513
Humans can be tracked with unique 'fingerprint' based on how their bodies block Wi-Fi signals
(www.theregister.com)
This is a most excellent place for technology news and articles.
Ironically, they're still wrong, because even in their wildest conspiracies, they didn't imagine Wi-Fi could be used to "take pictures" of a sort.
Tinfoil hat conspiracy theorists predate wifi by at least a decade