Let $X$ be the Fermat quartic $x^4+y^4+z^4+w^4=0$ in $\mathbb P^3$. It is known that $X$ contains infinitely many $(-2)$-curves, that is, smooth rational curves. (One way ofto obtain in infinitely many is to use the various elliptic fibrations on $X$, and use translations in the fibers.) Note however that these curves are typically not defined over $\mathbb Q$, even though $X$ is. My question is the following:
Is there a finite extension $K$ of $\mathbb Q$ wheresuch that all of the smooth rational curves are defined over $K$ and have a $K$-rational point?
I certainly suspect that the answer is no, but I don't see how to prove it.