Scientists have built a DNA-powered computer that can perform calculations using billions of molecules in a tiny drop of water. The system taps into the laws of physics to create what the scientists describe as a computing system that's more efficient than the conventional computers that are widely used today. Rather than continuously using energy to force a calculation through a series of processing steps, the DNA computer is designed so that its more "energetically favorable" state is the correct answer. In other words, the computer is built to use less energy than other biological computers, which integrate living cells with traditional hardware, would take to calculate the answer. "The c...