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Burkey- ESS
QUIZ Thursday
At the instant of the Big Bang,
all the matter, energy, time, &
space in the Universe was
condensed into a single, tiny
point. We call this Singularity.
Doppler Effect
Occurs when the source of sound waves
moves towards or away
Sound moving TOWARDS
Sound waves compressed
Higher frequency
Shorter wavelength
Sound moving AWAY
Sound waves stretched out
Lower frequency
Longer wavelength
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“Doppler Effect” with Light – is
called Red Shift
Red Shift
This change of light to longer wavelength
Light moving away
This is moving to the red-end of the light spectrum,
not that it’s necessarily red.
Blue Shift
This change of light to shorter wavelength
Light moving towards
This is moving to the blue(violet) end of the light
spectrum, not that it’s necessarily blue.
Radial Velocity
the speed at which objects are
approaching or receding from an
observer
+Positive that it
is receding
-Negative that it
is approaching.
Hubble’s Law
Galaxies that are moving AWAY from us are shifted to the RED end of the spectrum at a speed that is proportional to their distance.
Galaxies that are moving TOWARD us are shifted to the BLUE end of the spectrum
v = radial velocity Ho = constantd = distance to galaxy
v = H0 d
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NOW….
The Big Bang Theory
prevailing cosmological model that explains the
development of the Universe
abundant evidence has been uncovered in support
of the model
~13.75 billion years ago (also the
estimated age of our Universe)
Earth Space Big Bang Theory
I. The Universe was once in an extremely hot and
dense state which expanded rapidly.
II. In an instant, the universe expanded very quickly
III. Then it settled down to a slower rate of expansion,
cooling all the time
IV. After a few minutes it had cooled enough for
protons to form
Big Bang Theory (continued)
V. Hydrogen and helium were the raw ingredients
that were available for making stars
VI. Heavier elements were made inside stars dying
and exploding.
VII. Then newer stars created, many of them like our
solar system with abundance of complex
elements.
Evidence for Big Bang
**ALL was observational
“the four pillars of the Big
Bang theory“ the evidence to
support the theory.
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Evidence #1
The Universe is expanding
As the distance between galaxy clusters is
increasing today, it can be inferred that everything
was closer together in the past. *Red shifting by
Huble’s Law and a dark night sky.
What color is the sky at night?
DARK at night (Olber’s Paradox)
IF the universe were infinite in size, eternally old, and if stars shine all the time, then…
everywhere we look at night, we SHOULD see a star…but we DON’T.
the sky should be as bright as the Sun’s surface all of the time…but it’s NOT
We are surrounded by a cosmic particle horizon beyond which we can’t see.
Solution to Olber’s Paradox:
1. Much of the light is red-shifted
to the extent that the energy is
undetectable in the visible
spectrum..
2. Universe is not eternal. Light from
the most distant galaxies hasn’t had
time to reach us.
Will talk about the 4 pillars tomorrow.
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Edwin Hubble•Observed that nearly all galaxies are moving away from us with red shifting.
Therefore….The universe is expanding.
Hubble’s Law – from this guy!
1929
But, if all the galaxies are
moving away from us,
doesn’t that make us the
center of the universe???
Raisin Bread explains it all…
Cosmological Principle
From every galaxy, at
every time, the universe
looks the same in all
directions. Every galaxy
seems to be at the center
of the universe.
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Evidence #2
Cosmic Background Radiation
The bright intense light from the Big Bang - 13.7
billion years ago, still bathes the cosmos.
Space has a 2.7 Kelvin uniform background radiation temperature
•Wilson & Penzias at 1st thought it was background or “static” •It is believed to be microwave radiation left over from the Big Bang because it is isotropic (everywhere)
Color indicates temperature
http://map.gsfc.nasa.gov/universe/bb_tests_cmb.html
Evidence #3
Universe Composition
The Universe should be in abundances of lighter
elements.
Universe is ~75% Hydrogen, ~24% Helium
Evidence #4
Evolution of the Universe
The Universe is moving and changing. Something
must have started the movement.
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Everything is moving, orbiting,
rotating around and around.
Objects in motion stay in
motion.
Whatever it is, it doesn’t emit or absorb light like normal matter
So we’re calling it dark matter
We think it accounts for 23% of all the matter in the universe
We only can measure ~4%
Pie of matter and energy
[NASA]
Dark Matter – What is it??
So how do we know it’s there?
Dark Matter is such a
huge mass it bends
light. Only know
material.
Acting kind of like a
lens curling light
around it and altering
our view of distant
galaxies.
I LOVE memes!