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Public release date: 25-Apr-2013[ | E-mail |
Share ] Contact: Sean Bettam
s.bettam@utoronto.ca
416-946-7950
University of Toronto
Provides evidence that Einstein's predictions still hold true a century later
TORONTO, ON An international team of astronomers and an exotic pair of binary stars have proved that Albert Einstein's theory of relativity is still right, even in the most extreme conditions tested yet. The results of their research are described in the April 26 issue of Science.
"The unusual pair of stars is quite interesting in its own right but we've learned it is also a unique laboratory for testing the limits of one of our most fundamental physical theories, general relativity" says University of Toronto astronomy professor Marten van Kerkwijk, a member of the research team.
What makes the pair of stars exceptional are the unique characteristics of each and their close proximity to each other. One is a tiny but unusually heavy neutron star one of the most massive confirmed to date. Named PSR J0348+0432, it is the remnant of a supernova explosion, and is twice as heavy as the Sun yet is only 20 kilometres across. The neutron star is a pulsar that gives off radio waves that can be picked up on Earth by radio telescopes. The gravity at its surface is more than 300 billion times stronger than that on Earth and at its centre every sugarcube-sized volume has more than one billion tonnes of matter squeezed into it, roughly the mass of every human past and present.
The massive star spins 25 times each second and is orbited by a rather lightweight dwarf star every two and a half hours, an unusually short period. Only slightly less exotic, the white dwarf is the glowing remains of a much lighter star that has lost its envelope and is slowly cooling. It can be observed in visible light, though only with large telescopes it is about a million times too faint to be visible with the naked eye.
In the new work, led by Bonn PhD student John Antoniadis, very precise timing of the pulsar's spin-modulated emission with radio telescopes was used to discover a tiny but significant change in the orbital period of the binary, of eight-millionths of a second per year. Given the masses of the pulsar and the white dwarf, inferred with the help of observations of the light emitted by the white dwarf using techniques perfected by Antoniadis and van Kerkwijk this turns out to match exactly what Einstein's theory predicts.
Einstein's general theory of relativity explains gravity as a consequence of the curvature of spacetime created by the presence of mass and energy. As two stars orbit each other, gravitational waves are emitted wrinkles moving out in spacetime. As a result, the binary slowly loses energy, the stars move closer, and the orbital period shortens.
The test posed by PSR J0348+0432 is particularly interesting because the massive star is a truly extreme object in terms of gravity, even compared to other pulsars that have been used to test general relativity. As a result, it causes exceptionally strong distortion of spacetime. In many alternatives to Einstein's theory, this would cause the orbit to lose energy much faster than is observed.
"The observations disprove these alternatives," says van Kerkwijk, "and thus give further confidence that Einstein's theory is a good description of nature even though we know it is not a complete one, given the unresolved inconsistencies with quantum mechanics."
"We really are just at the beginning of our studies of this massive and bizarre stellar object," says Antoniadis. "It may become the new standard for testing general relativity as time goes on."
###
Note to media: Contact Sean Bettam for illustrations and an animation of the research described here.
MEDIA CONTACTS:
Marten van Kerkwijk
Department of Astronomy and Astrophysics
University of Toronto
mhvk@astro.utoronto.ca
Sean Bettam
Communications, Faculty of Arts & Science
University of Toronto
[ | E-mail | Share ] ?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Public release date: 25-Apr-2013[ | E-mail |
Share ] Contact: Sean Bettam
s.bettam@utoronto.ca
416-946-7950
University of Toronto
Provides evidence that Einstein's predictions still hold true a century later
TORONTO, ON An international team of astronomers and an exotic pair of binary stars have proved that Albert Einstein's theory of relativity is still right, even in the most extreme conditions tested yet. The results of their research are described in the April 26 issue of Science.
"The unusual pair of stars is quite interesting in its own right but we've learned it is also a unique laboratory for testing the limits of one of our most fundamental physical theories, general relativity" says University of Toronto astronomy professor Marten van Kerkwijk, a member of the research team.
