produce this measurement, a standard must be defined. It would be meaningless if
a visitor from another planet were to talk to us about a length of 8 “glitches” if we
do not know the meaning of the unit glitch. On the other hand, if someone famil-
iar with our system of measurement reports that a wall is 2 meters high and our
unit of length is defined to be 1 meter, we know that the height of the wall is twice