Is Everything Made of Massless Energy Particles?
Specifically this theory says, the elementary particles with mass (fermions, the ones that make up all matter) are actually composite particles made from massless particles. Meanwhile, the only elementary particles without mass (the photon and gluon) are already massless (meaning they have light speed momentum, but no rest mass; they are pure kinetic energy).
For a visual, the elementary particles can be seen in the image below. Notice that almost all have mass (potential energy) and an electric charge (kinetic energy stored as potential energy).
Factoring in the theory that the Higgs Boson is the only original massive particle, and that the Higgs “gave” all other particles their mass, and comparing that to the fact that we know larger composite particles get part of their mass from photons and gluons, we can say: all known matter and energy that isn’t “true empty space” is massless energy particles at its core and thus all particles with mass are composite particles (we obviously can’t confirm this is true for unknowns like dark energy).
All this means is that all particles with rest mass (potential energy) originate from particles with momentum and no rest mass (pure light speed momentum, kinetic energy), originally by interacting with the Higgs boson, and later by absorbing massless particles.
The simplest proof is that all particles with a charge have photons bound to them (we know because they can exchange “virtual photons”… plus there is only four forces, so if you have electric charge, you have electromagnetic energy AKA photons bound to you). This doesn’t prove that the Higgs imparts bosons like the photon or gluon as mass, but it does mean all particles with a charge are composite particles (as all “composite” means is consisting of more than one particles).
If we take the above explanation, then right off the bat we are only left with neutrinos, the Z boson, and the Higgs itself to explain. The other particles are composite by nature. Most of this can be understood by closer examination of photons, gluons, and the Higgs (as we do below).
This makes sense when we consider that E = mc2 tells us mass and energy are equivalent properties of a system (not exactly the same), that massless particles can add to the mass of a system, and that at the start of the big bang all forces were combined as an [almost] single force.
As a respected commenter said on Stack Exchange, “there is a real sense in which everything in the standard model + gravity is made of massless particles except the Higgs and possibly neutrinos.”
As another commenter said, “It’s certainly possible for a particle’s mass to come partially from kinetic energy of massless particles; for example, about half of a proton’s mass is the kinetic energy of its gluons. But the kind of mass that fundamental particles have, the kind that comes from the Higgs mechanism, doesn’t appear to be of that kind. Maybe someday we will discover that it is. (This would be the case if string theory turns out to be correct, for instance.) By the way, scientists do not believe that mass is fundamentally different from energy. Mass is just one type of energy.”
See the video below that for an introduction into a physical theory of [almost] everything.
Theory of Everything (Intro). We can reduce most of physics down to some basic rulesets (with lots of math), here is a quick video on this concept.
TIP: This subject is oddly difficult despite being fairly singular, kind of like binary computing (everything on your screen can be reduced to 1’s and 0’s, yet explaining the specifics of that is tricky). I suggest watching Richard Feynman speaking on Quantum Electrodynamics so you can hear one of the 20th centuries great thinkers describe how we have long known how fundamental the massless photon is to our universe.
How Can Everything Be Made of Massless Energy if All Matter Has Mass?
All matter has mass, yet all matter is made from massless energy particles at its core.
This can be explained by understanding that:
- Massless energy can contribute to the mass of a system (see mass energy equivalence and relativistic mass).
- “The Higgs Field” (which we cover below) can impart massless particles with mass.
Given these facts, and putting aside unknowns like dark energy, we can say confidently that, “everything in the universe that isn’t empty space, is at its core, massless energy particles in motion, and can be measured as mass-energy”.
TIP: If you aren’t familiar with elementary particles, I suggest checking out our breakdown of the standard model of particle physics. Also, I strongly suggest watching the explainer video below for more insight into the fundamentals of the universe.
The True Nature of Matter and Mass | Space Time | PBS Digital Studios. To understand how energy is massless, it helps to understand mass. See the different types of mass here.
FACT: It is worth noting that of all the elementary particles only the photon and gluon are massless, and only the photon can be observed as a free particle. The photon is the carrier of electromagnetic force, and the gluon carriers the strong nuclear force that “glues” other particles together (it’s literally the force that holds an atom’s nucleus together).
