Quantum theory also known as Quantum Mechanics, the theoretical basis of modern physics changes your perspective in how you see the world. Quantum Mechanics rules over every atom and tiny particles in every matter including stars, planets, rocks, building and us people. It explains the nature and behavior of matter and energy on the atomic and subatomic levels. Some of the behaviors are macroscopic and occurs only at extreme energies or temperature.
The uncertainty principle and the wave-particle duality of energy and matter provides a unified view of behavior of photons, electrons and other atomic-scale objects. According to quantum law, things have a sense that they do like to be tied to a single location or to follow a single path. It is like it can be at more than one place at a time.
Consider two billiard tables as a replica. When I hit a ball at one table it can have an immediate effect on the other table also without me being present. This is one another theory of quantum mechanics. Based on quantum mechanics, if people behaved like atoms in particles then you wouldn’t know where they are until you look for them.
The evolution of Quantum Mechanics began about 100 years ago when scientist were trying to figure out some unusual properties of light. In particular, the light through a gas when it is placed inside glass and heated. When the light is observed through a prism, it was seen that the light formed lines (pencil beams) of specific colours and not the usual continuous spectrum that you see when projected by cut glass on your table.
Some of the startling insights for this unusual property of light came from the Niels Bohr, a physicist who loved to discuss new ideas. Bohr was convinced that the solution lied in the heart of the matter, the structure of atom. According to him atoms resemble tiny solar system with even tinier electrons orbiting around a nucleus. Unlike a real solar system, this electrons cannot have any orbits. But they are definite and have a fixed orbit. According to Bohr, when atom is heated the electrons get agitated and leap downward from one fixed orbit to another forming energy in the form of light. The light produced is of very specific wavelength. This is the reason why lines of specific colors were produced and is called quantum leap.
The interesting part of this theory was that the electrons made leap from one orbit to another without moving through spaces. The reason behind this is that the electrons consist of discrete chalks of energy that cannot be divided further. This specific minimum quantity is called quanta. This is the reason why electrons can occupy only specific discrete orbits.
The double-slit experiment exposed quantum mechanics to its height. In this experiment the electrons were projected onto a screen by passing through two slits. It was found that instead of appearing at just two areas, the electrons appear all over the detective screen creating a pattern of strips. This lead to the concept of waves. How can particles be waves? That was the question scientists faced when this concept came into place. It’s like waves are not particles and similarly atoms are not waves. So how does this occur? In the initial stage scientist Schrodinger believed that the waves produced by a single electron is the description of an extended electron and the electrons got meshed out. That’s when the scientist, Max Born came up with the idea that it is a probability wave and the electrons are not smeared out. Born argued that the precise of the wave at any location is the likelihood of finding an electron there. It’s not like you will find electron at a particular location. It’s like what is the probability of finding an electron at a particular location.
When a single electron is passed through the slit, it is difficult to know where it will land. But using a mathematical equation for finding the electron’s probability wave, with great certainty it can be predicted where the electrons will land.
All the matter in the universe is made up pf atoms and subatomic particles that are ruled by probability and not certainty.
The concept of quantum mechanics helped in creation of the latest electronic devices like integrator, transistors etc.