The most fundamental level at which quantum mechanics operates is at the level of elementary particles and their interactions. Quantum mechanics provides a mathematical framework that describes the behavior of these particles, such as electrons, protons, and photons, at the microscopic scale.
According to quantum mechanics, particles do not have definite properties, such as position or momentum, prior to measurement. Instead, they exist in a superposition of all possible states until observed or measured, at which point their wave function collapses to a particular state. This probabilistic nature of quantum mechanics is a departure from classical physics, where particles are assumed to have well-defined properties at all times.
Quantum mechanics also introduces the concept of entanglement, which is a fundamental property of certain systems where the state of one particle is inseparably linked to the state of another, regardless of the distance between them. This phenomenon has been experimentally verified and has profound implications for concepts like quantum teleportation and quantum computing.
At the fundamental level of quantum mechanics, the behavior of particles is described by wave functions, which are mathematical functions that evolve over time according to Schrödinger's equation. These wave functions contain information about the probabilities of different outcomes when measurements are made.
It's important to note that quantum mechanics is a highly successful and well-tested theory, but it is still an active area of research. There are ongoing efforts to understand its foundations better and reconcile it with other fundamental theories, such as general relativity, in the quest for a more complete theory of physics, often referred to as a theory of quantum gravity.