- #211
sweetser
Gold Member
- 360
- 0
4-momentum charge
Hello:
In my research, I focus on equations, not the words to describe said equations. The reason is that I work intermittently in isolation. There is not a small group of folks working full time on rank 1 unified field theories, so there is no one to chat with about the work.
By making videos for the Stand-Up Physicist - the educational arm of my research efforts - I do have to think about word choices. In creating a show about 4-potentials, I had to give [itex]J^{\mu}_{m}[/itex] a name. I think of this as the same darn thing as the electric current density [itex]J^{\mu}_{q}[/itex] except that the electric charge [itex]q[/itex] has been replaced by a mass charge [itex]\sqrt{G} m[/itex]. I have been calling it the mass charge density by reason of analogy.
No one works with a mass charge density, so maybe that is a poor choice of words. The electric charge density is the electric charge in motion. A mass in motion is a 4-momentum. I should call [itex]J^{\mu}_{m}[/itex] the 4-momentum charge density. I include the word "charge" because the units for this tensor are not the same as a 4-momentum. Units matter. The appearance of [itex]G[/itex] indicates the expression is connected to gravity. There is also a [itex]c[/itex], which implies the expression is relativistic.
There might be a deeper message with the shift to "momentum charge". In the current way of thinking, energy-momentum is the most important characteristic of a system. The link to gravity is indirect. Energy-momentum gets added into the stress-energy tensor that curves spacetime according to general relativity. Treated instead as a charge, 4-momentum charge is directly connected to gravity and inertia. A momentum charge is always going to effect what happens with gravity, which is how it should be.
I am off to buy groceries, but I will be playing with the idea that all 4-momentums should be rewritten as 4-momentum charges. It is easy enough to change the units, but it is the implications that are fun to consider while shopping.
doug
TheStandUpPhysicst.com
Hello:
In my research, I focus on equations, not the words to describe said equations. The reason is that I work intermittently in isolation. There is not a small group of folks working full time on rank 1 unified field theories, so there is no one to chat with about the work.
By making videos for the Stand-Up Physicist - the educational arm of my research efforts - I do have to think about word choices. In creating a show about 4-potentials, I had to give [itex]J^{\mu}_{m}[/itex] a name. I think of this as the same darn thing as the electric current density [itex]J^{\mu}_{q}[/itex] except that the electric charge [itex]q[/itex] has been replaced by a mass charge [itex]\sqrt{G} m[/itex]. I have been calling it the mass charge density by reason of analogy.
No one works with a mass charge density, so maybe that is a poor choice of words. The electric charge density is the electric charge in motion. A mass in motion is a 4-momentum. I should call [itex]J^{\mu}_{m}[/itex] the 4-momentum charge density. I include the word "charge" because the units for this tensor are not the same as a 4-momentum. Units matter. The appearance of [itex]G[/itex] indicates the expression is connected to gravity. There is also a [itex]c[/itex], which implies the expression is relativistic.
There might be a deeper message with the shift to "momentum charge". In the current way of thinking, energy-momentum is the most important characteristic of a system. The link to gravity is indirect. Energy-momentum gets added into the stress-energy tensor that curves spacetime according to general relativity. Treated instead as a charge, 4-momentum charge is directly connected to gravity and inertia. A momentum charge is always going to effect what happens with gravity, which is how it should be.
I am off to buy groceries, but I will be playing with the idea that all 4-momentums should be rewritten as 4-momentum charges. It is easy enough to change the units, but it is the implications that are fun to consider while shopping.
doug
TheStandUpPhysicst.com