Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Einstein was right, McGill astrophysicists say

Observations of unique twin-pulsar star system show effects of general relativity

Researchers at McGill University's Department of Physics – along with colleagues from several countries – have confirmed a long-held prediction of Albert Einstein's theory of general relativity, via observations of a binary-pulsar star system. Their results will be published July 3 in the journal Science.

Pulsars are small, ultradense stellar objects left behind after massive stars die and explode as supernovae. They typically have a mass greater than that of our Sun, but compressed to the size of a city like Montreal. They spin at staggering speeds, generate huge gravity fields and emit powerful beams of radio waves along their magnetic poles. These illuminate Earth-based radio-telescopes like rotating lighthouse beacons as the pulsar spins. More than 1,700 pulsars have been discovered in our galaxy, but PSR J0737-3039A/B, discovered in 2003, is the only known double-pulsar system; that is, two pulsars locked into close orbit around one another. The two pulsars are so close to each other, in fact, that the entire binary could fit within our Sun. PSR J0737-3039A/B lies about 1,700 light years from Earth.

This new test of Einstein's theory was led by McGill astrophysics PhD candidate René Breton and Dr. Victoria Kaspi, leader of the McGill University Pulsar Group.

"A binary pulsar creates ideal conditions for testing general relativity's predictions because the larger and the closer the masses are to one another, the more important relativistic effects are," Breton explained.

"Binary pulsars are the best place to test general relativity in a strong gravitational field," agreed Kaspi, McGill's Lorne Trottier Chair in Astrophysics and Cosmology and Canada Research Chair in Observational Astrophysics. ""Einstein's theory predicted that, in such a field, an object's spin axis should slowly change direction as the pulsar orbits around its companion. Imagine a spinning top when its slightly non-vertical: the spin axis slowly changes direction, an elegant motion called 'precession.'"

The researchers discovered that one of the two pulsars is indeed precessing -- just as Einstein's 1915 theory predicts. If Einstein had been wrong, the pulsar wouldn't be precessing, or would precess in some other way.

Pulsars are too small and too distant to to allow us to directly observe their orientation, the researchers explained. However, they soon realized they could make such measurements using the eclipses visible when one of the twin pulsars passes in front of its companion. When this occurs, the magnetosphere of the first pulsar partly absorbs the radio "light" being emitted from the other, which allows the researchers to determine its spatial orientation. After four years of observations, they determined that its spin axis precesses just as Einstein predicted.

Even though spin precession has been observed in Earth's solar system, differences between general relativity and alternative theories of gravity might only shake out in extremely powerful gravity fields such as those near pulsars, Breton said.

"However, so far, Einstein's theory has passed all the tests that have been conducted, including ours. We can say that if anyone wants to propose an alternative theory of gravity in the future, it must agree with the results that we have obtained here."

Breton, Kaspi and colleagues in Canada, the United Kingdom, the U.S., France and Italy studied the twin-pulsar using the 100-metre Robert C. Byrd Green Bank Radio Telescope at the National Radio Astronomy Observatory in Green Bank, WV.

"I think that if Einstein were alive today, he would have been absolutely delighted with these results," said Dr. Michael Kramer, Associate Director of the Jodrell Bank Centre for Astrophysics at Manchester University. "Not only because it confirms his theory, but also because of the novel way the confirmation came about."

Mark Shainblum | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>