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Modern Physics PHGN 300 Fall 2009

Prof. Lawrence Wiencke

Welcome to Modern Physics!! PHGN 300 Fall 2012

Prof. Lawrence Wiencke TA Xiaoning Zang

Syllabus Organizational, Grading Short Survey Science and Engineering before Modern Physics http://inside.mines.edu/~lwiencke/PH300/F12 Or google mines ph300 2012

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PHGN 300 Topics • Review of Waves

• Special Relativity

• Light Quanta

• Atomic Models

• Intro to Quantum Mechanics

• Quantum Structure – Atoms, Solids

Solid State Devices

• Nuclei and Nuclear Physics

• Particle and Astrophysics

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1895

– First Electric Light Systems

– Moving Picture Projector

– First Automobile Race in US

– 1st female PhD in science earned

(Caroline Willard Baldwin) – Cornell

Most of the Physics Research –

Great Britain, Germany, France

Classical physics by the end of the 19th century

• Mechanics: – Galileo 1564-1642 ; Newton 1642-1727…

• Electromagnetism: – Coulomb 1736-1806 ; Ampere 1775-1836 – Faraday 1791-1867 ; Maxwell 1831-1879…

• Thermodynamics: – Carnot 1796-1832 ; Kelvin 1824-1907…

Kinetic Theory of Gases

• Thermodynamics and “atomic” theory of matter – Gay-Lussac 1778-1850: ideal gas: PV=nRT – Avogadro 1776-1856: the Avogadro number – 1895’s: Maxwell-Boltzmann velocity distribution

• It works… but, in 1895, nobody knows what an atom really is !

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1895

The atom considered fundamental unit of matter

• Inaccurate description

• Nucleus not yet discovered

no nuclear physics/engineering

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1895

No fundamental particles had been discovered

• No electron, muon, ..

• Also no proton or neutron

Higgs Boson (2012)

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1895 (II) • No Quantum Mechanics

– Deterministic philosophy

– Statistics and probability - motivated by???

– particle wave duality not understood

No Special Relativity

– But the speed of light had

been measured

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1895 (II)

• Astronomy – yes

– Spectroscopy of sun and stars

– Astrophysics – Newtonian

– Sun’s energy from gravity?

– Milky Way was the Universe

− no galaxies)

• Great debate about Nebula still 25 years away

– No Cosmology, No astro-particle physics

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Chemistry: First Periodic Table of elements ~1870 Dmitry Meldeleev

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Mechanical Engineering Steam power, industrial revolution

Strong material widely available – Steel

1890 – First US patent for ARC welding but no X-ray inspections

Electrical separation process for Aluminum invented in late 1880’s

Control systems existed limited to mechanical, hydraulic

No plastics, no lasers, no electronics No computer aided nothing

Engineering Hall 1894

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Materials Science

• Many metals known and studied

– Particulate and chemical/extraction metallurgical-and-materials processing

• No atomic physics

• No electron microscope

– (no electrons!)

• Band-Gaps? Photovoltaics

– Nano-Structures? Yeah, right.

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Electrical Engineering

• V and I really big

• Few buildings had electricity

AC (Westinghouse) vs DC (Edison)

• How is charge carried?

• Vacuum tubes just starting

• No transistors, circuit boards

• Maxwell’s equations known

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Electrical Engineering 1895

Phys. Rev. (Series I) 3, 49 (1895)

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Math/Computer Science • Mathematics – well ahead of the physics

– Calculus (Newton)

– Number theory, Group theory, Set theory,

– Euclidean and non-Euclidian geometry

– Complex variables

– And even many of the equations known for hundreds of years

• – Legendre polynomials, Taylor series

– World wide Application?

− Celestial Mechanics (navigation)

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Math/Computer Science •

• Calculations done by hand

– with look-up tables.

• No computers

– Hollerith Tubulator machine

– Idea described (Babbage)

– Idea of mechanical computations not pursued

– No transistors, no atomic physics

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1895 Hints and Hot Topics Discovery of Helium

– Structure in spectra of heated gasses (and stars)

– Propagation of Radio Waves

• What exactly is waving?

– Relation between Temperature and Color

• Can’t be reproduced by classical theories

– Nature of light

– Kinetic Theory of Gasses

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1895 Start of Revolution of concepts

• VERY FAST:

– Special relativity replaces Newton mechanics

• VERY SMALL:

– Quantum physics replaces Newton mechanics

• VERY LARGE:

– General relativity replaces Newton gravitation