itself, and time by itself. Instead, an added dimension had to be taken into account in the form of curved spacetime. Time now depended on velocity, and contraction became a fundamental consequence at appropriate speeds. 

Max Planck has been remembered as the theoretical physicist whose revolutionary discovery of energy quanta and formulation of fundamental quantum theory allowed for countless others to expand on the knowledge of atomic processes. The immensity of Max Planck's legacy is difficult to condense into mere words, but this excerpt from the obituary of the fabled scientist, published in The New York Times the day after his death, aptly summed it up: “Max Planck was one of the intellectual giants of the 20th century, and one of the [most] outstanding intellects of all time. As father of the Quantum Theory, he ranks with the immortals of science, such as Archimedes, Galileo, Newton, and Einstein.'

Niels Bohr was one of the most influential scientists of the 20th century, coming up with theories that reshaped humanity’s understanding of reality itself. At a time when classical physics was being challenged by new discoveries, Bohr emerged as one of the principal architects of quantum theory, helping to construct a framework that revealed the strange and counterintuitive laws governing the atomic world. His work transformed physics, chemistry, and technology.