Dear Madam/Sir,
Both space and time are emergent properties born out of the perception of sequence. While space is the interval between the ordered sequences of objects that also is the background structure, time is the interval between the ordered sequences of events, i.e., changes in structures by energy.
Dimension of objects is the perception that differentiates the "internal structural space" from the "external relational space". Since such perception is mediated by electromagnetic interaction, where an electric field and a magnetic field move perpendicular to each other in a direction perpendicular to both, we have three mutually perpendicular directions. Dimension is used to determine the state of objects: if fixed, then solid, if fluid, then liquid and if loosely held, then gas, if not related to each other, then plasma radiation. Since time does not fit this description, it is not a dimension.
Number is a property of substances by which we differentiate between similars: if there are no similars, it is one otherwise many. Many can be 2,3,...n depending upon the sequence of individual perceptions. Infinity is like one: without similars. But whereas the dimensions of one are fully perceptible, i.e., discrete, the dimensions of infinity are not fully perceptible: analog and not the same as any discrete number. Since mathematics is accumulation and reduction of similars and partly similars, it is limited to discrete numbers and not analog infinities. Yet, like two different quantities can coexist, two infinities can coexist. Hence space-time coexist and being infinite, coexist with everything else. Thus, everything happens in space-time and it cannot loose its sense. We have written this to weinberg@physics.utexas.edu.
Regards,
mbasudeba@gmail.com