Dark Energy
What is dark energy?
• Theorized force
opposing gravity.
• This force would
accurately explain the
current accelerating
expansion of the
universe.
• Possible it might be
related to the inflation
period of the early
universe.
Supporting Evidence
• Measurement of supernovae type Ia,
SN1997ff, actually predicted to be brighter
than it appears in space, thus providing
evidence that universe is expanding.
other Defining Properties
• Dark Energy is said to be uniform through
out space
Supporting Fact
• CMB anisotropy indicate the universe is
flat.
• Thus, matter density + energy density =
critical density.
• But, matter density only contributes 1/3 of
the critical density!
• So, in order for energy density to have
escaped detection it must be distributed
uniformly.
Importance of Dark Energy
• Currently it is estimated that the
composition of the universe is approx.
70% dark energy
• 25% dark matter
• 2-5 % matter (stars, H, He, neutrinos,
heavy elements)
Importance of Dark Energy
• Possibly predict the future of the universe.
• If repulsion from dark energy becomes
strong, could potentially lead to a Big Rip.
• Or, a variable dark energy might fade
away and then flip into a future that pulls
the universe together rather then pushing
it apart, into a Big Crunch
References
• Dark Energy and the New Cosmology,
http://supernova.lbl.gov/~evlinder/turner.pdf
• Dark Energy by Wikipedia
http://en.wikipedia.org/wiki/Dark_energy