The Dark Matter Mystery. Another candidate for the dark matter is the neutrino list of experimental sciencesby using many techniques, including astronomy, astrophysics, particle physics http://www.umich.edu/~lowbrows/reflections/1999/lsimmons.8.html
Extractions: Printed in Reflections: December, 1999. In other important studies, astrophysicists have measured the mass of the gas in and around elliptical galaxies and have additionally measured the movement of galaxies in galactic clusters, detecting what they call the "velocity dispersion" or the spreading out of the velocities (directional speeds) of galaxies orbiting around the centers of the galactic clusters. The velocities of the galaxies in the galactic clusters do not seem to slow down as expected as the individual galaxies get farther out from the centers of these galactic clusters. It is very puzzling for astrophysicists. This should not be! But, regardless, it is. In addition, the CMBR gives evidence of fluctuations in density which, because of gravitational instability, can only relate to the present structure if it is "non stuff." Because the CMBR possesses gravitational instability due to the observed fluctuations in density, it would seem that Omega (calculated as the density of the universe divided by what is called the "critical density of the universe") is very likely equal to 1. There are three possibilities in determining the Effective Omega (the density parameter of the universe divided by the critical density of the universe): Recollapse (meaning a closed universe) if Omega is greater than one.
Extractions: The present phase of work is aimed at solving the problems of building large volume detectors, as researchers hope to produce 400 detectors containing 70 litres of gel each in the next two years. In three years, these detectors will be installed more than two kilometres underground in the Sudbury neutrino observatory as part of a broad international project launched by a consortium of Canadian universities. The detectors must be placed in underground galleries so that no other type of radiation, cosmic or terrestrial, will disturb the experiment, which should extend over several years.
The Particle Astrophysics Group The Particle Astrophysics group at Sheffield aims to improve our understandingof dark matter and neutrinos. As such our activities http://www.shef.ac.uk/physics/research/pa/
Extractions: Dark Matter and Neutrinos constitute most of the material of the Universe and so are critical to our understanding of the structure of the Universe and even to our very existence in it. Yet the identity of Dark Matter remains unknown and our understanding of the properties of neutrinos remains poor. The Particle Astrophysics group at Sheffield aims to improve our understanding of dark matter and neutrinos. As such our activities are divided into two parts: A Dark Matter Programme and a Neutrino Astrophysics Programme which includes the ANTARES experiment. The group collaborates closely with the High Energy Particle Physics groups (HEP) and the Astrophysics groups in the department. Together these groups constitute about 1/3rd of the Physics Department, funded mainly by PPARC but also through grants from the Royal Society, EPSRC, Leverhulme Trust, overseas collaborators and industrial partners. The PA group has an active PhD. programme and an active summer student work experience programme. For more details of these and of jobs related to the PA group check Positions Vacant
Dark Matter Univ. CA. Berkeley Center for Particle Astrophysics dark matter Tutorial;Galaxy Rotation Curves; dark matter Candidates. Gravitational http://cassfos02.ucsd.edu/public/tutorial/DM.html
Extractions: Dark Matter in the Universe Dark Matter Observations of clusters and their galaxies, have uncovered one of the major mysteries in astronomy today. Clusters appear to be very stable entities - they contain mature galaxies with old stars, and seem to have been formed billions of years ago. But, when we calculate the amount of mass in a cluster using the orbital motions of its member galaxies, the result is too low for the cluster to be gravitationally bound. If the cluster contains only the mass we can observe, the gravitational force is insufficient to prevent the galaxies from "escaping".There must be more mass in the cluster than what we see. the measured values, probably in the form of a massive halo of dark matter. The same problem arises when we look at the galaxies themselves. The rotation curve of a galaxy shows how the orbital velocities of the stars change with distance from the center. If the galaxy rotated as a solid disk, the velocity would increase linearly with distance. If most of the mass were concentrated at the the center, as in our solar system, the velocities of the stars would decrease with the square root of the distance. But, that is not what is observed. Far past the point where no mass is visible, the rotation curves are flat! This means that the mass is still increasing as we move outward, even though we can't see anything! One again we have to call upon "dark matter". The galaxy must extend much farther out than the luminous matter indicates. In fact, the calculations require that there be at least 10 times more mass than we can see! Calculations suggest that this dark matter is likely to be in an extensive halo of dark matter.
