The cosmic microwave background (CMB), the "afterglow of creation," is a spectrum of 2.75K radiation. Small variations in the temperature at different directions on the sky give us clues to the large scale distribution of matter in the universe, spanning nearly 14 billion years of cosmic history. Small distortions of the spectrum -- departures from a perfect blackbody -- give deeper clues. We are currently using these spectral distortions in fundamental tests of cosmology, to probe theories...
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The physics underlying the accelerated expansion of the universe is unknown. Most of my recent research aims to explore various explanations. Examples include: a dynamical scalar field, quintessence; new gravitational phenomena; and alternative scenarios that dispense with dark energy altogether. My students and I develop these ideas, to make predictions for comparison with observations and experiments.
FACULTY CONTACT: Robert Caldwell
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A few years ago I proposed a new unification between Einstein's theory of general relativity and the weak nuclear interaction. The theory identifies the space-time symmetry of the local Lorentz group with the weak isospin symmetry. Recently in a paper with Marciano and Smolin, we showed that this theory emerges naturally in a first order action principle. In this project we will investigate the cosmological and particle physics implications of this new unification programme.
FACULTY...
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Abstract: The gaseous component of galaxies is a crucial but poorly-constrained aspect of galaxy formation and evolution. I will present results from the Keck Baryonic Structure Survey (KBSS), a unique spectroscopic survey designed to explore both the physical...
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Topic: "Journeys Through Black Holes with Schrodinger's Cat" (Video)
Abstract: We explore some of the properties of black holes and the evidence for their existence. Many puzzles arise when the laws of quantum mechanics are applied to black holes, which are only to be resolved by invoking new physics. Some of the competing hypotheses are described.
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Topic: "Exploring Quantum Phases of Matter with Ultracold Atomic Gases" (Video)
ABSTRACT: Quantum many-body systems frequently exhibit fantastic behavior that is quite different from that of "everyday" forms of matter. Superfluidity, superconductivity, quantum Hall states, and many even more exotic phases of matter are known to occur under the right conditions, but predicting the nature (and even existence) of these states in...
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Topic: "Has Voyager 1 Really Crossed the Heliopause?" (Video)
ABSTRACT: On Dec 3, 2013, a remarkable thing happened, marking a significant step forward for heliophysics: Ed Stone appeared on the Colbert Report announcing that Voyager 1 has crossed into interstellar space. The show was fantastic with both Ed Stone and Colbert delivering their respective A-games! But there is a potential problem with the interpretation. The...
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The Alfred P. Sloan Foundation today announced the selection of Dartmouth’s black hole researcher Ryan Hickox as a recipient of a 2014 Sloan Research Fellowships. He is one of 126 U.S. and Canadian researchers to receive a fellowship this year. The fellowships are awarded to early-career scientists and scholars whose achievements identify them as rising stars, who are considered the next generation of scientific leaders.
“For more than half a century, the Sloan...
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Topic: "Galaxy Collisions in Our Local Neighborhood" (Video)
Abstract: Our understanding of the dynamics of our Local Group of galaxies has changed dramatically over the past few years owing to significant advancements in astrometry and our theoretical understanding of galaxy structure. With the first direct proper motion measurement of M31, its future collision with the Milky Way is the most imminent major cosmic event...
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Topic: "Probing the quantum vacuum with high intensity lasers" (Video)
Abstract: A long-standing prediction of relativistic quantum theory is that a potential step greater than twice the particle mass, Delta V>2m, spontaneously emits charged particles. The same is true of gauge potentials, such as the electromagnetic field: When the electric field strength nears a critical magnitude determined by the electron mass, field...
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