And we are prejudiced because of our limitations. For instance, it is the inability to observe (vision/mind) additional dimensions which causes the presumption that the additional dimensions are compactified strings (Kaluza-Klein theory). Some theorists however do consider the possibility of higher dimensional dynamics. In these calculations, matter of all kinds arise in four dimensions as a result of vacuum in higher dimensionality.
Some physicists - such as Lisa Randall as I recall - also suggest that the reason gravity is so small by comparison to the other fields is that it is interdimensional. Following this open string theory - positive gravity is a space/time indentation and thus negative gravity would be a space/time "outdent" (which curiously corresponds to the acceleration of the inflation of the universe, i.e. dark energy).
Other physicists, such as Cumrun Vafa - suggest that there must be an extra temporal dimension which unifies the various string theories. Again, an extra dimension of time would go a long way to explain non-locality and superposition - but it is vigorously resisted because it would also do injury to physical causality (time being a plane instead of a line).
At bottom, our "vision" into such things is computational - like the Flatlanders in your story who discover their world is not two dimensional after all when they add up the angles on the triangle and it is not equal to 180 degrees.
"...there must be an extra temporal dimension which unifies the various string theories. Again, an extra dimension of time would go a long way to explain non-locality and superposition - but it is vigorously resisted because it would also do injury to physical causality (time being a plane instead of a line)".
A-G, I was wondering if you could further explain how, exactly, physical causality is injured by the extra time dimension. How would adding an extra time dimension change anything that we currently percieve to be true?