Having the Planck area lP^2 in the equation is of interest.

http://en.wikipedia.org/wiki/Planck_length"The Planck area, equal to the square of the Planck length, plays a role in black hole entropy. The value of this entropy, in units of the Boltzmann constant, is known to be given by A/4lP^2, where A is the area of the event horizon. The Planck area is the area by which a spherical black hole increases when the black hole swallows one bit of information, as was proven by Jacob Bekenstein."

The term lP^2/r^2 can therefore link our mass-energy to a density function that relates to the horizon black hole.

Another important point on this page is this.

"In doubly special relativity, the Planck length is observer-invariant."

So is length contraction valid or are space and time separate.