History of the Universe. Inflation, the Problem Solver. A. Horizon Why is the CMB radiation so isotropic? Flat Universe Why is the density of the Universe so close to critical? Structure Where does structure come from? GUTs suggest that Universe did undergo inflation.
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A. Horizon Why is the CMB radiation so isotropic?
Flat UniverseWhy is the density of the Universe so close to critical?
Structure Where does structure come from?
GUTs suggest that Universe did undergo inflation
strong nuclear force separates
extreme pressure overwhelms gravity
A. Horizonwhy is the CMB radiation so isotropic?
observe … temp is 2.725 K with variation of 1 part in 100,000
in BB … two points in opposite directions could look different
Universe tiny in past
cannot observe A+B
can observe A+B
B. Flatness why is the density of Universe so close to critical?
observe … matter density is 27% critical
in BB … no reason why density close to critical
Universe HAS to look flat if you inflate fast
C. Structure where does structure come from?
observe … CMB not completely uniform
observe … galaxies/clusters exist
in BB … quantum ripples in early Universe much too small
inflation superstretches ripples into macro sizes
REQUIRES DARK MATTER
Virial Theorem: for stable, self-gravitating, spherical
distribution of equal mass objects:
KE = –1/2 PE
KE per galaxy = 1/2 mgv2
KE of N galaxies = 1/2 Nmgv2 = 1/2 Mcv2
PE per galaxy = –1/2 Gmgmg/R
PE of N galaxies = –1/2 GNmgNmg/R = –1/2 GMc2/R
Assume random orbits (no preferred rotation):
1/2 Mcv2 = 1/4 GMc2/R
Mc = 2 v2R/G yields “Virial Mass”
(with lots of galaxies, can see how VM changes with radius)
HST/ACS images of 8X full moon
ground-based opt/ir/rad +
measure shapes of half million galaxies
to reveal “weak lensing”
dark matter clumps over time