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Physics is Phun November 2005 Einstein and the 2005 Year of Physics

In 1905, at the age of 25, Einstein published papers on Brownian Motion, the Photoelectric Effect, and Relativity.

This achievement has been called the most productive year for any scientist, ever.

The centennial of this event is celebrated as the 2005 Year of Physics

Quote of the Century: "The word ‘genius’ isn't applicable in football. A genius is a guy like Norman Einstein." --Joe Theismann, NFL football quarterback & sports analyst.

In the matter of physics, the first lessons should contain nothing but what is experimental and interesting to see. A pretty experiment is in itself often more valuable than twenty formulae extracted from our minds. -Albert Einstein

Some Reference materials: National Science Foundation web site American Association of Physics Teachers web site University of Maryland Physics Question of the Week web site National Science Foundation web site American Association of Physics Teachers web site University of Maryland Physics Question of the Week web site

Topics for this evening: 1.Brownian Motion 2.The Photoelectric Effect 3.Relativity

Brownian motion: is the small molecular motion inherent in all molecules, even at the lowest possible temperature.

Discovered by botanist Robert Browne ( ) “..in The story goes that Brown was studying pollen particles floating in water under the microscope.” From Wikipedia, the free encyclopedia.

Brownian Motion of smoke particles demonstration

Java applet of Brownian motion

Mechanical Model of Brownian Motion

“More accurate” description: statistical fluctuations requiring ~10,000 net molecular collisions to change particle motion.

Implications of Brownian Motion: 1. Air pressure 2. Diffusion of gases

Reducing Brownian Motion Minimizing molecular motion in atomic clocks increases accuracy of clocks and GPS.

William Phillips Professor of Physics, University of Maryland Nobel prize in 1997 for Laser cooling of atoms Video showing magnetically trapped block of cesium atoms

The Photoelectric Effect: describes the particle behavior of light.

Einstein received the 1921 Nobel Prize in Physics for work on the Photoelectric Effect

E f = h f E = photon energy h = Planck’s constant (~6.6x Joule-sec) f = light frequency

KE e = E f – W = hf - W A single photon of light is absorbed by an electron, causing it to be ejected from the surface of the metal. Graphic from Wikipedia, the free encyclopedia.

Demonstrations 1. Photoelectric effect in zinc 2. Full photoelectric effect

Applications: Solar power Solar engines Solar switches “Hydrogen” economy

2005 Nobel prize in Physics to Glauber, Hall, & Haensch (application of quantum nature of light to build atomic clocks to accuracy and thus improve GPS accuracy )

Relativity: deals in part with frames of reference and how we view physical phenomena.

Physics experiments are fully accurate only in an inertial frame of reference or in a local inertial frame. When might a physics experiment be correct?

Galilean Relativity and the Funnel Cart Demonstration

Local inertial frame of reference demonstration

Einstein’s favorite demonstration

The Speed of Light and the search for a Preferred Inertial Frame of Reference

The Michelson-Morley experiment

1. There is NO preferred frame of reference.

2. The speed of Light is the same in all inertial frames

Applications of Relativity

Michelson Interferometer with White Light Color Mixing: W = R + G + B W – R = G + B = C W – G = R + B = M W – B = R + G = Y

Michelson Interferometer setup using White Light

Michelson Interferometer with White Light

Michelson Interferometer with White Light Full motion of mirror for this video ~10 μ = 0.000,010m = 0.01 mm

We are on the web at Animated Gifs compliments of bellsnwhistles.com The End See you in January!