Worlds Within Meaning: What Is Mass? A Relational Inquiry

1 Mass as Model — From Weight to Inertia

We often speak of mass as though we know exactly what it is. It’s what makes objects heavy. It’s what resists acceleration. It’s what attracts other objects gravitationally. But mass is a curious kind of abstraction — indispensable to science, yet elusive when pressed for a definition. Is it a thing? A quantity? A property? Or something else entirely?

In this first post of our series, we take up mass not as a substance, but as a relational model. Following the same epistemological thread we used in Reframing Energy, we ask not what mass is, but how mass is made meaningful in different scientific contexts. We will see that mass only appears to be a unified concept. Historically and functionally, it has always been plural.

From Weight to Mass: A Conceptual Untethering

In ordinary experience, mass is conflated with weight. We speak of weighing a bag of flour or a person as if we are measuring their mass. But weight is a force — the downward pull of gravity on a body. Mass, by contrast, is what makes that gravitational pull proportional to the body in question.

This distinction is relatively recent. Before Newton, there was no clear need to distinguish between the heaviness of an object and its resistance to motion. But Newton’s Second Law — F = ma — introduced a new construal: force is what causes acceleration, and mass is what resists it. This gave mass a role independent of gravity: inertia.

Thus, mass began to function as a kind of relational constant: a means of correlating change in motion with the forces applied. It could now be inferred from observations even in zero gravity. This was not a redefinition, but an expansion of the abstraction — mass as weight and as inertia.

Mass as Inertial Resistance

What does it mean to say that an object “resists” acceleration?

It means that if we apply a given force to different objects, they will not all respond in the same way. Some will accelerate quickly; others more slowly. The idea of mass as inertia models this difference in response as a kind of relational capacity: a more massive object is one that requires more force to achieve the same change in velocity.

Importantly, this does not imply any metaphysical substance inside the object that is its mass. Mass in this view is not an entity, but a relational ratio: a way of modelling the difference between force and motion across instances.

This makes mass an interpretive tool, not a direct observation. We never see mass; we see effects (acceleration, gravity, momentum) that construe mass within a larger system of meaning.

Gravitational Mass and the Mirror Relation

But the story gets more curious. For centuries, experiments have shown that the inertial mass of an object (its resistance to acceleration) and its gravitational mass (the strength of its gravitational pull) are numerically equivalent. An object that resists acceleration strongly is also one that gravitational fields act upon strongly — and which exerts strong gravitational influence itself.

Why should this be so?

In Newtonian physics, this equivalence is simply assumed. The equations work because the same quantity appears in both the force law for gravity and the second law of motion. In Einstein’s general relativity, however, this equivalence becomes foundational — the equivalence principle. The idea is not that inertial and gravitational mass are equal by coincidence, but that they are the same relation seen from different vantage points.

Thus, even when mass appears in multiple guises — as weight, as inertia, as gravitational influence — it functions consistently as a relational construal of participation in a system of transformation: motion, interaction, curvature, or force.

What Mass Is Not

It may help to clarify what we are not claiming. We are not saying that mass is imaginary or arbitrary. Rather, we are saying that mass is not a thing in itself. It is not a blob of substance inside an object. It is not a hidden ingredient. It is a modelling device — a term that allows us to relate force, acceleration, weight, and energy across different systems of reference.

In a relational ontology, then, mass is not a property had by objects, but a construal of objecthood itself. To have mass is to be intelligible as a participant in certain kinds of relation — those that involve resistance, attraction, and transformation.

Toward Relativistic Reframings

In the next post, we will see how this abstraction is transformed again in the context of Einstein’s theory of relativity. There, mass begins to depend on the frame of reference. It becomes less like a static quantity and more like a relational effect — contingent on motion, energy, and spacetime geometry.

But even then, the core idea remains: mass is not an essence. It is a way of modelling how something participates in change.

2 Relativistic Mass — Motion, Frames, and the Vanishing Concept

In the first post, we saw how mass functions as a relational abstraction: not a substance within things, but a way of modelling their participation in gravitational and inertial systems. In this post, we follow the concept of mass into the relativistic domain, where its apparent solidity dissolves even further — and where the very idea of mass as a constant, intrinsic quantity begins to falter.

From Invariance to Relativity

In Newtonian physics, mass is invariant. Whether an object is still or moving, near or far, its mass is treated as the same — a stable quantity across all frames of reference. But Einstein’s theory of special relativity introduces a profound shift: not all observers agree on the measurements of time, space, or motion. As a result, physical quantities that once seemed absolute must now be reinterpreted as frame-dependent.

