Eroica, your post about the constantly accelerating space ship is interesting, but I don't think you're proving that SR is the cause of the time dilation. Critics of SR have oftened used space twins, saying that the aging shouldn't be for one twin only if SR were true. SR proponents then argue (ususally) that the situations arren't the same for the two twins, since one is accelerating on his trip while the stay-at-home isn't. So you're effectively removing that counter argument, and the question then is why should just one twin have aged?

In my view the likley solution is that SR is not the best version of relativity we have. Lorentzian relativity for example uses a preferred reference frame, and time dilation would only be expected in the twin that is moving at a greater speed in that frame.