You may have heard about the practice of using aluminum foil as a way to block  the reading of  your brain waves by nefarious technologies.

But does it work?......

Here's a study from MIT that thoroughly explores that question:

On the Effectiveness of Aluminium Foil Helmets: An Empirical Study

Ali Rahimi1, Ben Recht 2, Jason Taylor 2, Noah Vawter 2
17 Feb 2005

1: Electrical Engineering and Computer Science department, MIT.
2: Media Laboratory, MIT.

Abstract

Among a fringe community of paranoids, aluminum helmets serve as the protective measure of choice against invasive radio signals. We investigate the efficacy of three aluminum helmet designs on a sample group of four individuals. Using a $250,000 network analyser, we find that although on average all helmets attenuate invasive radio frequencies in either directions (either emanating from an outside source, or emanating from the cranium of the subject), certain frequencies are in fact greatly amplified. These amplified frequencies coincide with radio bands reserved for government use according to the Federal Communication Commission (FCC). Statistical evidence suggests the use of helmets may in fact enhance the government's invasive abilities. We speculate that the government may in fact have started the helmet craze for this reason.

But don't stop here -- go to the site to make sure you see all the visuals!

And if you are more of a visual learner,  there's a wonderful video of an Australian interviewer speaking with one of the authors!

[If all this Just for Fun is not for you, stay tuned, I have more serious thoughts in development...]