Monday, May 02, 2011

Negative Space

MSNBC and many other news outlets reported that one of the clues that led U.S. operatives to Osama Bin Laden's compound in a developed suburb of Abbottabad Pakistan just forty miles from the capital of that country was its lack of technology.
And unusual for a compound valued at more than $1 million: It had no telephone or Internet service.
Unless you have been living in a cave -- which, apparently, Bin Laden was not -- you are already aware of the concept of negative space. The Wikipedia article on this topic has an example of the image that introduced most of us to the idea.

Negative Space

Is the black and white image a vase, or opposing profiles of two men? This is when many children come to understand that what isn't there is just as important as what is there.

This breaking news found me smack in the middle of reading The Information: A History, A Theory, A Flood, a book on the history of information theory by science writer James Gleick. For me, it is a slow but rewarding read. Slow mostly because it's the kind of book that causes me to stare off in to space minutes at a time waiting for my brain to catch up making connections with existing material tucked away in its dark recesses. Material which for the most part hasn't been accessed since graduate school or my tenure at Bell Labs. The book is full of anecdotes and details about the lives of scientists, mathematicians, and engineers whose work ultimately informed my entire professional career and that of most of my colleagues: Turing, Gödel, Von Neumann, Nyquist, Shannon, and others.

Gleick's description of coding techniques, particularly that of Morse code, and of Shannon's and other's research into the redundancy of spoken and written natural languages, made me ponder how negative space, like the different durations of pauses between syllables, words, and sentences, was as or more important than the symbols that constitute the positive space in messages. Negative space is frequently crucial for correctly parsing the message, while much of the positive space is redundant because the symbols can be accurately predicted.

Gleick's example is the classic
f u cn rd ths
which nearly every English speaker can. But (and this is my example, not Gleick's) remove the negative space and
becomes much more cryptic. The negative space actually carries more information content than the redundant symbols in the positive space.

But more to the point of Bin Laden, although nearly every English speaker can read that first sentence with the redundant symbols removed, everyone also recognizes it as malformed. It violates the principle of camouflage: it fails to blend in with its environment.

What Bin Laden might have realized had he survived his encounter with U.S. operatives is that this principle now applies to technology as well, and most specifically to signals intelligence. If you want to go unnoticed, you have to blend in with your surrounding telecommunications environment. This means generating signals that have about the same level of traffic as your surround, about the same signal to noise ratio, and about the same information content. Otherwise, the negative space you have created in your ambient communications environment makes you stand out.

I suppose in the twenty-first century this would mean lots of outgoing Facebook updates and Twitter tweets whose topics are trivial and banal, and lots of incoming spam from Nigerian princes. I have no idea how to realistically fake those sorts of things, but I'm now convinced that keeping a low profile does not mean keeping no profile. You don't wear black to camouflage yourself in the woods; you wear something that looks like woods.

Just as negative results are still results, negative space still imparts information. Some things become obvious by their omission.

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