Energy waves, such as electromagnetic waves and acoustic waves, are fundamental concepts in physics. They can be described in terms of their properties, which include frequency, wavelength, amplitude, and propagation speed. In recent years, scientists have been investigating novel approaches to controlling and manipulating various types of waves for a variety of applications such as communication, imaging, medical treatments, and more.
Everyday life involves three dimensions, or 3D – up and down, left and right, and forward and back. However, in recent years, scientists such as Guoliang Huang, the Huber and Helen Croft Chair in Engineering at the University of Missouri, have investigated a “fourth dimension” (4D), or synthetic dimension, as an extension of our current physical reality.
Huang and a team of scientists from the MU College of Engineering’s Structured Materials and Dynamics Lab have now successfully created a new synthetic metamaterial with 4D capabilities, including the ability to control energy waves on the surface of a solid material. These waves, known as mechanical surface waves, play an important role in how vibrations travel along the surface of solid materials.
Conventional materials are limited to only three dimensions with an X, Y and Z axis. But now we are building materials in the synthetic dimension, or 4D, which allows us to manipulate the energy wave path to go exactly where we want it to go as it travels from one corner of a material to another.
Guoliang Huang
While the team’s discovery is only a starting point for other scientists to build on, the material has the potential to be scaled up for larger applications in civil engineering, micro-electromechanical systems (MEMS), and national defense.
“Conventional materials are limited to only three dimensions with an X, Y and Z axis,” Huang said. “But now we are building materials in the synthetic dimension, or 4D, which allows us to manipulate the energy wave path to go exactly where we want it to go as it travels from one corner of a material to another.”
This breakthrough discovery, called topological pumping, could one day lead to advancements in quantum mechanics and quantum computing by allowing for the development of higher dimension quantum-mechanical effects.
The concept of “4D” often refers to adding a temporal (time) dimension to the traditional three spatial dimensions (length, width, height). In this context, controlling energy waves in 4D could potentially involve manipulating waves not just in space but also in time. This might lead to advancements in fields like signal processing, waveguides, and metamaterials.
“The majority of the energy from an earthquake – 90% – occurs along the Earth’s surface,” Huang explained. “As a result, by covering a pillow-like structure in this material and placing it beneath a building on the Earth’s surface, it could potentially help keep the structure from collapsing during an earthquake.”
The research builds on previous work by Huang and colleagues, which demonstrated how a passive metamaterial could control the path of sound waves as they travel from one corner of a material to another.
