"simplified" spacetime and Emc2 vs Quantum Theory I tried to post this in the text book or homework section but it kept saying i was not allowed??? So, to attempt to keep to the rules of the site i will ask my question but also try and start a discussion to try and keep things interesting. Ive only recently been reading about maths and physics although ive always been interested in them. Unfortunatly my maths is pretty bad but im determined to impove it. I would also like to note that i am not doing any courses or exams and that this is purely out of interest. After reading about spacetime i was trying to work out the spacetime distance between two towns or more to the point the spacetime distance you would make on the journey between the two towns, if we break it down into different points of the journey ie: walking to bus stop from your house, waiting for the bus, travelling on the bus, walking to train station, waiting for the train, journeying on the train etc. Is there a "simplified" (for lack of a better word) way of calculating spacetime distance? Ive been working on it on and off but i feel overwhelmed, im quite confident with the theory behind spacetime but as usual im having problems with the math and things are not adding up (as far as i can tell). Thank you to anybody who has any suggestions or responses.