Lectures given at the NATO Advanced Study Institute on
Techniques and Concepts of High Energy Physics, St. Croix, USVI (2002).

astro-ph/0301448.

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Columbia University

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New York, NY 10027

kinney@plysics.columbia.edu

**Abstract.** These four lectures cover four topics in modern
cosmology: the cosmological constant,
the cosmic microwave background, inflation, and cosmology as a probe of
physics at the
Planck scale. The underlying theme is that cosmology gives us a unique
window on the
"physics of nothing," or the quantum-mechanical properties of the
vacuum. The theory of
inflation postulates that vacuum energy, or something very much
like it, was the dominant force shaping the evolution of the very early
universe. Recent
astrophysical observations indicate that vacuum energy, or something
very much like it, is also
the dominant component of the universe today. Therefore cosmology gives
us a way to study an
important piece of particle physics inaccessible to accelerators. The
lectures are oriented
toward graduate students with only a passing familiarity with general
relativity and knowledge of basic quantum field theory.

**Table of Contents**

- INTRODUCTION
- RESURRECTING EINSTEIN'S GREATEST BLUNDER
- Cosmology for beginners
- Einstein's "greatest blunder"
- Critical density and the return of the age problem
- The vacuum in quantum field theory
- Vacuum energy in cosmology
- THE COSMIC MICROWAVE BACKGROUND
- Recombination and the formation of the CMB
- Sachs-Wolfe Effect
- Acoustic oscillations and the horizon at last scattering
- INFLATION
- The flatness problem
- The horizon problem
- Inflation
- Inflation from scalar fields
- Density fluctuations from inflation
- The primordial power spectrum
- A worked example
- Inflationary "zoology" and the CMB
- LOOKING FOR SIGNS OF QUANTUM GRAVITY IN INFLATION
- CONCLUSION
- REFERENCES