Cosmology

Weak gravitational lensing is a powerful probe of modifications of General Relativity on cosmological scales, since such modifications can affect both how matter produces gravitational potential wells and how photons move within these wells. I will discuss alternative theories of gravitation and how we may constrain such theories using weak lensing observables, including those that could be obtained with the balloon-borne High Altitude Lensing Observatory (HALO). I will also discuss the "parametrized-post-Friedmannian" approach for obtaining model-independent constraints, in which new parameters are introduced to characterize the departure from General Relativity on large scales.

Over the last decade our picture of the universe has changed almost as much as it had in the preceding century. As a result, our picture of the future, both of the universe, and life within it, has dramatically altered as well. This talk will begin by reviewing the recent revolutionary developments in cosmology, and then address several fascinating questions that have arisen as a result of our discovery that the dominant energy of the universe resides in empty space: Can life be eternal in an eternally expanding universe,? Are the laws of physics tailored for the existence of life? What will science in the far future tell us about the universe?

What do we really know about the universe? What mysteries are today's top cosmologists investigating? Join a discussion with leading cosmologists to hear fresh perspectives on some of the deepest questions in modern science: What is the mysterious dark matter that fills intergalactic space? Was there another universe before the big bang, and what will happen to ours in the distant future?

One of the most obvious facts about the universe is that the past is different from the future. We can turn an egg into an omelet, but can't turn an omelet into an egg. Physicists have codified this difference into the Second Law of Thermodynamics: the entropy of a closed system always increases with time. But why? The ultimate explanation is to be found in cosmology: special conditions in the early universe are responsible for the arrow of time. This talk will be about the nature of time, the origin of entropy, and how what happened before the Big Bang may be responsible for the arrow of time we observe today.

Cosmology and cosmological implications of quantum gravity. Observable effects in cosmology help to identify the limits of general relativity, which could potentially be surpassed by modified theories of gravity and/or quantum gravity.

Cosmology of the early universe; theory and detection of gravitational waves, e.g. from the violent last stages of inspiral as two orbiting black holes coalesce. Using cutting edge quantum physics in designing practical, ultra sensitive gravitational wave detectors.

What, exactly, happened around the time of the Big Bang? Exploring new models inspired by superstring theory and supergravity, e.g. ones in which we live on “branes” that collide with a “big bang”. Satellite experiments to test such models.

String- and M-theory inspired scenarios for the cosmology of the early universe. Replacing the unphysical Big Bang-like beginning of our universe with bouncing scenarios of accelerated expansion followed by familiar evolution.

Theoretical models for cosmology – from standard to exotic (e.g. cosmic strings and monopoles). “Quantum creation” of multiple universes out of nothing; eternal inflation and the anthropic selection of a world that would ultimately become hospitable to life.

Observational cosmology, with particular focus on the formation and evolution of large scale structures in our universe like clusters of galaxies as large as 500 million light years. “Weighing” the universe, and mapping out the mysterious dark matter it contains.