This paper proofs, that NP-hard problems can be solved efficiently through abstract geometrical computations. These computations are based on signals, which are dimensionless and can move uniformly on a hypothetical real axis in time and space.
The authors claim the model to be only abstract and
...with no apriori ambition to be physically realizable.
In fact, this paper shows, that the practical limitation is due to the need for a black hole to absorb emerging limit points within calculations.
Actually, there exist several black hole analogues and the first one was created in 2009, based on a rubidium Bose–Einstein condensate using a technique called density inversion (1). A further method by lasing the phonons also detected self-amplifying Hawking radiation in 2014 (2).
Can such analogues of black holes be used to build the signal machines described above? In effect, such a machine could be able to solve NP-complete problems efficiently.
If not, what exactly are the physically limitations for building such signal machines. If it could be possible to built them, what would be the implications for complex theory and the N versus NP Problem?
(1) Lahav, et. al. "Realization of a sonic black hole analogue in a Bose-Einstein condensate", 2009 (see doi: 10.1103/PhysRevLett.105.240401)
(2) J. Steinhauer, "Observation of self-amplifying Hawking radiation in an analogue black-hole laser", 2014 (see doi:10.1038/nphys3104)