Einstein's Apple: His First Principle of Equivalence

TL;DR

This paper explores Einstein's first principle of equivalence, its historical development, and the role of torsion in gravitational theory, emphasizing teleparallelism as a framework for understanding reference frames.

Contribution

It provides a historical and conceptual analysis of torsion and teleparallelism in Einstein's gravitational theory, connecting past ideas with modern interpretations.

Findings

Constructed a homogeneous gravitational field in Minkowski spacetime.

Highlighted the role of torsion and teleparallelism in gravitational reference frames.

Discussed Einstein's introduction of torsion in 1928.

Abstract

After a historical discussion of Einstein's 1907 principle of equivalence, a homogeneous gravitational field in Minkowski spacetime is constructed. It is pointed out that the reference frames in gravitational theory can be understood as spaces with a flat connection and torsion defined through teleparallelism. This kind of torsion was introduced by Einstein in 1928. The concept of torsion is discussed through simple examples and some historical observations.