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SLAC And University Of Nevada Experiment Directly Measures Extreme Temperatures And Shows That Gold Resists 14 Times Beyond Its Melting Point.
Researchers from the United States have managed, for the first time, to directly measure the temperature of atoms in “dense and hot matter.” The result overturned a four-decade theory and revealed that gold melting may be more difficult than previously thought, even at extreme temperatures.
The experiment was conducted by scientists from the SLAC National Accelerator Laboratory and the University of Nevada, Reno.
The study paves the way for new measurements in extreme environments, such as planetary cores and fusion reactors.
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Unprecedented Measurement
According to the scientists, it has always been possible to calculate the density and pressure of matter under extreme conditions. However, accurately measuring the temperature was a challenge.
“We have good techniques to measure the density and pressure of these systems, but not the temperature,” explained Bob Nagler from SLAC.
The problem is old. Temperature estimates in environments like fusion reactors have very large margins of error. This compromises theoretical models used in physics for decades.
Innovative Technique
To solve this impasse, researchers created a new technique. In the Extreme Conditions Matter (MEC) instrument, they used a laser to heat a sample of gold just a few nanometers thick.
Shortly after, they applied a flash of ultra-bright X-rays. With this, the scientists were able to directly observe how the atoms vibrated, allowing them to accurately calculate the achieved temperature.
“Finally, we made a direct and unambiguous measurement, demonstrating a method that can be applied across the field,” said Tom White from the University of Nevada.
Record Temperature
The result surprised the team. Gold, which normally melts at 1,337 kelvins, remained intact at 19,000 kelvins. This is equivalent to 14 times its melting point. Gold melting, which seemed to occur much earlier at these levels, turned out to be much more complex than previously thought.
Despite the extreme temperature, the metal maintained its crystalline structure. According to scientists, this was possible because the heating happened very quickly, preventing the material from having time to expand or lose shape.
Theory Overturned
The discovery goes against the so-called “entropy catastrophe,” a theory formulated in the 1980s. According to this idea, there is an absolute limit to how hot a solid can get before disintegrating.
“We were surprised to find a much higher temperature in these superheated solids than we initially expected,” said White. “This refutes an old theory.”
The professor also highlighted that the Second Law of Thermodynamics was not violated. The observed behavior is possible when heating occurs in trillionths of a second. The melting of gold, in these experiments, did not happen even with extreme heat.
New Possibilities
For Nagler, it is possible that previous experiments had already reached these temperatures, but without researchers noticing, precisely due to the absence of direct measurement methods.
“If our first experiment using this technique led to a major challenge to established science, I can hardly wait to see what other discoveries await us,” he stated.
The study was published in the journal Nature.
