Contribution Of Scientists In Quantum Mechanics

Max Plank’s —The Blackbody Radiation

•   In 1909 Max Plank’s introduced concept of Quantum of energy (photon) to explainBlackbody radiation.

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• He proposed that energy of radiation (light) is Quantized and dependent of frequency as 𝐸 = ℎ𝑓

• where h is the planck's constant of value ℎ = 6.63×10−34𝐽 𝑠

Albert Einstein — The Photoelectric Effect

•  In 1905 Einstein confirmed Planck's quantum concept.  

• Einstein proposed that electromagnetic radiation (light) is quantized and exists in fixed amounts (quanta) or photons.

• The introduction of the photon concept enabled Einstein to give explanation to the photoelectric problem, by Hertz in 1887.

Niels Bohr —The model of Hydrogen atom  

• Bohr proposed that atoms can be found only in discrete states of energy.  

• The emission or Absorption of radiation (or light) by atoms, takes place only in discrete amounts of 𝐸 = hf.

Arther Holly Compton — Compton’s effect 

•  By scattering X-rays with electrons, He confirmed that the (X-ray) photons behave like particles.

• Loss in photon energy = gain in electron energy.

de Broglie — Matter is a wave and waves are a matter too! 

•  In 1923, de Broglie proposed that Matter waves.

• He showed that wave nature of matter by relation 𝜆 = ℎ / 𝑚𝑣 = ℎ/ 𝑝

• In 1927 by Davisson and Germer proved de Broglie hypothesis

Heisenberg — The Uncertainty Principle 

•  In 1925 , Heisenberg proposed that it is impossible to determine the exact position and momentum at same time. Δ𝑝𝑥. Δ𝑥 ≥ ℏ / 2

• There is always be the Uncertainty of ℏ.

• He says that Quantum mechanics is a completely in-deterministic theory, no one knows the future state of particles. E.g three wings of rotating fans.

• He formulated the Matrix Quantum Mechanics in which Eigen values are represented in matrices.

Erwin Schrödinger— The Schrodinger Wave Equation of Particle (SWE)

•  In Quantum Mechanics Schrodinger Wave Equation play a same role like Newton’s Second Law: 𝐹 = 𝑚𝑎

• In 1926, Schrodinger described the dynamics of microscopic particles with a wave equation called Schrodinger Wave Equation.

• Schrodinger Wave Equation is 2nd order differential equation 

                   i.e 𝐻Ψ = 𝐸Ψ 

                      − ℏ2/2𝑚 𝜕2Ψ/𝜕𝑥2 + 𝑉(𝑟) = 𝑖ℎ 𝜕Ψ/𝜕𝑡 

Where H is Hamilton Operator or Total Energy Operator, Ψ is the wavefunction , E is the Energy Operator, V(r) is potential and ℏ is modified formed of Planck’s constant

 .i.e ℏ = ℎ/2 = 1.054573 × 10−34𝐽𝑠 

• The solution of SWE is a Wavefunction Ψ(𝑟,𝑡). A wavefunction completely describes the de-Broglie waves in space with respect to time. 

• Schrödinger gave the wave formulation of Quantum Mechanics

Paul Dirac — Dirac Notations

• An easy Notation of wave function 𝜳 and Relativistic approaches or Combined Quantum Mechanics and Special Relativity

•  Dirac then suggested a more general formulation of quantum mechanics using two state vectors i.e Bras and Ket sVectors 

•  The Kets notation of wavefunction Ψ is |Ψ > while Bra notation of Ψ is < Ψ|.

• Where Kets |Ψ >= ∫ Ψ𝑑𝑥 and Bras < Ψ| = ∫ Ψ∗𝑑x.

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