- #31
ProfDawgstein
- 80
- 1
WannabeNewton said:
[ limits to the rescue :) ]
So you emailed him? Cool.
I don't think I need anything else right now, thanks.
Mass conservation charged dust
- Context: Graduate
- Thread starter WannabeNewton
- Start date
Click For Summary
Discussion Overview
The discussion revolves around the conservation of mass in a system of charged dust particles within a specific space-time framework. Participants explore the implications of energy-momentum tensors for charged dust and electromagnetic fields, examining the conditions under which mass current conservation can be assumed and its relationship to the divergence of the total energy-momentum tensor.
Discussion Character
- Technical explanation
- Conceptual clarification
- Debate/contested
- Mathematical reasoning
Main Points Raised
- One participant questions the assumption of mass current conservation before proving that the divergence of the total energy-momentum tensor is zero.
- Another participant suggests that mass is conserved because the electric field only affects the movement of the dust particles, not their mass.
- A different participant references Geroch's work on mass current conservation, noting that it assumes non-interacting dust and does not utilize the condition of zero divergence initially.
- Some participants discuss the implications of the equations of motion derived from energy and momentum conservation, suggesting that these lead to mass conservation in the context of general relativity.
- One participant offers an intuitive argument regarding the constancy of mass within a volume carried along by a dust particle, emphasizing that neither the rest mass of the particles nor their number changes over time.
Areas of Agreement / Disagreement
Participants express differing views on the assumptions regarding mass current conservation and the implications of electromagnetic interactions on mass. There is no consensus on the validity of these assumptions or the interpretation of Geroch's proof.
Contextual Notes
Some participants note the limitations of existing proofs, particularly regarding the interaction of dust particles and the assumptions made about their behavior. The discussion highlights the complexity of applying conservation laws in the presence of electromagnetic fields.