Researchers at the University of Nevada, Reno, and SLAC National Accelerator Laboratory have made a groundbreaking discovery regarding the properties of “warm dense matter.” Tom White and Robert Nagler, who both teach at NYU, co-led this groundbreaking study. It demonstrates that solid gold can be superheated to temperatures much higher than previously believed possible, overturning theories that had stood for decades. The team published their findings in the journal Nature, shedding light on this extreme state of matter that exists under conditions found in places like the sun and inside planets.
Warm dense matter describes a regime of matter with relatively high temperature and density. It can get really hot, sometimes frying into the hundreds of thousands of degrees Kelvin. This intriguing phenomenon has drawn the focus of researchers hoping to learn more about astrophysical processes and conditions. They study the field of the stormy plasma of stars, the crushing pressures of planetary interiors, and the mind-boggling forces at work in fusion reactors. Considerable advances have been achieved in the experimental measurement of the density and pressure of warm dense matter systems. Yet, measuring their temperature can quickly become a daunting task.
Superheating Gold Beyond Limits
In an extraordinary feat, White and Nagler’s team used a novel approach. They wanted to know how shock compression impacts the temperature of tissues and other materials. This technique was intended to reproduce the extreme pressure and heat found in the interior of worlds like Earth. To accomplish these conditions, in their experiment the researchers heated solid gold to a staggering 19,000 kelvins (about 33,740 degrees Fahrenheit). That’s more than 14 times the melting point of gold, in fact! It far surpasses the proposed entropy catastrophe limit, a theoretical boundary that scientists once believed to be unbreakable.
The findings of this study contest four decades of firmly established theory. They suggest that researchers might have accidentally exceeded the entropy catastrophe boundary for decades. The absence of effective techniques for directly measuring temperature of materials in extreme states creates this gap in understanding. In turn, we don’t have a complete understanding of these conditions.
Innovative Measurement Techniques
The breakthrough in temperature measurement came through the innovative use of ultrabright X-rays from the Linac Coherent Light Source (LCLS). This new, cutting-edge technology made it possible for the research team to take direct measurements of how quickly atoms were vibrating in the laser superheated gold sample. To explore it, they first blasted a pulse of ultrabright X-rays through the material. This enabled them to determine the atoms’ temperature by studying their vibrations.
White and Nagler’s method has the ability to precisely identify atom temperatures as high as 500,000 kelvins. This diverse span deepens our insight into the complex field of warm dense matter. It informs valuable pursuits like inertial fusion energy research. These innovations would open the floodgates to advances in clean energy generation and materials development.
Implications for Future Research
The potential impacts of this research go well beyond proving an academic point. Nagler said he’s looking forward to using this new temperature measurement technique in his group’s continuing research into inertial fusion energy at SLAC. This, in turn, may provide superior methodologies that increase efficiency and effectiveness across fusion reactors. Fusion reactors are a necessary step toward creating the world’s future fusion-powered energy sources.
The research widens an emerging perspective on warm dense matter. It provides scientists with unique information about how this exotic matter behaves under intense conditions. As researchers continue to explore this state of matter, further discoveries may emerge that challenge existing knowledge and expand the horizons of physics.
