Quantum Mechanics: The Beginnings
What happens with particles at the smallest of scales so tiny we can’t see them with our visible eyes?
Come with me through this series of posts explaining the basics of quantum mechanics and its intricacies and I’ll hope to show you the simplicity of it all. I guarantee: you’ll be amazed.
Here’s the main point of my series: Quantum Mechanics offers us with a radical way of thinking about our world and leaves us with interdisciplinary applications that will shape our future.
Here are the goals of this series of posts:
1. Outline the major events that formed this branch of physics
2. Describe in, simple words, the fundamental main ideas of Quantum Mechanics
3. Understand the essence of quantum computing
4. Understand aspects of current research into quantum technologies
Here’s an overview of my series of posts on Quantum Mechanics. I’ll publish these once a week beginning early August.
1. The Historical Beginnings (this one right now)
2. James Bond teaches you uncertainty, entanglement, and interference
3. What is the probability that you’ll learn a bit about probability, quantum computing, qubit, polarization, and psi? 100%!
4. If Quantum Physics is Real, is Reality Real? What Jaden Smith didn’t tell you about the reality of our world (and the quantum physics of what’s real)
5. What is a quantum computer? A (fuller) introduction to Quantum Computing
6. Ongoing Quantum Research #1 (quantum semi-conductors and you)
PART I: THE BEGINNINGS
In 1900, German physicist Max Planck exposed one of the earliest foundational stones of Quantum Mechanics. He wanted to quantify the stuff what we call electromagnetic waves. He wanted to augment what we fundamentally knew about the world.
Electromagnetic waves are like the waves in a swimming pool. Just like when you splash your friend in the water, so too are electromagnetic waves the result of their surrounding environment. In this case, however, electromagnetic waves are the result of the oscillating movement of the electric and magnetic fields around us. An electric and magnetic field is the spatial presence that electricity and magnets create. (N.B. a swimming pool, although, isn’t a perfect analogy to electromagnetic waves as, although both carry energy in some form, a swimming pool requires a medium, namely water, to move contents around, whereas electromagnetic waves can operate in environments without any medium).
Planck, in order to quantify electromagnetic waves, suggested that electromagnetic waves came in quanta. Quanta are like the mailmen which carry literal packets of energy. In fact, a good definition of quanta is that it is the minimum amount of a physical entity. So, for that matter, one could say to the grocery store person, “could I please have a quanta of corn please?” And, any reasonable grocery clerk might wonder how much of quanta of corn you might need after all he or she has probably sold quanta’s of corn in different sizes. Same applies to energy in the sense a quanta of electromagnetic waves can come in different energies. But what could explain why some quanta carry huge amounts of energy and why some had small amounts of energy? He proposed that the amount of energy of an object was the result of the frequency of that quanta’s electromagnetic wave.
But saying that energy was the composite result of many packets of energy opened a new box. For Einstein, in 1905, it meant to him that light, as a form of energy, is the result of quanta of energy, which he called photons. But, scientists had previously established that light was a electromagnetic wavelength — could light energy also be made up of elemental particles called photons? A good definition of a photon is an elementary particle which carries a quanta of electromagnetic radiation, such as a light.
Indeed, in addition to groundbreaking the idea of General and Special Relativity, Einstein also offered early inspiration for the idea that light behaves as both a wave and a particle.
Flash forward a few years and in 1913 cue Danish physicist Neils Bohr. According to Newtonian physics, an object that revolves around a center object has a constantly changing velocity and, so, a constant inward acceleration. Bohr tried to reconcile Newtonian physics with classical electrodynamics, and so, he came up with the idea that the energy of an orbiting electron is packed into discrete energy levels. To go from one energy level to another requires losing or gaining energy in the form of quantum leaps. This theory meant that electrons could only have certain energies only.
However, by 1925, German physicist Werner Heisenberg proposes the truly revolutionary. Among other limitations, Bohr’s model was based off only one model, the Helium atom, and couldn’t adequately adjust for the way electrons are oriented (their spin) or larger multi-electron atoms. Bohr’s model couldn’t be fully supported by classical physics.
Understanding that the idea of quantum leaps was a valid perspective, Heisenberg suggested that instead of these electrons taking concentric leaps forward or backward from the center, it had to be that electrons could disappear and reappear. Electrons no longer appeared to take steps away, and instead, stirred away.
Doing the math, Heisenberg found that electrons stir away in a particular fashion: one can only calculate their position by examining the instants in which they interact with another.
Heisenberg uses the properties of mathematical arrangements that represent systems of equations (called matrices) to demonstrate that the position and momentum of an electron cannot be both certain at the same time. This fundamental idea of quantum mechanics is called the uncertainty principle.
Here’s a wonderful definition of the Heisenberg Uncertainty Principle from Dr. Michael Raymer in Quantum Physics: What Everyone Needs to Know
Heisenberg’s Uncertainty Principle: the more precisely you can specify the position of a particle, the less precisely you can specify it’s momentum (velocity) and vice versa
By this point, we’ve focused on the absolute tiniest of scales. Electrons are to be found in everything that has atoms and so Quantum Mechanics is understanding the smallest of us.
Simple Definition of Quantum Mechanics: The study of all things small! You might realize right about now that Quantum Mechanics is truly resultant of the labor of tiny, tiny, tiny particles. And these developments implicate physics into something huge.
Main Point: Quantum physics/mechanics rests upon the foundations of physicists going way back to the early 1900s and their developments to the theories around waves, electrons, and light. In particular, one theory, the uncertainty theory, provides a grand insight to the whole of quantum mechanics.
Keywords: Quantum Leaps, uncertainty principle
SOURCES REFERRED TO THROUGHOUT THESE POSTS
Stephen Hawking’s A Brief History of Time, Carlo Rovelli’s Reality is Not What It Seems, and Bub’s Bananaworld all proved essential to the development of this blog piece. I cannot recommend Dr. Raymer’s Quantum Physics: What Everyone Needs to Know more too — it is a great introduction on the subject and I enjoyed reading it thoroughly. I have synthesized, condensed, explored, and expanded upon their ideas into what is hopefully a coherent ultimate documentation of what these bright thinkers have brilliantly communicated. Some of their explanations and/or analogies have been re-purposed here due to their educational significance.
In addition, I hold Richard Feynman’s lectures as a wonderful source for exploration.
