The Minkowski spacetime represents a 4-dimensional space with time as an imaginary dimension. That would be a seminormed space, contrary to the normed Euclidian space that we perceive. I think that the Minkowski spacetime is thought of as a mere mathematical model but our universe could actually exist in such a seminormed 4-dimensional space. With that assumption, our universe could then be a 4-dimensional spherical wave with an imaginary radius, propagating at the speed of light. This would explain the expansion of the universe and it would explain the big bang as the source of the wave.

This model would even explain why we perceive only three dimensions when there are obviously more of them. Our universe being the actual wave and not just occupying the space of the wave, we are constrained within this phenomenon.

Just as an analogy, a ripple on the surface of a pond would correspond to a unidimensional universe and its big bang could be a rock that was dropped in the water from outside of the plane that contains this "universe".

Of course, this raises many questions, the most important one being what is the physical property that varies with the wave. But leaving aside the unanswered questions, this looks to me like an intuitively sound model for the universe. Anyone heard of something similar and what do you guys think about it?