Is There a Bottom Most Scale?

What determines the boundaries of a thing? Are those boundaries defined physically? Or does that actually depend on our mind? And are these boundaries and objects actually generated and created by the human mind? If that's the case, that opens up some very radical possibilities. Does reality have a bottom most scale? So if youar student of science, you clearly see that there's many different scales at which we can look at reality. But is there a bottom of a scale? And for that matter, is there most scale?