"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.
Dave Finley | EurekAlert!
Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State
What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy