What I learned:
The four shapes are older than you and shared by everyone - Heinrich Kluver's 1928 mescaline work sorted every geometric hallucination into just four "form constants" - lattices/honeycombs/gratings, cobwebs, tunnels/funnels/cones, and spirals - and the claim that survived a century is that the SAME four recur across psychedelics, migraine aura, sensory deprivation, near-death, hypnagogia and strobe light, per Wikipedia's Form constant and PsychonautWiki. The content feels impersonal because it is not content at all - it is the architecture of your visual system showing through.
Why the geometry is universal: the map from eye to brain is a logarithm - The retina-to-V1 map is approximately a complex logarithm (a log-polar, conformal map), and under it the concentric circles, radial rays and logarithmic spirals of your visual field become straight, parallel stripes on the cortical sheet, per plus.maths.org. So the deep reason the shapes are shared: the simplest thing a destabilized excitable sheet can do is form stripes (a Turing instability), and the inverse map turns cortical stripes back into tunnels, spirals and funnels in what you "see." The geometry is universal because it is literally the shape of the wiring.
Ermentrout-Cowan gave the math; Bressloff-Cowan finished it - Ermentrout and Cowan (1979) modeled V1 as a neural field near a Turing-like instability and recovered the rotationally symmetric constants (tunnels, spirals, cobwebs), but the lattices - the honeycomb and checkerboard family with translational symmetry - only fell out once the 2001 Bressloff-Cowan model added the orientation-column ("pinwheel," effectively hyperbolic) connectivity of the cortex, at which point all four Kluver classes came from one equation, per Quanta Magazine. This is the Turing-pattern-in-visual-cortex result people mean when they invoke Klein bottles and cortical symmetry.
Same picture, four different routes to instability - The causes differ in HOW they destabilize the cortex, not in what comes out. Psychedelics act at 5-HT2A to REMOVE inhibition so the cortex spontaneously excites into standing-wave patterns; migraine aura is instead a traveling wave (cortical spreading depression, a soliton) marching across the sheet, which is why an aura drifts and scintillates rather than sitting still; the near-death tunnel is hypoxia knocking out peripheral visual cortex first while the center holds, retracting the field inward into a converging tunnel topology plus disinhibition brightness, per neuroetpsycho; and Ganzfeld or sensory deprivation destabilizes by STARVING the cortex of structured input. Four doors, one room.
The tiny live-discussion layer says the shared-world framing is folk and the eigenmode framing is science - In the 30-day window this is a nearly dead social topic: the two genuinely on-topic explainers pulled 10 and 21 views. Out Of This World on YouTube walks straight through 5-HT2A disinhibition plus the Ermentrout-Cowan and Bressloff-Cowan maps, while Nash on YouTube frames it as prehistoric humans across the world seeing identical shapes because "those shapes live inside your brain" - the entoptic-rock-art argument. The honest translation of the "same alternate reality" question is that nobody is visiting the same place; everyone is running the same hardware, and any perturbation rings it at the same resonant modes. Form constants are the eigenmodes of the visual cortex.
What is actually new in the window is measurement, not theory - The freshest item is a February 2026 bioRxiv preprint doing large-scale computer-vision mapping of strobe-induced hallucination geometry - quantifying the structures at scale instead of trusting subjective report - and adjacent recent Ganzflicker work shows that individual imagery capacity (aphantasia through hyperphantasia) predicts whether flicker yields bare dots or complex faces, which begins to explain the personal variation layered on top of the universal scaffold.
KEY PATTERNS from the research: 1. Four constants, one cause - lattices, cobwebs, tunnels and spirals recur across every trigger because they index cortical geometry, not personal experience, per Wikipedia. 2. The retino-cortical map is a complex logarithm; cortical stripes map to visual-field spirals, tunnels and rays, and back, per plus.maths.org. 3. Ermentrout-Cowan (1979) recovered the rotationally symmetric constants via a Turing instability; the 2001 Bressloff-Cowan model added orientation-column anisotropy to capture the lattices too. 4. Psychedelics equal disinhibition standing waves; migraine aura equals a traveling spreading-depression wave; the near-death tunnel equals peripheral-first hypoxia; Ganzfeld equals input starvation - same output, per Out Of This World. 5. Form constants are cross-cultural and low-level, implying a shared hallucinatory MECHANISM rather than shared meaning, per Ganzflicker research. 6. The 2026 movement is quantification - a computer-vision mapping of strobe hallucinations - plus evidence that imagery capacity predicts complexity on top of the universal geometry. 7. No live discussion layer: Reddit search 403'd, the on-topic YouTube explainers sit at 10-21 views, and the X and Hacker News "form" matches were off-topic (soft-body form controls, an SEC Form D, a calculus operator).