Comment by Rygian
As a layman on this topic, I understand that research does not need to work towards a predefined goal.
But for the sake of my understanding and edification, I would have loved to see some mention in the Abstract explaining the usefulness of the article. Is it "merely" a mental experiment to confirm that we know how to apply our equations in a synthetic environment? Do the conclusions influence or open venues for verifiable (experimental) research?
So they assume four-dimensional space-time of a certain shape, similar to how a two-dimensional sheet could be curved taking various shape. Then they calculate how would physical objects behave in space-time of that shape.
Can such shapes exist anywhere in our universe, realistically or even just theoretically? For all we know, perhaps not.