1. The Nobel Prize in Physics 2011
Bob Nichol (ICG Portsmouth)
“majority of its surface
area is only about 10
feet above sea level”

2. General Relativity Primer

3. Cosmology Primer I
 Assumptions
 Cosmological Principle; not special place, time or physics
 Homogeneous and isotropic; defines “simple” FRW metric
 Assume GR and FRW metric; solve to get Friedmann’s
equations (including Einstein’s Cosmological Constant)
H2
≡
˙a
a
⎛
⎝
⎜
⎞
⎠
⎟
2
=
8π
3
ρ −
k
R2 −
Λ
3

4. Cosmology Primer II
 Hubble discovered
the expansion of the
Universe in 1929
 Einstein dropped his
cosmological
constant
 Next 70 years was
the search for two
numbers!
 “Hubbles’ Constant”
 Density of matter
"0 #
$0
$c
=
8%G
3H0
2
$0
Distance from us
RecessionVelocity
Ω0 =1 for a flat universe

5. Distances and SNeIa
n
Thermonuclear explosions of White
Dwarf stars
White Dwarf accretes mass from or
merges with a companion star, growing to a
critical mass ~1.4Msun (Chandrasekhar)
A violent explosion is triggered at or near the
center, and the star is completely incinerated within
seconds. In the core, light elements are burned in
fusion reactions to produce ~0.6Msun Nickel.
The radioactive decay of Nickel and Cobalt makes

6. Standardizable Candles
A"er
correc(on,
σ~
0.16
mag
(~8%
distance
error)
Kim et al. 1997

7. Industrial Astronomy
Sciama Building
Only ~1 SNe per ~100 years in our Galaxy

8. SN Hubble Diagram (circa 1999)
Sciama Building
ICG only UK institute in SDSS-III
a=1/(1+z)
W
€
Ω0 = ΩM + ΩΛ
€
Ω0 = ΩM + ΩΛ

10. Nobel Prize 2011
"for the discovery of the accelerating expansion of the Universe
through observations of distant supernovae"

11. Baryon Acoustic Oscillations
 Initial fluctuation in DM. Sound wave driven out by
intense pressure at 0.57c.
Initial fluctuation in DM. Sound wave
driven out by intense pressure at 0.57c.
Photons free stream, while baryons
remain still as pressure is gone
Today. Baryons and DM in equilibrium.
The final configuration is the original
peak at the center and an echo (the
sound horizon) ~150Mpc in radius
Illustrations by
Martin White

12. Standard Rulers in the Sky
WMAP 1st year data
First year WMAP
power spectrum
150Mpc

13. Flat Universe
WMAP 1st year data
“Ruler” is 150Mpc and distance to CMB is known to high accuracy (z=1089)

14. Today
Densities known to ~10%

16. Energy of Nothingness!
Coincidence problem?
Log[a0/a(t)]
€
ρDE ~ a−3(1+w)
€
wi(z) ≡
pi
ρi

17. Cosmological Constant
€
ρDE ~ a−3(1+w)
(10120 too small)