To a philosopher, pinning down ‘Stuff’’ (water, sugar, salt, cement, apple pulp &etc) is a far from trivial task. Dr. Kristie Miller, for example, (Research Fellow and Research Adviser at the University of Sydney, Australia) has investigated ‘Stuff’ in a paper for American Philosophical Quarterly, 46(1): 1-19 – entitled ‘Stuff’.
Dr. Miller suggests that to aid in the philosophical consideration of what constitutes ‘Stuff’’, it could be beneficial to contemplate another category of Stuff called Stuff* (pron. Stuff-asterisk).
Simply put :
“Ultimately, I argue, on all but one theory of the nature of stuff, it is a mistake to identify so-called ‘paradigm portions’ of stuff with the portions of stuff that are the posits of those theories. Instead, ‘paradigm portions’ are what I will call portions of stuff*- portions that are related to, but not identical to portions of stuff. Once we recognise stuff and stuff* as distinct kinds of entity, we can see that some of our intuitions about stuff are preserved in terms of portions of stuff, and others are preserved in terms of portions of stuff*.”
‘Stuff’ is available in full here (Word .doc format)
Dr. Miller also investigates Time Travel.