I've been trying to get my head around time dilation in order to understand the relationship between space and time. I do not have a maths brain, I tend to understand things better as narrative concepts. I've read a lot of introductory material, but I'm having trouble making the link between the theory and reality. For example, my understanding of spacetime is that it is a mathematical model - grid-like in nature - that allows people to plot, measure, and predict space and time interacting. Time is shown as a dimension along with the three spatial dimensions and this makes it easier for people to... do various math things, that I accept are beyond my understanding at this point. So far, so fabulous. Then things move along to gravity, and I start to lose the plot. Because apparently gravity is caused by objects with mass warping spacetime. But an object - say a planet - is real, but spacetime is just a model that describes space and time in a way that makes it easier to understand. It's abstract. I can see the earth. I can feel gravity. Spacetime is an idea. So I go back and try to strengthen my understanding of the actual relationship between space and time. I read the light clock thought experiment. There's a lot of threads around this forum grappling with it and the less mathy ones helped me get my head round it. So the crux of my problem is this. I can understand that a light beam travelling between two mirrors could be seen to be traveling slower if the mirrors are moving, due to the extra distance travelled by the beam, and that it will depend on where you are in relation to the clock. But a clock - any clock at all - is just a device that measures time, not time itself. To me time is the way that humans experience events occurring in sequence. A person standing next to the clock on a horizontally moving spaceship and pouring a cup of tea should not take longer to fill the cup than a person making tea and viewing the moving clock from earth. The light beam may have to move longer between bounces but the tea should not take longer to hit china just because it's travelling horizontally, regardless of where you're seeing it from. A person returning to earth after a space journey should not be years older than their twin - the beam of light had longer to travel on the spaceship but how does horizontal movement affect how long it takes your cells to decay? Does the clock have magic powers?? What? What am I missing here???