in which Schrödinger (in 1918!) describes, "matter in the large essentially as a compressible fluid of constant density at rest under a constant spatially isotropic tension which ... must be equal to 1/3 of the rest density of energy".
The notation is old-fashioned, but check out Schrödinger's paragraph at the bottom of Harvey's page 5 !
https://arxiv.org/abs/1211.6338
in which Schrödinger (in 1918!) describes, "matter in the large essentially as a compressible fluid of constant density at rest under a constant spatially isotropic tension which ... must be equal to 1/3 of the rest density of energy".
The notation is old-fashioned, but check out Schrödinger's paragraph at the bottom of Harvey's page 5 !