Physicists Blast Gold to Astonishing Temperatures, Overturning 40 Years of Physics

Superheated Gold Defies ‘Entropy Catastrophe’ Limit, Overturning 40-Year-Old Physics

By Clara Moskowitz edited by Lee Billings

Gold normally melts at 1,300 kelvins—a temperature hotter than contemporary lava from a volcano. But scientists lately shot a nanometers-thick pattern of gold with a laser and heated it to an astonishing 19,000 kelvins (33,740 levels Fahrenheit)—all with out melting the fabric. The feat was fully sudden and has overturned 40 years of accepted physics concerning the temperature limits of strong supplies, the researchers report in a paper revealed within the journal Nature. “This was extremely surprising,” says research group member Thomas White of the University of Nevada, Reno. “We were totally shocked when we saw how hot it actually got.”

The measured temperature is effectively past gold’s proposed “entropy catastrophe” restrict, the purpose at which the entropy, or dysfunction, within the materials ought to power it to soften. Past that restrict, theorists had predicted strong gold would have the next entropy than liquid gold—a transparent violation of the legal guidelines of thermodynamics. By measuring such a blistering temperature in a strong within the new research, the researchers disproved the prediction. They realized that their strong gold was in a position to turn out to be so superheated as a result of it warmed extremely rapidly: their laser blasted the gold for simply 45 femtoseconds, or 45 quadrillionths of a second—a “flash heating” that was far too quick to permit the fabric time to broaden and thus saved the entropy throughout the bounds of recognized physics.

“I would like to congratulate the authors on this interesting experiment,” says Sheng-Nian Luo, a physicist at Southwest Jiaotong University in China, who has studied superheating in solids and was not concerned within the new analysis. “However, melting under such ultrafast, ultrasmall, ultracomplex conditions could be overinterpreted.” The gold within the experiment was an ionized strong heated in a means which will have precipitated a excessive inside stress, he says, so the outcomes won’t apply to regular solids below common pressures. The researchers, nevertheless, doubt that ionization and stress can account for his or her measurements. The excessive temperature of the gold “cannot reasonably be explained by these effects alone,” White says. “The scale of superheating observed suggests a genuinely new regime.”

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To take the gold’s temperature, the group used one other laser—on this case, the world’s strongest x-ray laser, which is three kilometers (1.9 miles) lengthy. The machine, the Linac Coherent Light Source on the SLAC National Accelerator Laboratory in California, accelerates electrons to greater than 99 p.c the pace of sunshine after which shoots them by means of undulating magnetic fields to create a really vivid beam of 1 trillion (10¹²) x-ray photons.

When this laser fired on the superheated pattern, the x-ray photons scattered off atoms inside the fabric, permitting the researchers to measure the atoms’ velocities to successfully take the gold’s temperature.

“The biggest lasting contribution is going to be that we now have a method to really accurately measure these temperatures,” says research group member Bob Nagler, a workers scientist at SLAC. The researchers hope to make use of the method on different forms of “warm dense matter,” equivalent to supplies meant to imitate the insides of stars and planets. Until now, they’ve had no good solution to take the temperature of matter in such toasty states, which normally final simply fractions of a second. After the gold trial, the group turned its laser thermometer on a bit of iron foil that had been heated with a laser shock wave to simulate situations on the middle of our planet. “With this method, we can determine what the melting temperature is,” Nagler says. “These questions are super important if you want to model the Earth.”

The temperature method must also be helpful for predicting how supplies utilized in fusion experiments will behave. The National Ignition Facility at Lawrence Livermore National Laboratory, for instance, shoots lasers at a small goal to quickly warmth and compress it to ignite thermonuclear fusion. Physicists can now decide the melting level for various targets—that means the entire area might be heating up within the close to future.