How quantum physics is different from classical physics?

In classical physics, dynamic variables are continuous values that vary smoothly. Quantum physics takes its name from the observation that certain quantities, especially energy and angular momentum, are restricted to certain discrete values or “quantified” under special circumstances. Quantum physics is used to describe the properties of elementary particles and is generally considered a fundamental theory in nature. Carlo Rovelli proposes another interpretation, which he defines as the “relational interpretation” of quantum theory.

But in the quantum world, the world that emerges close to the scale of atoms, things are different. Quantum physics predicts these patterns, which explain the different chemical and physical properties of all elements. Scientists call each of these discrete steps “quantum”, from the Latin word that means “how much”, and they say that the quantum properties with this ladder structure are “quantified”. However, when we leave the subatomic world, objects are better described according to the laws of classical physics, which means that at some point the quantum description of large bodies must be somehow reduced to Newtonian concepts.

This is known as the rise of classicality, which states that a quantum mechanical description of large objects must be the same as their classical description. However, active information was not considered information about us, the observers, but information about the particles themselves, which led Bohm to suggest that “the particles of physics have certain primitive qualities similar to those of the mind” (Bohm, 1990). The best they could do is launch it and then use quantum physics to calculate the probability that the spacecraft will reach a certain point at any given time. Unlike the usual formulations, this modification leads to the appearance of classicality in a thought experiment, which is problematic for standard quantum mechanics.

In trying to make sense of these puzzling and counterintuitive behaviors, physicists have presented many different interpretations of quantum physics.