I spend a lot of time talking about invisibility on this blog, as it is a subject near and dear to me: I did my PhD work, completed in 2001, on early historical forms of invisibility. I like to tell people that I’m an invisibility hipster, and that I worked on invisibility “before it was cool.”
The field has progressed dramatically since I first did my work, and in recent years I’ve been playing a bit of “catch up” with my own invisibility work, trying both to build on the newest insights as well as apply knowledge from the old theories.
This past fall, my student Elisa and I used this approach to ask and answer a curious question: can something be more invisible than invisible?
Our answer was published in a paper titled “Null-field radiationless sources,” that appeared in November in Optics Letters.* Ordinary invisible objects, including cloaking devices, are objects that don’t scatter any light outside the domain of the object; a potential null-field object will potentially not scatter light inside, as well!