By: Arman Momeni

Introduction:

Let’s presume you are a cruel cat owner. You place your mischievous cat Milton in a box and shut it with a lid. Inside of the box you also place a radioactive substance that controls a vial of poison. The radioactive substance has a 50% chance of radioactive decay and is connected to a Geiger counter that would instantaneously release the poison upon decay, ergo killing Milton.

According to the standard rules of probability, when you open the box, there is an equal probability that Milton is either dead or alive. Such rules of probability should remain the same even when the lid is closed; a 50% chance that the cat in the box is dead, and a 50% chance that the cat in the box is alive. This scenario makes sense, the probabilities are accurate, and your cat Milton, can either be alive OR dead. However, if one were to scale down this thought process all the way to the world of quantum mechanics (a subfield of physics designed to describe the behaviour of particles), they would find that the scenario does not hold true. According to quantum mechanics, until you open the box, your poor Milton is considered to be both alive AND dead. If your anything like me, your first thought would be: WHAT? How can it be possible for a cat to be both alive and dead? What does that even mean? Don’t worry you’re not alone, because it’s not supposed to make sense. This famous thought experiment, known as Schrödinger’s cat, was concocted by the Austrian-Irish physicist, Erwin Schrödinger, and was intended to illustrate the imbecility of quantum theory.

Schrödinger, in fact, was so revolted by the current understanding of quantum theory and his thought experiment that he decided to abandon physics all together and pursue the route of biological sciences. That alone should put into perspective just how confusing and mind-boggling the quantum world is. Schrödinger’s Cat attempts to explain the concept of quantum superposition, which claims that a particle is in multiple states at the same time until it is measured. While Schrödinger attempted to ridicule the absurd nature of quantum mechanics, his analogy has now become one of the best explanations of quantum superposition to date.

Quantum Superposition:

As stated above, quantum superposition elucidates the idea that particles do not have a coherent state until they are observed. This means that a particle that is observed as red may be in a state where it is both red and blue before it was observed. It’s a confusing stipulation, but it is in fact accurate when applied to the world of quantum mechanics.

In order to fully understand the ideas in the world of quantum mechanics, one must differentiate their understandings of the quantum world with that of the everyday world. In our world positions, momentums, and other quantities are always well-defined. If you were to look at a fire hydrant, it will be red, and it will have been red before you were to look at it; if you were to look at the pavement, it will be grey and it will have been grey before you were to look at it. These empirical principles still stand and are not falsified by the laws of quantum theory. Quantum theory exists as its own separate set of rules that apply to particles, such as electrons or photons (the smallest unit of a specific phenomenon).

Now you may be wondering, why does superposition occur? Our current understanding of particle physics portrays particle behaviors as mathematically wave-like, and as there are so many particles within our universe, these particle waves will eventually overlap, combine, and build complex patterns that cannot simply be measured as an absolute value. The simplest way of thinking of superposition is as a function that can have two answers, one positive and one negative (eg. in the function x^2 = 9, x can be -3 and 3). The world of quantum mechanics is all about probabilities and lacks the absolutes of our known world.

The Uncertainty Principle

It is important to note that because quantum particles act as waves, they pertain both a position and a momentum. However, it is impossible to measure the exact position and momentum of a particle at the same time. A wave is not in one exact location, but it spreads out over time. If one wanted to measure position they would be focused on a specific part of the wave, whereas if one wanted to measure speed they would be focused on the entirety of its movement. Therefore, you can’t measure the two values simultaneously, as the means of measurement are inconsistent with each other. This is the famous uncertainty principle, which was created by Werner Heisenberg in 1927 and explains why one can never be accurate about the position and speed of a particle. While this may seem irrelevant to the visible world, the uncertainty principle applies to anything that moves in a wavelike pattern (water, roller coaster, etc.).

Conclusion

If Schrödinger’s cat and the uncertainty principle confused you, you’re not alone, even scientists don’t fully understand the world of quantum science. As stated above, quantum mechanics was the reason Schrödinger switched career paths as a whole. Quantum mechanics is an extremely abstract field of physics, and there is still so much to be uncovered by scientists and theorists as a whole. There is a lot of controversy in the field of quantum mechanics as well, just like in the 20th century, scientists fail to agree on and understand several topics within quantum physics, such as how gravity works when it is applied to the subatomic level. Quantum Mechanics is a field that leaves a lot of doors open for future discoveries and provokes everyday people to formulate controversial paradoxes just like Schrödinger did with his cat Milton. Nonetheless, despite the world of quantum physics, the question still remains, what happened to Milton?

Works Cited

“1.9: The Heisenberg Uncertainty Principle.” Chemistry LibreTexts, 11 Aug. 2020, https://chem.libretexts.org/Courses/BethuneCookman_University/B-CU%3ACH-331_Physical_Chemistry_I/CH-331_Text/CH-331_Text/01%3A_The_Dawn_of_the_Quantum_Theory/1.9%3A_The_Heisenberg_Uncertainty_Principle

“Erwin Schrödinger.” Encyclopædia Britannica, 12 May 2023, www.britannica.com/biography/Erwin-Schrodinger.

“Quantum Uncertainty: Are You Certain, Mr. Heisenberg?” ScienceDaily, 18 Jan. 2012, www.sciencedaily.com/releases/2012/01/120116095529.htm#:~:text=Instead%2C%20quantum%20particles%20behave%20as,particle%20being%20measured%20or%20not.

“What Did Schrodinger’s Cat Experiment Prove?” Science Questions with Surprising Answers, www.wtamu.edu/~cbaird/sq/2013/07/30/what-did-schrodingers-cat-experiment-prove/.

“What Is Superposition and Why Is It Important?” Caltech Science Exchange, https://scienceexchange.caltech.edu/topics/quantum-science-explained/quantum-superposition#:~:text=Waves%20would%20spread%20outward%20from,become%20what%20is%20called%20superposed.

“What Is the Uncertainty Principle and Why Is It Important?” Caltech Science Exchange, https://scienceexchange.caltech.edu/topics/quantum-science-explained/uncertainty-principle#:~:text=Formulated%20by%20the%20German%20physicist,about%20its%20speed%20and%20vice