Weird Working Heat Engine: Soda Can „Stirling engine“ @ 860 rpm
The Future of Captchas: Facebooks Social Captcha Patent (Recognizing Friends)
In its latest salvo in the fight against spam, Facebook has filed a patent application for a “social CAPTCHA” system. CAPTCHAs, which ask people to re-enter a code displayed visually, have become well known as the main system for blocking spammers on the web. Facebook believes the social CAPTCHA will prevent spam even more effectively.…
