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# Physics 362 - PowerPoint PPT Presentation

Physics 362. Modern Physics Seminars. Future arguments. ·         Introduction to Astronomy ·         The Michelson-Morley Experiment ·         Consequences of relativity: relativity and time travel, relativity in everyday life ·         Measuring distances in astronomy and the Hubble law

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### Physics 362

Modern Physics Seminars

• ·        Introduction to Astronomy

• ·        The Michelson-Morley Experiment

• ·        Consequences of relativity: relativity and time travel, relativity in everyday life

• ·        Measuring distances in astronomy and the Hubble law

• ·        X-ray astrophysics

• ·        Nuclear Energy Production

• ·        Alternate energy sources (wind-mills, solar cells, etc.)

• ·        Principles of general relativity

• ·        Neutrinos

• ·        Superconductivity

• ·        Cosmology

• The failure of Classical Physics

• Classical mechanics and electromagnetism

• The Michelson-Morley experiment

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

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

Light for M1

Light for M2

Screen

Light for M2

Screen

Measuring the Refraction Index

Na

Nm

DN·l

Measuring the Refraction Index

Light for M1

Light for M2

Screen

L = thickness

n = index of refraction

 Number of wavelengths in the block (2 times):Nm=2L/ln=2Ln/l

Number of wavelengths in same distance without block:Na=2L/l=2L/l

 Phase change (in terms of wavelengths):DN=Nm -Na=2Ln/l- 2L/l= 2L/l (n-1)

Phase change:DN=2Ln/l- 2L/l= 2L/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.

µDL

Light for M1

Light for M2

DL=Dt·c

Screen

The Michelson-Morley Experiment

Light for M1

Light for M2

Screen

If light from M2 is delayed by Dt

v

u12=c+v

u21=c-v

u13=u31=

3

Beam Splitter

1

Mirror

2

Screen

The Michelson-Morley Experiment

Dt = t121 = t131 = Lv2/c3

• How can we measure the delay?

• There is no reference available that is at rest in ether!!!

• The experimental apparatus is rotated

u12=c+v

u21=c-v

u13=u31=

The Michelson-Morley Experiment

a)

Mirror

3

Beam Splitter

Dta = t121 = t131 = Lv2/c3

1

Mirror

2

Dla = c Dt

Screen

u12=u21=

u13=c+v

u31=c-v

v

The Michelson-Morley Experiment

b)

Beam Splitter

Dtb = t121 = t131 = - Lv2/c3

1

3

Screen

Mirror

Dlb = c Dt

2

Mirror

 Dl = Dla - Dlb = 2Lv2/c2 ~ 0.2 mm

Insert calculation of expected dL