Dark Sky, Dark Matter of the universe, structure of the stars and galaxies, radiation, and dark matter. physics,more appropriate for a graduate course in Physics or astrophysics. http://bookmarkphysics.iop.org/bookpge.htm?book=829h
Dark Matter Walter Stockwell, of the dark matter team at the Center for ParticleAstrophysics at UC Berkeley, describes this difference. The http://www.eclipse.net/~cmmiller/DM/
Extractions: Scientists using different methods to determine the mass of galaxies have found a discrepancy that suggests ninety percent of the universe is matter in a form that cannot be seen. Some scientists think dark matter is in the form of massive objects, such as black holes, that hang out around galaxies unseen. Other scientists believe dark matter to be subatomic particles that rarely interact with ordinary matter. This paper is a review of current literature. I look at how scientists have determined the mass discrepancy, what they think dark matter is and how they are looking for it, and how dark matter fits into current theories about the origin and the fate of the universe. In 1933, the astronomer Fritz Zwicky was studying the motions of distant galaxies. Zwicky estimated the total mass of a group of galaxies by measuring their brightness. When he used a different method to compute the mass of the same cluster of galaxies, he came up with a number that was 400 times his original estimate (1). This discrepancy in the observed and computed masses is now known as "the missing mass problem." Nobody did much with Zwicky's finding until the 1970's, when scientists began to realize that only large amounts of hidden mass could explain many of their observations (2). Scientists also realize that the existence of some unseen mass would also support theories regarding the structure of the universe (3). Today, scientists are searching for the mysterious dark matter not only to explain the gravitational motions of galaxies, but also to validate current theories about the origin and the fate of the universe.
How Dark Matter Created Dark Energy And The Sun There are a number of mysteries in astrophysics and cosmology that have remainedunsolved for decades. What is dark matter? How exactly are stars created? http://www.upublish.com/book.php?method=ISBN&book=1581125518
Dark Matter NonBaryonic dark matter Experiments and Other dark matter Searches. Gravitational Galaxyin Andromeda); MOA (Microlensing Observations in Astrophysics) (in New http://www.aeiveos.com/~bradbury/Astronomy/DarkMatter.html
Extractions: Our galaxy, the Milky Way, and other galaxies contain more matter than expected from visual observations. This so called " dark matter " is detected by the rapid rotation of matter in the outer regions of galaxies as well as the motion of the galaxies within galactic clusters. The gravity exerted by the dark matter holds the galaxies and clusters together and allows faster rotations than would be possible if it did not exist. It is estimated that 70% to 90% of the mass which should exist according to the laws of gravity cannot be seen in visible light images of the galaxies. Neutrinos Interstellar Gas Clouds Comets and Asteroids Interstellar (rogue) Planets Brown Dwarfs sun Red Dwarfs (~0.08 M sun sun White Dwarfs (~0.3 M sun sun Black Dwarfs (extremely old, cool white dwarfs, none should exist in the universe yet) Neutron Stars (1.4 M sun sun Black Holes: Massive, Stellar and Micro (> 4 M sun ) [derived from a single star] Dark Matter is an illusion. The need for Dark Matter to explain the rotational velocities of galaxies could simply be wrong, if the MOND theory is correct.
Astrophysics - The Dark Matter Myth PHYSICS & ASTRONOMY Thomas Smid, 1012-02 1308. Ether is The dark matter new. Durgadas Datta,04-30-03 2238. Ahoy mate! Welcome to the new Astrophysics Hatteras Campfire! http://astronomyphysics.com/read.php?f=2&i=83&t=83
Astrophysics - Dark Matter Is Ether PHYSICS & ASTRONOMY Topics, Author, Date. dark matter is Ether new. Durgadas Datta, 0430-032238. Ahoy mate! Welcome to the new Astrophysics Hatteras Campfire! http://astronomyphysics.com/read.php?f=2&i=104&t=104
Camps Aim To Make Girls A Power Point In Technology woman faculty member in the university s astronomy and astrophysics department,described the project as trying to see our galaxy s halo of dark matter in a http://www.suntimes.com/output/zinescene/cst-fin-ecol19.html
Extractions: Headlines blare that women have surpassed men as Web shoppers, reinforcing the stereotype of self-obsessed females frantically searching for clothes and makeup. But other statistics unearth a greater concern: Women make up 46 percent of the U.S. labor force, but only 23 percent of its scientists and engineers, according to the National Science Foundation. One of the local six-month camps is being hosted by DePaul University, where women wrote the camp curriculum and teach and mentor high school students from throughout the Chicago area. The 40 high school students ages 14 to 17 who were recruited to attend the camp started by learning the basics of computer use, software, photo editing and programming languages during Saturday sessions. Camp counselors then traveled to the girls' high schools during the week to help them hone their computer skills after school, whether it was doing schoolwork or a special project, said DePaul senior Danielle Dorneval. The camp ends with a graduation ceremony in early June.
Dark Matter In Galaxies dark matter in galaxies. The nature of dark matter. More than 60 years sinceit was first postulated, dark matter still remains unidentified. http://hermes.physics.ox.ac.uk/users/Astrophysics/guides/galaxies/dkmatter.shtml
Extractions: POINT-AGAPE In the early 1930's (pretty much the dawn of modern cosmology) two astronomers, Fritz Zwicky and Jan Oort , independently suggested that much of the matter which comprises our Universe remains to be detected. Their proposals were based on observations of the motions of visible stars in the disk of our Galaxy and of the motions of galaxies within gravitationally-bound clusters of galaxies. In both cases the stars or galaxies appeared to be moving much too fast to remain bound to the system they were observed to be in, yet they clearly had been confined to that system over much of the lifetime of the Universe - it seemed that some unseen or dark matter must be providing the necessary additional gravitational energy to keep the stars and galaxies bound together. The dark matter problem raises three important questions: Where is the dark matter located? How much more dark matter is there than visible matter? What is it made of?
