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pixel
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In the calculation of the precession of Mercury's orbit, why is the stress-energy tensor equal to 0? There is energy and momentum at the location of the planet.
pixel said:It seemed to me that if you are calculating an orbit (i.e. position, momentum etc.) of an object and the stress-energy tensor has components made up of the object's momentum, etc., then those components would be comparable to the things you are trying to calculate and hence not negligible..
pixel said:Still a little confused. One answer is that it's a good approximation to set the stress-energy tensor to zero. The other answer is that it's a fundamental fact that an object is not affected by its own field.
The stress-energy tensor being equal to 0 means that there is no energy-momentum density in the space-time surrounding Mercury. This is significant because it indicates that there are no external forces acting on Mercury, leading to a more accurate calculation of its orbit.
The stress-energy tensor plays a crucial role in the calculation of Mercury's precession. It is a mathematical object that describes the distribution of energy and momentum in space-time. In the case of Mercury's orbit, a stress-energy tensor of 0 indicates a lack of external forces and results in a more precise prediction of its precession.
Aside from the stress-energy tensor, there are other factors that can impact the precession of Mercury's orbit. These include the gravitational pull of other planets, the shape of Mercury's orbit, and any potential deviations from the theory of general relativity.
The calculation of Mercury's precession using the stress-energy tensor is highly accurate. In fact, it matches observations made by astronomers with an accuracy of about 0.01 arcseconds per century. This level of precision confirms the validity of Einstein's theory of general relativity.
The precession of Mercury's orbit is significant in the field of physics because it provides evidence for the theory of general relativity. It also demonstrates the importance of considering all factors, including the stress-energy tensor, in making precise calculations and predictions in the study of celestial bodies.