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in subjects: "Universe"

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The Age of the Universe: Concordance

Arguments on the Age of the Universe, t{sub u}, are reviewed. The four independent age determination techniques are: dynamics (Hubble Age and deceleration); oldest stars (globular clusters); radioactive dating (nucleocosmochronology); and white dwarf cooling (age of the disk). While discussing all four, this review will concentrate more on nucleocosmochronology due in part to recent possible controversies there. It is shown that all four techniques are in general agreement, which is an independ… more

Date: December 1, 1989

Creator: Schramm, D. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Neutrino fluctuat nec mercitur: are fossil neutrinos detectable

A brief report is presented on the question whether light (few eV to approx. 100 eV) neutrinos left over from the big bang are detectable. The answer is perhaps. If the weak current of leptons, like those of quarks, are not diagonal in mass eigenstates, a neutrino will decay into a lighter neutrino and a monochromatic photon. The corresponding photon line may be detectable provided: neutrinos are heavy enough to participate in galaxy clustering and neutrino lifetimes are, as in some weak intera… more

Date: April 1, 1980

Creator: De Rujula, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A progress report on the Berkeley search for distant supernovae to measure. Omega

Over the past two years, in collaboration with the Anglo-Australian Observatory, we have constructed a prototype version of the hardware and software needed to discover distant supernovae for a measurement of {Omega}, the ratio of the average density of the universe to the critical density. To make this measurement, we will use Type Ia supernova, which are now thought to be adequate standard candles for this purpose. 5 refs.

Date: March 1, 1991

Creator: Pennypacker, C.; Perlmutter, S.; Goldhaber, G.; Marvin, H.; Muller, R. (Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Center for Particle Astrophysics); Boyle, B.J. (Cambridge Univ. (United Kingdom). Inst. of Astronomy) et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Performance characteristics of a cosmology package on leading HPCarchitectures

The Cosmic Microwave Background (CMB) is a snapshot of the Universe some 400,000 years after the Big Bang. The pattern of anisotropies in the CMB carries a wealth of information about the fundamental parameters of cosmology. Extracting this information is an extremely computationally expensive endeavor, requiring massively parallel computers and software packages capable of exploiting them. One such package is the Microwave Anisotropy Dataset Computational Analysis Package (MADCAP) which has be… more

Date: January 1, 2004

Creator: Carter, Jonathan; Borrill, Julian & Oliker, Leonid

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Science & Technology Review March/April 2008

This month's issue has the following articles: (1) Science and Security in Sharp Focus--Commentary by William H. Goldstein; (2) Extending the Search for Extrasolar Planets--The Gemini Planet Imager will delve deep into the universe to identify planets that cannot be detected with current instrumentation; (3) Standardizing the Art of Electron-Beam Welding--The Laboratory's EBeam Profiler makes electron-beam welds consistent and improves quality control; (4) Molecular Building Blocks Made of Diam… more

Date: January 22, 2008

Creator: Chinn, D J

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Quantum entanglement of baby universes

We study quantum entanglements of baby universes which appear in non-perturbative corrections to the OSV formula for the entropy of extremal black holes in type IIA string theory compactified on the local Calabi-Yau manifold defined as a rank 2 vector bundle over an arbitrary genus G Riemann surface. This generalizes the result for G=1 in hep-th/0504221. Non-perturbative terms can be organized into a sum over contributions from baby universes, and the total wave-function is their coherent super… more

Date: December 7, 2006

Creator: Essman, Eric P.; Aganagic, Mina; Okuda, Takuya & Ooguri, Hirosi

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Boltzmann babies in the proper time measure

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: Article

Partner: UNT Libraries Government Documents Department

open access

The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-masswhite dwarf star

The acceleration of the expansion of the universe, and theneed for Dark Energy, were inferred from the observations of Type Iasupernovae (SNe Ia) 1;2. There is consensus that SNeIa are thermonuclearexplosions that destroy carbon-oxygen white dwarf stars that accretematter from a companion star3, although the nature of this companionremains uncertain. SNe Ia are thought to be reliable distance indicatorsbecause they have a standard amount of fuel and a uniform trigger theyare predicted to explod… more

