Interesting-Month-56 t1_j8ei6vc wrote on February 13, 2023 at 6:48 PM

Thanks for all the answers. TBH, I never understood the concept of time slowing down with acceleration, because if you choose the right reference frame, it would seem that the return trip requires the twin to experience negative acceleration. Though writing this, that’s still acceleration I guess.

My take away is that I don’t understand the framework behind relativity at all.

Weed_O_Whirler t1_j8f80cw wrote on February 13, 2023 at 9:35 PM

> if you choose the right reference frame, it would seem that the return trip requires the twin to experience negative acceleration.

While in relativity velocity is relative, accelerations are not. Accelerations can be measured and felt. Easiest example. You're driving along a perfectly flat road in the back of a windowless truck. There is no experiment you could do to determine what speed you're going. All speed feel the same. But if the truck accelerated- sped up, slowed down or even turned, you would notice.