If you own a cell phone then the glass screen is most likely a brand known as Gorilla Glass produced by an engineering company called Corning. Gorilla Glass (and some of its competitors) is known for its light and durable nature which has served the cell phone market well in recent years. Manufactured using a process known as ion exchange, Gorilla Glass appears to be a solid structure; You can hold it firmly, it is not malleable and you can shatter it of you really want but at an atomic level, this glass has a fluidic makeup. Its atoms are not arranged in a set structure so they are free to flow as they please. However, the process is slower than you might imagine.
Doug Allan and his research team observed a one-metre-square sheet of Gorilla Glass shrink by 5 micrometres in both width and length within the space of 10 days. After 18 months, the process had slowed significantly, shrinking only another 5 micrometres in that period of time.
Allan has theorised that the movement can be linked to the potassium and sodium ions that take part in the production process. When Gorilla Glass is created, these atoms have unfavourable positions in terms of energy potential. Over time, the atoms can find more appealing positions and become trapped between atoms in the overall structure. This occurs on a large scale throughout the entire glass structure thus allowing the glass to literally move.
The shrinkage is so miniscule that it will not cause any problems with your phone. It would take hundreds of years for the smallest of changes to become apparent. But if you’re still using the iPhone 5 or the Samsung Galaxy in 400 years, you’ll be very behind the times.