* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Physics News -> General relativity
Post Info TOPIC: General relativity
Blobrana


L

Posts: 131433
Date:
RE: General relativity
Permalink  
 

Study validates general relativity on cosmic scale, existence of dark matter

An analysis of more than 70,000 galaxies by University of California, Berkeley, University of Zurich and Princeton University physicists demonstrates that the universe - at least up to a distance of 3.5 billion light years from Earth - plays by the rules set out 95 years ago by Albert Einstein in his General Theory of Relativity.
By calculating the clustering of these galaxies, which stretch nearly one-third of the way to the edge of the universe, and analysing their velocities and distortion from intervening material, the researchers have shown that Einstein's theory explains the nearby universe better than alternative theories of gravity.
One major implication of the new study is that the existence of dark matter is the most likely explanation for the observation that galaxies and galaxy clusters move as if under the influence of some unseen mass, in addition to the stars astronomers observe.
Read more

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Atom Interferometer Provides Most Precise Test Yet of Einstein's Gravitational Redshift

Using an atom interferometer, scientists have tested one of the foundations of Einstein's general theory of relativity: that time slows down in a gravitational field. Their experiment proves that Einstein was correct with 10,000 times more precision than previous experiments. They achieve this precision by comparing the interference between matter waves separated by 4/1000 inch.
Read more

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Ever since Arthur Eddington travelled to the island of Príncipe off Africa to measure starlight bending around the sun during a 1919 eclipse, evidence for Einstein's theory of general relativity has only become stronger. Could it now be that starlight from distant galaxies is illuminating cracks in the theory's foundation?
Everything from the concept of the black hole to GPS timing owes a debt to the theory of general relativity, which describes how gravity arises from the geometry of space and time. The sun's gravitational field, for instance, bends starlight passing nearby because its mass is warping the surrounding space-time. This theory has held up to precision tests in the solar system and beyond, and has explained everything from the odd orbit of Mercury to the way pairs of neutron stars perform their pas de deux.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: A weak lensing detection of a deviation from General Relativity on cosmic scales
Authors: Rachel Bean
(Version v2)

We consider evidence for deviations from General Relativity (GR) in the growth of large scale structure, using two parameters, \gamma and \eta, to quantify the modification. We consider the Integrated Sachs-Wolfe effect (ISW) in the WMAP Cosmic Microwave Background data, the cross-correlation between the ISW and galaxy distributions from 2MASS and SDSS surveys, and the weak lensing shear field from the Hubble Space Telescope's COSMOS survey along with measurements of the cosmic expansion history. We find current data, driven by the COSMOS weak lensing measurements, disfavours GR on cosmic scales, preferring \eta<1 at $1<z<2 at the 98% significance level.

Read more (16kb, PDF)

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Despite the success of general relativity, one of the most important problems in modern physics is finding a theory of quantum gravity that reconciles the continuous nature of gravitational fields with the inherent 'graininess' of quantum mechanics.
Recently, Petr Horava at Lawrence Berkeley Lab proposed such a model for quantum gravity that has received widespread interest, in no small part because it is one of the few models that could be experimentally tested.
In Horava's model, Lorentz symmetry, which says that physics is the same regardless of the reference frame, is violated at small distance scales, but remerges over longer distance scales

Read more

__________________
Blobrana


L

Posts: 131433
Date:
General theory of relativity
Permalink  
 

Albert Einstein really did know what he was talking about, according to new research conducted by a team of astrophysicists from Swinburne University of Technology.
Published today in scientific journal Physical Review, the research tests Einsteins general theory of relativity when applied to a very unique pair of stars that are unequal in mass and size. The researchers found that Einsteins theory still stands up, almost 100 years after it was originally proposed.

Read more


__________________
«First  <  1 2 | Page of 2  sorted by
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Physics News -> General relativity


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard