In a surprising twist, a graduate student at UMass Amherst discovered a strange new fluid behavior that seems to defy thermodynamics.
While experimenting with oil, water, and magnetized nickel particles, he found that no matter how hard the mixture was shaken, it would always return to the same elegant urn shape. This behavior sparked curiosity among physicists, who eventually traced the cause to unusually strong magnetism altering the way the fluids interact. Though it has no immediate use, the finding opens new frontiers in soft-matter science.
A Surprising Discovery in Soft Matter
A team of researchers, led by a physics graduate student at the University of Massachusetts Amherst, has discovered a surprising new kind of fluid they’re calling a “shape-recovering liquid.” This unusual mixture appears to challenge long-standing ideas rooted in the laws of thermodynamics. Their findings, published on April 4 in Nature Physics, describe a blend of oil, water, and magnetized particles that, when shaken, consistently re-forms into a shape resembling the elegant curves of a Grecian urn.
“Imagine your favorite Italian salad dressing,” says Thomas Russell, Silvio O. Conte Distinguished Professor of Polymer Science and Engineering at UMass Amherst and one of the paper’s senior authors. “It’s made up of oil, water, and spices, and before you pour it onto your salad, you shake it up so that all the ingredients mix.” In salad dressing, those tiny spice particles help oil and water, normally incapable of mixing, blend temporarily in a process known as emulsification, which is governed by thermodynamic principles.
Magnetic Twist on a Classic Experiment
Emulsification plays a critical role in countless technologies beyond the kitchen. Graduate student Anthony Raykh was experimenting in the lab with a scientific version of salad dressing, only instead of spices, he used magnetized nickel particles, “because you can engineer all sorts of interesting materials with useful properties when a fluid contains magnetic particles,” says Raykh. He made his mixture, shook it up – “and, in a complete surprise, the mixture formed this beautiful, pristine urn-shape.” Even more surprising, the same shape returned every time, no matter how vigorously he shook it.
“I thought ‘what is this thing?’ So, I walked up and down the halls of the Polymer Science and Engineering Department, knocking on my professors’ doors, asking them if they knew what was going on,” Raykh continues. No one did. But it caught the eye of Russell and David Hoagland, professor of polymer science and engineering at UMass Amherst, the paper’s other senior author and a specialist in soft materials.
Solving the Mystery with Simulations
The team conducted experiments and reached out to colleagues at Tufts and Syracuse universities to construct simulations. Together, the collaborative effort determined that magnetism, strong magnetism, explains the inexplicable phenomenon Raykh had discovered.
“When you look very closely at the individual nanoparticles of magnetized nickel that form the boundary between the water and oil,” says Hoagland, “you can get extremely detailed information on how different forms assemble. In this case, the particles are magnetized strongly enough that their assembly interferes with the process of emulsification, which the laws of thermodynamics describe.”
Bending the Rules of Emulsification
Typically, particles added to an oil-and-water mixture decrease the tension at the interface between the two liquids, allowing them to mix. But in a twist, particles that are magnetized strongly enough actually increase the interfacial tension, bending the boundary between oil and water into a graceful curve.
Pushing the Boundaries of Possibility
“When you see something that shouldn’t be possible, you have to investigate,” says Russell.
While there’s no application for his novel discovery yet, Raykh is excited to see how this never-before-seen state can influence the field of soft-matter physics.
Reference: “Shape-recovering liquids” by Anthony Raykh, Joseph D. Paulsen, Alex McGlasson, Chaitanya Joshi, Timothy J. Atherton, Hima Nagamanasa Kandula, David A. Hoagland and Thomas P. Russell, 4 April 2025, Nature Physics.
DOI: 10.1038/s41567-025-02865-1
This research was funded by the U.S. National Science Foundation and the U.S. Department of Energy.
