Is there a difference between a liquid and a glass?

The name of this website was inspired by the title of the recent article in Metro that discussed glasses and liquids.

Prof. G O Jones, after whom Physics and Astronomy building in Queen Mary, University of London is named after, was working on the problem of liquid-glass transition. The problem has turned out be controversial, yet one of the most interesting challenges in condensed matter physics. Is there, from the physical point of view, a qualitative difference between a liquid and a glass?


Watch this on YouTube! Watch this on YouTube!

Bottom Camera View

Top Camera View

What is shown here?

We have set up five bitumen samples in glass tubes with different orifice diameters. Two webcams record the samples by taking the pictures from top and bottom angles every hour.

Two movie clips at the top show bitumen flow from both camera views, and correspond to approximately 24 days of real time. You can switch between top and bottom camera views by clicking on two small thumbnails in the left corner of the video.

The same process is shown in more detail as a selection of images in two clickable picture galleries below the movie clips.

Finally, at the bottom of the page, we show the latest pictures, taken at 10 A.M. every day.

How do we interpret this?

The bitumen appears stationary during the observation time of minutes, days and weeks, and therefore behaves like a solid glass. However, this particular bitumen will flow if you look at it for several months and longer, showing liquid behavior.

Although our everyday experience tells us that a solid glass is very different from a flowing liquid, this experiment shows that the difference is only quantitative but not qualitative. This applies even when a system flows during times exceeding the age of our Universe, as is the case for familiar silica glass and other "apparent" solids..

Physical laws in areas such as relativistic and quantum physics can appear counter-intuitive in terms of human experiences. This experiment challenges our intuition too, and illustrates the limits of our human experience when it comes to long time scales.

We would like the thank the following people who have contributed to this new installation:

David Dunstan, Anthony Phillips, Geoff Simpson, Ben Still, Dima Bolmatov, Alex Owen, Predrag Micakovic, Terry Arter, Bill Spence and Kostya Trachenko.

Further reading: see Physical Review B 83, 014201, 2011 for more details.

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