Abstract Classical and quantum mechanics are two very different theories, each describing the world within its own range of validity. It is often stated that classical mechanics emerges from quantum mechanics in a certain limit. This is known as the correspondence principle. According to Planck’s version of the correspondence principle, classical mechanics is recovered when the limit in which a dimensionless parameter containing Planck’s constant h goes to zero is taken, while Bohr’s version entails taking the limit of large quantum numbers. However, despite what is usually stated in textbooks, the relation between the two theories is much more complex to state and understand. Here we deal with this issue by analysing some key examples, in some of which also the analogously subtle relation between wave and geometric optics is considered. Implications for quantum mechanics teaching at undergraduate level are carefully discussed.
The correspondence principle states that classical mechanics emerges from quantum mechanics in the appropriate limits. However, beyond this heuristic rule, an information-theoretic perspective reveals that classical mechanics is a compressed, lower-information representation of quantum reality. Quantum mechanics encodes significantly more information through superposition, entanglement, and phase coherence, which are lost due to decoherence, phase averaging, and measurement, reducing the system to a classical probability distribution. This transition is quantified using Kolmogorov complexity, where classical systems require
O(N) bits of information, while quantum descriptions require
O(2N), showing an exponential reduction in complexity. Further justification comes from Ehrenfest's theorem, which ensures that quantum expectation values obey Newton's laws, and path integral suppression, which eliminates non-classical trajectories when
S≫ℏ. Thus, rather than viewing quantum mechanics as an extension of classical mechanics, we argue that classical mechanics is a lossy, computationally reduced encoding of quantum physics, emerging from a systematic loss of quantum correlations.
Classical mechanics and quantum mechanics contradict each other, and both are essential to explain the phenomena of the exclusively different realm of nature. On the other hand, Bohr's correspondence principle shows classical mechanics is the somewhat approximate version of quantum mechanics. Classically a particle with negative energy i. e. V E < is not allowed go through a forbidden region or disappearing from one well to another well. This paper gives the numerical studies for the trajectory of the particle in a double-well potential and presents quantum mechanical behavior such as tunneling in the complex plane for different energies. Our findings provide a route to solve the classical system with complex energy.
The correspondence principle addresses the connection between classical and quantum physics. The simple statement that quantum mechanics reduces to classical mechanics in the limit where the principal quantum number n approaches infinity, while found in many textbooks, is not true in general. In this article we will give special attention to the notion that the quantum frequency spectrum of a periodic system reduces to the classical spectrum in this limit. Two simple counter-examples—a particle in a cubical box, and a rigid rotator—will show us that the classical result is not always recovered in the limit of large quantum numbers.
A conception of the Correspondence Principle which Bohr deployed implicitly in developing a new theory of atomic constitution in 1913, is made explicit through an extensive examination of his classic paper of that year. Arguments are considered which purport to show that the application of the principle must be restricted to few isolated cases. These arguments are either defused or rejected. In particular an extensive review of issues concerning the interpretation of Quantum Mechanics is made to counter the claims that an insurmountable conceptual gap exits between the tenets of this theory and those of Classical Mechanics which makes it logically impossible for the latter to be regarded as the 'limiting case' of the former. In the light of a particular interpretation adopted and defended, a proposal is made that suggests that the Hamilton-Jacobi formulation of Classical Mechanics, as well as Maxwell's electromagnetic theory, can be viewed as 'limiting cases' of Quantum Mechanics. Having established a case for the global validity of the requirement imposed on physics by the Correspondence Principle, it is then argued that this requirement is indispensable if a particular brand of realism is adopted for the interpretation of theories in physics. Taking on board the assumption that an ultimate theory exists which mirrors the underlying physical constitution of the world, it is subsequently argued that the intertheory order established by the global imposition of the principle in physics, can be used to solve the problem of rational theory choice for this brand of realism.
Quantum and classical mechanics are fundamentally different theories, but the correspondence principle states that quantum particles behave classically in the appropriate limit. For high-energy periodic quantum systems, the emergence of the classical description should be understood in a distributional sense, i.e., the quantum probability density approaches the classical distribution when the former is coarse-grained. Following a simple reformulation of this limit in the Fourier space, in this paper, we investigate the macroscopic behavior of freely falling quantum particles. To illustrate how the method works and to fix some ideas, we first successfully apply it to the case of a particle in a box. Next, we show that, for a particle bouncing under the gravity field, in the limit of a high quantum number, the leading term of the quantum distribution corresponds to the exact classical distribution plus sub-leading corrections, which we interpret as quantum corrections at the macroscopic level.