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Reality of fields, language of particles – the Standard Model

[Communicating science]

To understand contemporary physics, particularly quantum theory, the Standard Model is essential. This article includes an excellent video overview:

• Quanta Magazine > Math Meets QFT > “A Video Tour of the Standard Model” by Kevin Hartnett, Senior Writer/Editor (July 16, 2021)

(quote) Physicists would like to move beyond the Standard Model to an even more encompassing physical theory.

And that, maybe, is where math comes in. Mathematicians will have to develop a fresh perspective on quantum field theory if they want to understand it in a self-consistent and rigorous way. There’s reason to hope that this new vantage will resolve many of the biggest open questions in physics.

The video is hosted and presented by Cambridge University theoretical physicist David Tong, and also available on YouTube:

• YouTube > Quanta Magazine > “The Standard Model: The Most Successful Scientific Theory Ever” (Jul 16, 2021)

(Description) The Standard Model of particle physics is the most successful scientific theory of all time. It describes how everything in the universe is made of 12 different types of matter particles, interacting with three forces, all bound together by a rather special particle called the Higgs boson. It’s the pinnacle of 400 years of science and gives the correct answer to hundreds of thousands of experiments. In this explainer, Cambridge University physicist David Tong recreates the model, piece by piece, to provide some intuition for how the fundamental building blocks of our universe fit together. At the end of the video, he also points out what’s missing from the model and what work is left to do in order to complete the Theory of Everything.

**Correction: At 13’50”, the photon should be included with the three fundamental forces. The animation here is incorrect, while the narration is correct.


Using helpful visuals, David Tong unpacks the Standard Model piece by piece – assembles the model from “the fundamental building blocks of our universe.” I like the way he points out two caveats early on:

  1. First, gravity is NOT included in the model, for two reasons:

(quote) The first is that, at the microscopic level, the force of gravity is so weak that it barely has any effect on a single subatomic particle. [But what about a “particle” on space-time?]

The second is that we don’t really know how to incorporate general relativity, which is a classical theory, into the quantum world.

  1. Second, quantum theory really is about fields – the language of “particles” is a convenient simplification.[1, 2]

(transcript) … the Standard Model is written in a language known as quantum field theory. This tells us that matter, at the fundamental level, is not really made up of particles. Instead, it’s made up of fields: fluid-like objects which are spread throughout all of space. These fields are engaged in an intricate, harmonious dance to a music that we call the laws of physics. The interactions between the fields produce the physical world in the form of particles. To understand the Standard Model, it’s more convenient to use the language of particles.

Notes

[1] Cf. my post “Reality is fields.”

As Sean Carroll noted in one of his lectures, “… you need to stop thinking of the world as particles. … That’s the secret we physicists have never told you.” (Particles as contextual realities.)

In my May 22, 2017 comment for “Reality is fields,” Paul Sutter noted:

(quote) In other words, you can slap a field and make some particles. A single particle is just the minimum possible amount of energy that a field can support. Every kind of particle that scientists know of, from the electron to a photon, is associated with its own space-time-filling vibrating field.

[2] See also this older YouTube video of David Tong’s lecture “Quantum Fields: The Real Building Blocks of the Universe.”

4 thoughts on “Reality of fields, language of particles – the Standard Model

  1. [Communicating science]

    A helpful overview of quantum physics, which includes these topics:

    • The Caltech Weekly > Caltech Science Exchange: Quantum Science and Technology

    What Is Quantum Physics?

    If you’re new to the field, we suggest you start here. Learn about the origins of quantum physics, also known as quantum mechanics, why mathematics is essential to the field, and how the act of observing the smallest objects can affect them.

    What Is Entanglement and Why Is It Important? (which includes a YouTube video)

    Entanglement is at the heart of quantum physics and emerging quantum technologies. Read about how scientists proved its existence, and watch Caltech scientists take a stab at explaining this “spooky” phenomenon.

    What Is Superposition and Why Is It Important?

    Go beyond Schrödinger’s cat and learn more about superposition, a concept that might be difficult to visualize but could hold the key to advancing technology such as quantum computers.

