Researchers in Poland have developed a liquid that’s super-light and flexible... until you shoot a bullet at it that is. Upon impact, their specially designed 'shear-thickening fluid', or STF, turns into a solid that's reportedly not just more comfortable than Kevlar - the most widely used material in bulletproof armour - but also offers even better protection against bullets and other projectiles. Created by the Moratex Institute of Security Technologies, the liquid is what's known as a non-Newtonian fluid. Unlike regular Newtonian fluids like water, which only change their structure according to temperature or pressure fluctuations, non-Newtonian fluids change their...