Looking Down from Above

There is this metaphor: In Flatland, inhabitants don't see the third dimension. We live in three dimensions, according to  this notion, we don't see the fourth space dimension.

The truth is that the whole dimension bit is a human construct. Mathematics is the work of man, paraphrasing Kronecker: God made Space; all else is the work of man.

It is the nervous system that structures our eyes' impressions and constructs three dimensions. Some combination of sensorial inputs, puts in time, for good measure; and there you have it: spacetime.

Kant was not completely wrong when he started to search in his mind for some transcendental insight on space and time. They are a priori conditions, he thought. Without them we cannot perceive and then think.

Obviously I have not proved this, otherwise you'll find it in some Neuroscience  refereed publication. Nevertheless I believe that Kant needed better experimental tools, pure meditation was not enough. Already Asian gurus had discovered that much.

The challenge is to take data with functional Magnetic Resonance Imaging, or some more modern tool and do the observations.

How do we build, three space and one time dimension?

I pose here that, most philosophers and physicists, still believe that spacetime is out there.

I am starting to doubt that.