deletions | additions       diff --git a/4-Dimensions.tex b/4-Dimensions.tex  index 3862faf..21270d8 100644  --- a/4-Dimensions.tex  +++ b/4-Dimensions.tex 
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\end{equation}  That is the electric field corresponds to the cross product of the spatial comonents of the four vectors, and that the magnetic field is the determinants of spatial components with time.  The elements of $B$ are signed areas of the parallellograms made in each basis direction $x,y,z$. \begin{equation}  \nabla\cdot\textbf{B}=  \frac{\partial}{\partial x}\begin{vmatrix} t_1 & x_1 \\ t_2 & x_2 \end{vmatrix}+  \frac{\partial}{\partial y}\begin{vmatrix} t_1 & y_1 \\ t_2 & y_2 \end{vmatrix}+  \frac{\partial}{\partial z}\begin{vmatrix} t_1 & z_1 \\ t_2 & z_2 \end{vmatrix}  \end{equation}