So, I've been reading Paradox: The Nine Greatest Enigmas in Physics, by Jim Al-Khalili and I'm not satisfied by his analysis of the Paradox of Twins. It raises more questions.
The way this paradox is resolved is by observing there is no paradox. To that end we say that the travelling twin experienced acceleration. But what exactly experienced acceleration?
I'm not interested in the paradox per se. What I'm interested in understanding is exactly what force allows for a system (the travelling twin, for instance) to be considered a single unit and to experience the effect of time dilation as a whole. And if this won't somehow spill out to any outer systems. At the scale of an atom our bodies are made up of as much empty space as the universe. But we implicitly know there's a force binding us into a consubstantial object in our own scale.
Now, the solar system, is it too a system. An outer system, at our human scale. It's entire mass counts with both twins. In a trip to the Oort Cloud, within our Sun's gravitational force, if the travelling twin went there and back a few times at the speed of light, wouldn't his mass (and that of his spaceship) contributed to an infinitesimal degree to an expanded lifetime of the Solar System?
If the two twins were two cells in your body, the travelling cell will remain young. The other cell (and the rest of your body) will age normally. Your body will however benefit from the young cell. Your body (the system) didn't experience the trip, but the system will still benefit from it as a whole. It is younger. It's made up of younger mass.
So... without experiencing any acceleration how come can the solar system become younger by the travelling twin actions?
