Gone are the days when police had to do with those bulky bullet-proof vests, scientists at the American Institute of Physics have come up with a solution to the problem. They have developed a thickening fluid that turns soft material into solid protective gear. After treating with the fluid soft bullet proof material becomes very hard and prevents the projectile from tearing through it. Tiny hard particles cluster together and jam when stuck by a sudden force. The liquid technology is being tested on Kevlar to make bullet proof vests lighter, more flexible and more comfortable. Plans are afoot by the US military to use the liquid technology to improve Kevlar vest for troops.Related link: http://www.youtube.com/watch?v=_KsW7oY-9NU