👉 The term "non-interchangeability" refers to a property or characteristic that cannot be changed without altering another property or characteristic. In other words, it is a characteristic that remains fixed even when one of its components changes. This concept arises in various fields such as physics, chemistry, biology, and engineering, where non-interchangeable properties are essential for understanding the behavior of systems at the fundamental level. Non-interchangeability can be understood from the perspective of statistical mechanics, which is a branch of