The gravitational waves things seem to be devilishly difficult to model with Einstein field equations , as they are very dynamic and not simétricas.Tradicionalmente The only way to approach the prediction of the possible effects of gravity waves was to estimate the parameters of the Einstein equation, assuming the objects that cause gravity waves do not generate strong gravitational fields themselves - and do not move at speeds anywhere near the speed of light.
The problem is that most likely candidate objects that could produce detectable gravity waves that is-(close neutron stars and binary black holes melt) - have exactly these properties. Are very massive bodies that often move at relativistic speeds (ie close to the speed of light).
Is not it strange then that the "rough estimate" described above actually works very well in predicting the behavior of close binary massive black holes merging. That is why recently published a document entitled: "On the unreasonable effectiveness of post-Newtonian approximation in gravitational physics" see here.
illustration showing a close binary system of two compact objects generated gravitational waves. Credit: NASA.
illustration showing the Laser Interferometer Space Antenna (LISA) the proposed system will use interferometry Laser to help monitor the fluctuations in the relative distance of three spacecraft deployed in an equilateral triangle with 5 million miles per lado.Se expected to be sensitive enough to detect the waves gravitacionales.Crédito: NASA.
So, first of all, no one has detected gravitational waves. But even in 1916, Einstein considered the likely existence and proved mathematically that gravitational radiation should emerge when you replace a spherical mass with a weight rotating in the same mass which, due to its geometry, create dynamic ebb and flow effects on spacetime.
To test Einstein's theory, is necessary to design highly sensitive detection equipment - and so far all attempts have failed. The hope now rests largely in the Laser Interferometer Space Antenna (LISA ), which is not expected to be launched before 2025. However
and sensitive detection equipment LISA, it is also necessary to calculate the types of events and what kind of data represent definitive evidence of a gravity wave - which is where all the theory and mathematics to determine the expected values is of vital importance.
Initially, theorists developed a post-Newtonian approximation (ie Einstein's time) for a rotating binary system - although it was acknowledged that this approach would work effectively only for low mass, low speed of the system - where any complication relativistic and tidal effects, resulting from its own gravity and the speed of binary objects in themselves, could be ignored.
Then came the era of numerical relativity , where the advent of supercomputers has really model all the dynamics of close binary mass moving at relativistic speeds, similar to the way that supercomputers can model very dynamic weather systems on Earth.
Surprisingly, or if you like for no reason, the calculated values \u200b\u200bof numerical relativity were almost identical to those calculated using the allegedly poor quality post-Newtonian approximation. The post-Newtonian approximation is simply not supposed to work for these situations.
All authors are left with the possibility that the gravitational redshift makes processes near very massive objects appear slower and gravitationally "weaker" to an outside observer than they really are. That would more or less explain the unreasonable effectiveness of post-Newtonian approximation.
more information HERE
source of information:
http://www.universetoday.com/83759/astronomy-without-a-telescope-unreasonable- effectiveness /
0 comments:
Post a Comment