Welcome to PHYS 201 Modern Physics Fall 2017

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1 Welcome to PHYS 201 Modern Physics Fall 2017 Meeting times: MWF 10:00-10:50am; F 2:00-2:50pm Co-requisite PHYS 251 Experimental Atomic Physics

2 Textbook Required text: Modern Physics by R. A. Serway, C. J. Moses, C. A. Moyer, Possibly useful math resource: M. L. Boas, Mathematical Methods in the Physical Sciences, 3 rd Ed.

3 Necessary background Prerequisites: This course assumes a solid background in first year physics and math. - Full year of calculus-based general physics PHYS Algebra-based general physics courses PHYS are less optimal. AP Physics is not usually sufficient. - Full year of calculus at the level of Math (and here AP credit is sufficient). This is a fast-passed and challenging course. Judge your preparedness before you dive in!

4 Grading 25% 30% There will be extra credit opportunities! 20% 20% Past years grade assignment A 92 B- 74 A- 87 C+ 69 B+ 84 C 64 B 79 C- 59 This assignment is likely to be adjusted for the test scores.

5 Homeworks 12 assignments, due beginning of the corresponding Friday class. Late assignments will be accepted with a 50% penalty when submitted on or before Monday class following the due date. Any assignment turned in after that time will not be accepted (unless you obtained a permission form me beforehand).

6 Homeworks Comments/responses: Modern Physics is a COLL200 course, reaching out into CSI (Cultures, Societies, and Individuals). There will be weekly reading assignments regarding the historical significance of the events discussed in class. After each discussion, you should read these essays and write roughly ½ page of thoughts, comments, and questions about the material.

7 My contact information Office: Small ixnovi[at]wm.edu or inovikova[at]physics.wm.edu Office hours: Wednesday 11am 12pm; Thursday 1-2pm Web-site: or in Blackboard Area of research: experimental atomic physics and quantum optics Research projects: quantum memory and slow light, miniature atomic clocks, squeezed light, optical microresonators, optical properties of thin films, etc. Lab location: Small 65, 34 (basement) Web-site:

8 Questions? Requests? Opinions? And now back to physics!

9 Birth year of modern physics Telephones Automobiles Electricity Industry (steam engine-driven)

10 And now back to physics! There is nothing new to be discovered in physics now. All that remains is more and more precise measurements. Lord Kelvin, 1900 The more important fundamental laws and facts of physical science have all been discovered that the possibility of their ever being supplanted in consequence of new discoveries is exceedingly remote Our future discoveries must be looked for in the sixths place of decimals. A. A. Michelson, 1900

11 Classical physics XIX century Mechanics Electromagnetism Thermodynamics Optics Speed c Quantum mechanics Special relativity 19 th -century physics General relativity 0 Log (size)

12 Classical physics XIX century Mechanics Electromagnetism Thermodynamics Optics XX century Modern physics Special and general relativity Quantum mechanics Atomic and molecular physics Nuclear and particle physics

13 Classical physics: Conservation laws Conservation of energy: The sum of energy (in all its forms) is conserved (does not change) in all interactions. Conservation of linear momentum: In the absence of external forces, linear momentum is conserved in all interactions. Conservation of angular momentum: In the absence of external torque, angular momentum is conserved in all interactions. Conservation of charge: Electric charge is conserved in all interactions.

14 Classical physics: Mechanics Newton s first law: An object in motion with a constant velocity will continue in motion unless acted upon in some net external force. Newton s second law: r F r = ma = d r ( mv) dt Newton s third law: r r F 12 = F 21

15 Classical physics: Mechanics Galilean transformation: Relates the time and space coordinates between two inertial systems in relative motion.

16 Classical physics: Mechanics Galilean transformation: Relates the time and space coordinates between two inertial systems in relative motion.

17 Classical physics: Electromagnetism Gauss s law (electricity) Gauss s law (magnetism) Faraday s law Ampere s law Differential form in vacuum r r r r r B E = 0 E = t r r r r r 1 E = = B 0 B c 2 t

18 Classical physics: Electromagnetism Wave equation solution: Maxwell s equations simplify to the wave equation for the electric (and magnetic) fields: r r 1 E E c t 2 2 = 2 2 which has a simple sine-wave solution: 0 r r r r E(, t) cos( ωt ± k ) c = ω / r k

19 Classical physics: Wave optics but what s waving??? A wave needs a medium to propagate - ether or aether. Light waves were found to be solutions to Maxwell s Equations, showing that light is electromagnetic wave, propagating at the speed c: But in what reference frame? Another problem with Maxwell equations their form changes under Galilean transformation!

20 Classical physics: Thermodynamics First law of thermodynamics: The change in the internal energy U of a system is equal of the heat Q added ti the system plus the work W done on the system. U = Q + W Second law of thermodynamics : It is impossible to convert heat completely into work without some other change taking place. Ideal gas equations: PV=nk B T

21 Ultraviolet catastrophe As an object gets hot, it radiates energy. Black body absorbs and emits radiation on all frequencies. An ideal blackbody radiator can be considered as a black box with a tiny hole. Classical thermodynamics failed to explain the spectrum of the blackbody radiation.

Birth of modern physics In a speech to the Royal Institution in 1900, Lord Kelvin himself described two dark clouds on the horizon of physics: The question of the

22 Birth of modern physics In a speech to the Royal Institution in 1900, Lord Kelvin himself described two dark clouds on the horizon of physics: The question of the existence of an electro-magnetic medium referred to as ether or aether. Special relativity The failure of classical physics to explain blackbody radiation. Quantum mechanics

23 Birth of modern physics (cont) Discovery of the X-rays (Roentgen, 1895) Discovery of Radioactivity (Becquerel, 1896) Nuclear physics Discovery of the electron (Thomson, 1896) Discovery of the Zeeman effect - splitting of atomic spectral lines in magnetic field (Zeeman, 1897) Quantum mechanics, atomic physics

24 What we are going to do this Special relativity semester Basics of quantum mechanics Introduction to atomic physics and spectroscopy Briefly: molecules, solid state physics, semiconductors, nuclear and particle physics

25 Why it is challenging? The effects we are going to discuss are outside of our everyday experiences. We have no intuition to guide us! The correct solution may seem as weird as any incorrect one.

26 The recipe of walking through the walls may work for you! Keep an eye on the goal. Believe in yourself. Pay no attention to the obstacles. And be sure to seek help and support when you need it!

Welcome to PHYS 201 Modern Physics Fall 2018

Welcome to PHYS 201 Modern Physics Fall 2018 Lectures: MWF 10:00-10:50 am Fridays 2:00-2:50 pm Co-requisite PHYS 251 Experimental Atomic Physics Textbook Required text: Modern Physics by R. A. Serway,