[empath75]

So, let's imagine you have a function that takes a phase space (ie, the positions, momentum, etc of a bunch of particles in normal 3+1 space time) as an argument and produces an evolution of that phase space in time. It's got a bunch of rules in the function regarding gravity.

Now imagine you've new function, which also takes a phase space as an argument, but instead of operating in 3 spacial dimensions, it has five. And that it doesn't have any rules regarding gravity.

Now imagine, you have a one to one mapping between states in those functions. So you can take a state in 3d space, translate it to 4d space -- run both functions for the same amount of time, and they both should produce states which you can still map to each other.