This paper focuses on the nonlinear self-interaction of gravitational waves and explores its impact on the spectrum of the resulting gravitational wave. While many authors primarily investigate the nonlinear effects within the framework of "gravitational memory," we take a different approach by conducting a comprehensive analysis of harmonic generation. Theoretical analysis indicates that higher harmonics do not possess suitable conditions for energy accumulation. However, our study presents intriguing evidence supporting the concept of "nonlinear gravitational memory": the conversion and accumulation of (...) gravitational wave energy into a persistent metric deformation in the background space (specifically referred here to as zero harmonics). In simpler terms, a wave leaves a lasting imprint on the background space, even after the gravitational pulse subsides. Furthermore, our study estimates the significance of this effect and demonstrates that it should not be disregarded. (shrink)

In einem an den Präsidenten des Basler Konzils, den Kardinallegaten Giuliano Cesarini gerichteten Brief vom 9. Februar 1436 erzählt der Konzilsgesandte Johannes de Ragusio aus Konstantinopel von seinen mit dem Patriarchen Ioseph II. geführten Verhandlungen über die geplante Kirchenunion. Er spricht von dem greisen Patriarchen im Ton größter Bewunderung und erzählt, daß er sich auch nach vier- oder fünfstündigen Gesprächen von ihm nur schweren Herzens trennen könne: certe, quando venio ad ipsum solus, cum interprete tamen Bathomio calogero, qui fuit (...) in Concilio cum Ysidoro, per quatuor aut per quinque horas, non valeo ab ipso separari. (shrink)