There are many methods of measuring time. However, since this is an abstract physics problem I don't see why time can't be defined in a more abstract manner e.g. as one of the consitituent dimensions of space-time that can be given a more or less arbitrary unit duration (just like the spatial dimensions can be given arbitrary units of length).Yes, this is the conclusion of the calculation in the wikipedia article as well. If you have two light clocks, one at rest in the primed frame and one at rest in the unprimed frame, then you can use light aberration to show time dilation is symmetric. (Each clock will exhibit light aberration and time dilation from the other frame and the values will be equal in magnitude.)[/QUOTE]
No you cannot.
We have one light source and the clock is at rest with the light source.