Scientists have created the world’s fastest-spinning object to help them better understand the effects of quantum friction in a vacuum: "nothingness" isn’t so empty after all.
In a recent study, a team of Purdue University researchers explain that they were able to best their own previous record for the fastest spinning object on Earth by creating enough angular momentum and torque to rotate a single dumbbell-shaped nanoparticle in a vacuum at 300 billion revolutions per minute. The fastest cars in the world rev their engines to around 10,000 revolutions per minute.
But this nanoparticle is more than just a quickly spinning top, it’s also the world’s most sensitive torque detector, which can detect the subtle drag effects of quantum particles. Researchers say this could help them better understand how friction created by quantum particles affects particles in a vacuum.
The study, published last week in the journal Nature Nanotechnology, describes how the researchers were able to achieve their results using careful laser manipulation of the nanoparticles. Silica nanodumbells, which look like two spheres attached together at their sides, were first diluted in water and then “launched” into the air using an ultrasonic nebulizer. The team used one laser to levitate the nanodumbell in place and a second to carefully apply torque to begin the rotation.
Unlike previous experiments which had achieved slower rotations and lower sensitivity at much colder temperatures, the researchers write in their study that their approach can be achieved at room temperature.
While breaking nanoparticle speed limits is an achievement unto itself, the torque sensitivity that this experiment unlocks is where the real excitement behind the findings lie. Scientists used to believe that vacuum chambers devoid of air were simply filled with nothing, but recent advances have revealed that might be far from the truth. Instead, it’s full of mysterious quantum effects: almost ghost-like forces from particles that appear to be there one moment and gone the next.
“[T]he electromagnetic vacuum behaves like a complex fluid and will exert a frictional torque on a nanorotor,” the authors write in the study. “While there have been many theoretical investigations on vacuum friction, it has not been observed experimentally yet. [But] our calculations show that the vacuum friction acting on a silica nanosphere rotating at 1 GHz near a flat silica surface will be large enough to be observed under realistic conditions.”
The torque sensitivity of their silica nanodumbell would allow researchers to observe extremely subtle drag effects on the particle in a vacuum chamber caused by the electromagnetism of quantum particles. Being able to measure these effects experimentally could lead to a better understanding of vacuum friction and nanomagnetism and, in turn, how objects at this tiny scale interact with their environment.
Just as torque sensors enabled Henri Cavendish to first measure the gravitational constant in 1798, the researchers hope that their nano-sized experiment will have similar effects on the future of physics and our understanding of how tiny, elusive quantum particles affect the physical world we live in every day.