One of these quantities is mass.

To make sense of this, physicists initially introduced the idea of relativistic mass — the idea that the mass of an object increases with velocity. This allowed the familiar equation F = ma to remain useful even in relativistic contexts. But the price was conceptual: mass was no longer a fixed property of an object, but a function of the relation between object and observer.

Relativistic Mass: A Transitional Abstraction

Relativistic mass is given by the formula:

Here, $m_0$ is the so-called rest mass — the mass of the object in the frame where it is not moving — and $v$ is its velocity relative to the observer.

As velocity approaches the speed of light ( $c$ ), relativistic mass increases without bound. This was a useful way to explain why objects cannot be accelerated past the speed of light: as their velocity increases, so does their inertial resistance — their effective mass.

But this concept quickly fell out of favour. Why?

Because it confuses relational effects with intrinsic properties. The object itself has not changed. What has changed is how we model its participation in motion relative to us. So rather than saying that mass increases, contemporary physics speaks instead of increasing energy.

Mass and Energy: A Relational Equivalence

This shift is crystallised in the most famous equation in science:

$E = mc^2$

Here, mass and energy are not just correlated — they are equivalent. But what kind of equivalence is this?

Not identity. A mass is not an energy, and an energy is not a mass. Rather, this is a modelled conversion relation: the energy contained in a system at rest (its rest energy) is proportional to its mass. This includes not only the kinetic energy of particles, but also potential energy stored in fields, bonds, and internal structures.

In this sense, mass is a summary measure of a system’s energy potential in a given frame.

And this is where the relational ontology becomes most helpful: mass is not what something is; it is how something participates in a system of energetic construals. When energy transforms, mass may appear or vanish — as in particle-antiparticle annihilation — but always as a function of the relation, not as a loss or gain of substance.

The Geometry of Mass

General relativity takes this even further. Here, mass is no longer defined by resistance or energy alone. Instead, mass (and energy and momentum together) are what cause spacetime to curve. And curvature is what causes other bodies to accelerate — not because they are “pulled” by a force, but because the geometry of the system determines the paths they follow.

Mass here becomes a participant in a field of mutual constraint. It is not the source of gravity, but a modeller’s tool for constraining how spacetime itself unfolds in the presence of energy.

The Vanishing of Relativistic Mass

For all these reasons, physicists today rarely speak of relativistic mass. They speak instead of rest mass and energy, and model systems in terms of their momentum-energy relations. This is not a loss of mass as a concept, but its disentangling from substance.

In modern terms:

Rest mass is frame-invariant: all observers agree.
Energy is frame-relative: different observers assign different values.
The relation between the two — $E = mc^2$ — is structural, not substantial.

This makes mass a kind of interpretive coherence between models of energy and motion. It is not a universal glue that holds things together, but a way of modelling participation in a system of reference.

Next: The Mass of Fields and the Structure of Space

In the next post, we turn to quantum field theory and the Higgs mechanism, where mass appears again — but this time as a function of field interactions. Here, mass is no longer just a property of particles, but an emergent feature of relational configurations within quantum fields.

The ontological implications deepen. And so does the need for a framework — like our relational one — that doesn’t assume the reality of “mass itself,” but treats mass as the meaning made of a system’s patterned participation.

3 Mass from Fields — The Higgs Mechanism and the Relational Emergence of Substance

In the previous post, we explored how the concept of mass dissolves into relations between energy, momentum, and spacetime curvature — and how modern physics discards the idea of “relativistic mass” in favour of energy-momentum frames. But if mass is not a stable substance, then where does it come from? How do particles — especially fundamental ones — come to have the inertial mass that resists acceleration?

This question leads us to one of the most astonishing developments in modern physics: the Higgs mechanism.

Not a Property, but a Participation

In quantum field theory, particles are not tiny bits of matter — they are excitations in quantum fields. Each particle type corresponds to a particular field pervading all of space. What we call a particle is just a quantised “bump” in one of these fields.

But initially, in the Standard Model, all these fields are massless. There is nothing in the early mathematics that grants particles the resistance to acceleration we associate with mass. The system works beautifully if all particles move at the speed of light.

But clearly, they don’t.

The solution proposed was not to assign mass to each particle as an intrinsic property, but to introduce a new field — the Higgs field — and to model mass as an effect of interaction with this field.

Here, mass is not a feature of the particle, but of the relation between the particle and the Higgs field. The stronger the coupling between the two, the greater the mass.

