Quantum Processes in Astrophysics

  • Martin Harwit
Part of the Astronomy and Astrophysics Library book series (AAL)


In Chapter 6, we considered a series of processes by means of which radiation could be absorbed or emitted by particles. But we restricted ourselves to situations in which the Maxwell field equations of classical electrodynamics could be applied. These equations break down on the scale of atomic systems. The electron bound to a positively charged nucleus does not lose energy because of its accelerated motion, although the classical theory of radiation predicts that it should. Instead, the ground state of hydrogen, or any atom, is stable for an indefinitely long period of time. Moreover, when energy is actually radiated away from one of the excited states, and the atomic ground energy state is finally reached, we always find that only discrete amounts of energy have been given off in each transition. Again, this is at variance with classical predictions.


Angular Momentum Oscillator Strength Absorption Cross Section Atomic System Equivalent Width 
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Copyright information

© Springer Science+Business Media New York 1988

Authors and Affiliations

  • Martin Harwit
    • 1
  1. 1.Smithsonian InstitutionNational Air and Space MuseumUSA

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