Schrödinger's cat is a thought experiment, often described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935. It was intended to illustrate the peculiarities and the problems of quantum mechanics applied to everyday objects, highlighting the conflict between what quantum theory tells us is true about the nature and behavior of matter on the microscopic level and what we observe to be true on the macroscopic level we are familiar with.
In this thought experiment, Schrödinger proposes a scenario where a cat is placed in a sealed box along with a radioactive atom, a Geiger counter, a hammer, and a vial of poison. If the Geiger counter detects radiation, indicating the radioactive atom has decayed, the hammer is released to break the vial of poison, killing the cat. According to quantum mechanics, until the box is opened and an observation is made, the radioactive atom is in a superposition of states, meaning it is simultaneously decayed and not decayed. Consequently, the cat, by this logic, is considered to be both alive and dead at the same time, existing in a state of superposition.
This thought experiment is not about animal cruelty but about illustrating the seemingly absurd implications of quantum superposition and quantum indeterminacy. When applied to microscopic particles, these principles are well-documented and accepted; however, Schrödinger's scenario extends this behavior to macroscopic objects (like a cat), which challenges our classical intuition about reality.
Schrödinger's cat has since become a symbol of the mysteries of quantum mechanics, embodying the difficulties of understanding the theory's implications for the nature of reality. It questions the role of the observer in the outcome of quantum events and the transition from quantum superposition to the definitive state observed in our everyday world. This thought experiment continues to be a central theme in discussions of quantum mechanics, demonstrating the intriguing and often counterintuitive nature of the quantum world.