>>And something similar from everyday life.
>>One day the speed of bypassing car might be measured with a ruler and a clock. The next day, if the same measurement gave a different answer, no one could tell if the speed of the car changed, the ruler length changed, or the clock ticking changed, or your car is moving differently, or your eyes became older.
>>
>>So what is here relativity for?
>>
>>>One day the speed of light might be measured with a ruler and a clock. The next day, if the same measurement gave a different answer, no one could tell if the speed of light changed, the ruler length changed, or the clock ticking changed.
>
>It is the 'speed of light' that is being discussed. The speed of cars is controlled by gas pedals, signs and the police. ;-) Wait until Dragen get's hold of this. Then you'll see some interesting discussion.

Present and accounted for, but you can count on me as if I was fully manned!

The first idea is the possible ways that the ruler could have changed:

a) he grew softer with age, and allowed for a constitution, parliament etc
b) he decided to become the bold ruler (the one who has a street here) and so now he's not a ruler, he's a ruler
c) there was a revolution, and he doesn't rule anymore, it's in the hands of the masses now. And we know that e=m*c², i.e. whatever the ruling about the speed of light, it multiplies with the masses.
d) he abdicated and there's an interregnum. Your measurements can be off by any factor, depending on your faction.

...and let's not forget that the clock may decide to use gnats instead of ticks.