Date: February 1, 2006

Creator: Howell, D.Andrew; Sullivan, Mark; Nugent, Peter E.; Ellis,Richard S.; Conley, Alexander J.; Le Borgne, Damien et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ROUND TRIP FROM SPACE

Whence came life on the surface of the earth? Whether or not a complete answer to this question may be found within the context, and content, of modern science, may be a moot question. It is our purpose to see how far we can devise an answer, and how satisfactory it may be, within that context. We trace a path from the primitive molecules of the primeval earth's atmosphere condensed from space through the random formation of more or less complex organic molecules, using the available energy sou… more

Date: October 29, 1958

Creator: Calvin, Melvin

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Discovery of the Most Distant Supernovae and the Quest for Omega

A search for cosmological supernovae has discovered a number of a type la supernovae. In particular, one at z = 0.458 is the most distant supernova yet observed. There is strong evidence from measurements of nearby type Ia supernovae that they can be considered as 'standard candles'. We plan to use these supernovae to measure the deceleration in the general expansion of the universe. The aim of our experiment is to try and observe and measure about 30 such distant supernovae in order to obtain … more

Date: May 1, 1994

Creator: Goldhaber, G.; Boyle, B.; Bunclark, P.; Carter, D.; Ellis, R.; Gabi, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Gamma-Ray Bursts Shower the Universe with Metals

According to the results from a Livermore computer model, some of the small change jingling in your pocket contains zinc and copper created in massive gamma-ray bursts (GRBs) that rank as the most impressive light shows in the universe. Livermore astrophysicist Jason Pruet and his colleagues Rebecca Surman and Gail McLaughlin from North Carolina State University (NCSU) reported on their calculations in the February 20, 2004, issue of ''Astrophysical Journal Letters''. They found that GRBs from … more

Date: January 13, 2006

Creator: Hazi, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Probing the Universe with Mirrors That Trick Light

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: Report

Partner: UNT Libraries Government Documents Department

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Measurement of CKM-angle gamma with Charmed B0 Meson Decays

This thesis reports measurements of the time-dependent CP asymmetries in fully reconstructed B{sup 0} {yields} (D{sup (*){-+}} and B{sup 0} {yields} D{sup {-+}} {rho}{sup {+-}}) decays in approximately 232 million {Upsilon}(4S) {yields} B{bar B} events, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center in California, as published in Ref. [14]. The phenomenon of CP violation allows one to distinguish between matter and antimatte… more

Date: July 17, 2007

Creator: Baak, Max Arjen & /Vrije U., Amsterdam

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

How did matter gain the upper hand over antimatter?

Antimatter exists! We routinely make it in laboratories. For every familiar particle type we find a matching antiparticle with opposite charge, but exactly the same mass. For example, a positron with positive charge has the same mass as an electron; an antiproton with negative charge has the same mass as a proton. Antimatter occurs naturally all over the universe wherever high-energy particles collide. The laws of physics for antimatter are very, very similar to those for antimatter--so far we … more

Date: January 30, 2009

Creator: Quinn, Helen

Item Type: Article

Partner: UNT Libraries Government Documents Department

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LHC Olympics Workshop and String Phenomenology 2006 Conference

This is the final report of the organizers of the String Phenomenolgy program of which the LHC Olympics and the String Phenomenolgy conference were a part. In addition, it includes the list of talks from our website which comprise the online proceedings. The KITP no longer publishes conferences proceedings but rather makes recordings and visuals of all talks available on its website at www.kitp.ucsb.edu Program talks are available at http://online.kitp.ucsb.edu/online/strings06/ Conference talk… more

Date: October 1, 2006

Creator: Gross, David

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Numerical Methods for Radiation Magnetohydrodynamics in Astrophysics

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Understanding the Fundamental Properties of Dark Matter & Dark Energy in Structure formation and Cosmology

