Such a universe would have to have so radically different a conception of physics that it doesn't really apply to this analysis. Orbits are a pretty fundamental concept and you lose those in n>3 spacetime.
The authors also didn't consider the possibility of different geometries - e.g. hyperbolic space or time[0], or perhaps Nil[1] space. However, I suspect they would all have the same stable orbit problem that n>3 space runs into.
More damning, IMO, are the ultrahyperbolic (n>1 & m>1) and elliptical (n=0 | m=0) PDE spacetimes. These are spacetimes in which you can't compute physics, period. No alternative rules of physics will save you.
[0] Not to be confused with the Hyperbolic Time Chamber in Dragon Ball Z
[1] An alternative non-Euclidean geometry built specifically to make Penrose stairs in
> Such a universe would have to have so radically different a conception of physics that it doesn't really apply to this analysis. Orbits are a pretty fundamental concept and you lose those in n>3 spacetime.
Everyone keeps referencing the same single paper that made this claim, but it is only true under certain assumptions.
Most modern theories of physics have more than 3 dimensions, starting with 5 for Kaluza Klein theory and up to 10+ with string theories.
There's lots of ways of having more than the usual 3+1 dimensions and still having stable orbits, 1/r^2 laws, etc..
Curled up dimensions is a common approach, but not the only one.
For example, even in 3+1 dimensional space time, fields are radiated not from zero-dimensional points, but from one-dimensional world lines! By extension, additional dimensions of time would work if fields were radiated from higher dimensional surfaces or hyper-planes.
In other words, as long as in the bulk three spatial dimensions it appeared that sources of charges were zero dimensional points, the other dimensions can do "whatever" and everything generally works out.
The authors also didn't consider the possibility of different geometries - e.g. hyperbolic space or time[0], or perhaps Nil[1] space. However, I suspect they would all have the same stable orbit problem that n>3 space runs into.
More damning, IMO, are the ultrahyperbolic (n>1 & m>1) and elliptical (n=0 | m=0) PDE spacetimes. These are spacetimes in which you can't compute physics, period. No alternative rules of physics will save you.
[0] Not to be confused with the Hyperbolic Time Chamber in Dragon Ball Z
[1] An alternative non-Euclidean geometry built specifically to make Penrose stairs in