inches, years, minutes, centimeters, are all very real measurements. Everything is relative to space/time. For our particular observation of space/time, these measurements cover most of the work that is necessary on earth to design and build structures. They are convenient in proportion to our eyes to make clear and accurate measurements. Althought the connection between space and time is difficult to comprehend, they are the same thing, however an inch or a centimeter obviously would not be the ideal increment of measurement for interplanetary travel.
Finshaggy, these measurements are only as real as the rest of the terminology we as human beings were taught to advance. I can assure you they are real, but yes we did as man, create this system, or these systems of measurement that we trust. Does is mean they are ideal? just like calendars, no. Space/time is every expanding and therefor these measurements will indefinitely become obsolete. As larger and smaller races and planets develop, as there is a universal bridge of society, a new measurement system will be proposed to our planet and widely accepted for its accuracy. It has already happened within our own planet time and time again.
The only reason heaphatus is asking the question about inches is because he is still insecure about his smaller than average penis, and needs to let go.