1. Origin of Universe - Big Bang
Dr. Charles Ophardt
EDU 370

2. Expanding Universe Big Bang Theory Universe began 15 billion years ago
Began as a huge expansion known as the Big Bang
Space and Time came into existence
All matter started to expand

3. Big Bang Big Bang Event created space and time
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

4. Big Bang II 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

5. Big Bang III 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

6. Big Bang IV 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

7. Big Bang V 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

8. Big Bang VI 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.

9. Big Bang is a Testable Model
Basic Assumptions are plausible
Empirical support
Reasonable sound physical basis
Real test
Does the Big Bang Model explain and make predictions that can be tested against observations?

10. Evidence for Big Bang 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

11. Universe is Expanding Hubble Expansion Law
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)

12. Universe is Expanding II
Hubble Law
H = v / d
H = Hubble Constant
V = velocity
D = distance
Hard to measure the Hubble Constant need velocity from red shift and distance from earth

13. Red Shift or Doppler Effect
If object moving away-light waves are stretched toward red spectrum
If object moving toward -waves are compressed toward blue spectrum

14. Doppler Shift
Lines in spectra move left for blue shift and move right for red shift
Blue shorter wavelength, red longer

15. Red Shift or Doppler Effect II
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

16. Abundance of Light Elements
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

17. Cosmic Microwave Background
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

18. Formation of Galaxies
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

19. Other Theories Steady State Model Postulate no origin to universe
Large scale features are constant
Maintain an average density of galaxies
Whole new galaxies must be popping into existence between old ones

20. Steady State II To explain Cosmic Background Radiation
A whole new class of weak microwave emitting sources must exist (about 100,000 times the total visible galaxies)
Lacks supporting evidence

21. Conclusion
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.

22. Questions I
Describe the universe as a system. Which statement is false?
A. The universe consists of all matter and energy that exists.
B. The universe is that it is mostly empty space
C. The matter of the universe tends to occur in clumps
D. The empty space is small compared to the size of the objects
themselves.

23. Questions II
Which statement about the evidence for the Big Bang Theory is false?
A. Universe is expanding and cooling
B. Theory predicts 25 % of total mass of universe should be helium
C. Cosmic Background Radiation is a measure of the background infrared light
D. Matter collapsed to form galaxies and stars

24. Questions III Which statement about the Big Bang Theory is false?
A. Photons of radiation collide and convert energy into mass
B. Protons combine with electrons to form neutrons
C. A proton combines with an electron to form a hydrogen atom
D. A helium atom is formed from 2 p + 2 n + 2 electron

25. Questions IV Which statement about the Hubble Law is false?
A. Almost all galaxies appeared to moving away from us
B. Hubble Law is based upon the observation of a red shift in spectrum of galaxies and stars
C. The red shift is smaller in faint galaxies since they are further away and moving faster
D. The most inaccurate term in the Hubble Constant is the distance to the object.

26. Questions V Which statement about the Red Shift is false?
A. If object is moving away the light waves are compressed toward the red spectrum
B. If object is moving toward you the light waves are shifted toward blue spectrum
C. Amount of red shift depends on speed
D. The faster an object moves, the greater the doppler shift

27. Questions VI Which statement about the CMB is false?
A. The thermal spectrum of CMB was not predicted before its observation
B. Expansion caused the hot universe to cool as it spread out
C. Radiation thinly spread to its present temperature of 2.7 degrees Kelvin
D. CMB is observed as uniform background microwave radiation at peak wavelength of 1 mm

28. References http://www.astronomynotes.com