\magnification=\magstep2


$$
{\rm spacetime\ vector\ } \quad = \quad (c \Delta t, 
       \thinspace \Delta x, \thinspace \Delta y, \thinspace \Delta z) 
$$

$$
{\rm STI} \quad = \quad \sqrt{ {(c \Delta t)}^2 - {(\Delta x)}^2 }
$$

$$
{{\rm STI}\over{c}} \quad = \quad \sqrt{ {(\Delta t)}^2 - {({{\Delta x}\over{c}})}^2 }
$$



$$
{\rm momentum-energy\ vector\ } \quad = \quad ( E,
       \thinspace p_x, \thinspace p_y, \thinspace p_z) 
$$


$$
{\rm ME} \quad = \quad \sqrt{ {{E}^2} - {p^2c^2} }
$$

$$
{  {\rm ME}\over{c}} \quad = \quad \sqrt{ {\left ({{E^2}\over{c^2}} \right)} - {p^2} }
$$

$$
{  {\rm ME}\over{c^2}} \quad = \quad \sqrt{ {\left ({{E^2}\over{c^4}} \right)} - { \left ( {{p^2}\over{c^2}} \right ) } }
$$




\bye
