cosmology equipped with his five senses, man explores the universe around him, and calls the...
Post on 19-Dec-2015
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Cosmology
Equipped with his five senses, man explores the universe around him, and calls the adventure "science".
-- Edwin Powell Hubble
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Distance scales
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Cosmic Distance Scale
Hubble’s Measured Rate of Expansion
v=H0r
H0=72 km/(sec Mpc)
The Big Bang Framework
CMB Redshift z = 1089
Quasar Redshift z= 6.4 Change in size of space = z+1
Key Observations Explained
"NASA/WMAP Science Team” http://map.gsfc.nasa.gov/m_mm.html
• CMRB temperature and lumpiness
• flatness of space
Large Scale Structure
The distribution of galaxies in a slice of the SDSS spectroscopic survey. (A. Pope, JHUhttp://cas.sdss.org/dr2/en/astro/structures/structures.asp)
Geometry of Space
But how is the rate of expansion changing?
Astronomers set out to measure the recessional velocities of very distant objects to find out how the expansion rate may be changing.
If space is flat and the universe is dominated by matter, our rate of expansion should be slowing down.
closed open flat
exp
ansi
on
Evidence for Acceleration
An Accelerating Universe
Best Model of Mass-Energy Density
4% Visible matter 23% Dark Matter
73% Dark Energy !