Before anybody asks, this comic is a play on the concepts of Minkowski Space and Euclidean Geometry as viewed from the perspective of a cartoon character. With a bit of Pinkie Pie thrown in for laughs.
According to the principals of physics our universe has 3 physical dimensions (Height, Width and Depth). With Time making up the 4th dimension (If you want to argue this one, go speak to your Physics Professor).
Cartoons are 2 dimensional (With Time as the third dimension). They have Height and Width, but not depth. An artist creates the illusion of depth by making an object bigger or smaller to make it seem closer (Frame 8) or further away (Frame 9). This is called false\forced perspective (If you want to argue this, go speak to your Art Professor).
Twilight is trying to explain this to Pinkie, who tries to prove her wrong by breaking into a whole other Dimension (OK, so …. it's basically another "Breaking the Fourth Wall" comic).
The title is a play on E=MC2, which is Einstein's Special Relativity as presented within Minkowski Space. There' no clever story behind it, it's the best Pun that I could come up with.
Drawn in Inkscape, compiled in Photoshop. I used 1 brush from Obsidian Dawn
Doctor Whooves in Frame 5 is Request: Dr. Whooves hugs?seriousby RichHap)