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ringerha
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The electromagnetic energy density is well-defined through the square of the Maxwell Field tensor. Why cannot such a quantity be defined for the grav. field?
atyy said:
Because the gravity in GR is not of a field nature but of geometric one. It is an effect of the curved space-time. That is why they introduce pseudo-tensors.ringerha said:The electromagnetic energy density is well-defined through the square of the Maxwell Field tensor. Why cannot such a quantity be defined for the grav. field?
The concept of energy density in a gravitational field refers to the amount of energy contained within a given volume of space due to the presence of a gravitational field. It is analogous to the energy density of an electric or magnetic field in electromagnetism.
Energy density in a gravitational field is calculated by dividing the gravitational potential energy by the volume of space in which it is contained. This can be expressed mathematically as U/V, where U is the gravitational potential energy and V is the volume.
The energy density of a gravitational field is much lower compared to that of an electric or magnetic field. This is because gravity is a relatively weak force compared to electromagnetism, and therefore the energy contained in a gravitational field is also lower.
The energy density of a gravitational field is affected by the strength of the gravitational force, the mass of the objects creating the field, and the distance between them. The closer together and more massive the objects are, the higher the energy density will be.
The concept of energy density in a gravitational field is important in understanding the behavior of celestial objects, such as planets and stars, and in predicting their movements and interactions. It is also relevant in the study of black holes and other extreme gravitational phenomena.