What is the principle behind vibration packing?

The sixties? What are you, a hippie? No, I guess not, if you were a PhD student at Princeton. A relative got married near Princeton a few years ago, so I had a chance to drive through the campus. Very beautiful. My late father-in-law graduated there in the 40s (I think).

Cool report. I wish I could have gotten in on the M&M study. We might have run out of particles.

But is there an engineering term for the phenomenon whereby irregular particles always become more densely packed. They never become less densely packed.

In psychology (and biology, I think), there is the term "homeostasis" which says that unstable systems tend to change (because they are unstable) and stable systems tend not to change (because they are stable). So over time, systems tend to become more and more stable (static) -- they tend toward stasis. I don't know if that term works for inert (non-living) systems, like M&Ms.

Jennifer Murphy

if you were a PhD student at Princeton

I used to teach in the Chem Eng department at the Indian Institute of Technology at Madras in the early sixties. Homeostasis is the mechanism by which a stable internal system (of variables like temperature, acid/base balance) is automatically maintained in spite of external changes in organisms. The term now includes other non biological systems.
To my knowledge there is no engineering term for this. We used to refer to it as packing of particles.

OK, thanks