The story of the great Greek physicist Archimedes amuses everyone. He ran stark naked on a crowded street to the palace of his king, shouting, “Eureka! Eureka!” which translates to, “I have found it! I have found it!” He had just solved one of the most intriguing questions in physics of his time. Greeks were always interested in the sciences, especially natural sciences like physics and formal science of mathematics. They combined the two in order to find solutions to many real-world problems of the day.

Their curiosity was furthered by Newton and Galileo who continued to study the physical world. Newton even devised advanced mathematics to solve questions that troubled many pioneers before him. Soon, however, physicists made a tremendous progress in the study of matter and they uncovered hidden knowledge about atoms and what resides inside them. These constituents of matter behave very differently from anything that preceded them and there was a need for a division.

### Classical physics is old physics?

Classical physics in any field comprises of physics that came before the modern concepts took hold. For instance, classical mechanics is the study of bodies like a baseball. The motion of a baseball can be described adequately with the help of laws of motion that Newton provided us with. But when it comes to electrons, the constituents of atom, classical physics is simply unable to explain what is going on. For that reason, modern principles of quantum mechanics are required to understand the motion of electrons.

However, this does not mean that classical physics is obsolete. Every new car that makes it way from the showroom to the road and beyond will follow the same laws that Newton wrote in his book more than 300 years ago. Classical physics is still as relevant as modern physics.

### What is the difference in their mathematics?

If that question sprang up in your brain, give yourself a pat because you have firmly understood that physics is understood using the language of mathematics. When it comes to the mathematics of classical physics, only those equations are valid which do not contain the constant that bears the surname of physicist Max Planck. Planck’s constant is a crucial concept in quantum theory. If you find it in any equation then you can be sure that the equation represents something that is true for the quantum world.

### Can we ignore classical physics?

In spite of the connotations attached with “modern” of modern physics, it cannot replace classical physics. Physicists tell us that quantum mechanics is true for small entities such as atoms. And as the size of the entity grows and its mass becomes more and more, the object starts to follow classical physics. So although quantum mechanics is still affecting the object, its effects can be ignored when dealing with bigger objects. In such cases, the classical definitions of its motion and interaction with other matter is sufficient. Researchers are working to define the limits where quantum effects stop affecting the physics systems and they attain a classical nature.