Sunlight melts snowflakes. Fire turns logs into soot and smoke. A hot oven will make a magnet lose its pull. Physicists know from countless examples that if you crank the temperature high enough, structures and patterns break down.

Now, though, they’ve cooked up a striking exception. In a string of results over the past few years, researchers have shown that an idealized substance resembling two intermingled magnets can — in theory — maintain an orderly pattern no matter how hot it gets. The discovery might influence cosmology or affect the quest to bring quantum phenomena to room temperature.

Several physicists expressed surprise and delight that such an effect is possible, even if only in theory.

“It just hits you in the face because it’s not what you expect,” said Fabian Rennecke, a researcher at the Institute for Theoretical Physics in Giessen, Germany, who was not involved in the work.

“I am quite intrigued and am thinking how to find a concrete realization of this framework,” said Jörg Schmalian, a physicist at the Karlsruhe Institute of Technology in Germany.

Turning Up the Heat

The discovery was sparked by an audience question at a lecture at the Hebrew University of Jerusalem in 2019. Zohar Komargodski, a physicist visiting from Stony Brook University, had commented that any form of order — such as the regular spacing of atoms in a solid or the alignment of atoms in a magnet — inevitably breaks down at sufficiently high temperatures. An audience member, Eliezer Rabinovici of Hebrew University, asked Komargodski if he was certain this was true. After the talk, the two began to collaborate, along with other colleagues.

They weren’t the first physicists to wonder. In the 1950s, Isaak Pomeranchuk had calculated that slightly heating supercooled liquid helium-3 atoms would make them freeze. A crystal known as Rochelle salt, which is used as a laxative, shifts to a more ordered structure at warmer temperatures. Curiosities like these motivated the physicist and future Nobel laureate Steven Weinberg to develop an idealized quantum theory of heat-resistant order in the 1970s. But in both liquid helium and Rochelle salt, further heating destroys the order. And Weinberg’s theory also failed above a certain temperature.

Was it possible for some pattern to persist forever, no matter how hot it got? Komargodski, Rabinovici and collaborators aimed to find out.

Heatproof Order

The physicists homed in on magnetism.

Picture a bunch of atoms arranged in a square grid. Each atom acts like a mini magnet with a north pole that points up or down.

If the atoms line up in some pattern — all pointing the same way, for instance — the material has magnetic order.

Imagine laying this grid directly on top of a second atomic grid. These new atoms can swing freely, pointing in any direction as opposed to only up or down. Nearby atoms will interact, with ripples in one grid triggering ripples in the other.

Now zoom out until the grid lines disappear and the system becomes a smooth sheet — a quantum field. The atoms have vanished, but the field still has two magnetic arrows at every point: one pointing straight up or down and another pointing in any direction.