Holy Areal Density, Batman!

In the hard disk business, the way to get more data capacity is to increase the number of bits you can store on a given piece of disk surface.  This is called “areal density”, and it's usually measured in bits per square inch.  Areal densities have been improving at a fairly steady rate ever since the '70s, and the density march continues.  Seagate has just demonstrated 1,000,000,000,000 bits per square inch (a terabit/sq. in.), and promises 60 TB (terabyte) disk drives as a result.  Wow!