The Growth of Quantum Physics

proven that the collision between two or more small quasicrystals results in the formation of a crystal which no longer possesses the grain boundary or the consequent imperfections. This process was virtually recreated in a lab multiple times in order to obtain the precise conditions necessary for the combining of these quasicrystals. (6) With our knowledge of quasicrystals increasingly growing, it is possible that quasicrystalline products will become more abundant and it may even become easier to find new types of them forming naturally beyond the walls of the labs.

-Erin

Theories of Light and Radiation that led to the Growth of Quantum Physics

Quantum Physics is arguably one of the most ground-breaking branches of physics today. It has shown us a whole new side to the scientific realm: the absurd rules that govern the very tiny. Quantum physics plays a part in much of everyday life, for instance helping our mobile phones to work, by helping to design the siliconebased elements of our phone circuits. Many concepts that are known today in quantum physics actually grew from discoveries about light and radiation made by physicists in the 18 and 19 hundreds. So, in this article I wanted to enlighten you about some of these discoveries and how they led to the growth of this theory. One of the first things that led to growth of quantum physics, was questions about the nature of light. This began with the renowned Isaac Newton, who had some very interesting ideas about particles. He held the belief that light was made up of many small particles called corpuscles. However, this belief was not held by some other scientists of the time. A Dutch scientist named Christiaan Huygens believed that light was a wave, comparing it to the way that pebbles caused ripples in water. At first, Huygens and his theory about waves was not shared by most at the time. However, later, a scientist named Young was able to prove that light was a wave. He used the double slit experiment to show that light did follow the pattern of the wave, as when light was filtered through a single slit and a double slit, it spread out in circles, behaving exactly as a wave should. However, we now know that light is actually a particle and a wave, depending on whether it is being observed or not.

Now these reflections on light were furthered by Gustav Kirchhoff’s discovery of blackbody radiation. This was essentially the spectrum of radiation emitted from a ‘blackbody’ or perfect emitter when it is heated. There is very little radiation emitted at short wavelengths, and long wavelengths, while a lot of radiation is emitted at middle wavelengths. This seemed confusing at the time, because it went against the classical

laws of physics. There should be far more radiation emitted at shorter wavelengths, as there should be an infinite amount of energy at these wavelengths. So, Kirchhoff’s discoveries seemed to disagree with traditional laws of physics when it came to shorter wavelengths, but fitted the pattern suggested by physics when it came to longer wavelengths. This was quite a conundrum, known as the ultraviolet catastrophe, however later developed by a man named Max Planck, who revolutionised quantum physics. Planck was most interested in thermodynamics, the study of thermal energy. He worked for a long time on the ultraviolet catastrophe and in the end, merged two equations, to create one that successfully described the blackbody radiation. However, Planck’s work was not finished. He then merged his blackbody radiation equation with some statistical equations, believing that energy emitted and absorbed by electrons in an atom must only be in a certain constant amount, called a quantum, and the energy of such a quantum must be related to its frequency where we get the name quantum physics. The equation he came up with was Energy = h x frequency, where h is a new constant named Planck’s constant; a constant that today has become central to quantum physics, describing the quantum nature of energy. Planck’s work showed that there was a limitation to classical physics, and so much more to explore beyond that, through light and particles. Now, Planck’s worth was furthered even more by none other than Albert Einstein. Einstein was very interested in developing Planck’s ideas and finding the physical implications to his equation. All he did was apply Planck’s ideas of quanta to electromagnetism. He said that light is not made up of waves, but little packets of lights, in essence, particles, which we now call photons. Photons each have the same frequency, explaining why the same amount of energy is emitted each time by electrons, as said by Planck. Now Einstein used this to explain the electromagnetic attractions, suggesting that when photon hits an electron, it gives it energy, causing it to move. Different wavelengths of light simply mean that each photon is carrying a different amount of energy. Einstein was actually against the idea of quantum physics when it began to be theorised, believing it to be too absurd, and describing a central part of it, quantum entanglement to be “spooky action at a distance”. However, this work of his on photons ended up contributing to the quantum theory of electrodynamics, which described electromagnetism at a quantum level, and it is this work that won him his famous Nobel Prize in 1922.

Now, these are just some of the ground-breaking theories that led to the growth of quantum physics, however they hold great importance. Newton’s questions about light led to people drawing more attention to the science of light, and Kirchoff’s blackbody radiation eventually led to Planck theorising his constant and Einstein theorising photons. Quantum physics is one of the most interesting and vital theories in physics, so I hope through this article I have shed some light on how it grew.

-Anantaa