For real inner product space $(V,\langle.,.\rangle)$ there is a $\Bbb C$-bilinear form $( , )$ on $V\otimes\Bbb C$. This extension gives rise to a Hermitian inner product, again denoted by $( , )$ on $V^2\otimes\Bbb C$. A vector $v\in V\otimes\Bbb C$ is isotropic if $(v, v) = 0$.
In physics a quantity is called isotropic if it has the same properties or characteristics along all axes.
Q: what is the geometric interpretation of isotropic vector?
Edit: There is a similar (maybe equal) concept known as Isotropic Vector Matrix. Is this related to isotropic vector?