Informazioni sul corso. • h p://www.fisica.uniud.it/~deangeli/corsi.html. • Scopo:
Discutere argomen speciali di ele romagne smo, con un cenno alla.
Fisica 3 (2013/14)
Alessandro De Angelis Univ. Udine, INFN/INAF Trieste & LIP/IST Lisboa Lezione 0
Informazioni sul corso h�p://www.fisica.uniud.it/~deangeli/corsi.html Scopo: Discutere argomen� speciali di ele�romagne�smo, con un cenno alla visione moderna. Formulazione covariante delle equazioni di Maxwell, radiazioni da par�celle accelerate, propagazione e quan�zzazione della radiazione ele�romagne�ca Insegnante: Alessandro De Angelis. Ricevimento: martedi’ 16:30-‐18:00 (o scrivetemi all’indirizzo
[email protected] ) Capitano del corso: Giovanni Soldà
[email protected] Orario: Lun e Mer dalle 13:00; Mar dalle 12:40
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Introducing myself…
Professor of physics at the University of Udine and at IST Lisboa, I am Chairman of the MAGIC gamma-‐ray telescope in La Palma (Canary Islands), and member of the collabora�on managing the Fermi gamma-‐ray satellite
Main interests: HE par�cle astrophysics (in par�cular with gamma rays) and fundamental physics with accelerators
Graduated in Padova (bubble chamber physics), post-‐doc (calibra�on and commissioning of a calorimeter) and then research associate and staff member at CERN (1993-‐1999) – Responsible of the so�ware for physics analysis of the DELPHI experiment at LEP. Wrote the first HEP paper using ar�ficial Neural Networks
Comeback to Italy in 1999, moving to gamma-‐ray astropar�cle physics (simula�on, so�ware, physics analysis) – Fermi satellite (then called GLAST), from NASA – MAGIC telescope, in Canary Islands. Scien�fic coordinator from 2005 to 2007
Author or co-‐author of more than 600 scien�fic publica�ons
Courses lectured during the recent years: Electricity and Magne�sm, Quantum Physics, Quantum ChromoDynamics, Astropar�cle Physics, Par�cle Physics 3
Course material No textbook is required, as a photocopy of the material corresponding to the lectures will be provided by the teacher to the responsible of the class or sites to download will be provided. Useful references follow:
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Evalua�on Homework: Students will be divided in groups of 2. During the semester sets of 2 exercises will be assigned to each group; the solu�ons will be discussed in the class ~1 week later (please prepare your solu�ons in a projectable format, ppt or pdf, and give them to the course coordinator). No evalua�on, but mandatory if you want to face the final test. Final test: 2 hours, free answer ques�ons and problems (similar to the homeworks). No books allowed (just one a4 page). Chance to do the final test on January 7th for the students who will do the homework Marks: Final test. Possibility of an oral examina�on if requested by the student. A�er the final test of Jan 7, oral examina�on including problems during normal examina�on seasons (Feb/Jul/Sep/Feb).
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Clouds At the end of the XIX Century, physics appeared to be at an apex William Thomson a.k.a. Lord Kelvin (1824-‐1907) in an address to the Bri�sh Associa�on for the Advancement of Science in 1900, said “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.” But later “The beauty and clearness of the dynamical theory, which asserts heat and light to be modes of mo�on, is at present obscured by two clouds. The first came into existence with the undulatory theory of light, and was dealt with by Fresnel and Dr Thomas Young; it involved the ques�on, How could the Earth move through an elas�c solid, such as essen�ally is the luminiferous ether?” 7
A cloud shielding light Studies on electromagne�sm mainly by Cavendish, Coulomb, Ampere, Faraday lead to the famous book “A trea�se on electricity and magne�sm” by J.C. Maxwell, published in final form in 1873 The electric and magne�c fields can be calculated from a set of 4 equa�ons, which in vacuo are
The dynamical effect on a charge is F = q (E + v x B) 8
Light Maxwell’s equa�on imply a wave propaga�on in-‐vacuo of the E, B fields:
(and the same for B), with the speed of the wave given by (ε0µ0)-‐1/2 Quo�ng Maxwell, “We can scarcely avoid the conclusion that light consists in the transverse undula�ons of the same medium which is the cause of electric and magne�c phenomena” 9
A complete theory; is it consistent? Only Einstein realized, 30 years later, that Maxwell’s equa�ons were inconsistent with mechanics The argument is subtle, and related to the exchange of reference frames => Maxwell’s equa�ons were defining a privileged reference frame 10
The other cloud is related to quan�za�on The spectra of light emi�ed by hot gases were discrete Nothing in the physics known at that �me could explain such a behavior
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