With colder than average temperatures encouraging Canberrans to take their Christmas celebrations indoors, the topic of temperature has become a rich source of awkward small-talk.
For chemists at Columbia University, however, nothing could be more engaging than the study of all things very cold. The discovery of some unexpected chemical interactions occurring at temperatures close to absolute zero has changed the way scientists understand the unimaginably chilly world of −273.15°C (that’s absolute zero, for those not intimate with the matter).
In a paper published in Nature in 2011, Professor Thomas Markland has predicted that glass will melt as it approaches absolute zero. Given that ‘melting’ is typically associated with higher temperatures (most glass starts to melt at about 1500°C), the concept of low temperatures causing such a change in state is somewhat counterintuitive. Markland’s prediction supports theories that the logic of classical physics blurs as absolute zero is approached.
On the Kelvin scale, a pleasant temperature for a day trip to the beach would sit at around 303K. Water freezes at 273K. At 230K, polar bears start to feel uncomfortable.
The lowest temperature ever reached in a laboratory stands at 0.000 000 000 45K, an incredible achievement by a research group at MIT in 2003. Reaching 0K is physically impossible; it corresponds to a state completely lacking in any form of energy. At 0K, literally nothing can happen.
The energy demands that must be met in order to study temperatures close to 0K are massive. By supercooling gases such as helium, scientists can create pockets of atmosphere colder than anything so far discovered in the universe.
It is in computer-simulated versions of these supercooled environments that Markland and colleges encountered the counterintuitive ‘melting’ of glass.
Markland describes the unusual shift from solid to liquid that glass underwent as temperatures approached 0K in a computational scenario.
As the energy of the particles in the computer-modelled glass decreased, they began to slide past one another, behaving like a fluid. It is suggested that this behaviour is due to quantum effects that are observed at very low energies, allowing particles to move around each other in ways they couldn’t at typical temperatures.
The implications of this research are not immediately practical. They do, however, open a new door into the study of materials science, which is, quite literally, the basis of the world we live in. It cannot be denied that the discovery would be, to say the very least, cool.
