At its core, quantum mechanics reveals that particles at the smallest scales do not adhere to the deterministic laws of classical physics. Instead, particles such as electrons and photons behave in ways that are probabilistic and inherently uncertain. One of the fundamental aspects of this theory is the dual nature of matter and light. The concept of wave-particle duality suggests that entities can exhibit both wave-like and particle-like characteristics depending on the experimental setup used to observe them. This duality led to groundbreaking experiments that demonstrated light interfering with itself and particles existing in multiple states simultaneously.

Central to quantum mechanics is the uncertainty principle, which posits that certain pairs of physical properties, like position and momentum, cannot both be precisely known at the same time. This principle does not imply a lack of precision in measurement techniques but rather indicates an intrinsic property of the quantum world. The probabilistic nature of these measurements means that we can only predict the likelihood of finding a particle in a particular state rather than determining its exact state. Such ideas were not only philosophically challenging but also required a fundamental rethinking of what it means to "know" something in the realm of physics.