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The 7 Basic Rules of Quantum Mechanics. Estimated Read Time: 8 minute (s) Common Topics: data, xf, quantum, state, rules. For reference purposes and to help focus discussions on Physics Forums in interpretation questions on the real issues, there is a need for fixing the common ground. There is no consensus about the interpretation of quantum ...
Classical mechanics. The rules of quantum mechanics assert that the state space of a system is a Hilbert space and that observables of the system are Hermitian operators acting on vectors in that space – although they do not tell us which Hilbert space or which operators. These can be chosen appropriately in order to obtain a quantitative ...
- Overview
- Advances in nuclear and subatomic physics
Within a few short years scientists developed a consistent theory of the atom that explained its fundamental structure and its interactions. Crucial to the development of the theory was new evidence indicating that light and matter have both wave and particle characteristics at the atomic and subatomic levels. Theoreticians had objected to the fact that Bohr had used an ad hoc hybrid of classical Newtonian dynamics for the orbits and some quantum postulates to arrive at the energy levels of atomic electrons. The new theory ignored the fact that electrons are particles and treated them as waves. By 1926 physicists had developed the laws of quantum mechanics, also called wave mechanics, to explain atomic and subatomic phenomena.
The duality between the wave and particle nature of light was highlighted by American physicist Arthur Holly Compton in an X-ray scattering experiment conducted in 1922. Compton sent a beam of X-rays through a target material and observed that a small part of the beam was deflected off to the sides at various angles. He found that the scattered X-rays had longer wavelengths than the original beam; the change could be explained only by assuming that the X-rays scattered from the electrons in the target as if the X-rays were particles with discrete amounts of energy and momentum. When X-rays are scattered, their momentum is partially transferred to the electrons. The recoil electron takes some energy from an X-ray, and as a result the X-ray frequency is shifted. Both the discrete amount of momentum and the frequency shift of the light scattering are completely at variance with classical electromagnetic theory, but they are explained by Einstein’s quantum formula.
Louis-Victor de Broglie, a French physicist, proposed in his 1923 doctoral thesis that all matter and radiations have both particle- and wavelike characteristics. Until the emergence of the quantum theory, physicists had assumed that matter was strictly particulate. In his quantum theory of light, Einstein proposed that radiation has characteristics of both waves and particles. Believing in the symmetry of nature, Broglie postulated that ordinary particles such as electrons may also have wave characteristics. Using the old-fashioned word corpuscles for particles, Broglie wrote,
For both matter and radiations, light in particular, it is necessary to introduce the corpuscle concept and the wave concept at the same time. In other words, the existence of corpuscles accompanied by waves has to be assumed in all cases.
The 1920s witnessed further advances in nuclear physics with Rutherford’s discovery of induced radioactivity. Bombardment of light nuclei by alpha particles produced new radioactive nuclei. In 1928 Russian-born American physicist George Gamow explained the lifetimes in alpha radioactivity using the Schrödinger equation. His explanation used a prope...
Sep 21, 2016 · LAW 4: Quantisation. Things come in bite-size chunks. The origin of quantum theory was, quite literally, a light-bulb moment. In 1900, Max Planck was trying to describe mathematically the energy ...
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Erwin Schrödinger proposed the quantum mechanical model of the atom, which treats electrons as matter waves. , represents the probability of finding an electron in a given region within the atom. An atomic orbital is defined as the region within an atom that encloses where the electron is likely to be 90% of the time.
- Why is the spin number expressed as +1/2 or -1/2, rather than just +1 or -1 ?In the spin quantum number the electrons are represented either by +1/2 or -1/2, and as shown in the quantum numbers video it is said that the elec...
- I've some questions on this statement: The square of the wave function represents the probability ...It's mostly a function in mathematics. It would be like asking "what is the average distance of a cosine wave from the center?" - and this might se...
- referring to the image on orbital shapes, why do the p,d,f orbitals have such "out of the blue" shap...The shapes have been calculated from Schrodinger's equation. Moreover , the shapes represent the region where the probability of finding the electr...
- So the formula for de Broglie equation says that lambda= h/mv and..the v of a stationary object will...Isn't to do with the fact that the velocity is not quite 0? if you know it is exactly 0 then the uncertainty in the position is infinite as well (m...
- On Schrödinger's equation, what exactly is the Hamiltonian operator? How do we work with it mathemat...This has to do with Laplacian operator (partial derivative) of a wave function. Here's the formula http://hyperphysics.phy-astr.gsu.edu/hbase/quant...
- In reference to Shrodinger's Equation, what's the difference between the V (wave function symbol) on...You can't cancel out the ψ's like that because Hψ is not H times ψ but rather H operating on ψ (that's what the ^ over the H indicates). The Hamilt...
- I have a really blurry picture of what it means for small particles to behave as both particles and ...I think I can safely say that nobody understands quantum mechanics. - Feynman So you are right on track! :) But to be more pedagogical, you can vie...
- Can we specify type of the wave in schrodinger wave? like transversal or longitudinalI never thought about it before. Its interesting question. My guess is that it is transverse. though, to honest, there is so much dispute about the...
- Does anyone know exactly what "spin" is? If a particle has "spin", it doesn't actually physically sp...Spin is just a property that electrons (and other particles) have. It got named spin back when people were working with the Bohr model and trying t...
- Do nodes of the 1s, 2s, 3s... subshells overlap? (wrt to the graph shown above, it seems they do) If...Atomic orbitals are defined by energy levels not positions. The electron clouds that are depicted are usually where there is a 90% chance of findin...
5 days ago · quantum mechanics, science dealing with the behaviour of matter and light on the atomic and subatomic scale. It attempts to describe and account for the properties of molecules and atoms and their constituents— electrons, protons, neutrons, and other more esoteric particles such as quarks and gluons. These properties include the interactions ...
Sep 12, 2022 · 7.1: Wavefunctions. In quantum mechanics, the state of a physical system is represented by a wave function. In Born’s interpretation, the square of the particle’s wave function represents the probability density of finding the particle around a specific location in space.