    What Is the Uncertainty Principle and Why Is It Important?

    Formulated by the German physicist and Nobel laureate Werner Heisenberg in 1927, the uncertainty principle states that we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy. Find out why.

    How Do Scientists Conduct Quantum Experiments?

    Let this comic take you inside the labs where researchers probe the subatomic world of quantum physics.

  2. “Fundamentals: Ten Keys to Reality” by Frank Wilczek:

    • “Can we consider ’empty space’ itself to be a material, whose quasiparticles are our ‘elementary particles’? We can, and we should. It is a very fruitful line of thought, as you’ll see in later chapters.”

    • “Particles are avatars of fields.”

  3. The language of matter particles and force-carrier particles persists, although – as Sean Carroll notes in his latest Thanksgiving blog post – “These days we know it’s all just quantum fields, and both matter and forces arise from the behavior of quantum fields interacting with each other.”

    • Preposterous Universe > “Thanksgiving – electromagnetism” by Sean Carroll (November 25, 2021)

    Physicists like to say there are four forces of nature: gravitation, electromagnetism, the strong nuclear force, and the weak nuclear force. … These days we know it’s all just quantum fields, and both matter and forces arise from the behavior of quantum fields interacting with each other. There is an important distinction between fermions and bosons, which almost maps onto the old-fashioned matter/force distinction, but not quite. If it did, we’d have to include the Higgs force among the fundamental forces, but nobody is really inclined to do that.

    The real reason we stick with the traditional four forces is that (unlike the Higgs) they are all mediated by a particular kind of bosonic quantum field, called gauge fields.

    When you have a force carried by a gauge field, one of the first questions to ask is what phase the field is in (in whatever physical situation you care about). … In the case of gauge theories, we can think about the different phases in terms of what happens to lines of force

    The simplest thing that lines of force can do is just to extend away from a source, traveling forever through space until they hit some other source. … That corresponds to field being in the Coulomb phase. … The magnitude of the force therefore goes as the inverse of the square — the famous inverse square law. In the real world, both gravity and electromagnetism are in the Coulomb phase, and exhibit inverse-square laws.

    But there are other phases. There is the confined phase, where lines of force get all tangled up with each other. There is also the Higgs phase, where the lines of force are gradually absorbed into some surrounding field (the Higgs field!). In the real world, the strong nuclear force is in the confined phase, and the weak nuclear force is in the Higgs phase. As a result, neither force extends farther than subatomic distances.

    So there are four gauge forces that push around particles, but only two of them are “long-range” forces in the Coulomb phase.

    To get complexity, you need to be able to manipulate matter [“pinpoint control”] in delicate ways with your force. Gravity isn’t up to the task — it just attracts. Electromagentism, on the other hand, … Unlike gravity, where the “charge” is just mass and all masses are positive, electromagnetism has both positive and negative charges.

    Electromagnetism facilitates complex structures, from which life itself emerges.

    It’s electromagnetism that allows energy to move from place to place between atoms …

  4. A useful historial recap about the photon.

    • Symmetry Magazine > “What is a photon?” by Amanda Solliday and Kathryn Jepsen (6-29-2021) – The fundamental particle of light is both ordinary and full of surprises.

    From wave, to particle, to boson …

    Secondly, the photon is now thought of as a particle, a wave, and an excitation – kind of like a wave—in a quantum field.

    “I like to think of a quantum field as a calm pond surface where you don’t see anything,” Ruiz [Richard Ruiz, a research associate at the Institute of Nuclear Physics in Krakow, Poland] says. “Then you put a pebble on the surface, and the water pops up a bit. That’s a particle.”

    Terms and people

    Wave – radio wave, microwave, X-ray, gamma ray
    Particle
    Radiation
    Photoelectric effect
    Gauge boson
    Laser pulse
    Electromagnetic spectrum
    Nanophotonics

    Christiaan Huygens
    Isaac Newton
    Thomas Young
    Léon Foucalt
    James Clerk Maxwell
    Max Planck
    Albert Einstein
    Philipp Lenard
    Robert Millikan
    Arthur Compton
    Gilbert Lewis (chemist)

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