In general relativity (GR), the metric tensor of spacetime is essential since
it represents the gravitational potential. In other gauge theories (such as
electromagnetism), the so-called premetric approach succeeds in separating the
purely topological field equation from the metric-dependent constitutive law.
We show here that GR allows for a premetric formulation, too. For this purpose,
we apply the teleparallel approach of gravity, which represents GR as a gauge
theory based on the translation group. We formulate the metric-free topological
field equation and a general linear constitutive law between the basic field
variables. The requirement of local Lorentz invariance turns the model into a
full equivalent of GR. Our approach opens a way for a natural extension of GR
to diverse geometrical structures of spacetime.Comment: Some corrections made in accordance with criticisms of the referee,
references added; this version supersedes the printed version (it contains
some slips due to the editorial policy