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History of the Universe

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A. HorizonWhy is the CMB radiation so isotropic?

Flat UniverseWhy is the density of the Universe so close to critical?

StructureWhere does structure come from?

GUTs suggest that Universe did undergo inflation

Milky Way

Solar System

phase transition

strong nuclear force separates

extreme pressure overwhelms gravity

Electroweak

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

smaller than

proton

cannot observe A+B

can observe A+B

B. Flatnesswhy 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. Structurewhere 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

1.0 Byr

3.5 Byr

13.7 Byr

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 +

space-based XMM-Newton

measure shapes of half million galaxies

to reveal “weak lensing”

conclude:

dark matter clumps over time

?