Free Republic

Scientists at Duke and Rutgers universities have developed a mathematical framework they say will enable astronomers to test a new five-dimensional theory of gravity that competes with Einstein's General Theory of Relativity. Charles R. Keeton of Rutgers and Arlie O. Petters of Duke base their work on a recent theory called the type II Randall-Sundrum braneworld gravity model. The theory holds that the visible universe is a membrane (hence "braneworld") embedded within a larger universe, much like a strand of filmy seaweed floating in the ocean. The "braneworld universe" has five dimensions -- four spatial dimensions plus time -- compared...

Scientists use quantum gravity to describe the universe before the Big Bang.Scientists may finally have an answer to a "big" question: If the Big Bang was the beginning of the universe, what could have caused it to happen? Using a theory called "loop quantum gravity," a group led by Penn State professor Abhay Ashtekar has shown that just before the Big Bang occurred, another universe very similar to ours may have been contracting. According to the group's findings, this previous universe eventually became so dense that a normally negligible repulsive component of the gravitational force overpowered the attractive component, causing...

Using a quasar located 12.3 billion light-years away as a beacon, a team of astronomers detected the presence of molecular hydrogen in the farthest system ever, an otherwise invisible galaxy that we observe when the Universe was less than 1.5 billion years old, that is, about 10% of its present age. The astronomers find that there is about one hydrogen molecule for 250 hydrogen atoms. A similar set of observations for two other quasars, together with the most precise laboratory measurements, allows scientists to infer that the ratio of the proton to electron masses may have changed with time. If...

A cyclic universe, which bounces through a series of big bangs and "big crunches", could solve the puzzle of our cosmological constant, physicists suggest. The cosmological constant represents the energy of empty space, and is thought to be the most likely explanation for the observed speeding up of the expansion of the universe. But its measured value is a googol (1 followed by 100 zeroes) times smaller than that predicted by particle physics theories. It is a discrepancy that gives cosmologists a real headache. In the 1980s, physicists considered the possibility that an initially large cosmological constant could decay down...

Big bounces may make the Universe able to support stars and life. A bouncing universe that expands and then shrinks every trillion years or so could explain one of the most puzzling problems in cosmology: how we can exist at all. If this explanation, proposed in Science1 by Paul Steinhardt at Princeton University, New Jersey, and Neil Turok at the University of Cambridge, UK, seems slightly preposterous, that can't really be held against it. Astronomical observations over the past decade have shown that "we live in a preposterous universe", says cosmologist Sean Carroll of the University of Chicago. "It's our...

In a lively lecture on big questions about science, faith and the evolution of the cosmos, the director of the Vatican Observatory told a packed auditorium at the AAAS [the American Association for the Advancement of Science] on 27 March that science is quite capable of explaining the remarkable complexity of the natural world without reference to an intelligent designer. The Rev. George V. Coyne said modern science has revealed a cosmos shaped by the interplay of randomness and necessity over the nearly 14 billion years since the Big Bang, a world of such fertile chemical variety that the emergence...

Indications of a change in the proton-to-electron mass ratio have shown up in comparisons of the spectra of hydrogen gas as recorded in a lab with spectra of light coming from hydrogen clouds at the distance of quasars. This is another of those tests of so-called physical constants that might not be absolutely constant. For example, the steadiness of the fine structure constant (denoted by the letter alpha), defined as the square of the electron's charge divided by the speed of light times Planck's constant, has been in dispute (see PNU 410). Some tests say alpha is changing, others say...

One universe or many? Panel holds unusual debate March 30, 2006 Special to World Science Scientific debates are as old as science. But in science, “debate” usually means a battle of ideas in general, not an actual, politician-style duel in front of an audience. Occasionally, though, the latter also happens. And when the topic is as esoteric as the existence of multiple universes, sparks can fly. According to one proposal, new universes could sprout like bubbles off a spacetime "foam" that's not unlike soap bubbles. (Courtesy Lawrence Berkeley National Laboratory) Such was the scene Wednesday evening at the American Museum...

String theory — the concept that all particles can be represented as strings or string-loops of incredibly minute length, oscillating at various frequencies — was initially developed to help explain why quarks, the tiny fundamental particles that make up protons and neutrons, are always confined within larger composite particles. However, string theory has evolved to allow scientists to deal with some wider issues. For example, they can use string theory to devise explanations for some grand problems in cosmology, such as the state of the universe — its shape, size, etc. — just after the Big Bang, when quarks roamed...

SEARCH RESULTS Evidence for Universe Expansion FoundEvidence for Universe Expansion FoundScientists: Find explains how universe formedCold War gamma-ray mystery solved in a flashU.S. spacecraft set to study cosmic bursts Front page March 17, 2006, 12:51AMOldest light shows universe grew fast, researchers sayFirst stars arose 400 million years after big bang, not 200 million years, as once thought By DENNIS O'BRIEN Baltimore Sun Scientists examining the oldest light in the universe say they've found clear evidence that matter expanded at an almost inconceivable rate after the big bang, creating conditions that led to the formation of the first stars.Light from...

