NPR

A friend let me know quite a while ago about this story presented on NPR’s site entitled “Mathematicians Explain Tape’s Tendency to Tear”. It’s an explanation of a recent Pedro Reis article in the journal Nature Materials describing the annoying tendancy of tape to narrow while unpeeling it from the roll. As the article explains, Reis’ work “could help engineers test thin films for strength and reliability” The audio of the story is also available on the NPR site.

I love this story because I can imagine Pedro first thinking about this problem while unpeeling a roll of tape. I don’t know if the inspiration actually came this way, but its a great mental image that conveys the idea that some of the most interesting problems to solve are right under our noses.

Here’s the abstract of the paper from Dr.  Reis’s website:

Thin adhesive films have become increasingly important in applications involving packaging, coating or for advertising. Once a film is adhered to a substrate, flaps can be detached by tearing and peeling, but they narrow and collapse in pointy shapes. Similar geometries  are observed when peeling ultrathin films grown or deposited on a solid substrate, or skinning the natural protective cover of a ripe fruit. In this work, we have shown that the detached flaps have perfect triangular shapes with a well-defined vertex angle; this is a signature of the conversion of bending energy into surface energy of fracture and adhesion. In particular, this triangular shape of the tear encodes the mechanical parameters related to these three forms of energy and could form the basis of a quantitative assay for the mechanical  characterization of thin adhesive films, nanofilms deposited on substrates or fruit skin.

Yesterday I listened to a fantastic podcast from the NPR program Intelligence Squared U.S.. From the website, “Intelligence Squared U.S. brings Oxford-style debating to America - one motion, one moderator, three panelists for the motion and against.” The specific program I listened to examines the question, “Is America Too Damn Religious?”, which is a particularly fascinating question to me. The panelists present a scope of different opinions on this issue, and most of the comments are well thought out. Everyone is generally respectful, which is a trait I find important in this type of programming. The reflections are at times theological, political, and practical, which was an interesting mixture to listen to. The entire program can be found here. It’s possible to download a free MP3 version of the program on this page. For those of you with iTunes, you can also find an abbreviated version of the debate by looking for the Intelligence Squared U.S. podcast (which is also free). The entire debate runs about 1.5 hours (the abbreviated podcast is about 1 hour), but I think it’s worth it. For those familiar with the issues surrounding this debate I wouldn’t expect to find too much new information, but what I thought was interesting was the particular representation of viewpoints associated with the panelists.