I try to avoid quoting another post as much as possible. My posts can already get long and it is a duplication of information.
I tried to answer the questions by trying to better explain myself and point to online sources people can go refer to.
If the questions and the answer to the questions all revolve around the understanding of dimension, then if I can explain well enough about the understanding of dimension then I have answered the whole group of questions.
I think I need to simplify the discussion.
I’ll answer one direct question at this time, using quotes to make you happy that I am directing my response to that specific question. Just answering one such question will make the post lengthy enough.
The fact that we can measure something we call "luminous intensity" absolutely in no way means that the Universe has more than one time dimension. All it means is that we're taking the third derivative of something with respect to time.
“Luminous Intensity” is something we can measure. It is a real phenomenon which can be quantified and measured, as opposed to an imaginary or abstract concept which has no real world observable way of measuring.
As something which we can measure, luminous intensity has what is defined as a dimension and the name of that dimension is referred to as luminous intensity. When you measure luminous intensity you do so using defined units quantities of luminous intensity in the dimension of luminous intensity.
Luminous intensity was determined to be base quantity by a group of people far more knowledgeable about the subject than I. As such, the related dimension of luminous intensity is considered to be a base dimension.
“Finally, it should be recognized that although the seven base quantities – length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity – are by convention regarded as independent, their respective base units – the metre, kilogram, second, ampere, kelvin, mole, and candela – are in a number of instances interdependent. Thus the definition of the metre incorporates the second; the definition of the ampere incorporates the metre, kilogram, and second; the definition of the mole incorporates the kilogram; and the definition of the candela incorporates the metre, kilogram, and second.”
I do not understand luminous intensity well enough to explain why this body of more knowledgeable people defined luminous intensity as being a base quantity and base dimension when the definition for the unit of luminous intensity, “candela” incorporates the meter, kilogram and second. Why would they not say it is a derived quantity?
The answer to why it is considered fundamental and not derived lies in the greater knowledge of the people who made that definition. I do not know why but I do know they have defined it so and that definition has been accepted as a world wide standard.
I do know that luminous intensity is a dimension and this relates to what dimension means which is the real confusion within this thread.