t 1 s

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(No Transcript)
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t 1 s d 10 ft V 10 ft/s
t 1 s d 18 ft V 18 ft/s
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Michaelson Morely ExperimentNo Ether
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Results

• No mater when and where they tested it, the speed
  of light was the same.
• Conclusion the speed of light is not relative to
  the motion of the observer the way all other
  waves are.
• The speed of light can change when it goes into a
  new medium, but it would be the same new speed
  regardless of how you were moving.

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Lorentz

• Mathematical exercise what equation would you
  have to use to predict/recreate the results of
  the Michaelson-Morely experiment?
• If V cant change, then have to shrink d and
  stretch t to compensate.

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Einstein

• Believed that Lorentz math isnt just a gimmick
  it describes what is physically happening.
• Einsteins First Postulate Relative motion has
  no influence on the speed of light.
• Consequence Space shrinks and time slows down
  when an object moves.

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According to Buzz
Note Rocket is actually green, but Buzz sees
the color red shifted.
Zippy Slow Motion
Buzz Regular Speed
V 0.95 C
V 0
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Symmetry

• You play a video on the TV in fast forward.
• Suppose its the twilight zone and the people in
  the TV are alive. Would they feel like time had
  sped up in their world?
• What would they see when they look out of the TV
  and watch us?
• Thats the way gravity alters time.
• But

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Zippys point of view?

• That is exactly what DOES NOT happen from Zippys
  point of view.
• Einsteins Postulate 2 rules of physics apply
  to all observers.
• Consequence We already know time depends on
  velocity and velocity depends on perspective. But
  not only do you and I experience different times
  when one of us is moving, we dont agree on who
  is moving, so we dont agree on whose time is
  altered.

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According to Buzz
Zippy Slow Motion and squished
Buzz Regular Speed, Regular Size
V 0.95 C
V 0
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According to Zippy
Buzz Slow Motion and Squished, And the universe
is smaller
Zippy Regular Speed, Regular Size
V - 0.95 C
V 0
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Zippy _at_ .99C
B
Buzz
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Clem _at_ .99C
Z
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Testing It

• Things that go near the speed of light
• Particles in particle accelerators
• Particles spat out by artificial nuclear
  reactions
• Particles spat out by naturally occurring nuclear
  reactions

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Micro Lesson on Radio Active Decay

• Protons, Neutrons, Electrons, and Photons are all
  stable. They stay what they are.
• Unstable particles spontaneously turn into two or
  more other particles.
• Pion ? muon and an anti-neutrino
• Muon ? electron and two neutrinos
• Half-Life tells you how long the particle will
  last before decaying.

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Example

• ?3 seconds means every 3 seoncds, the number
  of particles goes down by 50 of what was there a
  moment ago.
• T 0 64
• T 3 32
• T 6 16
• T 9 8

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Its how carbon-dating works

• Carbon 14 turns into nitrogen 14 with a half life
  of 5,730 /- 40 years.
• Carbon 14 is made in the atmosphere when
  high-energy photons collide with an atom and form
  an extra neutron.
• Some CO2 is made with C12 and some is made with
  C14. We know the ratio.
• C14 turns into N14
• So measuring the current C12 tells us the
  original C14 and knowing the ratio between the
  original C14 and the current N14 tells us how
  long ago the thing stopped absorbing CO2 out of
  the air.

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Back to Muons

• Created in the upper atmosphere when high-energy
  photon (called a gamma ray) hits an atom.
• Has to travel 10 km to reach the surface
• Half-life is 1.5 microseconds

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• 22 half-lives have passed, so divide 1 million by
  2, then divide by 2 another 21 times.
• 0.24 particles out of every million make it to
  the surface.

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Muons without relativity
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Muons With Relativity Earth POV
Muon life in slow motion
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Relativistic MuonsMuon POV
Muon life at regular speed.
Distance to earth surface is less.
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So How Many Do Make It?

• About 49,000

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Cleaning Up the Math Gamma (?)

• ? 1 v 0
• ? 2 v 0.866C
• ? 5 v 0.9798C
• ? 10 v 0.995C
• ? 100 v 0.99995C

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Gamma
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Length Contraction

• L0 is the length as measured by someone who is
  stationary relative to the object.
• The length of a table relative to a student.
• The length of a space ship relative to the pilot

• L is the length of the moving object.
• Length of ship relative to student.
• Length of table relative to pilot

The length of the moving object is always
smaller than what it should be.
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Time DilationMeans seconds get bigger, so they
go slower.

• T0 is the time that passes according to the
  stationary person or clock.
• The student looks at the students watch to time
  an event.
• The pilot looks at the pilots watch to time the
  same event.

• T is the time that passes according to a
  moving person or clock.
• The student looks at the pilots watch to time an
  event.
• The pilot looks at the students watch to time
  the same event.

One second always lasts longer for the moving
clock. i.e. Slow motion.
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• From the earths perspective, what changes
• Distance the muon travels?
• Size of muon?
• Rate of earth time?
• Rate of muons time?
• According to us, how much earth-time has passed
  during the trip?
• According to us, how much muon-time has passed
  during the trip?

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• From the muons perspective, what changes
• Distance the muon travels?
• Size of muon?
• Rate of earth time?
• Rate of muons time?
• According to muon, how far must the earth travel
  to reach the muon?
• According to the muons time, how long does the
  earth take to travel that distance?