Discontinuity: Maybe the World Moves the Way the Second Hand of a Clock Moves
If we look carefully at René Magritte’s “Le blanc-seing”, we can see that some parts of the woman who is riding a horse have been cut off. Generally, when we imagine a woman riding a horse, we imagine the shape to be fully connected throughout. Similarly, in a world that people live in, various values such as mass or speed exist continuously. However, in a world that is as small as a particle, physical quantities such as spin, exist in discontinuity as shown in the picture. Magritte intentionally cut the image when painting it. In a particle world, some values such as energy exist in a discontinuous manner under the law of nature, like this painting. The concept of having a lump sum that cannot be divided and has discontinuity is called ‘quantization’.
The energy of particles is quantized in a very small world. This means that it is only possible to choose energy values that were already determined. To illustrate, generally I am in a calm state. My excitement grows when I am energized. However, the amount of excitement that I can experience (or the amount of “energy steps I can climb” in excitement) is pre-determined. Particles that follow the quantization rule and “climb” a specific number of energy steps are called ‘quantum particles.’ Most of quantum particles have spin. A quantum particle can be on certain energy steps depending on its spin’s orientation. An electron, for an example, has spin 1/2 and can be on energy steps expressed in numbers -1/2 (down spin) or +1/2 (up spin). The electron switches between -1/2 and +1/2 energy steps when it absorbs or emits a quantum of energy. Other quantum particles have different values of spins which is multiples of integer (0, 1, 2 … ) or half integer number (1/2, 3/2 … ). For another example, a photon has spin number 1. Quantum mechanics is the academic field that studies how these quantum particles or quantum states behave, as well as the rules or the aforementioned quantization.
Do you remember how I introduced myself as a very small magnet at the beginning? The type of the magnet changes depending on the step I live in. The most basic physical step is when I am in the ‘Spin 1/2 state.” As I mentioned above, I can go to just two different steps. I will explain a little more about these steps in the next piece.