Hello. I have a problem with the statement that specific values, like the speed of light, have no meaning because we can change these values by a change of units. For measures attached with units the value(number) has no meaning "per se", I'm ok with that. (Unlike pure numbers like ratios of masses) But the number WITH the unit HAS a meaning: asking the question why the speed of light is 186000 mps is the same as asking why it is 300000 km/s but different from 187000 mps. What do you think?