The Dark Side of the Universe Scott Watson Dept. of Physics Brown University [email protected]
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Transcript of The Dark Side of the Universe Scott Watson Dept. of Physics Brown University [email protected]
The Dark Side of the Universe
Scott WatsonDept. of Physics
Brown University
http://www.het.brown.edu/people/watson/
Cosmic Conundrums
How will the Universe end?
How old is the Universe?
How did the Universe begin?
What is the Universe made of?
The Earth is one of nine planets orbiting our Sun. Itis the third closest to the Sun, and so far it is the onlyplace in the universe where we know there is life.
Large Scale Structure
Analyzing large scale structure provides information about the physics of the early universe!
Large Scale Structure
Quantum fluctuations in the early universe result in the large scale structure we see today!
Cosmic Microwave BackgroundQuick Facts:
• Cosmic microwave background (CMB) primordial light. • 3 degrees above absolute zero (-270 degrees celcius) • mm-cm wavelength• 400 photons per cubic centimeter •10 trillion photons per second per squared centimeter • Few percent of TV "snow" • Temperature slightly different on different patches of the sky - 1 part in 100,000.
Cosmic Microwave BackgroundFluctuations in density give rise to cold and hot
spots in the photon fluid
Not Just a Bunch of Pretty Pics
Power spectrum characterizes
and provides a testing of theoretical
models
Power spectrum measures the
strength of the fluctuations verses their
angular size of the sky
Type Ia Supernovae
Type Ia Supernovae are exploding stars
all of which behave in the
same way.
This allows us to deduce their
distance from us and how fast they are moving away
from us.
•The Universe is Flat!
• The Universe will live forever!
• The Universe is made of 65% unknown energy!
This is the so-called,
DARK ENERGY!
• The Universe is approximately 15 Billion years old!
More to come…
How are we going to figure this one out?
The Dark Energy must have the following properties,– Non-luminous (DARK)– Relativistic energy-like (ENERGY) due to
large negative pressure p<-1/3– Can only clump on scales beyond horizon– Couples to matter ONLY gravitation– Dominates only recently z ~ few (can not
interfere with LSS, BBN)
Detecting the Dark Energy is a SNAP!
SuperNova Acceleration Probe
SNAP will allow us to “weigh” the Dark Energy and deduce its properties