Fundamental Concepts of Quantum Mechanics and Atomic Reality

Quantum Physics: Foundations and Paradoxes

The atomic world began to reveal surprising and paradoxical characteristics from the viewpoint of classical or Newtonian physics.

The Wave-Particle Duality

Based on the investigations of Einstein and Planck, the wave-particle duality destroys the traditional opposition between matter and energy. Traditionally, it was felt that matter was discontinuous and particulate in nature, while energy was considered continuous and wavelike. Conversely, according to quantum physics, both matter and energy behave as particles and waves.

Planck discovered that energy is not emitted continuously but in quanta (discontinuous packets). Shortly after, Einstein identified light quanta, which he called photons. De Broglie proposed that not only photons but also electrons behave as particles and waves, a concept later confirmed by experiments.

Alternative Quantum Theories

Consistent with this dual reality, two alternative but equivalent theories were developed within quantum physics:

• Heisenberg's Matrix Mechanics: Explains discontinuous physical processes and particle nature.
• Schrödinger's Wave Mechanics: Explains continuous physical processes, thereby stressing the wavelike behavior of matter.

These theories generated the new physics. (FACT)

The Uncertainty Principle

Quantum mechanics cannot simultaneously and accurately establish both the position and the velocity of a particle, such as an electron. One reason for this is the inevitable interaction between the observer and the observed, since there can be no observation without the intervention of the observer.

Every measurement involves interaction between the observer and the observed object, which alters the conditions of the latter. This phenomenon occurs universally.

Quantum Superposition and Wave Function Collapse

This concept, sometimes referred to as the collapse of the wave function, addresses the nature of reality before measurement. It is often considered that the observer forces the system to adopt one state or the other. In reality, the two states are superimposed: reality is indeterminate, existing in all possible states at once, until observation requires the system to determine and adopt one of these states.

This concept is famously illustrated by the paradox known as Schrödinger's Cat.