Unit-7: Chp-1: Quantum Theory

PHYSICXION: Quantum theory, a cornerstone of modern physics, unveils the intricate dance of particles and waves in the tiniest realms.

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Quantum theory, a cornerstone of modern physics, unveils the intricate dance of particles and waves in the tiniest realms. Its insights power technologies like lasers and chips, securing data and enabling modern life. This theory's mystical touch has reshaped science, propelling us into a realm where the impossible becomes possible.

A brief view of its history:

Max Planck is considered the father of quantum theory. In 1900, he developed a theory to explain the emission of blackbody radiation, which is the radiation emitted by a perfect absorber of all frequencies of electromagnetic radiation.

Planck's theory was based on the idea that energy is emitted and absorbed in discrete packets, or quanta. This was a radical departure from the prevailing view of energy, which was that it could be emitted and absorbed continuously.

Planck's theory was initially met with skepticism, but it was eventually accepted and led to the development of quantum mechanics, which is the foundation of modern physics.

Other scientists who made significant contributions to the development of quantum theory include Albert Einstein, Niels Bohr, Erwin Schrödinger, and Werner Heisenberg.

Here are some of the key contributions of these scientists to quantum theory:

Albert Einstein: In 1905, Einstein published a paper that explained the photoelectric effect, which is the emission of electrons from a metal when it is exposed to light. Einstein's explanation showed that light can be thought of as consisting of discrete packets of energy, or photons.
Niels Bohr: In 1913, Bohr proposed a model of the atom that explained the emission of light by atoms. Bohr's model was based on the idea that electrons can only orbit the nucleus of an atom in certain allowed orbits.

Interesting facts:

Quantum theory is the weirdest new window of physics giving laws and theories of modern physics a new philosophical base. Some of them are,

The wave-particle duality: The wave-particle duality is a fundamental property of matter and energy that states that all matter and energy can behave like waves and particles. This means that particles can have wave-like properties, such as interference, and waves can have particle-like properties, such as momentum. The wave-particle duality is one of the most fundamental concepts in quantum mechanics, and it has important implications for our understanding of the world.

The double slit experiment: The double slit experiment is a classic experiment in quantum mechanics that shows that light and matter can behave like waves and particles. In the experiment, light or matter is shone through two slits, and a pattern of interference is observed on a screen behind the slits. This pattern can only be explained if light or matter is behaving like a wave. However, when individual particles are shone through the slits, they still create the same interference pattern. This shows that particles can also behave like waves.

The uncertainty principle: The uncertainty principle is a fundamental limit of quantum mechanics that states that it is impossible to know both the position and momentum of a particle with perfect accuracy. This is because the act of measuring the position of a particle changes its momentum, and vice versa. The uncertainty principle has important implications for our understanding of the world, and it has been used to explain many strange phenomena in quantum mechanics.

Schrödinger's cat: Schrödinger's cat is a thought experiment that illustrates the strangeness of quantum mechanics. In the experiment, a cat is placed in a box with a radioactive atom. If the atom decays, it will trigger a device that kills the cat. However, according to quantum mechanics, the atom is in a superposition of states, both decayed and not decayed. This means that the cat is also in a superposition of states, both alive and dead. Only when the box is opened is the cat's state determined.

Quantum tunneling: Quantum tunneling is the phenomenon where a particle can pass through a barrier that is classically impossible to pass through. This is because particles can behave like waves, and waves can interfere with each other in such a way that they can pass through a barrier. Quantum tunneling is used in many applications, such as transistors and scanning tunneling microscopes.

The black hole information paradox: The black hole information paradox is a paradox in quantum mechanics that arises from the fact that black holes destroy information. When matter falls into a black hole, it is crushed into a singularity, where the laws of physics as we know them break down. This means that the information about the matter that fell into the black hole is lost. However, quantum mechanics says that information cannot be destroyed. This paradox has not been resolved, and it is one of the most important unsolved problems in physics.

The Many Worlds Interpretation: The Many Worlds Interpretation is an interpretation of quantum mechanics that states that every possible outcome of a quantum event occurs in a separate universe. This means that there are an infinite number of universes, each with its own set of laws of physics. The Many Worlds Interpretation is a controversial interpretation of quantum mechanics, but it is one of the most popular.

Quantum teleportation: Quantum teleportation is the process of transferring the quantum state of a particle to another particle, even if they are separated by a large distance. This is done by entangling the two particles so that they share the same quantum state. When the quantum state of one particle is measured, the quantum state of the other particle is instantly determined. Quantum teleportation is a very promising technology, and it could be used to transmit information over long distances without the need for wires.

Quantum computing: Quantum computing is a type of computing that uses quantum mechanics to perform calculations. Quantum computers are much faster than traditional computers, and they could be used to solve problems that are intractable for traditional computers. Quantum computers are still in their early stages of development, but they have the potential to revolutionize many fields, such as cryptography, drug design, and materials science.

Quantum entanglement: Quantum entanglement is the phenomenon where two particles are linked together in such a way that they share the same fate, no matter how far apart they are. This is because the particles are described by a single wave function, and the wave function cannot be separated into two parts. Quantum entanglement is a very strange phenomenon, and it has important implications for quantum computing.

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CLASS NOTES :

Here full Class Notes PDFs are attached, which will help you to score well in the exam.

NOTE-1: Theory of Introduction to Quantum Physics.

NOTE-2: Solved Numerical (Easy and moderate level descriptive problems)

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