Science Current Events | Science News | Brightsurf.com
 
Email a Friend Send to a friend
Printer Friendly Print Precise Radio-Telescope Measurements Advance Frontier Gravitational Physics

Precise Radio-Telescope Measurements Advance Frontier Gravitational Physics

September 02, 2009

Scientists using a continent-wide array of radio telescopes have made an extremely precise measurement of the curvature of space caused by the Sun's gravity, and their technique promises a major contribution to a frontier area of basic physics.

"Measuring the curvature of space caused by gravity is one of the most sensitive ways to learn how Einstein's theory of General Relativity relates to quantum physics. Uniting gravity theory with quantum theory is a major goal of 21st-Century physics, and these astronomical measurements are a key to understanding the relationship between the two," said Sergei Kopeikin of the University of Missouri.




Kopeikin and his colleagues used the National Science Foundation's Very Long Baseline Array (VLBA) radio-telescope system to measure the bending of light caused by the Sun's gravity to within one part in 30,000. With further observations, the scientists say their precision technique can make the most accurate measure ever of this phenomenon.

Bending of starlight by gravity was predicted by Albert Einstein when he published his theory of General Relativity in 1916. According to relativity theory, the strong gravity of a massive object such as the Sun produces curvature in the nearby space, which alters the path of light or radio waves passing near the object. The phenomenon was first observed during a solar eclipse in 1919.

Though numerous measurements of the effect have been made over the intervening 90 years, the problem of merging General Relativity and quantum theory has required ever more accurate observations. Physicists describe the space curvature and gravitational light-bending as a parameter called "gamma." Einstein's theory holds that gamma should equal exactly 1.0.

"Even a value that differs by one part in a million from 1.0 would have major ramifications for the goal of uniting gravity theory and quantum theory, and thus in predicting the phenomena in high-gravity regions near black holes," Kopeikin said.

To make extremely precise measurements, the scientists turned to the VLBA, a continent-wide system of radio telescopes ranging from Hawaii to the Virgin Islands. The VLBA offers the power to make the most accurate position measurements in the sky and the most detailed images of any astronomical instrument available.

The researchers made their observations as the Sun passed nearly in front of four distant quasars -- faraway galaxies with supermassive black holes at their cores -- in October of 2005. The Sun's gravity caused slight changes in the apparent positions of the quasars because it deflected the radio waves coming from the more-distant objects.

The result was a measured value of gamma of 0.9998 +/- 0.0003, in excellent agreement with Einstein's prediction of 1.0.

"With more observations like ours, in addition to complementary measurements such as those made with NASA's Cassini spacecraft, we can improve the accuracy of this measurement by at least a factor of four, to provide the best measurement ever of gamma," said Edward Fomalont of the National Radio Astronomy Observatory (NRAO). "Since gamma is a fundamental parameter of gravitational theories, its measurement using different observational methods is crucial to obtain a value that is supported by the physics community," Fomalont added.

Kopeikin and Fomalont worked with John Benson of the NRAO and Gabor Lanyi of NASA's Jet Propulsion Laboratory. They reported their findings in the July 10 issue of the Astrophysical Journal.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

National Radio Astronomy Observatory



Related Gravitational Physics Current Events and Gravitational Physics News Articles Gravitational Physics Current Events and Gravitational Physics News RSS Gravitational Physics Current Events and Gravitational Physics News RSS
XMM-Newton uncovers a celestial Rosetta stone
ESA's XMM-Newton orbiting X-ray telescope has uncovered a celestial Rosetta stone: the first close-up of a white dwarf star, circling a companion star, that could explode into a particular kind of supernova in a few million years.

Vanquishing infinity
Quantum mechanics and Einstein's theory of general relativity are both extremely accurate theories of how the universe works, but all attempts to combine the two into a unified theory have ended in failure.

