MrSeb writes: "Seagate has demonstrated the first terabit-per-square-inch hard drive, almost doubling the areal density found in modern hard drives. Initially this will result in 6TB 3.5-inch desktop drives and 2TB 2.5-inch laptop drives, but eventually Seagate is promising up to 60TB and 20TB respectively. To achieve such a huge leap in density, Seagate had to use a technology called heat-assisted magnetic recording (HAMR). Basically, the main issue that governs hard drive density is the size of each magnetic 'bit.' These can only be made so small until the magnetism of nearby bits affects them. With HAMR, 'high density' magnetic compounds that can withstand further miniaturization are used. The only problem is that these materials, such as iron platinum alloy, are more stubborn when it comes to writing data — but if you heat it first, that problem goes away. With HAMR, Seagate has strapped a laser to the hard drive head; when it wants to write data, the laser turns on. Reading data is still done conventionally, without the laser. In theory, HAMR should allow for areal densities up to 10 terabits per square inch (magnetic sites that are just 1nm long!), and thus desktop hard drives in the 60TB range."