I suggest watching these videos from Float Head Physics. They’re just some of the clearest and most intuitive explanations of relativity I’ve seen, and any other explanation I give here would just be me attempting to paraphrase him.
https://www.youtube.com/watch?v=Zkv8sW6y3sY https://www.youtube.com/watch?v=Vitf8YaVXhc
He has a whole playlist on special relativity which is really insightful if you want an even deeper dive, as well as playlists on other things like general relativity and quantum mechanics, all of which are based on building intuition instead of starting with complicated math equations.
I’m not saying I couldn’t see cases where I would seriously consider using calculus in a sewing pattern, but it’s really not used in sewing pattern creation basically ever unless someone already knows it and has a very specific use case. I suspect the OP meant “calculations” or something similar and mis-typed.
Source: I still remember a fair amount of calculus and I sew