What Are the Physics of the Light in Your Head?
A morning at Greystone, after vibecoding a world into existence, asking whether the world inside the skull obeys laws of its own.
I had spent the morning vibecoding a game on Roblox — building a small world out of nothing but instructions, watching it cohere into something that obeyed rules I had written. Then I went for a walk through Greystone Mansion & Gardens, an iconic location for motion picture and television shoots that has been featured in dozens of films and TV shows, and the question that had been forming all morning finally arrived in a usable shape.
It started from a definition. Anything that is real has to have physics associated with it. Not physics in the narrow sense of equations on a chalkboard, but physics in the deeper sense: a thing is real if it obeys rules — if there are constraints on what it can and cannot do, regularities you can in principle write down.
Conscious experience is real. We know it is real because we are the ones experiencing it. Whatever else can be doubted, the fact of experience cannot. There is something it is like to be the thing reading this sentence. That something is the observer.
And if there is an observer, then qualia — the felt textures of experience, the redness of red, the weight of a thought — are not optional features of reality as it appears to us. They are the medium through which whatever we call reality reaches us at all. Without the observer, what we mean by real loses its first-person anchor.
So if qualia exist, they should also obey physics. They should have rules. There should be a structure to what they can and cannot do.
But here the question turns strange. How do you determine the physics of something that is not physical in the way photons are physical? Imagination has no obvious mass, charge, or extension in public space. The qualitative character of experience has no obvious place in ordinary mechanics. What are the laws of a reality that has no mass, no charge, no obvious extension in space? And how does that reality interact with the ordinary one — the one of photons and neurons and trees at Greystone?
Begin with what we can say. The qualia of vision live somewhere. They do not live nowhere. When I move my head, my visual field moves with me, which means whatever it is, it is coupled tightly to the body. There is plenty of evidence for correlation between neuronal activity and the contents of experience. There is far less evidence that neurons cause experience in the strong sense — only that the two march together. The honest position is correlation, not derivation.
So the visual field — the field of light inside the head — is real, is structured, and is coupled to the brain without being obviously identical to it. Which raises the question I could not stop turning over on the walk: how does the physics of the light in my head differ from the physics of the light outside it?
The light outside obeys Maxwell’s equations. It travels at a fixed speed in vacuum. It has a frequency, a wavelength, a polarisation. It carries momentum. It bends around mass. It has, by Einstein’s mass–energy equivalence, an energetic equivalent.
What about the light inside? It has spatial structure — I can point to where things are in my visual field. It has colour, brightness, motion. When I turn my head, it sweeps. When I close my eyes, it dims. It seems to obey some rules, but they are not obviously the rules of external optics. The light in my head does not refract through my own eye to reach itself. It does not need a vacuum. It does not seem to be made of photons in any sense a physicist would accept.
And yet it cannot be pure freedom either. It does not let me see behind my head. It does not let me see infrared. It does not let two contradictory colours occupy the same point. There are constraints. There is something like a physics here — just not one we have written down.
Einstein got special relativity by imagining himself riding a beam of light. The thought experiment was the lever. So let me try the equivalent move for qualia. If I were a particle of qualia in my own visual field — a single grain of seen-light — what would it be like to be me?
I would be located somewhere. A point in the field. I would have a colour-charge of sorts: a particular hue, a particular brightness, a particular saturation. I would have neighbours — other grains of the field — and my relationship to them would be lawful. I could not flicker independently of the field around me without producing the experience of noise or hallucination, which the system actively suppresses. The field has coherence. It enforces it.
When the head turns, I move. Fast. Across the entire visual hemisphere in a fraction of a second. So whatever I am, I am not bound by the speed of light in the external sense. The constraint on my motion is not c. The constraint is the rate at which the body can pivot, and the rate at which the field can remain coherent while it updates.
But there must be some limit. If the head turns infinitely fast, the field cannot keep up — it smears, blurs, breaks down into the streaks of saccadic suppression. So there is a limiting velocity here too. It is just not Einstein’s limiting velocity. It is the limit imposed by the integration time of the system — how fast the field can refresh itself and still remain a coherent field. Call it the speed of coherence rather than the speed of light.
Do these particles have something like mass? Something like energy? They certainly have intensity — a bright point of qualia is, in some functional sense, more energetic than a dim one. They have inertia of a kind: an after-image persists, a vivid impression takes longer to fade than a faint one. There is a conservation here that wants to be characterised. What does the field conserve as it moves? Not momentum in the Newtonian sense. But perhaps attention is its conserved quantity — a finite resource the field budgets across its grains, redistributing as the gaze moves.
There is a further wrinkle, and Greystone’s quiet made it loud — fitting, in a place where so many imagined worlds have been filmed, to be standing there asking what kind of world is being filmed inside the skull. Most of what I see is not arriving from outside. The biological channels that carry information from retina to cortex are wet, warm, and noisy — terrible substrates for faithful transmission. The eye delivers a low-bandwidth, heavily compressed signal full of gaps. The brain fills the gaps. What I experience as a continuous, high-resolution visual world is mostly the model the brain is running, lightly corrected by sensory data.
Which means the field of qualia in my head is largely decoupled from the external photon field. It is constructed. It has its own rules of construction — perceptual priors, expectations, completions — that are not derivable from optics alone. The physics of the light in my head is, to a large extent, the physics of a generative model running in real time.
This is why the comparison to external light keeps slipping. External light is what arrives. Internal light is what is built, partly from what arrives and partly from what the system already expects to be there. The two systems are coupled, but they are not the same system. They have different conservation laws because they are doing different jobs.
External light conserves energy and momentum because it propagates through spacetime. Internal light — the visual field of qualia — conserves something else. Coherence, perhaps. Predictive accuracy. The integrity of the self/world model. These are not yet quantified. But the fact that they can be violated — in dreams, in psychedelics, in pathology — suggests they are real constraints, not metaphors.
So what is the physics of qualia? I do not have it. I am not sure anyone does. But I think the question is the right one, and I think it dissolves a confusion that has haunted philosophy of mind for a long time.
The confusion is this: people have asked whether qualia are physical, meaning whether they reduce to the physics we already have. The answer is plainly no. Internal light is not external light. The field in my head is not Maxwell’s field.
But the dichotomy is wrong. The choice is not physical or non-physical. The choice is which physics? Qualia are real. Anything real has rules. Therefore qualia have a physics. It is simply not the physics of the icon. It is the physics of the field that runs the icon.
This connects directly to where the essay series has been going. If pattern is prior to substrate — if the conscious agent has its own symmetries and its own conservation laws, more fundamental than those of the biological interface — then the visual field is one of the places those deeper laws make themselves felt. The field in your head is not an epiphenomenon of neural firing. It is the generative model showing itself from the inside, obeying its own constraints, carrying its own conserved quantities.
When I turned my head at Greystone and watched the live oaks sweep across my visual field, I was not watching photons. I was watching a field of qualia respond to a head-rotation by re-cohering its grains, faster than light could have travelled the equivalent external arc, and slower than the integration time of the system would allow it to fragment. Somewhere between those two limits is a physics that has not yet been written.
It would be worth writing.
This essay is part of an ongoing exploration of consciousness, physics, and the deeper philosophical traditions that shape the world of #2084 BIOMAN Chronicles.
The question beneath it is simple to ask and difficult to escape: what is most real about us, and what remains when the form through which it appears falls away?
If this inquiry speaks to you, stay close. There is more to come.
For readers following the wider Bioverse arc: