Our best estimate for the topology of the universe at the largest scale is that it is 'flat'. If it has curvature, it's below the margin of error we are able to

Our best estimate for the topology of the universe at the largest scale is that it is 'flat'. If it has curvature, it's below the margin of error we are able to measure it at. The only thing we know that can curve space significantly is gravity, but it would take truly stupendously strong gravity fields to significantly change basic results from classical geometry, such as those close to the event horizon of a black hole. Even then we can calculate it accurately nowadays so our results would still correspond to theirs even in those circumstances.