This atomic process kick-started quantum mechanics

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Before Heisenberg’s bold leap into matrix mechanics, a quiet revolution was already underway. In this video, I present the overlooked insights that laid the foundation for quantum theory — from Einstein’s radiation work and the A and B coefficients to the surprising concept of stimulated emission, which lead to the maser and the laser. This is the forgotten genesis of Heisenberg’s matrix formulation of quantum mechanics.
This video was republished due to a undesirable typo in the previous version, thanks to ‪@suryamgangwal8315‬ for pointing out the typo.


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[References]

∘ A. Einstein, "Emission and Absorption of Radiation in Quantum Theory," Verhandlungen der DPG, 18, 318 (1916)
∘ A. Einstein, "On the Quantum Theory of Radiation," Phys. Z. 18, 121 (1917)
∘ W. Heisenberg , "Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen," Z. Phys. 33, 879(1925)
∘ A. Einstein, "Approximative Integration of the Field Equations of Gravitation," Preussische Akademie der Wissenschaften, Sitzungsberichte, 1916 (part 1), 688
∘ P.A.M. Dirac, "The quantum theory of the emission and absorption of radiation," Proc. R. Soc. Lond. A114, 243 (1927)
∘ Einstein's letter to M. Besso (Aug. 1916) https://einsteinpapers.press.princeto...
∘ Einstein's letter to J.J. Laub (Nov. 1910) https://einsteinpapers.press.princeto...
∘ Einstein's letter to M. Besso (Sep. 1916) https://einsteinpapers.press.princeto...
∘ Einstein's letter to M. Besso (Jul. 1918) https://einsteinpapers.press.princeto...


[Credits]

Movement of microparticles by beams of laser, by technomi, free use on pickupimage
A. Einstein in 1916, by P. Ehrenfest , public domain
General relativity, by M. de Hacker under CC BY 3.0
M. Planck, public domain
A.H. Compton, public domain
Laser Facility, by Science and Technology Facilities Council under CC BY-SA 2.0
Visible lasers, by Greg Vojtko/U.S. Navy, public domain
Apparatus Used in Measuring Radiant Energy, AIP
Lenard tube, public domain
Spectral lines, by Sassospicco/Jhausauer, public domain
Population inversion 3level, by B. Mellish under CC BY-SA 3.0
Charles Townes and first maser, by D. Rubin, public domain
Nicolay G. Basov, public domain
Aleksandr Prokhorov, public domain
Charles Townes in 1964, public domain
Interview Charles Townes, South Carolina ETV
World's first laser, by T. and K. Maiman under CC BY-SA 4.0
Theodore Maiman, public domain
Laser light show, by Z. Zhang, free use on Pexels https://www.pexels.com/video/vibrant-...
Laser cutting machine, by Z. Urbonas, free use on Pexels https://www.pexels.com/video/laser-cu...
Titan: Laser Manufacturing Lab-Additive Manufacturing, by Tekniker TV    • Titan: Laser Manufacturing Lab-Additive Ma...  
Laser Communications, by NASA's Goddard Space Flight Center / Dave Ryan, public domain
Laser surgery, by CMRF Crumlin under CC BY 2.0
Couple Paying at the Counter in the Grocery, by J. Sparrow, free use on Pexels https://www.pexels.com/video/couple-p...
Cats playing with laser light, by N. Ali, free use on Pexels https://www.pexels.com/video/two-cats...
Markov Processes, by thekirbster under CC BY 2.0
Transition Matrix, by thekirbster under CC BY 2.0
Dispersive Prism, by Spigget/Cepheiden under CC BY-SA 3.0
Rudolf Ladenburg, by G.F. Hund under CC BY 3.0
John C. Slater, public domain
Laser pointer with a cat, by Cottonbro Studio, free use on Pexels https://www.pexels.com/video/playing-...



AIP: American Institute of Physics, Emilio Segrè Visual Archives
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