Hello,
Physicists have formulated a "Calabi-Yau space", to show the supplementary dimensions in the string theory. But this space have six dimensions, and the M theory, the presentest string theory, have seven supplementary dimensions...
So, what is this Calabi-Yau space in the string...
The Einstein's equation is right for inert particle only. Yet a photon has a kinetic energy only, so a nil energy at pause.
The complete equation is E²=m²c4+p²v²