1. Lecture 41 – Cosmology- Final Remarks
We can see objects (galaxies, supernovae) at huge distances in space and time. A z=1 galaxy is at a distance of 8.6 billion light years.
The brightness of an object at such a distance depends on how much the universe has expanded since that time

2. What is found for Type Ia SN

3. The Expansion of the Universe is Accelerating
Not explicable in terms of a Friedmann universe
Behavior requires addition of “Cosmological Constant” to the theory
Physically, corresponds to “Dark Energy”, an energy field the produces long range, repulsive force
Dark energy can contribute to Omega, make it 1

4. Contemporary “Precision” Cosmology
Omega of Baryonic matter = 0.02 – 0.05
Omega of all matter = 0.33
Omega of Dark Energy = 0.67
Age of Universe = 13.7 Gyr
Inflation occurred 1E-34 sec after Big Bang, during which universe puffed up by factor of 1E+25
Total = 1

5. In spite of precision, still some (very) unsatisfactory aspects
Nature of the Dark Matter unknown. When (if ever) will we confirm its existence in a laboratory?
Nature of the “Dark Energy” is completely unknown

6. Implications for our view of ourselves
“The Realization that the majority of the matter in the universe might be non-Baryonic is the ultimate Copernican viewpoint; not only are we in no special place in the universe, but we aren’t even made out of the same stuff as dominates the matter density of the universe.”
Andrew Liddle – An Introduction to Modern Cosmology