Imagine a universe where heat no longer flows, where atoms quiver less and less until their restless dance finally halts. This is the realm of absolute zero, the coldest conceivable temperature, a place physicists have long treated as a mysterious frontier. For over a century, scientists observed a curious behavior in matter at this limit: its specific heat, the very property that resists changes in temperature, vanishes. Yet, despite decades of study, a clear, classical explanation for this strange phenomenon remained elusive. Until now.
Professor José-María Martín-Olalla, from the Department of Condensed Matter Physics at the University of Seville, has breathed new life into this old puzzle. In his recent publication in Physica Scripta, he reveals a direct connection between the vanishing of specific heats at absolute zero and one of the most fundamental principles of the universe: the second law of thermodynamics. This revelation reframes a century-old mystery with fresh clarity.
Revisiting a Century-Old Puzzle
In the early 20th century, physicists were confronted with an unsettling observation. Classical physics dictated that changing a material’s temperature always required exchanging energy. But as temperatures approached absolute zero, specific heats—the measure of a material’s resistance to temperature change—seemed to disappear. A change in temperature at this ultimate cold no longer demanded energy.
Einstein, in 1907, offered a first glimpse of understanding using quantum physics, explaining why specific heats vanished. Yet this insight remained unlinked to the overarching framework of thermodynamics. Alongside Nernst’s theorem, which captured another fundamental property of matter at absolute zero, this behavior was codified as the third law of thermodynamics. While elegant, the explanation felt somewhat fragmented, disconnected from the universal narrative of entropy and energy conservation that defines classical thermodynamics.
A Classical Connection
Professor Martín-Olalla’s work reshapes this narrative. He proposes that the vanishing of specific heats is not just a quantum curiosity but a natural consequence of the second law of thermodynamics itself, rooted in the principle of equilibrium stability. In other words, matter behaves at absolute zero not because of a special law, but because of the universal tendency of systems to remain stable until disturbed.
“The microscopic interpretation of the vanishing of the specific heats alludes to the quantum nature of matter,” he explains, “but the paper shows that, in general, nature avoids situations that would lead to an unstable state at absolute zero.” This simple yet profound insight reframes absolute zero from a mysterious limit into a predictable outcome of classical thermodynamic principles.
The Role of Thermal Stability
To understand this, it helps to consider what thermal stability means. Thermal stability is the property of a system that ensures its equilibrium persists until an external force intervenes. For temperatures above absolute zero, this condition requires specific heats to remain positive. Martín-Olalla’s analysis shows that the same principle, when extended to absolute zero, dictates that specific heats must vanish as temperature approaches zero.
In this way, the vanishing of specific heats emerges naturally from the logic of stability, rather than from an additional law. It is a remarkable example of how deep principles—long understood in one context—can illuminate phenomena that once seemed mysterious.
Completing the Thermodynamic Picture
This paper builds on Martín-Olalla’s previous work published in European Physical Journal Plus in June 2025, where he linked Nernst’s theorem to the second law of thermodynamics, correcting an original idea of Einstein’s. Together, these studies suggest a bold simplification: the two classical laws of thermodynamics, energy conservation and entropy increase, are sufficient to explain the macroscopic properties of matter across all temperatures, even at absolute zero. The third law, once seen as essential, becomes unnecessary.
The implications are profound. With these two laws alone, physicists can understand the behavior of matter from the fiery cores of stars to the frozen reaches of absolute zero. The universe, in its extremes, obeys a coherent and unified set of rules.
A Dance Between Classical and Quantum
Though the vanishing of specific heats has long been framed in quantum terms, Martín-Olalla’s work bridges the gap between classical and quantum thinking. He shows that the observed behavior is not merely a quirk of quantum mechanics but a consequence of nature’s preference for stability. Matter, even at temperatures approaching zero, behaves predictably, following the rules of thermal equilibrium.
“Matter behaves near absolute zero as predicted by thermal stability. There is no need for a new principle to codify regular and predictable behavior,” he emphasizes. It is a subtle reminder that while quantum mechanics provides the microscopic details, the macroscopic behavior of matter often flows from timeless, classical principles.
Why This Matters
Beyond the elegance of unifying old puzzles under familiar laws, this research has practical and philosophical significance. It streamlines our understanding of thermodynamics, reducing the conceptual overhead needed to describe matter at all temperatures. It reinforces the universality of the second law, showing how deeply the principle of increasing entropy shapes reality, even in extreme environments.
Moreover, it strengthens the bridge between classical and quantum physics. By demonstrating that absolute zero behavior is not a special anomaly but a predictable outcome of stability, it provides a new lens for understanding materials, energy, and the fundamental constraints of nature.
Finally, the work is a testament to the enduring value of revisiting old problems with fresh eyes. A century-old puzzle, once explained in pieces, now fits into a coherent story, revealing the hidden threads connecting energy, heat, stability, and the cosmos itself.
The Quiet Certainty of Absolute Zero
In the end, Martín-Olalla’s research invites us to see absolute zero not as a realm of mystery but as a realm of inevitability. The universe, in its quiet precision, ensures that matter behaves in predictable ways, even when stripped to its coldest extremes. The vanishing of specific heats is not a cosmic accident or an isolated law. It is the universe’s quiet affirmation that stability and order persist, even in the absolute silence of zero temperature.
Physics, in this story, becomes less about abstract rules and more about understanding the poetry of nature. It is the narrative of a universe that, at its coldest, still dances to the rhythm of timeless laws.
More information: José-María Martín-Olalla, Thermal stability originates the vanishing of the specific heats at absolute zero, Physica Scripta (2025). DOI: 10.1088/1402-4896/ae22a5
