Origin of
Universe Big Bang
Big Bang
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Big Bang Event created space and
time
Happened roughly 15 Billion YA
No time before and no space
outside of it
Explosion occurred everywhere
filling all space from the beginning
with energy.
At instant of Big Bang, universe
was infinitely dense and hot
Big Bang II
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Immediately after Big Bang:
Universe consisted of primarily
radiation with some matter
From extremely dense and hot
beginning, universe expands and
the matter begins to cool
As it expands matter dominates
within 1,000 years of the beginning
Big Bang III
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First few seconds:
Photons of radiation collide and
convert energy into mass
Protons, electrons, and neutrons
formed
Universe cooled from 100 million
trillion trillion degrees to 10 billion
degrees
Big Bang IV
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After three minutes:
Temperature falls to one billion
degrees
Protons and neutrons combine to
form the nuclei of helium, deutrium,
and a few other light nuclei.
Temperatures were too high for
other elements to form
Big Bang V
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After 300,000 years:
Universe cooled to 3000 degrees
Electrons combine with atomic
nuclei to form neutral atoms
Proton + electron = H atom
2 p + 2 n + 2 electron = He atom
From this time radiation is unable
to interact with gas.
Background microwave radiation
now at 3 degrees Kelvin
Big Bang VI
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Stars and Galaxies:
After one billion years:
Small perturbations in the matter
resulted in condensation
Stars formed from condensation of
matter
Stars have conditions to form the
rest of the elements.
Evidence for
Big Bang
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1. Universe is expanding and
cooling
2. Theory predicts 25 % of total
mass should be helium
3. Cosmic Background Radiation
4. Collapse of matter to form
galaxies and stars
Universe is
Expanding
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Hubble Expansion Law
1929 - almost all galaxies
appeared to moving away from us
Observation - red shift in spectrum
Red shift larger in faint galaxies
(further away and moving faster)
Red Shift or
Doppler Effect
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If object moving away-light waves are
stretched toward red spectrum
If object moving toward -waves are
compressed toward blue spectrum
Doppler Shift
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Lines in spectra move left for blue shift
and move right for red shift
Blue shorter wavelength, red longer
Red Shift or
Doppler Effect II
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Amount of shift depends on speed
The faster an object moves, the
greater the doppler shift
Example: an emission line of hydrogen
is shifted less by close galaxies than
faraway ones.
This means faraway galaxies are
moving faster than nearby ones.
Sound of train whistle works the same
Abundance of Light
Elements
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Observed abundances of:
Hydrogen Deuterium, helium, and
lithium
Formed in first 3 minutes of big
bang
Helium calculated to be 25% and
observed in that amount
These elements are not produced
in required quantities in observed
stellar fusion
Cosmic Microwave
Background
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The thermal spectrum of CMB was
predicted before its observation
Expansion caused the hot universe
to cool as it spread out
Radiation thinly spread to its
present temperature of 2.7
degrees Kelvin
Observed as uniform background
microwave radiation at peak
wavelength of 1 mm- detected with
a RadioTelescope
Formation of
Galaxies
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At 10,000 years, temperatures fall
so that massive particles begin to
dominate
Gravitational forces begin to
dominate
Stars form from the increasing
density of matter
Clusters of stars form galaxies
Conclusion
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The Big Bang theory is one of the
most strongly supported theories in
all of science.
It explains the observed facts
It has made successful predictions;
It has stood the test of time;
There is no alternate theory that
the professional scientific
community deems valid.