Transcript Redshift - drvee.com

Electromagnetic Spectrum
Element Spectrum
• Each element has a spectral “fingerprint”
— a pattern of bright or dark lines that is
UNIQUE to that element.
• Pay attention — there’s a quiz …
Which
element am I?
RUBIDIUM
Redshift: Definition
Specific elements
in atmosphere of
Light from our Sun:
star absorb specific
Photons of all energies (colors)
photon energies,
Low
Energy
Photons
leaving black lines.
High
Energy
Photons
ThePhotons
size of the
lose
redshift
tells and
us
energy
the speed
of red if
become
more
thestar
starisormoving
the
Light from a star or galaxy moving
away
galaxy
away
from us.
from us: WHAT’S DIFFERENT?
Redshift: Definition
Star at rest:
Photon looks
normal
(Alternately: Wavelength is normal)
Star moving
away:
Photon looks
redder
(Alternately: Wavelength is longer)
Redshift: Calculation
Erest = energy of photon from a star that’s not moving
AT REST
E rest  E galaxy
redshift =
E galaxy
velocity of galaxy = redshift  speed of light

MOVING
AWAY

Egalaxy = energy of photon from a galaxy that’s moving away
Redshift: Real Data
VINTAGE VERSION: Spectra
recorded on photographic plates.
These spectra show shifts in a
hydrogen line compared to the
laboratory (at rest) spectrum.
MODERN VERSION: Fiber optic
scanning and full digital spectrum
plots (from the Sloan Sky
Survey)
Galaxy UGC 12915
Galaxy KUG 1750
Galaxy IRAS F09159
Redshift Riot
Complete the worksheet …
Red Shift Riot
km
20,000  0
s
 183
109  0
MYr
BRHS10
Redshift: Interpretation
• We can measure redshift
• Redshift means galaxy is moving away
• All galaxies (except our nearest
neighbors) are redshifted
• All galaxies are moving away
• Therefore, the universe is
EXPANDING
SCIENTISTS ARE NOT
GUESSING !
Expansion of the Universe
We are NOT at
the center of
the Universe
with galaxies
flying through
the Universe in
all directions
Expansion of the Universe
• Space itself is
expanding
• Objects are not
THEN
NOW
Redshift Riot
• Bungee Universe Demo
• Do “Expansion” worksheet
What is the Universe
expanding into?
• The Universe is expanding into nothing
• EMPTY SPACE is still something and has a
here, a there, distances and time.
Here
distance
time
There
• NOTHING has no here, no there, no distance,
and no time.