It appears curved to us because we mathematically transformed the reference frame.
If you are allowed to transform your geometric space to say “no straight lines” then there are no straight lines in math either. Because you could perform a transform on the straight line into a curved geometry.
Unfortunately (fortunately?) the space they’re traveling through is curved. It was a good attempt though neutrinos.
Edwin A. Abbott has entered the chat…
Not to mention quantum fuzzing
It appears curved to us because we mathematically transformed the reference frame.
If you are allowed to transform your geometric space to say “no straight lines” then there are no straight lines in math either. Because you could perform a transform on the straight line into a curved geometry.