Physicists announced Thursday that they now have the smoking gun that shows the universe went through extremely rapid expansion in the moments after the big bang, growing from the size of a marble to a volume larger than all of observable space in less than a trillion-trillionth of a second. The discovery — which involves an analysis of variations in the brightness of microwave radiation — is the first direct evidence to support the two-decade-old theory that the universe went through what is called inflation.It also helps explain how matter eventually clumped together into planets, stars and galaxies in a...

Dark matter could be "sterile" neutrinos, whose decay led to the formation of stars in the early universe Dark matter may have played a major role in creating stars at the very beginnings of the universe. If that is the case, however, the dark matter must consist of particles called "sterile neutrinos". Peter Biermann of the Max Planck Institute for Radio Astronomy in Bonn, and Alexander Kusenko, of the University of California, Los Angeles, have shown that when sterile neutrinos decay, it speeds up the creation of molecular hydrogen. This process could have helped light up the first stars only...

A team of astronomers from France, the USA, Japan, and Korea, led by Denis Burgarella has recently discovered new galaxies in the Early Universe. They have been detected for the first time both in the near-UV and in the far-infrared wavelengths. Their findings will be reported in a coming issue of Astronomy & Astrophysics. This discovery leads to the first thorough investigation of early galaxies. Figure 1 shows some of these new galaxies. The knowledge of early galaxies has made major progress in the past ten years. From the end of 1995, astronomers have been using a new technique, known...

Three cosmic enigmas, one audacious answer 09 March 2006 Exclusive from New Scientist Print Edition Zeeya Merali DARK energy and dark matter, two of the greatest mysteries confronting physicists, may be two sides of the same coin. A new and as yet undiscovered kind of star could explain both phenomena and, in turn, remove black holes from the lexicon of cosmology. The audacious idea comes from George Chapline, a physicist at Lawrence Livermore National Laboratory in California, and Nobel laureate Robert Laughlin of Stanford University and their colleagues. Last week at the 22nd Pacific Coast Gravity Meeting in Santa Barbara,...

The world's largest particle detector is nearing completion following the construction of its 'endcap' at the University of Liverpool. Its assembly of advanced apparatus, at the University’s Semiconductor Detector Centre, has been a joint effort by physicists, engineers and technicians from the Universities of Liverpool, Glasgow, Lancaster, Manchester and Sheffield as well as CCLRC Daresbury and Rutherford Appleton Laboratories. The endcap is part of a semiconductor tracker (SCT) based at the heart of ATLAS - a giant particle detector the size of a five-storey building. The SCT will become part of the world’s largest particle accelerator – the Large Hadron...

Newswise — Researchers at Northeastern University and the University of California, Irvine say that scientists might soon have evidence for extra dimensions and other exotic predictions of string theory. Early results from a neutrino detector at the South Pole, called AMANDA, show that ghostlike particles from space could serve as probes to a world beyond our familiar three dimensions, the research team says. No more than a dozen high-energy neutrinos have been detected so far. However, the current detection rate and energy range indicate that AMANDA's larger successor, called IceCube, now under construction, could provide the first evidence for string...

Chinese astronomer from the University of St Andrews has fine-tuned Einstein’s groundbreaking theory of gravity, creating a ‘simple’ theory which could solve a dark mystery that has baffled astrophysicists for three-quarters of a century. A new law for gravity, developed by Dr. Hong Sheng Zhao and his Belgian collaborator Dr. Benoit Famaey of the Free University of Brussels (ULB), aims to prove whether Einstein’s theory was in fact correct and whether the astronomical mystery of Dark Matter actually exists. Their research was published on February 10th in the Astrophysical Journal Letters. Their formula suggests that gravity drops less sharply with...

On Tuesday, Feb. 14, noted physicist Dr. Franklin Felber will present his new exact solution of Einstein's 90-year-old gravitational field equation to the Space Technology and Applications International Forum (STAIF) in Albuquerque. The solution is the first that accounts for masses moving near the speed of light. New antigravity solution will enable space travel near speed of light by the end of this century, he predicts. Felber's antigravity discovery solves the two greatest engineering challenges to space travel near the speed of light: identifying an energy source capable of producing the acceleration; and limiting stresses on humans and equipment during...

Astronomers have measured the temperature of dark matter for the first time. The discovery should help particle hunters to identify exactly what this mysterious substance is made of. Although dark matter cannot be seen, its existence can be inferred from its gravitational interaction with stars around it, which stops rapidly rotating galaxies from flying apart. Astronomers estimate that, on average, dark matter must be about six times more abundant than normal, visible matter in our Universe. But very little else is known about dark matter. "Even knowing it was dark was pretty profound," says Gerry Gilmore of Cambridge University, UK,...

Supersymmetry and Parallel Dimensions Harvard Physicst Randall among world’s leading string theorists Published On Friday, January 06, 2006  1:00 AM By ADRIAN J. SMITH Crimson Staff Writer Professor of Physics Lisa Randall ’83, recently named one of Newsweek’s most influential people of 2006, rose to the top with her theories on gravity. (Photo credit: CRIMSON/GLORIA B. HO) Professor of Physics Lisa Randall ’83 saw how strong gravity could be during a climbing fall in New Hampshire two years ago. She was performing a “challenging” move when she took a surprising fall, she says. Instead of stopping the fall, her support...