This program is concerned with developing and verifying the validityof observational methods for constraining the properties of dark matter and dark energy in the universe. Excellent progress has been made in comparing observational projects involving weak gravitational lensing using both ground and space-based instruments, in further constraining the nature of dark matter via precise measures of its distribution in clusters of galaxies using strong gravitational lensing, in demonstrating the p… more

Date: February 1, 2008

Creator: Ellis, Richard, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

International linear collider reference design report

The International Linear Collider will give physicists a new cosmic doorway to explore energy regimes beyond the reach of today's accelerators. A proposed electron-positron collider, the ILC will complement the Large Hadron Collider, a proton-proton collider at the European Center for Nuclear Research (CERN) in Geneva, Switzerland, together unlocking some of the deepest mysteries in the universe. With LHC discoveries pointing the way, the ILC -- a true precision machine -- will provide the miss… more

Date: June 22, 2007

Creator: Aarons, G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Study of Nuclear Reactions with 11C and 15O Radioactive Ion Beams

Nuclear reaction study with radioactive ion beams is one of the most exciting research topics in modern nuclear physics. The development of radioactive ion beams has allowed nuclear scientists and engineers to explore many unknown exotic nuclei far from the valley of nuclear stability, and to further our understanding of the evolution of the universe. The recently developed radioactive ion beam facility at the Lawrence Berkeley National Laboratory's 88-inch cyclotron is denoted as BEARS and pro… more

Date: May 14, 2007

Creator: Lee, Dongwon

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Comments on an Expanding Universe

Various results are obtained for a Friedmann-Robertson-Walker cosmology. We derive an exact equation that determines Hubble's law, clarify issues concerning the speeds of faraway objects and uncover a 'tail-light angle effect' for distant luminous sources. The latter leads to a small, previously unnoticed correction to the parallax distance formula.

Date: December 12, 2005

Creator: Samuel, Stuart & Samuel, Stuart

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

New Prospects for High-energy Neutrinos from gamma-ray Bursts

High-energy neutrinos from Gamma-Ray Bursts (GRBs) have been expected since the pre-Swift era. Such signals may be detected by future large neutrino detectors such as IceCube. Recently Swift has shown several novel phenomena. We suggest the new prospects for high-energy neutrino emission in the Swift era. Expected signals, if detected, are useful for revealing of the nature of GRBs.

Date: January 9, 2008

Creator: Murase, K.; /Kyoto U., Yukawa Inst., Kyoto; Nagataki, S. & /KIPAC, Menlo Park

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Energy and Technology Review

This journal contains 7 articles pertaining to astrophysics. The first article is an overview of the other 6 articles and also a tribute to Jim Wilson and his work in the fields of general relativity and numerical astrophysics. The six articles are on the following subjects: (1) computer simulations of black hole accretion; (2) calculations on the collapse of the iron core of a massive star; (3) stellar-collapse models which reveal a possible site for nucleosynthesis of elements heavier than ir… more

Date: March 1, 1983

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Broken symmetries at high temperatures and the problem of baryon excess of the universe

A class of gauge theories, where spontaneously broken symmetries, instead of being restored, persist as the temperature is increased is discussed. A renormalization group analysis of this phenomena suggests that there may be more than one phase transition in these models with at least one symmetric phase. Applying these ideas to the specific case of soft CP-violation in grand unified theories, a mechanism to generate the baryon to entropy ratio of the universe is discussed. 34 references.

Date: June 1, 1979

Creator: Mohapatra, R.N. & Senjanovic, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Phase Transitions and Dark Matter Problems

The possible relationships between phase transitions in the early universe and dark matter problems are discussed. It is shown that there are at least 3 distinct cosmological dark matter problems: (1) halos; (2) galaxy formation and clustering; and (3) ..cap omega.. = 1, each emphasizing different attributes for the dark matter. At least some of the dark matter must be baryonic but if problems 2 and 3 are real they seem to also require non-baryonic material. However, if seeds are generated at t… more

Date: October 1, 1984

Creator: Schramm, D. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department