Well, typical presumptions of that era. Lorentz was wrong.
Lorentz, no doubt, was thinking in terms of a mass rotating and having a momentum factor. Why wouldn’t he?
Well, he shouldn’t because the effect of mass is not within the particle, but emitted by the particle.
A similar argument could be, and was, made concerning the atom.
How could an electron be orbiting and not emitting radiant energy?
Science actually gave up and skipped over that one and just accepted the idea of quantumization as a fundamental principle without per se cause. Actually quantizing occurs for an exact and predictable reason and is not merely a fundamental force, but an aberrant effect.
The spin of particles is similar. It implies that there should be energy involved and even lost, but in reality, it doesn’t work like that. The mass is not what spins, but merely the particle. There is no momentum involved. The mass is the resultant effect of the particle’s spinning. But don’t try to correlate a spin to mass, because what is measured as “spin”, not spinning. It is the magnetic moment of a particle that is spinning that is measured. A particle can have no measurable “spin”, magnetic moment, yet have the same mass as any other, because the spinning that is within, isn’t polarized such as to yield an identifiable moment.
Actually, a better way to think of it is;
A particle is spinning and tumbling energy that produces mass.
It is not a spinning and tumbling mass that produces energy.
The precise manner it tumbles is what determines its “spin” type.
I can’t interpret that.