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Gravitational Wave Sources May Be “ Closer ” Than We Think
| Content Provider | Semantic Scholar |
|---|---|
| Author | Qadir, Asghar |
| Abstract | It has been argued that the energy content in time varying spacetimes can be obtained by using the approximate Lie symmetries of the geodesics equations in that spacetime. When applied to cylindrical gravitational waves, it gives an enhancement of the waves. While, according to this proposal, the energy of the waves does go to zero asymptotically, it decreases as the inverse square root of the radial distance instead of the inverse of the distance. Since SN1987A showed distinct asphericity, a substantial portion of the energy could have come out as gravitational waves. As such, the claim of Weber to have observed gravitational waves from it needs to be reassessed. In the early days of Relativity there were doubts raised about the reality of gravitational waves as they were solutions of vacuum field equations. Weber and Wheeler demonstrated that they would impart momentum to test particles in their path [1]. This demonstration was extended to test particles in the path of plane gravitational waves by Ehlers and Kundt [2]. A general closed formula for the momentum imparted to test particles in an arbitrary spacetime was given by Qadir and Sharif [3]. Though it seemed obvious that " the waves must carry energy " , there was no clear measure available for the energy carried by them. This is because there is generally no energy conservation in Relativity and hence no definition of mass or energy. One way to avoid this problem is by defining a stress-energy " pseudo-tensor " (see for example [4]), but it is observer dependent and not generally accepted for defining the energy by relativists (see for example the discussion of the pseudo-tensor in [5]). A deeper approach is to define some measure for the breaking of time translational symmetry [6, 7, 8, 9, 10, 11, 12] and use that to provide a measure for the energy density in the spacetime. None of these attempts showed unambiguous success as they did not lead to any basic new physical insights or predictions. Unlike electromagnetic waves, gravitational waves undergo self interaction due to the non-linearity of Relativity. This self-interaction could, in principle cause damping like Landau damping of electromagnetic waves [13], due to their interaction with matter, or cause an enhancement such as might be expected on the basis of the work on colliding gravitational 1 waves [14, 15], where singularities are formed due to the interaction between two plane … |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://arxiv.org/pdf/0903.0252v1.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
