The young field of quantum thermodynamics, which tries to reconcile quantum theory with the 200-year-old science of heat and entropy, is booming. It’s also causing some heated disputes.

Many physicists hope that rebuilding thermodynamics from the laws of quantum mechanics will help to settle long-debated conundrums. There are practical implications, too. The field could help to resolve whether the concepts of heat and efficiency apply to tiny electronic components and even atom-sized machines.

But despite proliferating approaches — many of which were presented at the Fifth Quantum Thermodynamics Conference this month in Oxford, UK — the field is as contentious as ever. The crux of the issue is whether the fundamental laws that govern heat and energy on large scales also dictate the behaviour of nanoscale systems — or whether new laws are needed.

Interest is growing: this year, more than 100 scientists attended the quantum thermodynamics conference, says co-organizer Vlatko Vedral, a physicist at the University of Oxford. That is double the attendance in previous years.