#### Neddy Bate

**Valued Senior Member**

The only way he can "put himself in her position" is to change his velocity and become stationary wrt her. And he doesn't do that, after his original departure.

As long as he remains stationary in HIS inertial reference frame (the one that is moving away from her at 0.866 ly/y), he MUST accept the fact that the clocks in his inertial frame were synchronized purely by using the assumption that the speed of a light pulse is 186,000 miles per second. So if his clocks aren't synchronized (which they CAN'T be, if he agrees with her), the speed of a light pulse in his frame CAN'T be 186,000 miles per second. And if the speed of a light pulse in his frame ISN'T 186,000 miles per second, then Special Relativity ISN'T correct. I believe Special Relativity IS correct. That means that the current age of his home twin (according to HIM) is what his "helper friend" (who is stationary in his frame [and who therefore shares his "NOW" moment] and who happens to be momentarily co-located wrt her at the instant that he wants to know her current age) says it is. There is just no "wiggle-room" here.

Have you tried to calculate what the speed of light would be if he uses her clocks and measuring rods instead of his own? Hint: it does not violate SR because it is still c. The apparatus of SR is designed to ensure that the speed of light measures c in both reference frames. So your claim that he cannot use her clocks and rods due to it violating constancy of the speed of light is false.