Kaksoisreikäkoe

Kaksoisreikäkoe, often translated as the double-slit experiment, is a fundamental experiment in quantum mechanics that demonstrates the wave-particle duality of matter and light. First performed with light by Thomas Young in the early 19th century, it has since been replicated with electrons, neutrons, atoms, and even molecules. The experiment involves directing a beam of particles or waves towards a barrier containing two closely spaced slits.

When waves, such as light, are passed through the double slits, they diffract and interfere with each other. This interference creates a pattern of bright and dark fringes on a screen placed behind the barrier, characteristic of wave behavior. If particles were acting purely as discrete entities, one would expect to see two distinct bands on the screen, corresponding to the particles passing through each slit.

However, the surprising result of the double-slit experiment is that even when particles are sent through one at a time, they still produce an interference pattern. This suggests that each individual particle, when not observed, behaves like a wave and passes through both slits simultaneously, interfering with itself. The act of observation, or measurement, causes the wave function to collapse, and the particle then behaves as a localized entity. The implications of the kaksoisreikäkoe are profound, challenging classical notions of reality and measurement, and forming a cornerstone of quantum physics.