Physics 362 Modern Physics Seminars Future arguments

Physics 362 Modern Physics Seminars

Future arguments Ø · Introduction to Astronomy Ø · The Michelson-Morley Experiment Ø · Consequences of relativity: relativity and time travel, relativity in everyday life Ø · Measuring distances in astronomy and the Hubble law Ø · X-ray astrophysics Ø · Nuclear Energy Production Ø · Alternate energy sources (wind-mills, solar cells, etc. ) Ø · Principles of general relativity Ø · Radiation processes Ø · Neutrinos Ø · Superconductivity Ø · Cosmology

Today’s seminar n The failure of Classical Physics n n Classical mechanics and electromagnetism The Michelson-Morley experiment

The Michelson Interferometer

Fringe Interference

Parallel Fringes

Fringe position A change in the distance of one of the two mirrors introduces a phase change between the two light beams.

Fringe position When the mirror is moved by ½ l, the path is change by l and the fringe pattern is moved by one fringe.

Measuring the Refraction Index

Measuring the Refraction Index Light for M 1 Light for M 2 Screen

Measuring the Refraction Index Light for M 1 Light for M 2 Screen

Measuring the Refraction Index Light for M 1 Na Light for M 2 Nm DN·l Screen

Measuring the Refraction Index L = thickness n = index of refraction Number of wavelengths in the block (2 times): Nm=2 L/ln=2 Ln/l Number of wavelengths in same distance without block: Na=2 L/l Phase change (in terms of wavelengths): DN=Nm - Na=2 Ln/l- 2 L/l= 2 L/l (n-1)

Measuring Distances Phase change: DN =2 Ln/l- 2 L/l= 2 L/l (n-1) The length of an object can be expressed in terms of the wavelength of light!!! For this experiment A. A. Michelson received the Nobel Price in 1907.

The Michelson Interferometer 1881

The Michelson-Morley Experiment

The Michelson-Morley Experiment Light for M 1 Light for M 2 Screen µDL If light from M 2 is delayed by Dt Light for M 1 Light for M 2 DL=Dt·c Screen

The Michelson-Morley Experiment v Mirror 3 u 12=c+v u 21=c-v Beam Splitter 1 u 13=u 31= Mirror 2 Screen Dt = t 121 = t 131 = Lv 2/c 3

The Michelson-Morley Experiment How can we measure the delay? There is no reference available that is at rest in ether!!! The experimental apparatus is rotated

The Michelson-Morley Experiment

The Michelson-Morley Experiment a) v Mirror u 12=c+v u 21=c-v 3 u 13=u 31= Beam Splitter 1 Mirror Dta = t 121 = t 131 = Lv 2/c 3 2 Dla = c Dt Screen

The Michelson-Morley Experiment b) v u 12=u 21= u 13=c+v u 31=c-v Beam Splitter Screen 1 2 Mirror 3 Mirror Dtb = t 121 = t 131 = - Lv 2/c 3 Dlb = c Dt Dl = Dla - Dlb = 2 Lv 2/c 2 ~ 0. 2 mm

The Michelson-Morley Experiment

The Michelson-Morley Experiment Insert calculation of expected d. L