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Boltzmann babies in the proper time measure

Description: After commenting briefly on the role of the typicality assumption in science, we advocate a phenomenological approach to the cosmological measure problem. Like any other theory, a measure should be simple, general, well defined, and consistent with observation. This allows us to proceed by elimination. As an example, we consider the proper time cutoff on a geodesic congruence. It predicts that typical observers are quantum fluctuations in the early universe, or Boltzmann babies. We sharpen this… more
Date: December 20, 2007
Creator: Bousso, Raphael; Bousso, Raphael; Freivogel, Ben & Yang, I-Sheng
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Probing the Universe with Mirrors That Trick Light

Description: For astrophysicists, stargazing may be different than for most people, who are content to admire a star's beauty or possibly make a wish. More than a few astrophysicists wish they could be closer to the stars--or to at least have more sophisticated probing instruments--to understand more about the universe. Astrophysicists study x-rays originating from our Sun, stars, and supernova remnants to understand the extreme physical processes occurring there. In recent years, Livermore researchers have… more
Date: September 20, 2005
Creator: Hazi, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Numerical Methods for Radiation Magnetohydrodynamics in Astrophysics

Description: We describe numerical methods for solving the equations of radiation magnetohydrodynamics (MHD) for astrophysical fluid flow. Such methods are essential for the investigation of the time-dependent and multidimensional dynamics of a variety of astrophysical systems, although our particular interest is motivated by problems in star formation. Over the past few years, the authors have been members of two parallel code development efforts, and this review reflects that organization. In particular, … more
Date: November 20, 2007
Creator: Klein, R I & Stone, J M
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Partner: UNT Libraries Government Documents Department
open access

Seeing the Universe in a Grain of Dust

Description: Imagine traveling halfway to Jupiter--3.2 billion kilometers--for a small handful of comet dust. That's the mission for the National Aeronautics and Space Administration's (NASA's) Stardust spacecraft launched on February 7, 1999. This past January, Stardust flew by Comet Wild 2's nucleus and through a halo of gases and dust at the comet's head, collecting cometary dust particles released from the surface just hours before. In 2006, the spacecraft will deliver the less than 1 milligram of parti… more
Date: September 20, 2005
Creator: Hazi, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Small Particle May Answer Large Physics Questions

Description: In one of those interesting intersections of particle physics, astrophysics, and cosmology, scientists from Lawrence Livermore National Laboratory, the University of California at Berkeley (UCB), the University of Florida (UF), and the National Radio Astronomy Observatory (NRAO) have joined together to try to pin down an elusive particle. This particle, called the axion, if it is found to exist and is not just a hypothesis, would be a long-sought relic from the first fractional second of the bi… more
Date: September 20, 2005
Creator: Hazi, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Global View Beyond the Standard Model

Description: By 1973, the theoretical foundations of the Standard Model of fundamental interactions had been completed. In the decades that followed, new particles and phenomena predicted by the Standard Model were discovered in a dramatic series of experiments at laboratories around the world. This began with the discovery of the charm quark at SLAC and Brookhaven, predicted by Glashow, Illiopoulos and Maiani from flavor properties of the SM. The W and Z bosons were produced directly in experiments at CERN… more
Date: January 20, 2008
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Probing gravitation, dark energy, and acceleration

Description: The acceleration of the expansion of the universe arises from unknown physical processes involving either new fields in high energy physics or modifications of gravitation theory. It is crucial for our understanding to characterize the properties of the dark energy or gravity through cosmological observations and compare and distinguish between them. In fact, close consistencies exist between a dark energy equation of state function w(z) and changes to the framework of the Friedmann cosmologica… more
Date: February 20, 2004
Creator: Linder, Eric V.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Novel interferometer spectrometer for sensitive stellar radial velocimetry

Description: We describe a new kind of stellar radial velocimeter based on the series combination of a wide angle Michelson interferometer and a disperser, and which we call a fringing spectrometer. The simplest instrument response of the interferometer produces smaller instrumental noise, and the low resolution requirements of the disperser allows high efficiency and creates an etendue capability which is two orders of magnitude larger than current radial velocimeters. The instrument is compact, inexpensiv… more
Date: May 20, 1999
Creator: Erskine, D & Ge, J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Solid State Technology Meets Collider Challenge

Description: Probing the frontiers of particle physics and delving into the mysteries of the universe and its beginnings require machines that can accelerate beams of fundamental particles to very high energies and then collide those beams together, producing a multitude of exotic subatomic particles. The proposed Next Linear Collider (NLC), being developed by Stanford Linear Accelerator Center (SLAC), Lawrence Livermore and Lawrence Berkeley national laboratories, and Fermi National Accelerator Laboratory … more
Date: September 20, 2005
Creator: Hazi, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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