PhD Student at École de technologie supérieure studying Carbon Nanotube MEMS.

Arguably the most complex branch of Physics, it can actually be broken down into few basic theories

**What is Quantum Mechanics** Quantum Mechanics can be defined as the study of the interaction of subatomic particles with each other or with electromagnetic radiation. As simple as it may sound, the concepts of Quantum Physics sometimes directly contradict Classical Physics and hence can be very difficult to grasp. However, this branch of Physics has greatly helped us to better understand the building blocks of matter and all universe. **Wave-Particle Duality** Quantum theory suggests that all elementary particles can behave both as a particle and a wave. This theory was first formulated by Einstein who studied the work of Max Planck and modified it accordingly to fit the model. Einstein arrived at the conclusion that light is actually made of particles called "Photons". Niels Bohr through his experiments further verified Einstein's concept in what can be thought of as the birth of Quantum Physics. **Principle of Superposition** Erwin Schrodinger designed a thought experiment which involved a cat inside a box with a radioactive source. He argued that the chance of the cat surviving or dying is 50% but according to Quantum Physics at the instant, before the box is opened, the cat is equal parts alive and dead. only when the box is opened do we see a definitive result but until then it is all probability. This translates to the fact that Quantum objects can exist in 2 states at once which forms the Principle of superposition which is again a consequence of the wave-particle duality. **Uncertainty Principle** Heisenberg proposed the famous "Uncertainty Principle" which states that since the elementary particles have a dual nature, one can never predict the exact speed and the exact position of the particle at the same time. Uncertainty arises due to measurement- measuring position changes the velocity of the body and vice versa due to the dual nature of subatomic particles.