Infinity is really hard to experience. Math works with it – in fact, math works with all sorts of different infinities – but everything we actually see has boundaries. We don’t even know if space is infinite – most probably it isn’t because we haven’t seen anything beyond twenty-nine billion light-years or so. From this, science actually estimates the size of the observable universe around 93 billion light-years.
On the other hand, physics tells us that these very distant objects are moving away very fast, and there’s no telling if and where they will stop. Math has a term for that, too: finite but unbounded.
A person has boundaries. They don’t necessarily start at our skin. If a stranger moves too close (to our taste), we feel violated. When we feel possessive about our belongings, we like putting them within our boundaries. Right now I’m sitting in a café, with my bag and coat on another chair across the table. If someone came and took – touched – them, I would feel violated. Does this make them part of me – do my boundaries extend to them across the table?