1. Ch. 14 Cosmology (or “The Whole Enchilada”)

2. The Universe on the Largest Scale
A. No evidence for structure
B. Somewhat Homogeneous
1. Strands & voids
2. Similar anywhere, though
C. Isotropic: Same # of galaxies in every direction

4. NRAO - void found in 2007

8. II. The Big Bang
A. Olber’s Paradox - why isn’t
the sky bright?
B. Early 1900’s discoveries
1. Vesto Slipher found most galaxies were red-shifted
2. Edwin Hubble (1923) - distance to galaxies (Andro.)

9. C. Hubble’s Law (1929) 1. Hubble compared his
distances to Slipher’s velocities: v = Hod
2. Galaxy 2x farther/2x faster
3. Hubble “time”:
1/Ho ~ 15 billion yrs.
(assumes constant velocity)

10. D. The Big Bang
All matter & radiation were confined to a single point –the “singularity”, or “primeval atom”.
The point expanded rapidly
The location & velocity of galaxies today is a result of this “explosion” of space

11. The Big Bang

12. 4.Hubble’s Law holds as
viewed from anywhere
Ex/ Coins on a balloon
5. There is no center of the universe- space itself expanded!
Ex/ Raisin bread

13. E. Cosmological Redshift:
A photon’s wavelength is stretched as the universe expands
Ex/ Wave on a balloon

14. III. Cosmic Microwave Background
A. Penzias & Wilson
Bell Labs (1964)
B. Radio hiss was the
leftover radiation of
the Big Bang
C. Universe at 380,000 yrs. old

15. D. Severe redshift
of orig. radiation
E. Current
blackbody temp: 2.7 K
F. Seemed to be smooth, though
G.Proven by COBE (1989) -not smooth

16. COBE

17. WMAP

18. F. Relativity
1. “Space tells matter how to move..
..& matter tells space how to curve”
2. Einstein’s cosmological constant was meant to halt the universe

19. IV. Dark Energy & the Accelerating Universe
Fate of the universe
1. Bound or unbound?
2. Critical density: Mass/gravity
needed to halt expansion
3. Big Crunch
4. Big Chill:
Expansion forever

20. B. Critical density measurements
The ratio of the actual density to the critical density is Ωo.
Ωo < 1 Expansion
Ωo > 1 Contraction
Galaxy counts : Ωo = .01
Ωo = including dark matter (up to 95% MCluster is dark)

21. 1st Direct “Map”
of Dark matter

22. C. Acceleration
2 groups in the ‘90s compared nearby & distant Type I supernovae
Distant galaxies receding less rapidly than Hubble’s Law predicts
Universe is accelerating!!

24. D. DARK ENERGY ??
1. “Vacuum pressure”- force exerted on empty space
2. Only noticeable on very large scales
3. As space expands, greater effect
4. Not matter or radiation. #1 influence on universe a new cosmological constant?

25. E. What We Know
1. Composition
a. 65% Dark energy
b. 31% Dark matter
c. 4% Regular matter
2. The universe is 13.8 billion yrs. old
a. Consistent with globular clusters
(oldest are ~ 12 billion yrs. old)
b. Consistent w/ dark energy

26. 3. Evidence for Inflation!
a. Universe experienced faster than-light expansion early on
(Alan Guth, 1980)
b. Gravity waves expanded
during this “inflation”
c. Imprint of gravitational
waves detected in the CMB (2014)

29. V. M-theory & Before the Bang
A. “M” for membrane?
B. In 1995, Edward Witten united the 5 versions of string theory
C. Had to include an 11th dimension (!)
D. Do membrane collisions create new universes? (i.e. the Big Bang)
E. Do we actually live in
a “Multiverse”???
V. M-theory & Before the Bang

30. F. Penrose / Hawking and the
Singularity
1. Hot, dense point
2. How does one escape a black hole?
3. What is inside a black hole?

31. Deep
Field
2014