What makes the pair of stars exceptional are the unique characteristics of each and their close proximity to each other. One is a tiny but unusually heavy neutron star one of the most massive confirmed to date. Named PSR J0348+0432, it is the remnant of a supernova explosion, and is twice as heavy as the Sun yet is only 20 kilometres across. The neutron star is a pulsar that gives off radio waves that can be picked up on Earth by radio telescopes. The gravity at its surface is more than 300 billion times stronger than that on Earth and at its centre every sugarcube-sized volume has more than one billion tonnes of matter squeezed into it, roughly the mass of every human past and present.
The massive star spins 25 times each second and is orbited by a rather lightweight dwarf star every two and a half hours, an unusually short period. Only slightly less exotic, the white dwarf is the glowing remains of a much lighter star that has lost its envelope and is slowly cooling. It can be observed in visible light, though only with large telescopes it is about a million times too faint to be visible with the naked eye.
In the new work, led by Bonn PhD student John Antoniadis, very precise timing of the pulsar's spin-modulated emission with radio telescopes was used to discover a tiny but significant change in the orbital period of the binary, of eight-millionths of a second per year. Given the masses of the pulsar and the white dwarf, inferred with the help of observations of the light emitted by the white dwarf using techniques perfected by Antoniadis and van Kerkwijk this turns out to match exactly what Einstein's theory predicts.
Einstein's general theory of relativity explains gravity as a consequence of the curvature of spacetime created by the presence of mass and energy. As two stars orbit each other, gravitational waves are emitted wrinkles moving out in spacetime. As a result, the binary slowly loses energy, the stars move closer, and the orbital period shortens.
The test posed by PSR J0348+0432 is particularly interesting because the massive star is a truly extreme object in terms of gravity, even compared to other pulsars that have been used to test general relativity. As a result, it causes exceptionally strong distortion of spacetime. In many alternatives to Einstein's theory, this would cause the orbit to lose energy much faster than is observed.
"The observations disprove these alternatives," says van Kerkwijk, "and thus give further confidence that Einstein's theory is a good description of nature even though we know it is not a complete one, given the unresolved inconsistencies with quantum mechanics."
"We really are just at the beginning of our studies of this massive and bizarre stellar object," says Antoniadis. "It may become the new standard for testing general relativity as time goes on."
###
Note to media: Contact Sean Bettam for illustrations and an animation of the research described here.
MEDIA CONTACTS:
Marten van Kerkwijk
Department of Astronomy and Astrophysics
University of Toronto
mhvk@astro.utoronto.ca
Sean Bettam
Communications, Faculty of Arts & Science
University of Toronto
[ | E-mail | Share ] ?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Source: http://www.eurekalert.org/pub_releases/2013-04/uot-bbs042413.php
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Leap Motion has just announced that its 3D gesture controller hardware ship date will be delayed, from May 13 for pre-orders and May 19 for general retail availability to July 27. The delay was caused by a need for more testing from the Leap Motion beta testing community, and an expansion of that group with additional members, according to Leap Motion CEO Michael Buckwald, who held a press conference today to discuss the missed dates. This is not good new for a company that has spent a lot of time promoting its product and securing high-level partnerships (with Asus, HP and Best Buy) up until now. The hype that Leap Motion has been able to build only means that users will be more disappointed by any delays in its launch window, and the effect on public perception is certainly one the hardware startup would like to have avoided. Still, some 12,000 developers have received units and already used them to do impressive things, so Leap Motion is hardly in danger of being branded ‘vaporware’ as of yet. Leap Motion says it wants to make sure that the product they deliver is the best they can offer, and says that there is “nothing catastrophically wrong” with the hardware as of yet. The company?believes?that it could have shipped by the original date if it had really pushed things, but wanted to make sure that things were ready for prime time. The new July 22 ship date is firmly set, according to Buckwald, and this is “the first and only delay there will be.” When asked if there was a specific cause, Buckwald said it’s more about beta testing everything in general, but that there will definitely be a focus on getting more input on how customers interact with the product. In general, it sounds like there’s some concern about making sure that user experience is pleasant among not only Leap Motion’s more technical users, but also the general public, too. Buckwald says it has addressed most of the technical issues around gesture tracking, and now the emphasis is squarely on usability testing, and those who are already seeded with early hardware will essentially act more as consumer testers. “If you’d asked me a year ago what was the biggest challenge, I’d have said it would be the hardware side,” Buckwald said, but went on to explain that the software aspect is now
