Gold Does Something Unexpected When Superheated Past Its Melting Point

1:0:50

2025-08-03

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Gold remains perfectly solid when briefly heated beyond previously hypothesized limits, a new study reports, which may mean a complete reevaluation of how matter behaves under extreme conditions.

The international team of scientists behind the study used intense, super-short laser blasts to push thin fragments of gold past a limit known as the entropy catastrophe; the point at which a solid becomes too hot to resist melting. It's like a melting point, but for edge cases where the physics isn't conventional.

In a phenomenon called superheating, a solid can be heated too quickly for its atoms to have time enter a liquid state. Crystals can remain intact way past their standard melting point, albeit for a very, very brief amount of time.

Typically, the entropy catastrophe is thought to be three times the standard melting point. Using a new method for calculating the energy of reflected X-rays to accurately measure absorbed heat energy, the team found gold could be heated 14 times that limit before it finally liquified.

As surprising as it sounds, the results don't break any laws of thermodynamics – they just show that sometimes reactions happen too quickly for the laws of thermodynamics to apply. It seems the atoms inside gold have nowhere to move to for a brief period of time, allowing thermal energy to dissipate before the structure can give way.

The researchers were able to reach 19,000 Kelvin (that's around 18,700 degrees Celsius or just over 33,700 degrees Fahrenheit), with the gold retaining its solid structure for more than 2 picoseconds (a picosecond is a trillionth of a second) – long enough to prompt the researchers to reconsider existing models.

"This measurement not only surpasses the previously predicted bounds of the entropy catastrophe but also suggests a much higher threshold for the superheating of solids, thereby rewriting the fundamental understanding of the stability of the solid phase under extreme conditions," write the researchers in their published paper.

The implications here are intriguing and exciting for physicists: it's possible that some solids don't have a melting point at all, at least when superheated for ultra-short periods of time.

"Our experiments clearly demonstrate that the previously proposed limit of superheating can be exceeded by far if the material is heated fast enough," write the researchers.

There are all kinds of areas where this new knowledge is going to be useful. Super-quick heating events happen everywhere from asteroid collisions deep in space, to nuclear reactors here on Earth, and scientists are now going to have a better understanding of what's happening within these events.

The researchers want to see if other solids react in the same way as gold in future studies, as well as exploring the entropy catastrophe further: essentially redrawing the chart of when solids can no longer exist as solids.

"Maybe we thought we solved it in the 1980s with this superheating limit, but now I think it's an open question again," physicist Thomas White, from the University of Nevada, told Alex Wilkins at New Scientist.

"How hot can you make something before it melts?"