Quantum superposition

Quantum superposition is the fundamental principle that a quantum system, such as an electron, can exist in multiple possible states simultaneously. Rather than being in one definite position or energy level, the particle exists as a blend of probabilities. It is only upon observation that the system 'chooses' a single state.

When a quantum system in superposition is measured or observed, the superposition collapses, and the system instantly takes on one specific, definite state. This instantaneous transition is known as the collapse of the wave function. Before the measurement occurred, the particle existed only as a set of mathematical probabilities.

No, we cannot observe quantum superposition in large, everyday objects due to a process called quantum decoherence. Macroscopic objects constantly interact with their surrounding environment—like light, heat, and air molecules—which instantly forces them out of superposition. Therefore, superposition is an effect strictly limited to isolated microscopic particles.

The most famous thought experiment is Schrödinger's cat, proposed by physicist Erwin Schrödinger in 1935. The scenario proposes placing a hypothetical cat inside a sealed box with a mechanism tied to a quantum event, resulting in the cat being simultaneously both alive and dead until the box is opened. It highlights how absurd superposition appears when scaled up to everyday objects.