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Concluding Comments For the Course
Cosmology
• Fascinating Past
• Highly accomplished present (for example, the material covered in this course).
• Really exciting future
The History of the Universe Today
Galaxy Formation
Last Scattering
Nuclear & High Energy Physics
Inflation?
Extra Dimensions?
Time
High Energy & Temp
Anti-Gravity?*!
Concluding Comments For the Course
Cosmology
• Fascinating Past
• Highly accomplished present (for example, the material covered in this course).
• Really exciting future
Concluding Comments For the Course
Cosmology
• Fascinating Past
• Highly accomplished present (for example, the material covered in this course).
• Really exciting future
Atomic energy levels
Emission
Absorption
Present: Deep understanding of our universe comes from
1) Application of known laws of physics
Present: Deep understanding of our universe comes from
3) Putting Data and physics together to get the big picture Big Bang Theory
What we know about the big picture
1) On large scales the matter in the Universe is spread out very smoothly (“Homogeneous”)
Mean density:29 310 /gram cm
2) The Universe is expanding
Hubble law: v Hr
3 / sec
100
mH
lightyears
The homogeneity of the Universe
Isotropy of the microwave background (from the “edge of the observable universe”) to one part in 100,000
Galaxy
The History of the Universe Today
Galaxy Formation
Last Scattering
Nuclear & HEP
Inflation?
Extra Dimensions?
Time
High Energy & Temp
Anti-Gravity?*!
Present: Deep understanding of our universe comes from
4) Exploring and observing consequences of the Big Bang such as
CMB: The edge of the observable universe
The Edge of the Observable Universe:
As we look back in space we look back in time. We see:
Here & Now
Light traveling from far away =from distant past
Long ago (about 14 Billion years) the Universe was so hot and dense it was opaque: The edge of the observable universe
Today:• Only 2.726K above absolute Zero
• “Microwave Radiation” (The “Cosmic Microwave Background”: CMB)
• 1,000,000 times weaker than ambient radiation in a pitch dark room.
Properties of the Edge of the Observable Universe:
Here & Now
Similar to surface of Sun at time of emission
(~ 6000 )K
Today:• Only 2.726K above absolute Zero
• “Microwave Radiation” (The “Cosmic Microwave Background”: CMB)
• 1,000,000 times weaker than ambient radiation in a pitch dark room.
Properties of the Edge of the Observable Universe:
Here & Now
Similar to surface of Sun at time of emission
(~ 6000 )KCools off due to cosmic expansion
Same thing happens with stars “Oblers’ paradox” (see section 23.4)
The History of the Universe Time
High Energy & Temp
New Image of the “Last Scattering Surface” from NASA’s WMAP satellite released Feb 11 2003
2009
Updated after WMAP announcement, Feb 2003
Real data
Simulated data
Real data !
1993
Maps of the microwave sky (the “edge of the observable
universe”
WMAP map of the “edge of the
observable universe”
plotted as a sphere
Note: we are really on the inside looking
out
Present: Deep understanding of our universe comes from
4) Exploring and observing consequences of the Big Bang such as
Formation of Nuclei
The History of the Universe Today
Galaxy Formation
Last Scattering
Nuclear & High Energy Physics
Inflation?
Extra Dimensions?
Time
High Energy & Temp
Anti-Gravity?*!
Present: Deep understanding of our universe comes from
5) New ideas such as cosmic inflation that seem to explain the start of the Big Bang and fit the data nicely
• Characteristic oscillations in the CMB power
Adapted from
Bennett et al Feb 11 ‘03
WMAP
“Active” models
Inflation
I.1 Successes
Tem
pera
ture
Pow
er
Angular scale
Cosmic acceleration (newest data)
Using supernovae (exploding stars) as cosmic “mileposts”, acceleration of the Universe has been detected.
Supernova
Preferred by modern data
Amount of gravitating matter
A
mount
of
“anti
gra
vit
y”
matt
er
“Gravitating” non accelerating matter
Here for inflation
Supernova
Preferred by modern data
Amount of gravitating matter
A
mount
of
“anti
gra
vit
y”
matt
er
“Gravitating” non accelerating matter
Here for inflation
Accelerating “Dark Energy” is what makes U=1 (required to give consistency with inflation)
Acceleration or (required for inflation) is possible (+)
Dark Energy *very* poorly understood (-/+)
Dark Energy (accelerating)
70%
Dark Matter 25%
Ordinary Matter (observed in labs)
5%
95% of the cosmic matter/energy is a mystery. It has never been observed even in our best laboratories
The future is exciting because
2) Fantastic new data sets will enable us to explore these mysteries (and hopefully resolve some of them)
The future of cosmological data
•The James Webb (Next Generation) Space Telescope
Proposed Launch Date:
August 2011
Supernova
Preferred by modern data
Amount of ordinary matter
A
mount
of
“anti
gra
vit
y”
matt
er
“Ordinary” non accelerating matter
Here for inflation
Proposed new experiment
The SNAP Satellite
The future of cosmological data
• The LSST (Large-aperture Synoptic Survey Telescope) NB: the director of LSST is Prof Tony Tyson of UCD
The future of cosmological theory
• The new data will allow us to resolve hotly contested issues
• Expect progress on:
•Can we explain/understand the beginning of the universe?
• What is accelerating the universe?
• What caused the galaxies to form?
•What is the fundamental nature of matter and gravity?
For the future:
-I hope this course has made you better able to understand new results as they are reported in the press.
-Feel free to come around to my office hours at any time in the future with questions.
- Perhaps some of you would like to make a career in cosmology research (feel free to see me & discuss that)