dirkpitt wrote:

Kip Thorne's results appear to

**conflict** with the

original 1979 paper on visualizing rotating black holes by Jean-Pierre Luminet.

This stackexchange post explains the current situation:

http://physics.stackexchange.com/a/151311Thanks, DW, for contributing more info to this topical subject.

Yet, if two such BH lensing visualizations look partially different, it seems too early to me to call this a

**conflict**.

My little plea below is to try to conceptionally separate possible calculational errors from various inequivalent modelling assumptions ...

Did you check carefully the inherent simplifications e.g. about the intricate BH angular momentum structure, and various other possible modelling assumptions in the respective codes?

As young theoretical physicists my wife and I once calculated analytically various implications of the BH angular momentum barrier that is quite unlike to what we are used to in standard quantum mechanics (text book) scenarios. The BH case tends to lead to "Regge like poles" in the complex angular momentum plane and correspondingly to various

**orbiting phenomena** of "test particles" (photons!...) approaching the BH etc...

Given the substantial complexity of BH lensing, it would not be surprising to me if various simplifications had been tacitly implemented here and there...Such steps are often unavoidable (notably in computer codes), be it for reasons of speed or otherwise.

Just to name a familiar, much simpler setting: consider strong lensing of galaxies from lenses that correspond to single galaxies or galactic clusters. In the literature, one finds plenty of inequivalent assumptions about such spacially extended lenses (as the two of us know very well

).

- Simplification to spherically or axially symmetric lenses;

- simplification to single point lenses with the deflection angle alpha_hat matched to the total mass of the lensing galactic cluster/ galaxy under consideration;

- modelling the galactic cluster as a sum of point lenses;

- making various assumptions about the radial mass distribution of extended lenses;

- working strictly in the optical limit i.e. neglecting next order corrections from General Relativity. The latter have all been worked out in the literature...;

- ...and much more...

Despite significant diagreements in resulting visualizations using these simplifying scenarios, one would not speak of

**conflicts** here. Each of the above scenarios have certain regions of approximate validity the limitations of which should of course be pointed out clearly.

Fridger