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Presentation on Origin of Quantum Theory

Apr 08, 2018

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Paras Gupta
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    SUBMITTED TO:- Mr. Anoop Kumar

    BY:Paras Gupta(CS-A)Sachin Kumar Mishra(CS-B)

    Sarmendra Dubey(CS-B)

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    Max Planck

    1900 : Max Plank introduced the concept of energyradiated in discrete quanta.Found relationship between the radiation emited by

    a blackbody and its temperature.E=h quanta of energy is proportional to the

    frequency with which the blackbody radiate

    assuming that energies of the vibrating electronsthat radiate the light are quantized obtain anexpression that agreed with experiment .

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    Albert Einstein The photoelectric effect

    N ot explained by Maxwell's theory since the rate of electrons not

    depended on the intensity of light, but in the frequency.

    1905: Einstein applied the idea of Plank's constant to the problemof the photoelectric effect light consists of individual quantumparticles, which later came to be called photons (1926).

    Electrons are released from certain materials only when particular frequencies are reached corresponding to multiples of Plank'sconstant .

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    Niels Bohr

    1913 : Bohr quantized energy explain how electrons orbit a nucleus.

    Electrons orbit with momenta , and energies quantized.

    Electrons do not loose energy as they orbit the nucleus, only change their energyby "jumping" between the stationary states emitting light whose wavelengthdepends on the energy difference.

    Explained the R ydberg formula (1888), which correctly modeled the lightemission spectra of atomic hydrogen

    Although Bohr's theory was full of contradictions, it provided a quantitativedescription of the spectrum of the hydrogen atom

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    S cientific revolution 1925 to January 1928W olfang Pauli: the exclusion principle

    W erner Heisemberg, with Max Born and Pascual Jordan ,- discovered matrix mechanics first version of quantum mechanics.

    Erwin Schrdinger:- invented wave mechanics, a second form of quantum mechanicsin which the state of a system is described by a wave function,

    Electrons were shown to obey a new type of statistical law, Fermi-Dirac statistics

    Heisenberg :Uncertainty Principle.

    Dirac :contributions to quantum mechanics and quantumelectrodynamics

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    Werner Karl Heisenberg : Brief Introduction

    1901 - 5Dec : H e was born in Wrzburg, Germany

    1914 :Outbreak of World War I.

    1920 he entered at the University of Munich Arnold Sommerfeld admitted him to his advanced seminar.

    192 5. 29 June R eceipt of H eisenberg's paper providing breakthrough to quantummechanics

    1927 . 23 Mar. R eceipt of H eisenberg's paper on the uncertainty principle.

    1932 . 7 June R eceipt of his first paper on the neutron -proton model of nuclei.

    1933 .11 Dec. H eisenberg receives N obel Prize for Physics (for 1932).

    1976 . 1 Feb. Dies because of cancer at his home in Munich.

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    Uncertanity Principal

    Position Momentum Uncertanity

    Principle.

    Energy - time uncertainty principle.

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    PositionPosition- -momentummomentum uncertanityuncertanity

    It states that we cnt measure the exectposition and momentum of a particle atsame time.

    The more accurately you know the position(i.e., the smaller ( x is) , the less accuratelyyou know the momentum (i.e., the larger( p is); and vice versa.

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    Quantum mechanics 1925-1927

    T he leading theory of the atom when H eisenberg enteredat University was quantum theory of Bohr.

    Although it had been highly successful, three areas of research indicated that this theory was inadequate:

    y light emitted and absorbed by atomsy the predicted properties of atoms and moleculesy T he nature of light, did it act like waves or like a stream

    of particles?

    1924 physicists were agreed old quantum theory had tobe replaced by quantum mechanics.

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    H eisenberg set the task of finding the newquantum mechanics:

    Since the electron orbits in atoms could not be observed, hetried to develop a quantum mechanics without them.

    By 1925 he had an answer, but the mathematics was sounfamiliar that he was not sure if it made any sense.

    T hese unfamiliar mathematics contain arrays of numbers known as matrix.

    Born sent H eisenbergs paper off for publication.

    All of my meagre efforts go towardkilling off and suitably replacing theconcept of the orbital path which cannotobserve H eisemberg, letter to Pauli

    1925

    T he breakthrough to quantum mechanics:

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    The wave-function formulation

    1926: Erwin Schrdinger proposed another quantummechanics, wave mechanics .

    Appealed to many physicists because it seemed todo everything that matrix mechanics could do butmuch more easily and seemingly without giving upthe visualization of orbits within the atom.

    I k new of [H eisemberg] theory, of c ourse, but I felt d isc ourage d , not to say repelle d , by the metho d s of trans c en d ental algebra, whi c h appeare d d iffi c ult to me, an d by the lack of v isualizability.- Schrdinger in 1926.

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    Conclusion

    T he history of Quantum mechanics its not easy, many eventspass simultaneously difficult period.

    Quantum mechanics was created to describe an abstractatomic world far removed from daily experience, its impact on

    our daily lives has become very important.

    Spectacular advances in chemistry, biology, and medicine

    Quantum information

    T he creation of quantum physics has transformed our world,bringing with it all the benefitsand the risksof a scientificrevolution.

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