 
Summary: arXiv:grqc/0412102v211Aug2005
THE PHYSICAL MEANING OF THE "BOOSTROTATION
SYMMETRIC" SOLUTIONS WITHIN THE GENERAL
INTERPRETATION OF EINSTEIN'S THEORY OF
GRAVITATION
SALVATORE ANTOCI, DIERCKEKKEHARD LIEBSCHER, AND LUIGI MIHICH
Abstract. The answer to the question, what physical meaning should
be attributed to the socalled boostrotation symmetric exact solutions
to the field equations of general relativity, is provided within the general
interpretation scheme for the "theories of relativity", based on group
theoretical arguments, and set forth by Erich Kretschmann already in
the year 1917.
1. Introduction
In the same year 1915, when Einstein and Hilbert [1, 2] gave the final
mathematical expression to the long efforts done by Einstein for finding a
generally covariant theory of gravitation based on the absolute differential
calculus of Ricci and Levi Civita [3], Erich Kretschmann published a long
article [4], entitled "¨Uber die prinzipielle Bestimmbarkeit der berechtigten
Bezugssysteme beliebiger Relativit¨atstheorien", in which a minute analysis
of the relation between observation and mathematical structure in a the
