Quantum Field Theory | The Fabric of Reality
Philosophy has long asked the question “What is Reality?” While it’s daughter, physics has been more precise by asking instead: “What is it made of?” The answer, as we shall see, takes us into quantum field theory.
One of the first answers to this question was supplied by the philosopher Democritus nearly 2500 years ago when he espoused his atoms in the void metaphysic. The father of atomism, he set up the still prevailing view that material objects occupy space, building on the notion that space itself is a kind of container.
Today, however, the view supplied by modern quantum field theory paints a much different picture. No longer are material objects situated in space, but rather, material objects are the macroscopic effect of properties or conditions of space. For as we shall discover, with regards to quantum field theory, space itself has properties that manifest as physical effects. Space does. Now, what’s positively fascinating about fields is their essential “immaterial” and irreducible nature far more resembles mind than that of matter. And in quantum field theory, fields fabricate matter.
The Fundamental “Object”
Quantum field theory tells us the fundamental object(s) of the universe is unbounded fields, or rather, a single unified field made up of many distinct but superimposed, interpenetrating, and cooperating in parallel fields. These fields are ubiquitous and pervade the entire universe. It may help us to think of them as separate sheets or fabrics but we must remember they do not stack atop one another but are instead enmeshed within one another.
All of the material objects that we see and all of the fundamental forces we know, are the result of the complex interrelationships of charge distributions and energy-momentum fluctuating in these quantized fields. Now, I’ve used a lot of fancy language and I still haven’t even defined a field yet…. or a quantum for that matter.
A field is defined as a property or condition of space that has physical effects. So, the magnetic field, as the father of fields Michael Faraday would say, is a property of “mere” space. The very fabric of reality is a magnetic field that allows “lines of force” to transmit energy and momentum across “thin air,” through “essentially” nothing. Yet we know it is not nothing, thanks to Faraday, we know it’s a field. And not only is the fabric of existence a magnetic field, but it’s also a gravitational or metric field, an electromagnetic field, a Higgs field, a gluon field etc. I’m sure you get the picture.
Quanta
In QFT there is no such thing as empty space as a kind of container, but rather space itself has properties that manifest as physical effects. One can think of space as a paradoxical material immateriality. Now you might be wondering what happened to the atoms of Democritus. Well, atoms are composite entities made up of smaller, more basic sub-atomic energy-momentum fluctuations that are but (somewhat) localized vibrations confined to their particular field. In fact, these minimal excitations of the field are called quanta. A single one, a quantum. People tend to think of quanta as particles but they are certainly not particles.
A quantum is a discrete, minimal unit of energy that, wave-like is a spread-out vibrating oscillation in a field. The word quantum does not refer to the size or magnitude of the field vibration but rather emphasizes its discrete nature. Although it is spread out and everywhere it remains a single unit and so must act as one. It is discrete because it is its own unit, lives and dies a life of its own, and can exist only as a particular minimum energy value. A value given by Plank’s constant related to the frequency of its oscillation.
Further, these quanta are described by what’s called a wave-function and consulting the wave function can tell you all of the properties of that quantum, but with a little uncertainty because in QFT you can only calculate the probabilistic results of interactions. And also, there was this guy named Heisenberg who illustrated an intrinsic and undeniable indeterminacy with regards to a quantum’s position and velocity, thus also giving to a quantum a minimum “size.”
Interacting
Should a single quantum — spread out in its field — encounter an atom with which it wishes to interact, it must do so as a unit, no matter how spread out it is and it must do so instantaneously. This is called quantum collapse and is governed by the probability of necessary interaction. The appearance of an interaction makes it “look like” a particle is present. But with a fields-only view, as i being argued here, we should think of this moment as nothing but the spatio-temporal location where the energy-momentum of the quantum transfers between fields or interacts with other quanta within its own field.
In an all-fields or fields-only view, we can solve the incomprehensible wave-particle duality by asserting that no particle exists! And the entanglement paradox can be understood by illustrating that entangled quanta also act as a unit, instantaneously, regardless of distance between them. This is so for the simple fact that the two are no longer two, but entangled, have become one, quanta to quantum.
So that’s the basics of quantum field theory. A mere scratching the surface. There exist properties of space that allow quanta of energy-momentum to spin and dance about, to respond to charges and manifest macroscopic phenomena. No particles exist, the necessary behaviour of quanta can give the impression that they do….. But they don’t!
As Art Hobson writes in his book Tales of the Quantum :“Reality is made of waves in unseen fields.”
For more on the all-fields view, check out Hobson’s new book Tales of the Quantum.
Casey Mitchell is an avid reader and incurable thinker who finally thought to pick up the pen to share his thoughts on life and love and the meaning of existence. A lover of philosophy, he is consistently perplexed and amazed by the ever-unfolding universe. He is the creative pulse behind SophiasIchor.com and writes to share his curiosity and thoughts about this mystery we live.
This article (Quantum Field Theory | The Fabric of Reality) was originally created and published by Sophias Ichor and is published here under a Creative Commons license with attribution to Casey Mitchell and sophiasichor.com It may be re-posted freely with proper attribution, author bio, and this copyright statement.