Bohr, von Neumann and Quantum Mechanics

 


There were two pioneers of quantum mechanics. They are Niels Bohr and John von Neumann. Analysis suggests that their ideas were more similar than previously thought.

In the beginning years of quantum theory, these two thinkers had two separate ideas about how measurements of quantum states should be explained. Bohr believed that these measurements require a division between the quantum system being measured and the classical device performing the measurement. Von Neumann believed that quantum mechanics applies to everything, including the measurement device.

In the 100 years since these theories were first explored, quantum researchers have seen these two theorists as having conflict with each other.  New research shows both Bohr's and von Neumann's theories are far closer than previously thought. The research was published in The European Physical Journal, with Frederico Laudisa as head author. 

Measurement is at the core of Bohr's interpretation of quantum mechanics.The most important of these measurements being the interactions between quantum systems and classical measurement devices. He developed these theories in the late 1920's. They didn't include a formal model of the process of measurement. The works focused on the need for classical concepts when describing quantum experiments. 

This led to early debates between the classical and quantum theorists. Early textbooks on the matter didn't discuss the idea that quantum laws should be applied to classical systems during measurements. 

In 1932, von Neumann drafted a new measurement tool. It suggested that quantum mechanics must govern the properties of both the measurement device and the quantum states. Theorists saw this as in direct conflict with Bohr's theories. 

In the new research, Laudisa raises interesting questions about the conflict. Mainly, whether Bohr would have disputed von Neumann's theories. He looked closely at Bohr's ideas, and he argued that Bohr's views on classical concepts were aligned with von Neumann's theories.

Based on this new theory, Laudisa is now studying the similarities between the views of both researchers regarding measurement. He hopes to provide a more accurate history of the measurement process in quantum mechanics. 

An interesting look back at our past...

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