^{3}/s

^{3}. I would like to know if there is some way to deduce it from experience, like any other physical laws in the deductive science.

Metric system (not just SI but also cgs and other conventional systems) can be reduced to min. four independend irreducible units of space, time, mass and current (or their combinations). RS reduces the metric system by two more units - mass and current. Current can be got rid of by similarity between voltage and force:

F=dp/dt U=dP/dt

where F is force, dp is change of momentum, dt change of time, U is voltage, dP chage of magnetic flux. In order to have the same units, in the second relation current must be speed times some constant. However for mass I didn't find any such similarity (and I doubt there is one - the playground with relations containing only time and space is quite small).

I wonder - can the relation between space, time and mass be somehow shown without "theory contamination"? (E.g. the relations above describe only the experience, they don't represent any particular theory. On the other hand 'electron' is a result of a theory used to explain certain experience. 'An electron was accelerated by 5V' is a "theory contamined" description. It is not necessarily right or wrong, but you have to use some theory to understand the statement.)

Thanks for answeres

Jan