Re: Why Einstein geometrized away Newton's "force of gravity"

pmb says...

[Stuff about electric and magnetic fields from two
different frames]

I hold that the same is true for inertial forces.

It seems to me that the equation

m D/dtau U = F

already treats all observers and all coordinate systems
equivalently. You can use whatever coordinates you like
to compute the components of U, and the components of F,
and you can compute the derivative D/dtau.

I'll put this into
tensor form in the future. When I do I hope to show that the inertial
force is represented by a 4-vector which is not a 4-force. Thus one
need distinguish between 4-force and 4-vector which represents an
inertial force.

I just don't understand what *benefit* there is in talking
about inertial forces. Mathematically, the difference is
a triviality: In the equation

m (d/dtau U^u + Gamma^u_vw U^v U^w) = F^u

you can, if you like, move the Gamma term to the other side
of the equation to get:

m d/tau U^u = F^u - m Gamma^u_vw U^v U^w

Then you can call the right side F_total^u.

but what is the advantage of doing that? You say
that it is to express things from the point of view
of the noninertial observer. But in what way did
the original equation fail to do that?

--
Daryl McCullough
Ithaca, NY

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