It is commonly assumed that the most correct description of the electromagnetic world is the abstract one, and that topological constructs, such as lines of force are not covariant. In this Letter, we show that for a $y$-invariant system with a $p$-polarized electromagnetic field, it is possible to construct absolute (i.e., Lorentz invariant) lines in $(t,x,z)$ space-time, which we call electric spaghettis (ESs). The electromagnetic field is fully described by the ES topology that transcends the limit between space and time, plus a new invariant, the characteristic parameter $\eta$. In a Fabry-Perot resonant slit grating, three ES patterns can be distinguished, corresponding to three regions: null straight lines in plane-wave regions, rounded rhombi in the interference region inside the grating, and Bernoulli's logarithmic spiral patterns—the first ever described fractals—in the funneling region.

• Received 25 August 2022
• Accepted 15 November 2022

DOI:https://doi.org/10.1103/PhysRevA.106.L060201