\(dS \geq 0\)
From the second law of thermodynamics, this simple equation best represents me. Any place I organise ends up getting messy after some time.
\(R_{\mu \nu} - {1 \over 2}g_{\mu \nu}\,R + g_{\mu \nu} \Lambda = {8 \pi G \over c^4} T_{\mu \nu}\)
This many-in-one is a set of greatest equations known as Einstien's Field Equations that decribes the space-time.
\({\partial^2 \xi \over \partial t^2} = v^2 \nabla ^2 \xi\)
Somehow, this equation appears almost everywhere I seem to think - sound, light, water, gravity, slinky, etc. This is the wave equation.
\begin{align*}
\mathcal{L} &= - \frac{1}{4} F_{\mu \nu} F^{\mu \nu} \\
&+ i \bar{\psi} \gamma^\mu D_\mu\psi + h.c. \\
&+ \bar{\psi}_i y_{ij} \psi_j \phi + h.c. \\
&+ |D_\mu \phi|^2 - V(\phi)
\end{align*}
The simplified Standard Model Lagrangian describes most of the interactions as processes in our Universe.