“Gravity crystals” aren’t just consumable items in Fortnite anymore. A scientist has figured out how to use cheap household materials to create gravity crystals to study the exotic interiors of distant dead stars right here on Earth.
The new concept was developed by Alexander Bataller, a physicist at North Carolina State University, who will present his research this week at the annual meeting of the American Physical Society’s Division of Plasma Physics in Fort Lauderdale, Florida.
Bataller was inspired to develop an accessible technique that could demonstrate Wigner crystallization, which is a pattern that forms when electrons experience a very specific set of conditions.
To create a Wigner crystal, electrons must be confined to a space that forces them to remain close together even though they naturally repel each other. These conditions are met in white dwarf stars, which are the remnants of stars that have exploded in supernova and collapsed into super-dense spheres about the size of Earth.
“Our own star will become a white dwarf,” Bataller said in a phone call. “That is a natural part of its evolution, so if you care about our star then you’ll probably want to know what happens later on in its life.”
While scientists have theorized about Wigner crystals for decades, these patterns remain “one of the most elusive states of matter” to study experimentally, according to a recent study in Science.
“That’s kind of what gets me excited about this,” Bataller said of his gravity crystal concept. “This is a phenomenon that has been studied in astrophysical contexts as far as white dwarf stars, but it’s also taken million-dollar experiments like ion traps and dusty plasma traps.”
These experiments involve studying Wigner crystals on very small scales, but Bataller wondered if the same principles could be recreated with larger objects such as metal balls. He found that Wigner crystals can be simulated by applying an electric charge to balls made of aluminum and copper. These balls, which represent the electrons, are placed into a regular mixing bowl that keeps them confined by gravity.
The material “doesn’t have to be metal per se, as long as they’re charged and rolling around inside of a bowl or a gravity well, as you might call it,” Bataller explained. “That’s why I gave them the name ‘gravity crystals’ because what ties everything together is to use gravity as the confining force.”
Bataller found that a number of different materials could simulate Wigner crystallization at these macro scales, including insulators like Teflon balls charged up with static electricity inside shot glasses.
The technique is mainly intended to be an educational technique that can demonstrate a classical system in an affordable way.
“What I’m hoping to do is outreach for undergraduates and high school students to use this platform to do science,” Bataller said. “It’s a cool educational tool for students to get experimental experience in a really accessible system.”