11/2/10. Physics. May the Force be With you Obe Wan Konabe. Video. A Typical Physics Problem. A gun mounted on a moving traincar.

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1 Physics May the Force be With you Obe Wan Konabe Video A Typical Physics Problem A gun mounted on a moving traincar. 1

COURSE MODULE INFORMATION Dr Rick Goulding C3004 rgoulding@mun.ca 864 6111 Course WEB PAGE: www.physics.mun.ca/~rgoulding/index.html Here you will find course notes and other material.

Physics Believed earth was center of solar system (geocentric) Knew earth was a sphere (Eratosthenes 276 194BC) Aristarchus proposed sun centered (heliocentric) model of solar system Archimedes made

2 COURSE MODULE INFORMATION Dr Rick Goulding C Course WEB PAGE: Here you will find course notes and other material. History of Physics The Greeks Cul[vated the study of Natural Philosophy Aristotle( BC) Student of Plato observa[on of physical phenomena Physical Laws Wrote first Physics book Aristotle s Physics Believed earth was center of solar system (geocentric) Knew earth was a sphere (Eratosthenes BC) Aristarchus proposed sun centered (heliocentric) model of solar system Archimedes made many contribu[ons in fluids and mechanics Ptolemy wrote many scien[fic papers which became basis for later advancement Greeks developed scien[fic method Most of Greek work was lost. Some was salvaged through Islamic philosphers who reinterpreted the Greek in the context of their religion. 2

Galileo Galilei The Rise of Physics and mathema[cs Knowledge was dominated by Law, medicine and theology Galileo studied Copernicus and felt that math was the key to understanding the mo[on of the

) >big job >publica[ons Dialogue Concerning the Two Chief Worlld Systems > house arrest Galileo started new focus on experimenta[on > start of a new age in science Descartes believed that mo[on was

3 Galileo Galilei The Rise of Physics and mathema[cs Knowledge was dominated by Law, medicine and theology Galileo studied Copernicus and felt that math was the key to understanding the mo[on of the planets. Discovered moons of Jupitor in 1609 (First telescope?) >big job >publica[ons Dialogue Concerning the Two Chief Worlld Systems > house arrest Galileo started new focus on experimenta[on > start of a new age in science Descartes believed that mo[on was due to objects following the influence of corpuscles. Planetary mo[on was caused by vortex mo[on of corpuscles in space. Decartes did not believe that a vacuum could exist. Isaac Newton The Big Picture hjp://en.wikipedia.org/wiki/isaac_newton 4 January March 1727 Built first prac[cal refrac[ng telescope Developed a theory of colour, emperical law of cooling Co inventor of Calculus and Generalized Binomial Theorem Published Principia 1687 Laid groundwork for classical mechanics Law of Universal Gravita[on Newton s Three law s of Mo[on Showed Kepler s laws came from law of Universal Gravita[on Saw the Big Picture!! Principia dominated science for next three centuries!! I saw the cresent. You saw the Whole of the Moon The Waterboys 3

The Middle Years 1750 1900 Calculus and mathema[cal analysis applied to many problems Mid 1800 s, theories of the energy of physics were developed.

4 The Middle Years Calculus and mathema[cal analysis applied to many problems Mid 1800 s, theories of the energy of physics were developed. These theories made physicists rethink how the physical world worked. James Clerk Maxwell (June 1831 Nov 1879) led the way with his Kine[c Theory of gases and his theory of electromagne[c radia[on Showed EM radia[on, light and magne[c fields were all products of the electromagne[c field > second great unifica[on! These two discoveries laid down the groundwork for Modern Physics which was just around the corner! Maxwell is considered to be as great a scien@st as Newton and Einstein! Physics in 1900 The problems: 1. Blackbody Radia[on 2. Photoelectric Effect 3. Certain types of radioac[vity could not be explained 4. An ether around the earth through which EM radia[on was postulated to travel could not be found. 4

Einstein and Quantum Mechanics 1. Special Theory of Rela[vity which gave mass energy equivalence(e=mc 2 ) 2. Postulated that light could be a par[cle which was quan@zed(e=hf).

5 Einstein and Quantum Mechanics 1. Special Theory of Rela[vity which gave mass energy equivalence(e=mc 2 ) 2. Postulated that light could be a par[cle which was quan@zed(e=hf). This was a revolu[onary idea! Neils Bohr used this idea to explain the hydrogen atom and the light frequencies emijed by hydrogen gas. This was the beginning of Quantum Mechanics. This explained the Photoelectric Effect 3. Einstein s General Theory of Rela[vity showed that the force of gravity and mo[on in an accelera[ng frame are indis[nguishable. Homework: Look at THIS VIDEO Rela@vity Cartoon 5

Quantum Mechanics The Roaring 20 s 1. Bohr s idea was expanded to full scale theory in 1920 s. 2. Debroglie(1925)( showed that light could behave as a wave(par[cle wave duality) 3.

