In quantum mechanics, observation is not just a confirmation, but an important factor that determines reality. We explore the meaning of superposition and observation through Schrödinger’s cat experiment and examine the differences between classical physics and quantum mechanics.
“Steven Hawking said, “When I hear someone talk about Schrödinger’s cat, I take out my gun. The reason he took out his gun was because he was so tired of hearing about Schrodinger’s cat. Anyone who studied physics might have found Schrödinger’s cat so boring that they never wanted to hear about it again. This thought experiment has been repeated and discussed countless times, from textbooks to academic papers to public lectures. As a result, it may feel like an old joke to physicists. However, the story of Schrodinger’s cat is an interesting thought experiment that allows you to experience the strangeness of the quantum world without having to major in physics. Aren’t you curious to know what Schrodinger’s cat story is and why ‘Steven Hawking’ was talking about it?
Schrodinger’s cat is a thought experiment proposed to criticize the Copenhagen interpretation, which introduced uncertainty into physics. Let’s say there is a cat in a box, and the place connected to the box and the valve is filled with poisonous gas. And next to the box is a machine that detects radiation, so the moment radiation is detected, the valve will open and the cat will die, but if no radiation is detected, the cat will live. Now, if we say that there is radioactive material here that has a 50% chance of collapsing every hour, will the cat be dead or alive in an hour? Or should we say that it will be in a strange state, neither dead nor alive?
The Copenhagen School interpretation, which Erwin Schrödinger hated so much, is as follows. Before the box is opened, the state of being alive and the state of being dead are superimposed, but the state is determined at the moment of observation. If the physical concept of superposition seems a little difficult, let me give you a simple example to explain it. There is a ball in a box, and the ball must be either red or blue. However, in the quantum world, a superposition state is possible in which both red and blue can be present at the same time, and it is only possible to confirm that the ball is of one color by taking it out of the box and observing it. In other words, the state in which an object (ball) has two states (red and blue) simultaneously and probabilistically is called a superposition state. Therefore, the Copenhagen School of Physics broke with the existing view that an object must have a single state and proposed a new quantum mechanical view that two states can coexist probabilistically.
This interpretation caused a great backlash among physicists at the time, including Erwin Schrödinger. The reason was that scientific facts are not determined by observation, but are revealed probabilistically by observation. In the world of classical physics created by Isaac Newton, all objects were always precisely predictable by the laws of physics and therefore could not have two states at the same time. However, according to the quantum mechanical interpretation created by the Copenhagen School, two states must be recognized as coexisting states of superposition. This was like a complete collapse of the existing world view of physics. Quantum mechanics revealed a reality completely different from the physical world we experience in our daily lives, and the debate about it has influenced various fields, including philosophy and the humanities, beyond the scientific community.
Ironically, however, the thought experiment designed by Erwin Schrödinger to disprove the theories of the Copenhagen School ultimately had the significance of advancing the theory. The Copenhagen School redefined observation as a very important interaction that had been overlooked. When we think of observation, we may easily think of what we see with our eyes, but a more accurate expression of observation in science is the interaction with the experimental system. If you can see what is inside the box with your eyes, it is because photons reflected from the object inside the box interact with photons entering your eyes. In other words, we have come to realize that in quantum mechanics, the act of observation is no longer independent of the system being observed, but is an act of interaction.
Schrödinger’s cat was designed to criticize quantum mechanics. However, it is ultimately a thought experiment that helps us to understand the paradoxical aspects of quantum mechanics and at the same time to understand the new physical world view that quantum mechanics brings. It is also an experiment that helps us understand what the act of observation means in comparison to classical physics. In classical physics, everything was deterministic, and observation was merely an act of confirming results. In quantum mechanics, however, observation becomes an act of creating results, which completely changes our fundamental understanding of the physical world. I hope that the above article will give readers the opportunity to imagine Schrödinger’s cat experiment for themselves and feel the mystery and strangeness of the quantum world.
