Scientists report asymmetry between heating and cooling
New research claiming a fundamental asymmetry between heating and cooling prompts people to revisit what they thought thermodynamics already established: that adding heat and removing heat are not mirror-image processes, especially far from equilibrium. Commenters relate the idea to everyday phenomena such as building design, air conditioning vs. heating efficiency, and the Mpemba effect, while also grappling with microscopic explanations involving particle motion, entropy, and energy transfer. The thread broadens into skepticism about popular-science headlines and grant-writing hype, highlighting how theoretical advances are often sold with speculative applications like micromotors and self-assembling materials.
Building design and practical implications
- Some argue ideal buildings are highly insulated “boxes” needing minimal active heating or cooling, with ventilation and heat‑recovery systems handling air quality and CO₂.
- Others say optimal design depends heavily on climate: southern regions prioritize passive cooling (light colors, shutters), colder regions prioritize heat retention—but sometimes sacrifice insulation (large unshaded windows) for daylight and wellbeing.
- One commenter suggests it’s generally better to insulate for warmth and then actively cool in hot weather, since external energy (sun) can power cooling more easily than we can harvest low‑grade heat for warming.
Symmetry vs asymmetry in thermodynamics
- Several readers are surprised the article treats heating/cooling symmetry as a new question; they assumed thermodynamics is fundamentally asymmetric (entropy, irreversibility).
- Others note that near equilibrium, simple textbook models do treat heating and cooling symmetrically; the new work concerns far‑from‑equilibrium behavior.
- There is debate and confusion around entropy explanations, with some pointing out the common “disorder” analogy is misleading.
Microscopic mechanisms and intuition
- Some frame heating as adding energy “constructively” to particles, while cooling involves energy leaving particles but being reabsorbed by neighbors, reducing net efficiency.
- A simplified explanation of the reported result: it takes more energy to move a microscopic particle a given distance by “cooling” than by “heating”; one intuition offered is that if motion is already random and energetic, it’s easier to bias that motion than to generate it from low energy.
- There is back‑and‑forth about what temperature means at the single‑molecule level, whether individual molecules have a temperature, and how kinetic and potential energy relate to heat.
Devices, applications, and research funding
- The “why no microwave‑like fast cooler?” question triggers discussion:
- Microwaves heat by EM radiation tuned to water; blast chillers cool by convective heat transfer from the outside in, so they are not true “reverse microwaves.”
- Laser cooling is mentioned as a counterintuitive example of radiative cooling.
- The paper’s mention of potential applications (micromotors, microscale transport, self‑assembling/self‑repairing materials) is widely recognized as standard grant‑writing language: speculative, funding‑oriented, and often stretched but not outright dishonest.
Related phenomena and side topics
- Mpemba effect (hot water sometimes freezing faster than cold) is raised as a possibly related asymmetry, but others note it is disputed and context‑dependent.
- Some mention absolute zero as a hard lower bound on cooling but acknowledge it’s practically distant; others mention ultra‑high temperatures and black holes as conceptual upper limits.
- A few compare market “volatility drag” to Brownian‑motion‑like behavior, but others stress that financial systems only loosely “mirror” physical models, not obey them.