@@linmp2709 你confuse左加速度同速度。速度依個概念係reference frame dependence,即使你冇move過,不過我用光速1/3光速行緊,我永遠同自己係靜止嘅,所以,係我嘅reference frame,你係以光速1/3光速行緊。所以你身邊嘅時空冇唔同。因為相對論的一個基本假設就係物理不取決於reference frame。不過acceleration 係 coordinate-independent,即係話無論你用邊個inertial reference frame,加速度都係一樣,所以acceleration先係令兩人“時間流速”唔同的原因。 如果要更GR嘅treatment,應該首先搵出space time metric $g_{\mu, u}$, 然後計 the invariance interval $ds^2 = g_{\mu, u}dx^\mu dx u$, 然後再計proper time, $\tau = -int \sqrt(g_{\mu, u}dx^\mu/d\lambda dx u/d\lambda) d\lambda$, 咁一切就會好清晰。如果你睇唔明嘅話呢,建議去買一本Weinberg S. Gravitation And Cosmology.. Principles And Applications Of The General Theory Of Relativity, 或者 Wald, Robert M. General Relativity. Chicago :University of Chicago Press, 1984. 可以skip曬 manifolds theory先,讀左Special Relativity果個chapter。感謝🙏。