How fast does glass break?

First Winter day (or Summer day if you are down under) and so it is appropriate to “freeze”. Actually, it is not freezing in the way of cold, rather freezing in the way of slowing down something that we probably watched many times but we never actually see what happened because it was way too fast: the shattering of glass.

The Slow Mo Guys have created a channel on YouTube to show in slow motion many phenomena that are part of common experience but that we seldom really see in detail since they are way too quick for our eyes to follow. I am having fun watching them.  Their last experiment is about looking at how fast glass break (watch the clip).

They use a plier to crack a  glass pane and the crack rapidly (very very rapidly) propagates shattering the pane. The measured speed of the crack propagation reaches 1.400 ms, that is 4 times the speed of sound!

What fascinates me is the kind of equipment they use. A digital camera that can record over 70,000 frames per second (the number of frames also depends on the frame resolution, in the clip they first use a full resolution at 28,000 frames, then they reduce the resolution to push up the frame rate).

Inside the camera is a computer that has to process each single frame and this gives an idea of the processing capacity microprocessors have achieved.

Looking at this I also thought that just 50 years ago it would have been impossible to watch a glass cracking at such a slow motion rate, and the glass cracks so fast that it was impossible to see anything! Now it is something that we can do in our backyard (their video camera is still quite expensive but it is not astronomically expensive!).

As with many other tools that humankind built over the centuries this one is also augmenting our capabilities. Magnifying lenses and telescopes have augmented our vision capabilities, digital cameras are extending our capability in processing “time”. We can shorten it (time lapse) or stretch it (slow motion).

Interestingly, our brain perceives time in different ways, not like a Swiss clock. Sometimes, time runs slower, in others it runs faster and scientists are just discovering the mechanisms leading to the perception of time. Think about time perception when dreaming… A whole story may unfold in what seem hours and yet it happens in a second. Our perception of time is very much related to experience and feeling, rather than to a physical clock.
In the next decades we might be able to steer the brain to process time in a desired way creating a symbioses between sensors and perception. Looks like science fiction but it may be just round the corner.

About Roberto Saracco

Roberto Saracco fell in love with technology and its implications long time ago. His background is in math and computer science. Until April 2017 he led the EIT Digital Italian Node and then was head of the Industrial Doctoral School of EIT Digital up to September 2018. Previously, up to December 2011 he was the Director of the Telecom Italia Future Centre in Venice, looking at the interplay of technology evolution, economics and society. At the turn of the century he led a World Bank-Infodev project to stimulate entrepreneurship in Latin America. He is a senior member of IEEE where he leads the New Initiative Committee and co-chairs the Digital Reality Initiative. He is a member of the IEEE in 2050 Ad Hoc Committee. He teaches a Master course on Technology Forecasting and Market impact at the University of Trento. He has published over 100 papers in journals and magazines and 14 books.