Tiny Glass Sphere Achieves Record Heat in Unique Engine Experiment

Researchers have created a remarkable engine using a minuscule glass sphere that reaches the equivalent of 13 million Celsius, nearly as hot as the core of the sun. This innovative device, measuring just 5 micrometers across, is levitated in a near-vacuum by an electric field and exhibits extraordinary properties that challenge conventional understanding of thermodynamics at the microscale.

The findings, detailed in a forthcoming paper in Physical Review Letters, reveal that the glass sphere behaves as if it possesses extreme heat, despite not actually being hot to the touch. The effective temperature arises from the sphere’s overall motion, rather than from the agitation of individual molecules that typically define temperature. According to James Millen, a physicist at King’s College London and coauthor of the study, “It is moving as if you had put this object into a gas that was that hot. It moves around like crazy.”

This phenomenon is particularly significant given the tiny scale of the object. John Bechhoefer, a physicist at Simon Fraser University, who was not involved in the study, expressed admiration for the achievement. “Creating effective temperatures that high at that scale is very nice,” he stated. The research indicates that larger engines might achieve even higher effective temperatures, which could have important implications for various applications.

Understanding high temperatures is crucial for evaluating engine performance. In thermodynamic terms, the glass sphere functions as a heat engine, transferring heat from a high-temperature source to perform mechanical work. While conventional engines typically demonstrate a ratio of hot to cold temperatures around 3, this new engine boasts a remarkable ratio of approximately 100.

The research team observed that the engine’s efficiency fluctuated dramatically, at times reaching 10 percent efficiency and, in some instances, exceeding 200 percent. Strikingly, the engine occasionally exhibited behavior contrary to expectations, such as cooling down instead of heating up. Millen remarked, “Thermodynamics down at the microscale is really, really weird. I really think it’s as unintuitive as something like quantum mechanics.”

This unusual behavior is significant for understanding processes within biological systems, particularly how tiny structures like proteins are influenced by their surroundings. The researchers aim to leverage their engine to investigate biological motors, such as kinesin, which transport cargo within cells. While the tiny glass sphere does not perform practical functions in a traditional sense, Millen notes, “It’s a perfect analog of an engine,” allowing scientists to explore the mechanics of such small devices.

As the glass sphere moves within the electric field, it experiences changes in temperature, a phenomenon known as position-dependent diffusion. This aspect is particularly relevant for biological processes, including protein folding. Uroš Delić from TU Wien praised the study, stating, “Creating an engine with a single one of these attributes — extreme temperature, a large hot-to-cold temperature ratio or position-dependent diffusion — would make for a nice experiment. This work combines all three, so that’s quite cool — or hot.”

The implications of this research extend beyond theoretical exploration. As scientists continue to understand the unique behaviors of microscopic engines, they may unlock new avenues for innovation in various fields, including materials science and biotechnology. In the ever-evolving landscape of scientific inquiry, this tiny glass sphere stands as a testament to the complexities and wonders of the physical world.