Thursday, October 30, 2008

Some Quanta/Packets of Matter/Energy

An atom was named that way assuming that it was non-divisible into smaller units. But because of the growth of scientific geniuses, techniques and technologies, atoms were found to be divisible into the constituents like protons, neutrons and electrons. Protons and neutrons were also found to be composite particles themselves, formed out of quarks. Still we can consider them as units or quanta of matter/ energy, in fact matter is equaivalent to energy (E = mc^2). Here are some units of matter and energy:
(1) Proton - A constituent of an atomic nucleus with one unit positive (+1e) charge. (2) Electron - A constituent of an atom with one unit negative (-1e) charge. (3) Photon - A quantum of light/energy ( hf , h being planck's constant and f bing the frequency of radiation). (4) Phonon - A quantized mode of vibration occurring in a rigid crystal lattice, such as the atomic lattice of a solid (5) Gluon - An elementary particle that causes quarks to interact, and is indirectly responsible for the binding of protons and neutrons together in atomic nuclei. (6) Exciton - A quasiparticle formed by the combination of an electron and a positive hole which is free to move through a nonmetallic crystal as a unit. (7) Plasmon - A quasiparticle resulting from the quantization of plasma oscillations (8) Doppleron - A quantum of energy or momentum emitted or absorbed in the processes regarding the Doppler effect for atoms in the standing light wave. (9) Polaron - A quasiparticle composed of an electron and its accompanying polarization field. (10) Graviton - A postulated quantum that is thought to be the carrier of the gravitational field. (11) Magnon - A quasiparticle carrying a fixed amount of energy and lattice momentum, can be viewed as a quantized spin wave. (12) Tachyon - A hypothetical particle that travels at superluminal speed (>c) , first proposed by Arnold Sommerfeld. (13) Polariton - A quasiparticle resulting from strong coupling of electromagnetic waves with an electric or magnetic dipole-carrying excitation. (14) Ion - An ion is an atom or molecule which has lost (cation) or gained (anion) one or more valence electrons, giving it a positive or negative electrical charge.

Note: This was first written by me in THE NPS GOOGLE GROUP in May 06, 2008.

Tuesday, October 28, 2008

What is Quantum Mechanics?

Quantum Mechanics is the science of the small. If we are to consider the interactions between the molecules, atoms and the sub-atomic particles, we need to follow the quantum mechanical procedures. Thus, in a sense, quantum mechanics is a tool to study the behavior of the atomic and subatomic particles. The fundamental equation of Quantum Mechanics is the Schrodinger equation, which is like Newton's second law of motion in Classical Mechanics. We treat matter as a wave or a wave packet and a wave function, commonly denoted by 'psi' is assigned to the matter wave. Under different initial and boundary conditions as specified in the problem, the Schrodinger equation is solved to get the wave function for that particular problem. The more meaningful quantity is the modulus square of the 'psi' function - which gives the probability of finding the particle at any place. There is nothing certain in quantum mechanics, all is what is probabilistic. The probability of finding a particle is high where the square of the 'psi' function is high. The integral of the square of the 'psi' function in overall space is 'one', meaning that the particle must be situated somewhere in the space defined in the problem.

The World Of Small

I have chosen the topic of my blog 'The World Of Small' to indicate the world reigned by Quantum Mechanics. The advent of the Twentieth Century brought two EXTREME WORLDS- the world of the big -the world explainable by the Einstein's Relativity and a little later -the world of the small- the world governed by Quantum Mechanics. The groundbreaking 1905 paper by Albert Einstein on the Special Theory of Relativity and his 1916 paper on General Relativity are the two seminal papers which lead one towards the world of the big. On the other hand, the great works by Bohr, Schrodinger, Heisenberg and Dirac laid the strong and sound foundation of Quantum Mechanics which lead one to the world of the small. Here I would like to mention that the Quantum theory of radiation- the radiation by a black body is not continuous but in the form of quanta or packets was already given by Max Planck!

I have started this blog as a student who is learning and trying to learn more towards the world of the small but I am equally interested towards the world of the big too, so in this sense I am more interested to see a sound marriage between the BIG and the SMALL (to understand the world better way) - as the one put forward by the great physicist Stephen Hawking - The Quantum Theory of Gravity.

Hey, it's a start !