Description: Hidden variables are theoretical constructs that seek to provide a more complete explanation of quantum phenomena by introducing additional parameters not considered in standard quantum mechanics. In quantum mechanics, systems are described by wave functions that encapsulate all information about the system’s state. However, these wave functions do not always provide an intuitive picture of the underlying reality. Hidden variables attempt to address this limitation by suggesting that there are additional, unobservable factors that determine the behavior of particles at the quantum level. This approach seeks to restore a sense of determinism in quantum mechanics, which is often perceived as inherently probabilistic. Hidden variable theories can be classified into two main categories: local hidden variables, which maintain the principle of locality, and non-local hidden variables, which allow for instantaneous interactions between separated particles. The relevance of hidden variables lies in their ability to offer an alternative to the standard interpretation of quantum mechanics, challenging the notion that nature is fundamentally random and suggesting that there is an underlying order that we do not yet fully understand.
History: The concept of hidden variables dates back to early discussions about the interpretation of quantum mechanics in the 20th century. One of the most significant milestones was Albert Einstein’s work in 1935, when he, along with Boris Podolsky and Nathan Rosen, published the famous ‘EPR paradox’ paper. This paper questioned the Copenhagen interpretation of quantum mechanics and suggested that there must be some hidden variable that explained the instantaneous correlation between entangled particles. Over the decades, several physicists, such as David Bohm, developed hidden variable theories, proposing models that attempted to reconcile quantum mechanics with a more classical determinism. However, Bell’s theorem, formulated by John Bell in 1964, demonstrated that local hidden variables could not account for all experimental results of quantum mechanics, leading to an ongoing debate about the nature of quantum reality.
Uses: Hidden variables are generally used in theoretical physics and quantum mechanics research to explore alternative explanations for quantum behaviors and correlations. They can provide insights into the fundamental nature of reality and the underlying mechanisms that govern quantum systems. Additionally, hidden variable theories influence discussions surrounding the interpretation of quantum experiments and contribute to the philosophical debates about determinism versus randomness in physics.
Examples: An example of the application of hidden variable theories is the research conducted to explain the results of experiments related to quantum entanglement, such as the Aspect experiments, which tested the predictions of quantum mechanics against those of local hidden variable theories. These investigations aimed to determine whether determinism can be restored within the framework of quantum mechanics and what implications this might have for our understanding of reality.