FACT: When we say “massless” we mean that light speed particles don’t have a “rest mass“. They do however have momentum. We won’t harp on this but do see: How can a photon have no mass and still travel at the speed of light? and How does a photon exhibit inertia? (Also check out some new theories surrounding the photon and the EmDrive summarized by MIT Technology Review).
FACT: All massless energy has properties of mass-energy and motion (although in truth, little more than motion is really needed to explain things). Massless Energy (E) is kinetic energy moving at light speed (the speed of light in a vacuum, the max speed of the universe). Mass (m) is potential energy not moving at light speed (typically due to being bound to a system of one or more particles, and having the pure energy conserved as other fundamental properties like “charge” and “spin”, types of motion). In systems of one or more particles energy can be conserved as mass and mass can be conserved as energy (Einstein‘s mass-energy equivalence). This fact is the key to understanding how massless particles can work together with the massive Higgs Field to create massive particles.
The Big Bang, the Higgs Field, Gauge Bosons, and Let there Be Mass
The core concepts are a little heady, so let’s back up a second, or, rather, 13.8 billion years.
At the start of the big bang, there is a singularity of forces. The forces split into gauge bosons (force carriers) and the Higgs boson. The Higgs boson and gauge bosons are massless at this point. The Higgs boson and it’s field become massive from “spontaneous symmetry breaking” (arbitrary rule change) as the universe cools (somewhere between 10−12 and 10−6 after the bang).
When massless particles pass through the now massive Higgs field, they are “imparted” with mass via a process called the “Higgs Mechanism.” In simple terms, the massive Higgs field permeating the universe impedes their movement, and that process binds kinetic energy as potential energy (AKA mass).
From about 10−12 seconds after the big bang forward, mass (potential energy) and energy (kinetic energy) can simply be thought of as mass-energy.
Confused? Watch this simple and awesome explainer video.
The Higgs Boson, Part II: What is Mass?
TIP: There are different ways to measure mass. So you may want a refresher on that.
TIP: Elementary particles can be understood as both a wave-like uni-directional field, and a measurable point in a field (an excited state). The photon and Higgs bosons are measurable parts of the surrounding fields interacting with each other. It’s easier to think of them as particles but more useful to understand them as fields.
How Massless Particles Become Massive
All massless energy particles must always move at light speed (in a true vacuum), all particles with mass can never move at light speed or faster than light speed.
A simple way of describing this is saying, “all Energy (E) is massless energy particles moving at light speed, and all Mass (m) is the effects of massless energy particles not moving at light speed (c).”
If you can imagine “trapping” a particle moving at light speed in a quantum sized quark or electron as “charge” or “spin”, you can understand why all that motion/energy trapped in a very tiny space would add “mass” (potential energy) to the particle, and sure enough, Einstein’s mass-energy equivalence equation ( E=mc2) backs up this logic.
So massless particles can add to the mass of a system by being bound to the system. However this doesn’t explain how a single massless energy particle can become massive, for that we need the “Higgs Mechanism”.
The Higgs Mechanism
The “Higgs Mechanism” is essentially a field with mass, permeating the physical universe, which massless photons can bounce around in, changing direction.
We know massless energy, like photons, can’t do anything aside travel at “light speed” (why it’s called light speed), but the caveat (as noted above) is that they can be slowed by and bounce off something with mass. You can experiment with this if you shine a flashlight at a mirror, or trap light in a photonic crystal.
You might think of this as an object passing through molasses. Molasses isn’t a pure vacuum, so massless energy is slowed in molasses (the molasses makes the massless massive, try saying that ten times fast). For the laws of conservation of work, something has to happen when you slow down massless energy.
In this case, pure kinetic energy is conserved as the mass (potential energy) resulting in new particles. These new particles can “trap” or “absorb” photons as a “charge” themselves, and can interact with other particles.
This process results in the known elementary particles and all larger physical systems from composite particles to atoms, to molecules, to elements, to elephants, to the solar system, to the Milky Way.
