One G in the spacecraft will be indistinguishable from 1 G on Earth. The difference, as I pointed out in my first post is that the space twin experiences this acceleration at a long distance away, and that makes a difference in how the two twins perceive each other's clocks.

In any case, Ryback, we're not really in disagreement here. The accelerations the space twin experiences place him in a very non-inertial frame while the earth twin can be considered to be in an inertial one for the purposes of the experiment. My disagreement with the person who originated the thread is that I (and other physicists) know that SR is not sufficient for a full description of the twin paradox. Because of the accelerations (indistinguishable from gravitational fields) that the space twin experiences a full explanation requires general relativity.

__________________
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind." - William Thompson, 1st Baron Lord Kelvin

"If it was so, it might be, and if it were so, it would be, but as it isn't, it ain't. That's logic!" - Tweedledee

This isn't right. This isn't even wrong. - Wolfgang Pauli