The Higgs Field as Medium of Resistance

Imagine moving through a medium — honey, say — that resists your motion. The more strongly you interact with it, the harder it is to accelerate. The Higgs field functions analogously in the quantum realm. Particles that interact more intensely with the field are harder to accelerate. What we measure as “mass” is really the effect of their participation in this universal relational medium.

This is a profound shift in ontology:

Mass does not belong to the particle.
Mass is not “in” the particle.
Mass is what the particle becomes by participating in the Higgs field.

Once again, mass is not a thing but a relation — not a possession but a mode of co-emergence.

The Higgs Boson: An Instance of Potential

In 2012, the detection of the Higgs boson — the quantised excitation of the Higgs field — offered experimental confirmation of this framework. But from a relational perspective, the Higgs boson is just an instance of the meaning potential modelled by the Higgs field. The boson does not cause mass; it is a sign of the field’s participation in our systems of measurement.

Here we may distinguish:

Field: a structured potential for participation.
Interaction: an instance of relation within that potential.
Mass: the interpretive construal of such participation as resistance to motion.

This echoes the system/instance distinction in our semiotic model. Just as meaning emerges from the co-selection of features in a semiotic system, mass emerges from the co-participation of fields in the unfolding of energetic relations.

A Relational Ontology of Emergence

The Higgs mechanism doesn’t add a hidden “thing” to particles. It adds a relational structure to the system — a way of understanding how particles, fields, and observers are all co-constituted in interaction.

What we call “mass” is the meaning we make of this interaction. It is not simply that a particle has mass because it exists in a field; rather, it is that a particle means mass in relation to the field. The “property” we identify emerges only within the system of construals that includes both observer and observed, model and measurer, potential and instance.

Toward Gravity: The Next Relational Step

But if the Higgs mechanism accounts for inertial mass — resistance to acceleration — what about gravitational mass? Why do massive particles warp spacetime? Why does energy bend the path of light?

In the next post, we return to general relativity, not just as a theory of geometry, but as a relational construal of influence. We’ll ask: how can mass, which emerges from participation in a quantum field, also function as the source of gravitational curvature?

What unites these seemingly separate domains?

A relational ontology may help us bridge them.

4 Gravitational Mass — Curvature as Relational Construal

In the last post, we explored how inertial mass arises through the interaction of particles with the Higgs field — not as a property of the particle, but as an effect of participation. Now we turn to gravitational mass: the mass that causes spacetime to curve and produces the familiar pull we experience as gravity.

In Newtonian physics, inertial and gravitational mass were assumed to be the same, with no explanation for why. In Einstein’s theory of general relativity, this equivalence is elevated into a principle — but the interpretation of mass takes a radical turn.

Gravity, in this framework, is no longer a force. It is the curvature of spacetime itself, and mass is what causes that curvature.

But what is mass, if not a thing?

And what is curvature, if not a deformation of some invisible substrate?

Gravity Without Gravitons

We often think of gravitational attraction as a pulling force between two masses. But general relativity does away with that image entirely. There is no force pulling objects together. Instead, objects follow paths of least resistance (geodesics) in curved spacetime.

The curvature itself is described by Einstein’s field equations, which relate the energy-momentum tensor (a distribution of energy and momentum in spacetime) to the geometry of spacetime.

In short:

Energy–momentum tells spacetime how to curve. Spacetime tells energy–momentum how to move.

So if mass “causes” gravity, it does so by being a relation within a system: an organised pattern of energy and momentum that conditions the shape of possible trajectories.

Mass as a Condition for Geometry

From a relational perspective, we don’t begin with mass and add curvature. Instead, we begin with a system of relations between observers, measurements, and potentials. Curvature is not a substance; it is a construal of the differential relations between those observers and the unfolding energetic system.

In other words, what we interpret as “mass causing spacetime curvature” is our way of actualising the system’s tendencies — through spacetime geometry — into instances of motion and resistance.

Mass becomes the semantic marker we apply to systems whose energetic organisation induces differential constraints on other systems.

It’s not that the object bends spacetime by virtue of something it has; rather, the object participates in relational patterns that, when actualised in our measurements, mean curvature.

The Equivalence Principle as a Semiotic Relation

Einstein’s equivalence principle tells us that the experience of gravity is indistinguishable from the experience of acceleration. In relational terms, this means:

Gravitational meaning and inertial meaning are interpretations of the same interactional structure.

There is no ontological difference between being pushed back in your seat by a rocket and being pulled down by Earth's gravity — because there is no external absolute space to distinguish them. Instead, what we call “gravitational mass” is an emergent meaning, produced by the relation between the local instance (your body) and the systemic field (Earth’s energetic structure).

