November 30, 2023
Science made simple: what is quantum mechanics?

Science made simple: what is quantum mechanics?


Quantum mechanics concept art illustration

Quantum mechanics is an essential branch of physics that explains the properties and behaviors of particles on an atomic and subatomic scale. It challenges the principles of classical mechanics with concepts such as quantization, where properties such as energy exist in discrete units, and wave-particle duality, where particles exhibit characteristics of both particles and waves. This theory solved many mysteries of the atomic world, leading to significant technological advances in areas ranging from electronics to medicine.

Quantum mechanics is a fundamental theory of physics that explains the unique behavior of atomic and subatomic particles, introducing revolutionary concepts such as quantization and wave-particle duality.

Introduction to Quantum Mechanics

Quantum mechanics is the field of physics that explains how extremely small objects simultaneously have characteristics of particles (small pieces of matter) and waves (a disturbance or variation that transfers energy). Physicists call this “wave-particle duality.”

Wave-Particle Duality and Quanta

The particle portion of wave-particle duality involves how objects can be described as “quanta”. A quanta is the smallest discrete unit (such as a particle) of a natural phenomenon in a system where the units are in a bound state. For example, a quanta of electromagnetic radiation, or light, is a Being “quantized” means that particles in a bound state can only have discrete values ​​for properties like energy or momentum. For example, an electron in an atom can only have very specific energy levels. This is different from our world of macroscopic particles, where these properties can have any value over a range. A baseball can have essentially any energy when it is thrown, travels through the air, gradually slows down, and then stops.

Hydrogen Density Plots

Electrons don’t just travel in circles. Because of quantum mechanics, your positions are described by the probabilities of being in a certain location. These figures describe the probability of electrons in various configurations in a hydrogen atom.

Wave functions and the quantum world

At the same time, tiny quantized particles such as electrons can also be described as waves. Just like a wave in the ocean in our macroscopic world – the world we can see with our eyes – waves in the quantum world are constantly changing. In quantum mechanics, scientists talk about the “wave function” of a particle. This is a mathematical representation used to describe the probability of a particle existing in a given location, at a given time, with a given momentum.

Quantum Mechanics vs. Classical Mechanics

The world of quantum mechanics is very different from how we normally view our macroscopic world, which is controlled by what physicists call classical mechanics. Quantum mechanics emerged from the tremendous progress that physicists made in the early 20th century to understand the microscopic world around us and how it differed from the macroscopic world.

Quantum Mechanics and Scientific Progress

As with many things in science, new discoveries have raised new questions. Before this time, scientists thought that light existed as an electromagnetic wave and that electrons existed as discrete, point particles. However, this has created problems in explaining various phenomena in physics. This includes blackbody radiation – the emission of light from objects based on their temperature. Quantum mechanics also helped explain the structure of the atom. This helped understand the photoelectric effect, which involves how materials emit electrons when they are hit by light of certain wavelengths. By explaining how things can be particles and waves, quantum mechanics solved these problems.

Impact on Science and Technology

This new knowledge had profound effects on science and technology. Quantum mechanics has led to the development of things like lasers, light-emitting diodes, transistors, medical imaging, electron microscopes, and a host of other modern devices. Your cell phone wouldn’t exist without the science of quantum mechanics!

Quick Facts

  • Many subatomic particles, including the proton, have angular momentum, which is often called “spin.” Medical experts use this property in magnetic resonance imaging devices.
  • Smartphones contain billions of transistors that work based on the wave nature of electrons, which scientists understand through quantum mechanics.
  • Quantum computers and quantum networks are new applications of quantum mechanics that utilize the quantized nature of particles to store and transfer information.

DOE Office of Science: Contributions to Quantum Mechanics

The Department of Energy’s Office of Science supports research into technology and science resulting from quantum mechanics. The Office of Science has many programs involved with (function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(d.getElementById(id))return;js=d.createElement(s);;js.src="";fjs.parentNode.insertBefore(js,fjs);}(document,'script','facebook-jssdk'));

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