# Is (net) force invariant in special relativity?

I am aware that acceleration is not invariant under lorenrz transformations, but I was sure that the first postulate of special relativity implied that newton’s second law in its original form, F=dp/dt, where p is the relativistic momentum, was invariant. However, the following 2 questions imply otherwise:

Relativistic electromagnetism and electromagnetic forces on 2 protons

Magnetic force between 2 moving charges

It seems that the magnetic force between 2 moving charges depends on the frame of reference, and even goes to 0 in the relativistic limit. Doesn’t this violate the first postulate of special relativity?

$$\mathbf F=\frac{d\mathbf p}{dt}$$
$$\mathbf F’=\frac{d\mathbf p’}{dt’},$$
does not mean that force doesn’t transform under a Lorentz boost. It does transform, in the same way as the time derivative of relativistic momentum does. $$\mathbf F’\ne\mathbf F$$.
See this paper for a discussion of the Lorentz transformation of a three-force $$\mathbf F$$.