This brings us full circle: both inertial and gravitational mass are semiotic effects — different actualisations of the same relational potential.

From Curvature to Construal

Let us restate what we have learned so far:

Inertial mass emerges from participation in a field.
Gravitational mass emerges from patterned relations within the field of energy–momentum.
In both cases, mass is not a substance but a relational construal of system-internal dynamics.

Curvature itself is a metaphenomenon — a second-order reality. It is the semiotic shape we give to material-order tendencies.

What mass means, in gravitational contexts, is a condition for differential motion: a way of encoding the probability landscape that arises from energy–momentum configurations.

And so, again, we find:

Mass is not a thing, but a meaning.

Next: Mass–Energy Equivalence Revisited

Now that we’ve established mass as a relational construal — both inertial and gravitational — we return to the famous equation:

E = mc²

This is often taken to mean that mass is energy, or that the two can be converted. But what does that really mean in a relational ontology?

How can we understand this equation, not as a translation between substances, but as a construal of co-participation?

Let’s explore that next.

5 Energy–Mass Equivalence — A Relation, Not a Conversion

“Mass is energy.”

“Energy is mass.”

“E = mc².”

We hear these phrases so often that they seem self-evident. They are treated as if they express a kind of deep interchangeability, a conversion of one thing into another. But this casual equivalence often obscures more than it reveals. What kind of relation is really being expressed by Einstein’s famous equation?

To answer that, we need to set aside the idea of mass and energy as substances, and instead ask:

What does it mean to construe mass and energy as equivalent?
And how does this equivalence function in our relational ontology?

Not a Conversion, but a Co-Construal

In popular explanations, E = mc² is treated as a conversion formula: a certain amount of mass can be turned into energy, and vice versa. This metaphor works well in contexts like nuclear reactions or particle annihilation, where mass seems to “disappear” and energy is released.

But this notion implies an underlying substance ontology, in which mass and energy are things that exist independently and can be exchanged.

In our relational ontology, neither mass nor energy is a thing. Both are relational construals of system-internal dynamics — tendencies and constraints actualised as meaning through interaction.

So rather than a conversion of substances, mass–energy equivalence is a semiotic alignment between different construals of the same relational potential.

E = mc² is not a transmutation; it is a change in viewpoint.

Energy as Temporal Relationality

We’ve said before that energy is not a stuff but a condition for change — a relation across time that constrains what is possible next. Energy is how we mean transition within a system: its potential to act or be acted upon.

In this light, rest mass (m) becomes a way of semanticising the condition for participation in those transitions, even when no spatial movement occurs.

So in E = mc², we can read:

E as the system’s temporal potential (its total capacity for unfolding),
m as the system’s resistance to relational motion (a kind of semantic inertia), and
c² as the scaling relation between space and time.

Together, the equation construes energy as a distributed unfolding of mass across spacetime.

The Speed of Light Squared: Not Just a Constant

The presence of c² — the square of the speed of light — is not incidental. In physics, c is more than a speed: it is the fundamental conversion ratio between units of space and time. It gives us the relational geometry of the universe.

Squaring it amplifies this relation to cover energy, which emerges from interactions within spacetime.

In other words, c² is the bridge between how we construe participation in spatial systems (mass) and participation in temporal systems (energy).

It tells us how much temporal potential (energy) a spatial constraint (mass) represents.

This does not suggest that mass becomes energy, or vice versa. It suggests that both are co-actualisations of the same deeper potential — viewed through different semiotic lenses.

Mass and Energy: Two Sides of One Construal

In our model, mass and energy are not separate substances being shuffled around. They are different meanings actualised from the same relational field.

Where mass construes resistance to relational motion, energy construes potential for relational change.

And in certain configurations — such as particle–antiparticle annihilation — we experience this not as one becoming the other, but as a reconfiguration of participation: from one pattern of constraints (mass) to another (kinetic energy, photons, etc.).

Mass doesn’t vanish. It is reconstrued.

The Deeper Relational Insight

Einstein’s equation, then, gives us more than a way to calculate the energy content of a resting object. It points to a profound semiotic unity:

The capacity for change and the resistance to change are not opposites.
They are complementary construals of the same participatory potential.

In this sense, mass–energy equivalence is not a feature of particles, but a meta-meaning about systems: how they endure, how they unfold, and how they constrain each other’s possibilities.

Next: Mass, Meaning, and the Observer

If mass is not a substance, but a meaning construed from relational participation — then what is the role of the observer?

How do mass and energy become meaningful in a particular context?

And what happens when we make measurements — when the potential becomes actual?

