First things first, so that answers will more closely approach my level of understanding; I have only completed multivariable calculus and linear algebra and haven't yet taken a "real" physics course. I am part-way through Penrose's "Road to Reality" though. Secondly, this question stems from an argument I was destined to lose on YouTube. I'm not looking for an argument just (hopefully) helpful answers. The original question (as stated in the title): Is matter infinitely divisible? I wrote physicists at the top 20 Google-returned sites asking just this question and of those who responded, the overwhelming answer was "No one knows" (<- Verbatim reply from UCSD). (There was also one "No" answer and one "I believe it is.") 1) As I understand it, discounting everything else, Planck's Length is the smallest we could ever hope to zoom in on, not necessarily the smallest there is, is this correct? 2) I have read a few articles from the mid '90's about the possibility of a substructure discovered in quarks, what came of this, was it disproven? 3) If there is a smallest length and corresponding smallest bit of matter, can someone outline motion for me at that level? Below are my general thoughts on the matter and why I have difficulty imagining a smallest subunit. Assume there is a length which cannot be subdivided; Ill call it k. Take a piece of matter of size k and move it over one k unit. Since k is not divisible anything moving onto k must cover it completely instantly for if it were to at any point cover it partially, you would have subdivision of k. This implies that the movement between the two points takes no time what so ever. But instant is faster than the speed of light and so conflicts with the laws of the physics. (Obviously I really know nothing of physics, but alas I copied this from a different conversation I had in which I pretended to know something and so leave the paragraph as is for completeness sake.) I'm probably leaving a lot out that I wanted to ask but will stick with this for now. Thanks in advance for all who help.