hey
i don't know anything about physics so i'm turning /sci/
does anybody know what the göbel metric solution to the einstein field equations is and what it says about time travel
please drop me some answers
well the wiki link is cool but i'm not from an english-speaking country and i don't know nothing about physics
can somebody make the effort and spell this out for me a lil bit or at least what it says about time travel
If you have no idea what GR is about, it's going to be hard for me to say much.
a) It requires a cosmological constant that is a certain value relative to the matter density. The constant cannot be changed, and we cannot go around the entire universe setting up the required density for whatever constant the universe turns out to have.
b) Almost all matter fields interact with each other: dust particles of any density exert non zero pressures on each other, which breaks this metric.
c) The wiki does not state if the metric is stable to perturbations (I doubt it).
tl;dr we probably can't use this metric to make time machines.
I do believe it allows for time travel, but probably not in the same sense science fiction would depict it as.