In the next and final post of the series, we’ll explore the observer-dependent nature of mass, and how this construal is shaped by the semiotic act of observation itself.

6 Mass and Meaning — The Role of the Observer

Throughout this series, we’ve reconceived mass not as substance but as relation — a meaning we construe when systems resist motion, curve space, or unfold change. We’ve seen mass and energy not as things but as semiotic construals of participation in spacetime relations.

But there remains one crucial question:

For whom is this meaning actual?
Who — or what — is the observer in whose semiotic act mass becomes real?

This final post turns to the role of the observer in the meaning of mass, and to the deeper implications of seeing all scientific abstraction as dependent on the act of meaning-making.

The Observer Makes Mass Meaningful

In a relational ontology, mass has no inherent substance. It becomes actual only when a system participates in a relation that constrains — or is constrained by — others.

But no relation is meaningful in itself. Meaning arises when a participant construes the relation: when it instantiates a value from the field of what could have been meant.

So mass — like all construals in this ontology — depends on an observer-participant.

The act of observing here is the act of semiotic participation: constraining the potential through actualisation.

To say a system has mass is to say:
It has been construed as resisting participation in motion
by an observer engaged in meaning-making.

Measurement as Semiotic Act

In physics, mass is always inferred through measurement. We measure inertia, gravitational influence, or resistance to acceleration. But what is measurement in a relational ontology?

It is not passive detection, but active construal — the instantiation of a feature from a meaning potential, shaped by the observer’s position and purpose.

A measurement doesn’t reveal what is; it constrains what becomes.
It is an actualisation from potential, shaped by the observer’s relation to the observed.

So when we “measure the mass” of an object, we’re not uncovering a property that was just sitting there waiting to be read. We are selecting, from the system’s relational potential, a meaning — one that makes sense within the configuration of the measuring system itself.

This is true even at cosmic scales. When we infer the mass of a distant galaxy from gravitational lensing, we are constraining the field of potential relationalities into a specific instantiation — meaningful in our own semiotic terms.

The Centre of Mass and the Centre of Meaning

Physicists speak of the centre of mass — a point that summarises how mass is distributed in a system.

In our ontology, this is not a location of substance but a semiotic centre: the point from which relational resistance is construed as balanced. It is an artefact of the construal, not an inherent fact of the system.

And, strikingly, the observer's position relative to this centre changes the actualisation of meaning:

From the perspective of the gravitational centre, time dilates and space contracts.
From the perspective of the accelerated observer, mass increases.

These aren’t distortions of some objective mass. They are different semiotic realisations — meanings construed from different positions of relational participation.

Mass is always a positioned meaning.
There is no view from nowhere — only views from somewhere.

Mass as Memory: The History of Participation

Finally, we might say that mass is the memory of a system’s participation in relations that resist motion and constrain change.

In a dynamic universe, meaning arises from repetition: from the actualisation of patterns that come to function as potentials. The more a relation is instantiated — the more it matters — the more it constrains future possibility.

In this light, we might see mass not only as resistance, but as historical inertia: a system’s remembered tendency to participate in certain ways.

Mass is the sedimented meaning of motion resisted.
A construal of what has come before, shaping what comes next.

A New Way of Asking

This series began with a simple question: What is mass? But we’ve seen that this question, when asked relationally, unravels the very fabric of how meaning is made.

Mass is not a thing. It is not a property. It is not a fixed unit of substance.

Mass is a meaning — a construal of resistance, participation, and temporal potential — made actual in the act of observation.

It is a relation between.

It is a view from.

It is a trace of.

Encore: The Meaning of c²

E = mc²

This is not just a formula. It is a sentence in the grammar of participation.

The presence of c² — the square of the speed of light — is not incidental. In physics, c is more than a speed. It is the conversion ratio between space and time: a statement of how distance and duration are relationally woven into one another.

To square it is to amplify that relation — not linearly, but exponentially — so that it can hold the weight of energy.

Energy is the meaning we construe when systems unfold in time.
Mass is the meaning we construe when systems resist in space.
c² is the bridge: a relational constant that links these construals.

It tells us:

How much temporal potential — how much unfolding, transformation, and capacity for change — is stored within a given spatial constraint.

It tells us that every resistance to motion (mass) is also an invitation to become (energy).

That what holds in place can, under relation, become what sets in motion.

That the universe conserves meaning, even as it transforms it.

c² is not a number. It is the ratio by which spatial participation is transfigured into temporal emergence.

A grammar of spacetime.

A signature of the relational real.

02 June 2025

What Is Mass? A Relational Inquiry