CDMS Experiment Results Refute Recent WIMP Dark Matter Claim in the crystals from those that are likely to be dark matter interactions, says atUC Berkeley, and the head of the Center for Particle Astrophysics where he http://www.lbl.gov/Science-Articles/Archive/dark-matter-CDMS.html
Extractions: Some light may soon be shed on dark matter, the invisible stuff of which most of the universe seems to be made. The Cryogenic Dark Matter Search (CDMS), a collaboration of researchers from 10 institutions including the Lawrence Berkeley National Laboratory, has announced the achievement of "the world's best discrimination in the search for dark matter." Their findings appear "incompatible" with the findings reported by another multi-institutional collaboration. OUR MILKY WAY GALAXY APPEARS TO BE SURROUNDED BY A HALO OF GAMMA RAYS. ONE POSSIBLE CAUSE FOR THIS HIGH-ENERGY GLOW ARE WIMPS WEAKLY INTERACTING MASSIVE PARTICLES THAT WOULD BE THE PRIME CONSTITUENTS OF DARK MATTER, THE INVISIBLE STUFF OF WHICH MOST OF THE UNIVERSE SEEMS TO BE MADE. Photo courtesy of NASA Various astronomical observations together with more than 70 years of combined astrophysics and particle physics research have shown that perhaps as much as 90 percent of the known universe is made up of matter that is visible to us only by its gravitational effects. Since it cannot be seen by the light it emits, this matter has been dubbed "dark." The nature of dark matter holds implications for the evolution, structure, and ultimate fate of the universe, as well as for our current physics models. Consequently, astrophysicists and cosmologists have undertaken an intense search for the source of dark matter. One of the prime potential candidates is a family of weakly interacting massive particles or "WIMPS."
Extractions: By Lynn Yarris, LCYarris@lbl.gov One of the prime candidates for dark matter, the mysterious "missing mass" of the universe, may have been spotted. Scientists at the Center for Particle Astrophysics (CPA) have reported the first evidence for the existence of MACHOs MAssive Compact Halo Objects stars too small to shine that are concentrated in the halo of galaxies. Working with a specially equipped telescope on Mount Stromlo, near Canberra, Australia, the scientists detected a sudden, brief brightening of what is usually a dim star in the Large Magellanic Cloud galaxy. This brightening was attributed to a phenomenon known as "microlensing," in which the gravity of a massive invisible object acts like a magnifying lens while it crosses in between a visible star and a telescope on earth. Ninety percent or more of the matter that makes up the universe is considered to be "dark," meaning it does not radiate any light, even though observations of its gravitational effects confirm its existence. There are two major schools of thought as to the nature of dark matter. One contends that dark matter primarily consists of exotic non-baryonic particles, relics from the early universe known as WIMPs (Weakly Interacting Massive Particles). The other argument is for ordinary baryonic matter (protons, electrons, and neutrons) MACHOs, such as brown dwarfs and planets the size of Jupiter, which are too small to be seen directly.
F3901 Translate this page matter ghost matter astrophysics.6. Spiral structure.(p1). Commentaires. survitessespéripéhériques, voir article Repulsive dark matter, Geometrical Physics A http://www.jp-petit.com/science/f300/f3900/f3901.htm
F3401 dark matter , but this http://www.jp-petit.com/science/f300/f3400/f3401.htm
Extractions: Matter ghost-matter astrophysics. 1.The geometrical framework. The matter era and the newtonian approximation. (p1) Matter ghost-matter astrophysics. 1.The geometrical framework.The matter era and the newtonian approximation. Jean-Pierre Petit and P.Midy Observatory of Marseille,France We study a system of mass particles involving both attractive and repulsive forces, corresponding to a two-fold geometry. The geometrical framework is precised, as well as a cosmological model, for matter dominated era. In small curvature and low velocities conditions the Newton law and the Poisson equation are derived (newtonian approximation), which justifies the chosen interaction law. 1) Geometrical framework. In the precedent paper we explored the phenomenological aspects of a two populations system whose dynamics implies both attractive and repelling forces. The geometric framework was briefly presented. Let us return to that question. z g and g * and assume they describe the geometries of the two folds. We assume they are both Riemanian, with the same signature (+ - - -). The physics in the two folds are identical, and Special Relativity holds in. We assume that light follows the null-geodesics in each folds. But, on geometrical grounds, light cannot travel from a fold to the other one.
