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The History of Quantum Mechanics
Brittany HallAurel LazarJohn HodgeJesse Mahn
1900: •Max Planck
proposed theory about black-body radiation
1918: •Max Planck
won Nobel prize in physics
1913: •Neils Bohr proposed
atomic structure
theory
1921: •Won the
Nobel Prize in Physics for his discovery
and explanation of the law of
the photoelectric
effect.
1905:•Albert Einstein wrote the paper, "On a Heuristic
Viewpoint Concerning the Production and
Transformation of Light“; proposed
the idea of energy quanta dealing
with the photoelectric
effect.
1922: •Neils
Bohr won Nobel
Prize in physics
•Stern-Gerlach
Experiment (Verified the space quantization theory)
1924: •Louis De Broglie
published his doctoral thesis, “Recherches sur
la théorie des quanta”, which introduced his
theory of electron waves.
1929: Louis De
Broglie won the Nobel Prize in
Physics for hypothesis.
1933: •Otto Stern measures
the magnetic
moment of the proton •Schrodinger wins Nobel prize for his Schrodinger
Equation
1936: Publishes paper on
Wave Mechanics
and Schrödinger's Equation
1925:
•Heisenberg developed
the Heisenberg Uncertainty principle
•Wolfgang Pauli
developed the fourth quantum
number- the spin number
1932: •Werner
Heisenberg won Nobel
Prize in physics
1943: •Otto Stern
receives Nobel prize in
Physics
1944: •Wolfgang Pauli won
Nobel Prize in physics
1940: Pauli
proves Spin-
Statistic Theorem
This Timeline has much Entropy.
Erwin Schrödinger
• In 1926, at the University of Zurich, published a series of 4 papers– Wave Mechanics & Schrodinger’s
Equation– Solved Quantum Harmonic Oscillation,
the Rigid rotor, diatomic molecules and rederived his equation
– Compared his approaches to Heisenerg– Showed how to work with time
Schrödinger’s Equation
• While this appears to be a rather complicated equation, it is.
• means at time t• i is the square root of –1• Planck’s constant divided by 2π• Derivative with respect to time• ψ(t) = Wave Function• H(t) = Quantum Hamiltonian
Erwin Schrödinger
• First paper has been universally celebrated as one of the most important achievements of the twentieth century, and created a revolution in quantum mechanics, and indeed of all physics and chemistry
• Nobel Prize 1933• Schrödinger’s Cat
Thought Experiment - 1935
Schrödinger’s Cat
• Decay of gas kills cat• 50% chance of
decay• 50% dead cat?
Otto Stern & Walter Gerlach
• Otto Stern and Walter Gerlach are famous for their Stern-Gerlach experiment, in which they shot a beam of silver atoms through a non-uniform magnetic field, showing that the atoms split up into only 2 bands
• This verified the space quantization theory, and tested whether particles had intrinsic angular momentum
Stern-Gerlach Experiment
More on Otto Stern
• Developed Molecular Ray Method
• Demonstrated the wave nature of atoms and molecules
• Measured atomic magnetic moments
• Corrected the proton’s magnetic moment
• Nobel Prize in Physics in 1943
Werner Heisenberg
• Won Nobel Prize in 1932 in Physics "for the creation of quantum mechanics, the application of which has, inter alia, led to the discovery of the allotropic forms of hydrogen".
• Heisenberg pointed out that it is impossible to know both the exact position and the exact momentum of an object at the same time. Applying this concept to the electron we realize that in order to get a fix on an electron's position at any time, we would alter its momentum. Any attempt to study the velocity of an electron will alter its position. This concept, called the Heisenberg Uncertainty principle, effectively destroys the idea of electrons traveling around in neat orbits. Any electron that is subjected to photons will have its momentum and position affected.
More on Heisenberg
• Invented Matrix Mechanics
• Formulated the Copenhagen Interpretation of Quantum Mechanics with Bohr
• Proposed Proton-Neutron model of atomic nucleus
Heisenberg's Experiment
Wolfgang Ernst Pauli
• Nobel Prize in Physics in 1945• The exclusion principle (No two electrons may exist in the same
quantum state) provided the reason for electrons in atoms being arranged in shells with the maximum number of electrons being 2, 8, 18, 32… etc, from the first to the nth shell.