6 Quantum Mechanics The Roaring 20 s 1. Bohr s idea was expanded to full scale theory in 1920 s. 2. Debroglie(1925)( showed that light could behave as a wave(par[cle wave duality) 3. Heisenberg s Uncertainty Principle (1927)showed that for very small things you can measure momentum or posi[on but not both. 4. Paul Dirac produced rela[vis[c quantum theory in Theories got more complicated but couldn t quite fit known results. 6. Einstein did not like the probabilis[c nature of quantum mechanics and said I do not believe that God plays dice? What happened next. Quantum mechanics evolved and cumulated in the late 1940s in the quantum electrodynamics (QED) of Richard Feyman,Freeman Dyson, Julian Schwinger and Si I[roTomonaga. Feynman, Schwinger and Tomonaga received the 1965 Nobel Prize in Physics. QED, a quantum theory of electrons, positrons, and the electromagne[c field, was the first sa[sfactory quantum descrip[on of a physical field and of the crea[on and annihila[on of quantum par[cles. It was called Theory of everything! Par[cle physics evolved. Key features were the existance of short lived virtual par[cles governed by the Uncertainty Principle. Par[cles from nothing! Feyman was one of the great minds of science hjp://en.wikipedia.org/wiki/richard_feynman Feynman explaining Atoms The Pleasure Of Finding Things Out(Part1) The Pleasure Of Finding Things Out(Part2)) 6

7 What keeps protons in nucleus together? Repulsive force is very strong! Yukawa predicted existence of a powerful but short range force carried by a par[cle called a Pion whose size was bigger than an electron but smaller than a proton. Pion was discovered in 1947 as were many par[cles such as the neutron and positron. Par[cle accelerators built to search for new par[cles Stanford Linear Accelerator Murray Gell Mann and Zweig proposed that protons, neutrons were composed of smaller par[cles called quarks. It is impossible to see a free quark! 7

Standard Model Quantum Chromodynamics The Standard Model was finalized in the 1970 s which [ed together

Par[cle accelerators have confirmed most parts of this model A theory called string theory holds promise

This theory requires strings of size much smaller than anything we know and 11 dimensions!

depending on how they vibrate, they might be seen in 3 dimensional space as majer, light, or gravity.

8 Standard Model Quantum Chromodynamics The Standard Model was finalized in the 1970 s which [ed together all forces except for gravity. Par[cle accelerators have confirmed most parts of this model A theory called string theory holds promise to bring gravity into the fold. This theory requires strings of size much smaller than anything we know and 11 dimensions! These strings vibrate Strings become Membranes These "strings" vibrate in mul[ple dimensions, and depending on how they vibrate, they might be seen in 3 dimensional space as majer, light, or gravity. It is the vibra[on of the string which determines whether it appears to be majer or energy, and every form of majer or energy is the result of the vibra[on of strings. Five string theories by late 80 s M theory incorporated all 5 string theories. Looks like a very good theory. 8

Professor of Mathema[cs 1669 Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy )

9 Newton s Laws of Mo[on Nature and Nature's laws lay hid in night; God said, Let Newton be! and All was Light. Alexander Pope Sir Isaac Newton Born 1642 in Lincolnshire, England Elected Fellow of Trinity College, Cambridge 1667 Lucasian Professor of Mathema[cs 1669 Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy ) published Elected Member of Parliament 1689 Master of the Royal Mint 1699 President of the Royal Society in 1703 Knighted in Cambridge 1705 Died in

10 Dynamics and Newton s Laws Newton formulated the laws that governed the mo[on of celes[al objects (planets, moons). These are contained in Newton s three laws of mo[on and his universal law of gravita[on These laws correctly described the mo[on of the planets and also predicted the mo[on of Halley s comet. Newton s laws describe the dynamics of objects, what causes that mo[on. 4 2 Newton s First Law of Mo[on Newton s First Law An object at rest or in motion at constant speed remains at rest or in motion as long as no net force acts on it. A force is just a push or pull CONTACT forces arise from physical contact Ac[on at a distance forces do not require contact, ie. Gravity and electric force 10

11 Constant velocity is the natural state of majer. Law of is the natural tendency of a body to remain at rest or in mo@on at constant speed along a straight line. Mass is a measure of iner@a An object has iner[a that resists changes in its velocity. Newton s law is true for all iner[al observers The net force on an object is zero Examples of First Law: The velocity is constant 5 3 Newton s Second Law of Mo[on Forces arise when objects interact Gravita[onal force Fric[onal force Electromagne[c forces Forces have Direc[on Magnitude Force is a Vector 11

12 net force accelera[on Newton s Second Law net force accelera[on mass 12

13 Newton s Third Law When objects interact they exert a force on each other. If object 1 exerts a force on object 2 then object 2 exerts a force on object 1 that is equal in magnitude and opposite in direc[on Lecture 15 Example: Man standing on Earth Example: Two hockey players are standing at center Ice.Big Bob(100kg) pushes Pe[te Pierre(50 kg) with a force of 200N. What is the accelera[on of each player? 13

THE SCIENTIFIC REVOLUTION

THE SCIENTIFIC REVOLUTION REVOLUTION: a sudden, extreme, or complete change in the way people live, work, etc. (Merriam-Webster) THE SCIENTIFIC REVOLUTION Time of advancements in math and science during