Chapter 3-3 Schrödinger's Cat
Related to the "observer effect" is "Schrödinger's cat". This term is often used by literati as a metaphor to describe something in an uncertain, unpredictable (superposition) state.
Before explaining it, it's important to understand that the quantum world does not have a concept of time. In the real world, time follows the continuity of "past→present→future", but elementary particles do not follow this time concept. An elementary particle occurring in the "present" can reach the "past" or even the "future" in the next instant.
Furthermore, quantum mechanics does not have a spatial concept and can be located in multiple places simultaneously. In classical physics, an object can only be in a definite state; for example, a ball can only be in one position at any given moment. However, in quantum mechanics, elementary particles can be in a superposition of multiple states simultaneously. This means that a particle can be in multiple positions, with multiple momenta, or multiple spin directions at the same time.
To illustrate in a straightforward manner, in the objective world, we might ask: Where is Tom right now? He is currently on the third floor doing homework; at this moment, time and space are unique. However, in the quantum world, Tom can simultaneously be on the second and third floors of this building, and in the next instant, he might switch to the fourth or fifth floors, or exist on any floor simultaneously, as if he has mastered the art of cloning. This property of superposition is a unique and peculiar phenomenon in quantum mechanics.
Figure 3.6: "Schrödinger's Cat" Thought Experiment
"Schrödinger's cat" explains this quantum "superposition state" (the ability of a quantum system to be in multiple states simultaneously before being measured). It is a famous "Thought Experiment" proposed by Austrian physicist Erwin Schrödinger in 1935. The main purpose was to extend the quantum behavior of the microscopic world to the macroscopic world for elaboration and explanation. In this hypothetical experiment, Schrödinger placed a cat in a box containing radioactive material. There is a fifty percent chance that the radioactive material will decay. If it decays, the cat dies; otherwise, the cat lives.
The intriguing aspect of this experiment is that before the box is opened, no one knows the condition inside. There is a fifty percent chance of radioactive decay occurring, which means the cat could be dead or alive. At this point, the cat is not definitively alive or dead but exists in a "superposition" state of "alive and dead". Only when we open the box and observe it does our "observation" determine whether the cat is alive or dead.
Although "Schrödinger's cat" is a thought experiment conducted within the field of quantum mechanics, in our macroscopic world visible to the human eye, there is usually a single state of "either dead or alive", not a "superposition" of "both dead and alive". However, people are clearly more fascinated by the dialectical significance of this thought experiment, often using "Schrödinger's cat" to metaphorically describe the unpredictability or uncertainty of events: if we do not take action on something, there will be two possible outcomes — doing it or not doing it. When no choice is made, everything is unknown; once we act, there is only one outcome. Human actions thus become the critical step.
Scientists have extended "Schrödinger's cat" to many physical problems and philosophical debates, such as: what governs our world? Is it determinism or probabilism? For example, if you have a girlfriend but have not yet defined the relationship, you cannot be sure if she is your girlfriend—she is in a superposition state. If a person has cancer, should they spend money on treatment or not? Not treating it could lead to recovery or death; treating it might waste money—treatment and non-treatment are in a superposition state. Should you go for an interview for a new job? Even if you go, you might get hired or not — being hired or not is in a superposition state. Over 2000 years ago, during the Spring and Autumn period, Confucius said: "To love someone is to wish them to live; to hate someone is to wish them to die. To wish both life and death is perplexing." This is the same principle.
In reality, a person cannot walk two paths simultaneously. To avoid the "Schrödinger's cat" phenomenon, we should not hesitate too much when making life choices. Only by taking action will you know the outcome, and whatever the result is, it will have an impact on you.
From another perspective, this once again confirms the "Uncertainty Principle". If we pinpoint a spot on a two-dimensional table, theoretically, we can accurately pass our finger over this spot countless times. However, if we try to hit this spot with a stone from above, the final landing point will be discrete and "uncertain". This also hints at a "higher" possibility: the existence of the world is related to the observer. The world might be pre-designed, but we don't know who the designer is yet. Or perhaps the world is not real at all but a virtual one. Many may not want to believe this, but think about it: when you play a game, can the characters in the game know they are in a virtual world?
