Friction's hypothesis is, at its core, a metaphor. The discussion of culture as rubbing, producing heat, and so melting, exploding, etc. is the central thesis, a critical derivation of the idea of "culture clash." To be sure, Tsing can back up each claim she makes with non-metaphorical knowledge, but this misses the point in my view. What's important to me is the ability to produce meaning at the metaphorical level. Tsing is especially interesting in this regard because she does not merely offer us a fresh metaphor; rather, she takes an initial metaphor ("clash") and, accepting its consituent parts (ie culture as physical and as touching) reframes the outcome (as "friction")-- working in a metaphor for culture, changing it-- and thus changing the nature of culture, as if this analysis of the terms of the metaphor were somehow an analysis of culture itself, that the constituitive logic of the metaphor were something which reflected (rather than pinpointed or exceeded) the substance of its subject.
I am intrigued by the ease with which metaphor is used as a tool for knowledge, and how manipulating it is often considered a sufficient examination of that which it takes as its subject.