1. Cosmological Expansion and Dark Energy

2. Spectroscopy and Redshift
Everything known about the universe comes from what we can see.
Spectroscopy tells about composition, among other things.
The redshift, z, is
Redshift tells about relative motion, rotation, etc.
It turns out that nearly everything is redshifted.

3. Hubble Law
In 1920s, Edwin Hubble finds that redshift is proportional to distance.

4. Hubble Law
(phys.org)

5. Cosmological Expansion
This redshift is not due to relative motion, but due to the universe itself expanding (cosmological redshift).

6. Expansion Rate is Increasing
2011 Nobel Prize in Physics awarded to Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess (for their work from 1997)
"for the discovery of the accelerating expansion of the Universe through observations of distant supernovae“ (nobelprize.org).

7. What is causing this? Dark Energy
Term coined by Michael Turner in
Doesn’t interact with light (dark)
Pushes things apart.
Does not clump together like matter (smooth).
Very mysterious…How can we understand this?

8. Dark Energy Survey (DES)
Over 120 scientists from 23 institutions in 5+ countries.
Started 2013, ends 2018.
Uses the Dark Energy Camera (DECam) in Chile.
(darkenergysurvey.org)

9. Dark Energy Survey (DES)
Mounted in Victor M. Blanco Telescope
Looks at
Type 1a Supernovae (cosmic acceleration)
Baryon Acoustic Oscillations (cosmic acceleration)
Galaxy Clusters (structure and expansion)
Gravitational Lensing (dark matter)
(darkenergysurvey.org)

10. The Q Continuum
Simulation being performed on the Titan supercomputer at U.S. DOE’s Oak Ridge National Lab. (October 29, 2015)
Models large scale structure of Universe.
Involves half trillion particles; from 50 My after Big Bang to present. Over 90% of Titan’s Computational power used.
(phys.org)

11. Associated with Dark Energy
What is the geometry of the universe?
Flat? (Euclidean)
Closed? (spherical)
Open? (hyperbolic)
How did it start? (Did it start?)
How will it end? (Will it end?)
Big Rip
Big Crunch
Big Bounce