Scientists closer to making invisibility cloak a reality
J.K. Rowling may not have realized just how close Harry Potter's invisibility cloak was to becoming a reality when she introduced it in the first book of her best-selling fictional series in 1998. Scientists, however, have made huge strides in the past few years in the rapidly developing field of cloaking. Ranked the number five breakthrough of the year by Science magazine in 2006, cloaking involves making an object invisible or undetectable to electromagnetic waves.

A Newtonian system that mimics the baldness of rotating black holes
The rotating black hole has been described as one of nature's most perfect objects.

Cardiff researchers could herald a new era in fundamental physics
Cardiff University researchers who are part of a British-German team searching the depths of space to study gravitational waves, may have stumbled on one of the most important discoveries in physics according to an American physicist.

UCSB professor's paper on safety of large hadron collider to be published in Physical Review D
Particle colliders creating black holes that could devour the Earth. Sounds like a great Hollywood script.

LIGO observations probe the dynamics of the crab pulsar
The search for gravitational waves has revealed new information about the core of one of the most famous objects in the sky: the Crab Pulsar in the Crab Nebula.

UO plays key role in LIGO's new view of a cosmic event
An international team of physicists, including University of Oregon scientists, has concluded that last February's intense burst of gamma rays possibly coming from the Andromeda Galaxy lacked a gravitational wave. That absence, they say, rules out an initial interpretation that the burst came from merging neutron stars or black holes within Andromeda.

MU Physicist Says Testing Technique for Gravitomagnetic Field is Ineffective
Albert Einstein's theory of general relativity has fascinated physicists and generated debate about the origin of the universe and the structure of objects like black holes and complex stars called quasars.

GEO600 starts continuous search for Gravitational Waves
The joint German-British Gravitational Wave Detector GEO600 has now entered an 18-month run of continuous measurement.
More Gravitational Physics Current Events and Gravitational Physics News Articles
Theory and Experiment in Gravitational Physics

Theory and Experiment in Gravitational Physics
by Clifford M. Will (Author)

This is a revised edition of a classic and highly regarded book, first published in 1981, describing the status of theory and experiment in general relativity. This book offers a comprehensive survey of the intensive research and testing of general relativity that has been conducted over the past three decades. As a foundation for this survey, the book first introduces the important principles of gravitation theory, developing the mathematical formalism that is necessary to carry out specific computations so that theoretical predictions can be compared with experimental findings. It provides an up-to-date survey of experimental results, not only for Einstein's "classical" tests, such as deflection of light and the perihelion of Mercury, but also for new solar-system tests, never...

Physics of the Gravitational Curvature.

Physics of the Gravitational Curvature.
Dr. Julie Trudeau (Primary Contributor)



General Relativity: With Applications to Astrophysics (Theoretical and Mathematical Physics)

General Relativity: With Applications to Astrophysics (Theoretical and Mathematical Physics)
by Norbert Straumann (Author)

This text provides a comprehensive and timely introduction to general relativity. The foundations of the theory in Part I are thoroughly developed together with the required mathematical background from differential geometry in Part III. The six chapters in Part II are devoted to tests of general relativity and to many of its applications. Binary pulsars are studied in considerable detail. Much space is devoted to the study of compact objects, especially to black holes. This includes a detailed derivation of the Kerr solution, Israel's proof of his uniqueness theorem, and derivations of the basic laws of black hole physics. The final chapter of this part contains Witten's proof of the positive energy theorem.

The book addresses undergraduate and graduate students in physics,...

Hog Wild R.O.M.P.-Randomly Oscilating Magnetic Pendulum

Hog Wild R.O.M.P.-Randomly Oscilating Magnetic Pendulum
by Hog Wild

Experience Two Dimensional Magnetic Energy At Your Desktop! Designed to illustrate the chaotic and random forces that effect us all, ROMP is also just plain fun. ROMP

History of Gravitational Theory: Physics, Gravitation, Newton's law of universal gravitation, Mechanical explanations of gravitation, Introduction to general relativity, Graviton, Quantum gravity

History of Gravitational Theory: Physics, Gravitation, Newton's law of universal gravitation, Mechanical explanations of gravitation, Introduction to general relativity, Graviton, Quantum gravity
by Frederic P. Miller (Editor), Agnes F. Vandome (Editor), John McBrewster (Editor)

In physics, theories of gravitation postulate mechanisms of interaction governing the movements of bodies with mass. There have been numerous theories of gravitation since ancient times.

