Welcome to the world of stochastic thermodynamics, where chance reigns and things get weird.
A team of scientists from King’s College London (KCL) has built the world’s smallest engine. It consists of a single particle microscopically, it is smaller than a human cell, and levitates in a vacuum.
By shaking this particle with “noisy” electric fields, the team of researchers managed to heat it to impressive temperatures. 10 million degrees Celsius —millions of degrees hotter than the surface of the Sun and more than three times the temperature of the solar corona, our star’s fiery outer atmosphere.
Although it breaks records, the temperature reached in , recently accepted for publication in the magazine Physical Review Lettersis just the most striking detail, says . The real discovery is in bizarre physics what happens at this scale.
Hot and Random
In classical physics, a motor is any mechanism that converts one form of energy into another. For example, heat is added and work is done. Simple, elegant and always within the rules of thermodynamics. But on smaller scales, things become strange.
To build this engine, researchers used a device called quadrupole ion trapor more simply, a Paul Trap.
This machine uses oscillating electric fields to trap a single charged microparticle, making it levitate in a near-vacuum. This configuration isolates the particle from the surrounding environment.
Next, the team applied a random and “noisy” voltage to the trap electrodes. This “noise” violently shakes particlemaking it move and generate a large amount of heat.
But, unlike a steam enginehis behavior was not predictable. In each engine cycle, the particle sometimes behaved in a “stochastic”, i.e. random. When exposed to a heat source, the particle could cool rather than heat up, a direct contradiction of what one would expect.
According to everything we learned in school about classical physics, this behavior violates the laws of thermodynamics. But on very small scales, the laws of thermodynamics don’t work the way we’re used to.
In this emerging field, called stochastic thermodynamicsthe laws of thermodynamics are respected on averagebut sometimes strange and counterintuitive behaviors arise.
In this field, an atom, on average, follows statistical laws — but in each of its individual cycles, there is no average: everything is “fluctuation”.
“Engines and the types of energy transfer that occur in them are a microcosm of the broader universe,” he says Molly Messageresearcher at King’s College London and first author of the study.
“The study of steam engines gave rise to thermodynamics, which in turn revealed some of the fundamental laws of physics. The continued study of engines in new regimes offers the possibility of expanding our understanding of the universe and the processes that drive its development”, he adds.
“By understanding thermodynamics at this unintuitive level, we can design better engines in the future and carry out experiments that challenge our perception of nature”, concludes Message.
Interestingly, this investigation is related to the concept of protein envelopment.
An engine for understanding proteins
This reduced scale may seem disconnected from reality. But life itself It sometimes operates on this scale. Bacteria, viruses and the molecular machines inside our cells are all single-particle engines. They do not work with predictable averages; live in the midst of thermal noise.
This becomes even more exciting from a practical point of viewas this strange particle engine can function as a “analog computer” to model protein folding.
Proteins are the engines of life. They are long chains of amino acids that must “fold” into precise and complex three-dimensional shapes to reach their final configuration and function.
When proteins “misfold”, can clump togetherleading to devastating diseases such as Alzheimer’s, Parkinson’s and cystic fibrosis. The challenge is that predicting how a protein folds is one of the hardest problems in science.
Os digital supercomputers face great difficulties in simulating protein folding, as they have to calculate billions of atomic movements on nanosecond scales, which requires astronomical computational power.
The KCL engine solves this problem by working like an “analog computer”: instead of calculating the problem digitally, physically simulate it.
In this process, a floating particle represents the proteinwhile tuned electric fields and “noisy” voltages mimic the random thermal forces that a real protein experiences inside a cell, allowing researchers to directly observe the folding process.
“The advantage of our method in relation to conventional digital models is the simplicity. Proteins fold in milliseconds, but the atoms that make them up move in nanoseconds,” says Molly Message.
“These divergent time scales make it very difficult for a computer to model them. By simply observing how the microparticle moves and deriving a series of equations from that, we avoid this problem completely”, he concludes.
Like the steam engines that powered the Industrial Revolution and modern physics, this microscopic engine could take us to the next frontier — where the chaos is not a system error, but the system itself.
