Good morning! It is with great pleasure that I welcome the speakers and all attendees of this webinar, titled “Trends in the Second Law of Thermodynamics”. The webinar will feature three presentations by esteemed experts in the field, covering a wide range of topics related to the Second Law of Thermodynamics and its applications.

The first talk will explore nuclear processes through a classical thermodynamic approach. Unlike conventional nuclear physics analyses, engineering thermodynamics considers changes in entropy—a parameter often overlooked. Notably, entropy plays different roles in fission (ΔS > 0) and fusion (ΔS < 0) reaction. While fission reactions are always spontaneous regardless of temperature, in fusion reactions, temperature acts as a very powerful amplifier of the entropic term (- TΔS). At very high temperatures, this amplification can significantly reduce the thermodynamic spontaneity of fusion processes. This occurs because a portion of the Q-value is used to balance the entropic term, which has a non-negligible impact on the energy efficiency of fusion systems. This effect should be considered in the design of future tokamaks.

In the second talk, we will elucidate the relationship between the Second Law of Thermodynamics and the Carnot engine. It is commonly believed that the First Law of Thermodynamics prohibits a perpetuum mobile of the first kind, while the Second principle prohibits a perpetuum mobile of the second kind. In addition, the Carnot engine is often regarded as an unrealistic model of an ideal engine. However, there is one obvious and another potential loophole in the above-mentioned approach. Firstly, located between the Carnot engine and the perpetuum mobile of the second kind is a perpetuum mobile of the third kind, which is exactly prohibited by the Second Law of Thermodynamics. Secondly, the Carnot engine is not a form of prohibited perpetuum mobile. Before a model of a real Carnot engine can be developed, it is necessary to define what exactly such an engine is supposed to represent. Paradoxically, it does not necessarily need to be a reversible engine. The concept of this engine should be the compatibility of work with a comparative cycle that mirrors the Carnot cycle.

In the third talk, we investigate what happens when we move away from equilibrium and the Second Law of Thermodynamics. When particles distribute themselves across different energy levels, a Boltzmann distribution typically emerges. Most textbooks feature derivations showing how the Boltzmann distribution maximizes entropy. A Boltzmann distribution also occurs when “noisy” Brownian particles move in a potential well. However, they only do so if the noise is Gaussian, i.e., the kicks that each particle receives from the surrounding particles follow a Gaussian distribution. Lévy noise is a generalization of Gaussian noise; however, it features a “fat” power law tail and a resulting infinite variance. There is no comprehensive nonequilibrium theory as there is with equilibrium noise. But it appears that many nonequilibrium setups in physics, i.e. setups where energy is converted or transported, exhibit Lévy noise. Notable examples include systems in plasma physics and astrophysics. Conversely, simulations and derivations suggest that the introduction of Lévy noise leads to non-Boltzmann distributions, violations of detailed balance, and dissipation of energy.

Date: 30 May 2025

Time: 10:00 am CEST | 4:00 pm CST Asia | 6:00 pm AEST

Webinar ID: 889 6490 7888

Webinar Secretariat: journal.webinar@mdpi.com