First email: 6 July 2019
Dear Prof. Dr. Alan Parry:
I hadn’t realized that “spherically symmetric spacetimes” had become a discipline specialty; and I was delighted to find your survey (however difficult for me) at this stage in my academic development. I will be asking for a little guidance from Steven Strogatz of Cornell so I do not read too much into the processes that have been defined to date. That’s my problem. I am prone to read too much into data where I do not comprehend the boundary conditions.
Particularly, I would also ask you if you think the Fourier transform has any bearing on your insights within your survey? Strogatz wrote a sensational “Pi Day” article in 2015 that opened that door for me. It was published in none other than The New Yorker!
Thank you for your work in 2012 and 2014 to publish and update your earlier articles: https://arxiv.org/abs/1210.5269
This section of this page will be developed in conjunction with another about the Fourier transform and harmonic analysis.
Wikipedia: “Spherical symmetry is a characteristic feature of many solutions of Einstein’s field equations of general relativity, especially the Schwarzschild solution and the Reissner–Nordström solution. A spherically-symmetric spacetime can be characterized in another way, namely, by using the notion of Killing vector fields, which, in a very precise sense, preserve the metric.” See: proper time. …the radial derivative of the circumferential radius in a freely-falling frame; this becomes explicit in the tetrad formalism. Also: https://en.wikipedia.org/wiki/Spin_connection