This question already has an answer here:
- What is time dilation really? 8 answers
I have been asked to retitle this question and I have been asked to edit the question to adhere to mainstream physics. And I simplified it. So here it is:
Two cars approach each other at the same constant speed relative to earth. Special theory of relativity (SPR) tells us that the clocks inside each car will run slower than an identical clock at rest. Most importantly, the clocks inside each car run at the same (slower) rate because they are traveling at the same speed. SPR also tells us that whenever relative motion exists between two inertial frames of reference, the approaching clocks will run at different rates. Yet in this case the approaching clocks run at the same rate (as demonstrated above). How can SPR explain this paradox?