Could a region of space be engineered to allow for a limited form of time travel?
In short, this seems to say the exact opposite of your claim: https://en.wikipedia.org/wiki/Dust_solution
> I could be wrong but I think you're outside your field on this one.
And in contrast what would that make of you??
I'm saying that if there in some point in the future (because we can see it now) is sufficient mass density in the region of space of that big ring, and it is rotating, we tick every box we know of to theoretically allow for an eternal circle. "Engineering" it would mean that someone wanted some type of eternal existence, which is the profound idea at play here.
Engineering things without the technology to manufacture it happens all the time. Just because we can't imagine how to build it does not mean we can't calculate if it could exist.
That "only" is important but unintuitive. It means space and time can not be separated from mass.
Light travels very fast but space is very big, so the light from stars we see is very old - some of the lights have outlived their stars, so I assume you meant the past but tbh I'm unsure
What we're talking about here are closed timelike curves. There's models which suggest they could exist inside a singularity, but they're not going to outside without something which seriously breaks other areas of physics (Tipler cylinders etc).
A singularity is a dimensionless point. It has no inside. Did you mean a black hole? If so, the Kurtzgesagt cartoon explains this.
The second part of you sentence seems to have a broken sentence structure. Can't make sense of it.
...but [closed time-like curves are] not going to [exist] outside [of a singularity] without something which seriously breaks other areas of physics (Tipler cylinders etc. [are examples of such theoretical instances which would break other areas of physics]).