The behavior of electrons and other quantum particles as both waves and particles is a fundamental concept in quantum mechanics and is known as wave-particle duality. It is not a matter of electrons behaving differently when observed versus unobserved, but rather a fundamental property of quantum objects.
In the quantum world, particles such as electrons are described by wave functions, which are mathematical descriptions that incorporate both wave-like and particle-like characteristics. The wave function represents the probability distribution of finding a particle at a particular location or with a specific momentum.
When an electron is not being observed or measured, its wave function evolves according to the Schrödinger equation, which is a mathematical equation that describes the behavior of quantum systems. The wave function spreads out and exhibits wave-like behavior, meaning it can interfere with itself, diffract, and exhibit other wave phenomena.
However, when a measurement or observation is made to determine the position or momentum of the electron, the wave function collapses to a specific value corresponding to the measurement. This collapse is known as wave function collapse or the measurement problem in quantum mechanics. After the collapse, the electron is localized to a specific position and behaves more like a particle.
The reason for this behavior is still a topic of debate and interpretation in quantum mechanics. The Copenhagen interpretation, which is one of the widely accepted interpretations, states that the act of measurement disturbs the system and causes the wave function to collapse to one of the possible outcomes. Other interpretations, such as the Many-Worlds interpretation or the de Broglie-Bohm theory, propose different explanations for wave-particle duality.
It's important to note that the wave-particle duality is not unique to electrons but applies to other quantum particles as well. It is a fundamental property of the quantum world and is supported by extensive experimental evidence.