Download Time is Relative

Relativity
Mohammad El-Hilo
Associated Prof. in Physics
PhD in Physics (Magnetism) in 1990
Every thing is
relative,
nothing is
absolute
Albert Einstein
"One thing I have learned in a long
life: that all our science, measured
against reality, is primitive and
childlike -- and yet it is the most
precious thing we have."
"I
Albert Einstein
see in Nature a magnificent
structure... that must fill a
thinking person with a feeling
of humility..."
Every Thing Is Relative
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Motion Is relative
Length and shape are relative
Time is relative
Color is relative (frequency and energy)
Mass is relative
There is a
finite
probability that
the chicken is
still at the
middle of the
road
Erwin Schrödinger
The chicken
crossed the
road or the
road crossed
the chicken?
Albert Einstein
Motion is Relative
Motion of the rocket as
seen by one on earth
Motion of the rocket as seen by
one in a fixed place in space
Length and Shape are Relative
The road
is 9 m
wide as
seen by
the
chicken
The
road is
3m
wide
Rocket is moving at
0.94c relative to the road
Time is Relative (Time Dilation)
A spaceship is flying a distance of 5 light hours, for
example from Earth to the planet Pluto. The clock in the
spaceship goes more slowly than the clock on Earth.
Frequency is Relative
f observed
1 v / c

f source
1 v / c
( Approaching )
f observed
1 v / c

f source
1 v / c
(Re ceding )
The Electromagnetic Spectrum
Frequencies: 4 - 7.5 x 1014 Hz
Wavelengths: 750 - 400 nm
Quantum energies: 1.65 - 3.1 eV
At what speed I
should drive to see
a red traffic light
green?
fsource(RED)=4.8E14Hz
fobserved(Green)=5.6E14 Hz
f observed
1 v / c

f source
1 v / c
( Approaching )
If you approach the traffic light at a
speed of 0.15 C, (12,500,000 km/h)
then you see a red traffic light green
Doppler Effect and Mobile
fsource= 900MHz
fobserved= 900MHz+150 Hz
50 m/s
Gravitational Deflection of Light