A video of a glass walkway cracking under a man's weight went viral ... and you can even hear the sound of glass breaking as you walk. Mashable Trend Report: Coming Soon! Decode what’s viral ...

Video Analysis of Crack Speed When you have a video ... but not faster than the speed of sound in glass (4540 m/s). Actually, HyperPhysics lists the speed of sound in Pyrex at 5640 m/s.

But what if you suddenly saw the glass beneath your feet begin to crack? In a rather horrifying ... to give the appearance and sounds of shattered glass when walked across.