This every-particle-for-itself movement serves as the foundation for all of electronic theory. It explains why a warm wire resists more than a cold wire, and why a round wire conducts as well as a square wire.<\/p>\n
But since the 1960s, theorists have suspected that electrons can be coaxed to act more like their watery counterparts, and to form an electron fluid.<\/p>\n
In recent years, a string of experiments has confirmed that prediction. Last fall, in the most dramatic demonstration yet<\/a>, Dean and his collaborators arranged for electrons to form a type of shock wave that occurs when a quickly flowing fluid crashes into a slowly flowing fluid. It was a surefire sign that electrons were flowing at extremely high speeds. \u201cThat\u2019s really the frontier right now,\u201d said Thomas Scaffidi<\/a>, a physicist at the University of California, Irvine who was not involved in the experiment.<\/p>\n Making electrons behave like water might someday lead to the development of new kinds of electronic devices. And extending the familiar theory of water to electrons could spawn a new way of thinking about quantum materials.<\/p>\n Thudding vs. Flowing<\/p>\n Andrew Lucas<\/a>, a theoretical physicist at the University of Colorado, Boulder, compares electrons traveling down a wire to pinballs traveling around a pinball machine. Once they enter the playing field, pinballs bounce around in every direction, flying off flippers and bumpers. They travel up the machine, down the machine, and all around it. Similarly, when electrons in a copper wire collide with vibrating copper atoms or with \u201cimpurities\u201d in the metal \u2014 spots where some other atom has usurped an atom of copper \u2014 they ricochet in all directions.<\/p>\n On average, pinballs do tend to travel farther down than up; in this sense they \u201cflow\u201d downward. Analogously, the \u201cflow\u201d of electrons emerges only in an average sense; an electric field, perhaps generated by a battery, establishes an ever-so-slightly preferred direction in the wire.<\/p>\n Cory Dean, a physicist at Columbia University, leads the lab that created the most dramatic recent demonstration of an electron fluid.<\/p>\n But this is a peculiar type of flow. An electron collides with an impurity much in the same way a hacky sack collides with the floor: It thuds more than it bounces. The impurity saps the electron\u2019s energy, preventing it from building up much momentum. Consequently, electrons move through a wire a bit like water seeping through packed sand, a motion physicists describe as a \u201cdispersive\u201d flow.<\/p>\n In contrast, water molecules flowing down a pipe collide almost exclusively off each other. And when they collide, they bounce like billiard balls: They share their momentum and keep on moving.<\/p>\n This ability of water molecules to \u201cconserve\u201d their momentum defines the nature of liquidity. Since collisions with obstacles don\u2019t drain their momentum, water molecules can engage in complicated collective motions, flowing in faster- and slower-moving zones and in swirling eddies.<\/p>\n In 1963 Radii Gurzhi,<\/a> a Soviet physicist, was the first to calculate exactly what would happen if electrons found themselves in a situation where they could only knock into each other, conserving momentum like water molecules.<\/p>\n Gurzhi found that the difference would lie in how the electric current reacted to heat. Warming a copper wire typically impedes electric current, since vibrations in the copper atoms intensify and more greatly impede electrons. But Gurzhi calculated that if momentum were conserved, heat would make electrons move more readily \u2014 similar to the way warm honey is runnier than cool honey.<\/p>\n His observation became known as the Gurzhi effect, but it didn\u2019t attract much attention at the time. It seemed like a theoretical curiosity, with little relevance to real electrons, trapped as they were in real-world wires \u201cfull of dirt and impurities,\u201d Lucas said.<\/p>\n Fifty years later, that would change.<\/p>\n Enter Graphene<\/p>\n In 2004, Andre Geim and Konstantin Novoselov announced the discovery of graphene, a honeycomb sheet of carbon atoms they could peel off a block of pencil lead using only Scotch tape. The effort earned them a Nobel Prize.<\/p>\n A layer of graphene was like a pinball machine with no bumpers; almost every atom was in its place. \u201cIt\u2019s just a thermodynamically beautiful crystal. It comes out of the earth well formed, with very few impurities,\u201d said Dean, who specializes in graphene experiments.<\/p>\n A metallic tip just nanometers across picked up tiny variations in the graphene\u2019s electric field, revealing a fluid shock wave where supersonic electrons suddenly slowed down.<\/p>\n It took physicists about a decade to figure out how to study graphene without interference from other materials. But when they did, they detected electrons truly flowing.<\/p>\n In one early experiment, in 2017, Geim and his collaborators carved a choke point into a strip of graphene, poured electrons through, and measured the resistance. They found that as they turned up the temperature, the resistance fell<\/a> \u2014 the Gurzhi effect in action.<\/p>\n And in 2022, physicists at the Weizmann Institute of Science in Israel managed to directly watch electrons flowing. They shaped a material with some similarities to graphene, called tungsten diselenide, into a vertical wire flanked halfway down by two circles resembling Mickey Mouse ears. As electrons flowed into the ears on their way down the wire, the group monitored their motion by measuring the magnetic field the electrons generated when moving around the wire. In doing so, they saw<\/a> fluidic electric currents swirling backward into the ears \u2014 electron whirlpools. The whirlpools resembled the eddies that form when part of a river\u2019s current runs into a bend and turns upstream.<\/p>\n![\"Close-up](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/02\/Cory-Dean-cr-Courtesy-of-Cory-Dean.webp.webp\")
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