Gravitational Physics of Stellar and Galactic Systems (Cambridge Monographs on Mathematical Physics)

Gravitational Physics of Stellar and Galactic Systems (Cambridge Monographs on Mathematical Physics)
by William C. Saslaw (Author)

This text describes the gravitational interactions and evolution of astronomical systems on all scales, from small groups of stars through galaxies and clusters of galaxies to the Universe itself. In a rapidly developing area of astronomy, it is the first comprehensive treatise on the subject to be published since the early 1960s. Concentrating on the basic physics, at a graduate student level, it also develops many astronomical applications in considerable detail. The book is self-contained. Most results are derived from preceding ones in a straightforward way. It is written to bring out the physical content behind the mathematical formulae, and contains a number of exercises and suggestions for research topics. Bibliographies with nearly 300 selected references provide gateways into the...

Gravitational Collapse and Spacetime Singularities (Cambridge Monographs on Mathematical Physics)

Gravitational Collapse and Spacetime Singularities (Cambridge Monographs on Mathematical Physics)
by Pankaj S. Joshi (Author)

Physical phenomena in astrophysics and cosmology involve gravitational collapse in a fundamental way. The final fate of a massive star when it collapses under its own gravity at the end of its life cycle is one of the most important questions in gravitation theory and relativistic astrophysics, and is the foundation of black hole physics. General relativity predicts that continual gravitational collapse gives rise to a space-time singularity. Quantum gravity may take over in such regimes to resolve the classical space-time singularity. This book investigates these issues, and shows how the visible ultra-dense regions arise naturally and generically as an outcome of dynamical gravitational collapse. It will be of interest to graduate students and academic researchers in gravitation...

Gravitational Physics: Exploring the Structure of Space and Time (Physics in a New Era Series)

Gravitational Physics: Exploring the Structure of Space and Time (Physics in a New Era Series)
by Nrc Comm on Gravitational Physics (Editor), National Research Council (Editor)

Discusses gravitational physics as it applies to astrophysics and cosmology and quantized geometry of spacetime. Softcover.

Proceedings of the International Summer School on: Experimental Physics of Gravitational Waves Urbino, Italy September 6-18, 1999

Proceedings of the International Summer School on: Experimental Physics of Gravitational Waves Urbino, Italy September 6-18, 1999
by International Summer School on Experimental Physics of Gravitational w (Author), M. Barone (Author), M. Barone (Editor), G. Calamai (Editor), M. Mazzoni (Editor), R. Stanga (Editor), F. Vetrano (Editor), Universita Di Urbino Istituto Di Fisica (Editor)

Proceedings of the International Summer School on Experimental Physics of Gravitational Waves, held in Ubrino, Italy, September 6-18, 1999. Introduces needed theoretical instruments and presents current discussion on fundamental physics, as well as an exploration of gravitational wave antennae. Many other topics are also discussed, such as optics and signal processing.

  Gravitational Lensing (Lecture Notes in Physics)
by Y. Mellier (Author), B. Fort (Author), G. Soucail (Editor)

This is an exhaustive review of our theoretical and observational knowledge of gravitational lensing 10 years after the discovery of the first lensed quasar, Q0957+561. Gravitational optics, optical, infrared, and radio observations of quasar-lens candidates, microlensing, arcs in clusters of galaxies, and radio rings are presented. In particular, the continuing survey of quasar-lens candidates, the new measurement of the time delay in 0957+561, the suspended microlensing effect through the galaxy 2237+030, as well as the discovery of new arcs and the measurement of new redshifts for two of them are presented. Numerous papers on the modelling of arcs and rings show how it should be possible to probe dark matter with these unexpected gravitational telescopes. Finally, tables summarize all...

© 2010 BrightSurf.com