This principle is significant for the fact that it explains why matter occupies space exclusively for itself and does not allow other material objects to pass through it, at the same time allowing lights and radiations to pass. It states that no two identical fermions may occupy the same quantum state simultaneously. A more rigorous statement of this principle is that for two identical fermions, the total wave function is anti-symmetric
More on Pauli
• Derived observed spectrum of H2, supporting Heisenberg
• Proved Spin-Statistics Theorem
• First named Neutrinos
Max Planck andBlack Body Radiation
• Emission of light from hot objects (objects appear black before heating)
• How does the intensity of the electromagnetic radiation emitted by a black body depend on the frequency of the radiation and the temperature of the body?
• Interpolated between the laws of Wien and Rayleigh-Jeans
• Assumed that energy exists in individual units (discrete bundles)
• First proposed in a meeting on October 19, 1900
Planck’s Contributions
• Formula predicts the spectral intensity of electromagnetic radiation at all wavelengths from a black body at temperature T
•h is Planck’s constant which is measured in J.s
•6.63x 10-34
•Energy is always emitted or absorbed as a whole number multiple of h (2hv, 3hv…)
Planck
• Later simplified this to E=hv in which E is energy, h is Planck’s constant, and v is frequency
Walk the
More stuff on Planck• Basically states that energy is always
emitted or absorbed in discrete units, called quanta (quantized)
• Gave the name “quantum”, which means “fixed amount,” to the smallest quantity of energy that can be emitted/absorbed as electromagnetic radiation
• Awarded Nobel Prize in Physics in 1918 for this
• *No major flaws or errors• This is regarded as the start of quantum
physics
Neils Bohr
• Introduced his concepts by borrowing ideas from quantum physics (Max Planck) in 1913
• Presented a model of atomic structure that still stands true today
• Started by assuming that electrons move in circular orbits around the nucleus
• Determined that chemical properties of an element are determined by the number of electrons in its outer shell
More Bohring Information
• Idea that an electron can drop from a higher-energy level to a lower one, emitting a photon
• Also determined that:– Electron exists a certain
distance from the nucleus– Electrons have circular orbits– No energy is given off if an
electron stays in one location
• Received Nobel prize in 1922 for physics
Flaws • His assumptions about the energy given off when an electron drops to a lower-energy level only stands true for hydrogen (other elements are too large)
• Problem with describing an electron merely as a small particle circling the nucleus
Prince Louis-Victor de Broglie
• Won the Nobel Prize in Physics in 1929
• Professor at the Faculty of Sciences at Paris University
• Elected a member of the Academy of Sciences of the French Institute in 1933
• Broglie stated that all matter has a wave-like nature
• States that any moving particle or object had an associated wave
• Created a new field in physics, called wave mechanics, uniting the physics of light and matter
Broglie’s Equation
λ= the particle's wavelength h= Planck's constantp= the particle's momentum m= the particle's rest massv= the particle's velocity c= the speed of light in a
vacuum
More on de Broglie
• Equation used to describe the wave properties of matter, specifically, the wave nature of the electron
• The de Broglie relation shows that the wavelength is inversely proportional to the momentum of a particle and that the frequency is directly proportional to the kinetic energy of the particle
Albert Einstein• Won the Nobel Prize in Physics in
1921 for his discovery and explanation of the law of the photoelectric effect
• Widely regarded as one of the greatest physicists of all time
• Formulated the theory of relativity and made significant contributions to quantum mechanics and statistical mechanics
• Also famous for formulating E = mc2
The Photoelectric Effect
• The photoelectric effect is the emission of electrons from matter upon the absorption of electromagnetic radiation, such as ultraviolet radiation or x-rays
The Photoelectric Effect• When light shines on a metal surface, the surface
emits electrons
• A polished, negatively charged piece of metal such as zinc will lose its charge if it is exposed to ultraviolet light. This phenomenon is called the photoelectric effect
The Photoelectric Effect
• The photoelectric effect can be modeled by the equation:
Ekin = h f – W
Ekin = maximal kinetic energy of an emitted electronh = Planck constant (6.626 x 10-34 Js)f = frequencyW = work function (the energy required to free an electron from the material)
The Photoelectric Effect
• In 1905, Einstein's work predicted that the energy of the ejected electrons would increase linearly with the frequency of the light
• At this time his idea could not be proven but, in 1915, it was found to be accurate when Robert Andrews Millikan experimentally determined the relationship to be linear
Summary
• All of these men are interrelated in their discoveries; some proved the discoveries of others, others borrowed ideas and concepts
The End