Lecture 2 - Why Chocolate Melts and Jet Engines Don't Why is there an inflatable velcro wall in the Royal Institution and what does a head louse really look like? This demonstration made quite a few people at the RI very nervous, note the proximity of the giant Velcro wall to the priceless paintings and chandeliers that live in that room. To make things a little more difficult we put a scanning electron microscope (worth tens of thousands) right next to it. But it did mean that, in one room, you could see what happens to Velcro on big scale and on a very small scale -- surely a world first?! The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Our editorial policy: http://www.rigb.org/home/editorial-policy Subscribe for the latest science videos: http://bit.ly/RiNewsletter