FACT: Atoms are made out of elementary particles with mass holding photons as a charge. The other forces simply work to keep those elements in place (strong force and gravity) or decay those bonds (weak force).
The Higgs Mechanism Explained | Space Time | PBS Digital Studios. Even intrinsic mass is still just “bound” energy. Watch the videos on the page for clearer explanations with visuals..
TIP: If a particle has mass, then it’s likely holding a charge or spinning at +1⁄2 or -1⁄2. That means it can collide with an anti-particle and shoot out free photons. Only photons, gluons, and Higgs are their anti-particles. Learn more here.
Everything is Energy (Sort of), But Dark Matter Matters…
While it is important to understand mass and energy, and to understand that all massive particles and systems are comprised of bound massless energy on some level, it isn’t good to oversimplify past that point or to ignore the mechanics of more complex massive systems. Despite the potential simplicity of the universe, we still don’t understand things like dark energy and dark matter.
We shouldn’t reduce the universe to, “everything is photons” or “everything is energy”, as that is (while not exactly incorrect) overly simple. In that same way we don’t want to say something like “everything is vibrating strings” either, because string theory is unproven. We shouldn’t even say everything is the Higgs, Photons, and Gluons because we’d be ignoring fermions (the elementary particles that make-ups objects with mass, matter) and the other bosons (like the Z+W which cause entropy in atoms). Even if we could ignore some elements of the standard model for a simpler theory, it’s not very useful to consider energy without taking mass into account as they are so fundamental to the systems that form all the matter in the universe.
Einstein and all scientists for the past 100 years have found mass to be a fundamental property of the universe (despite the layer of bound massless quanta beneath it). The fact that mass and energy can be conserved as each other is called “mass-energy equivalence” (E=mc2), and thus there is wisdom at simplifying things only to “everything has measurable properties of mass-energy and motion”, this allows us to consider mass, energy, motion, and mass-energy as “things” and doesn’t force us to explain the mass and motion of standard model particles in terms of the nature of massless energy.
In short, it is good to know about the Higgs and the formation of massive particles, but more useful to work with mass, energy, spin, charge, fermions, and bosons and the other elements as presented by the standard model.
TIP: Saying “everything is energy” is analogous describing magnetism as just a positive charge. Sure, but it seems silly not to discuss the negative charge (analogous to mass). Fundamental things have at least a binary nature, a duality. From a singularity arises duality, in the universe we explain the breaking of a symmetric singularity as “symmetry breaking”.
How Massless Parts Can Make up a Whole
A seeming sticking point of mass-energy equivalence is that something with mass can’t become massless. However, this rules applies to bound systems with mass (systems of one or more particle interactions).
Mass-energy equivalence does not say that the parts of a system can’t be massless; rather it fairly clearly shows that the parts of a system will (almost) always have less mass then the system as a whole. This is because kinetic energy is bound in systems, and that creates mass (just as it does with a single particle).
The equation just says things with “rest-mass” can’t travel light speed. So to go light speed systems must disassemble back into the masslessness from which they came. We can see this in anti-particles, which when they collide with a particle annihilate each other leaving behind just a photon as radiation.
How Massless Energy Adds Mass to a System
Radiation (kinetic energy, photons) affects the mass of an object. If I turn on a flashlight, it loses mass. If I shine a light into a crystal (crystals can hold light) the mass of the crystal increases. Even though the photons themselves have no mass, when that light speed energy is bound to the system it adds to the system’s mass.
So massless energy particles, which in this case become an electromagnetic force of photons, can link to systems (strong force) or radiate away from them (via electroweak force). If we radiate away enough photons we are just left with elementary particles and their “intrinsic mass“.
We think that, at some core level, even those elementary particles with mass can be explained as the effects of massless particles. And again, the only massless particle we can observe roaming free is the photon (a free electron is essentially a photon; sometimes they are called virtual photons too, but we can’t observe those).
At this point, if you would like to know more I suggest the standard model. That will explain the elementary particles and the forces in detail.