Atlas of physical theory
60 nodes, seven branches, three layers. The leftmost column is the shared foundation — classical mechanics, electromagnetism, thermodynamics and statistical mechanics, special relativity, quantum mechanics — used by every branch. The other six run left to right by scale. The bottom layer works extraordinarily well and still carries cracks deep inside; the middle layer holds problems that are confirmed but not closed; the top layer is chasing them. This page answers “where is physics stuck right now”; how models reduce to one another, and when to switch, belongs to the model relationship graph.
How to read this atlas
The horizontal axis is the research branch. The leftmost column is the shared foundation — classical mechanics, electromagnetism, thermodynamics and statistical mechanics, special relativity, quantum mechanics — which belongs to no single branch and is the common language of all of them. The other six run by typical scale: particle physics (10⁻¹⁸–10⁻¹⁵ m), AMO (10⁻¹⁰–10⁻⁹ m), condensed matter (10⁻⁹–10⁻³ m), astro & cosmology (10⁷–10²⁶ m); quantum information and plasma / complex systems are not tied to one scale.
Three layers answer three different questions. The foundation layer says what you calculate with today; the crack layer says where that calculation stops working; the frontier layer says who is chasing the crack. Dashed lines mean “this route tests that problem” — not “belongs to” and not “solves”.
Whitespace is information. AMO and condensed matter have nothing in the foundation layer: both reuse the methods of quantum field theory and the Standard Model rather than owning a separate theoretical base. A branch and a framework are not the same thing.
“In progress” is not “breakthrough”. That layer records routes and experiments under way, not a judgement about which will succeed. A single crack usually carries several competing routes — quantum gravity most of all: string/M theory, loop quantum gravity, causal dynamical triangulations, non-commutative geometry and holographic approaches sit side by side, unordered.
Three kinds of line, three directions. Thin teal lines sit inside the foundation layer: one theory reduces to another in some limit — relativity returns to Newton as v/c → 0, general relativity yields Newtonian gravity in the weak, slow limit. Pink dashed lines run from a crack back to the foundation it grows out of: dark matter sits on ΛCDM, the hierarchy problem on the Standard Model. Amber dashed lines run from a frontier route to the crack it tests. Selecting a node deepens the relevant lines and reveals the criterion on a foundation edge (e.g. S/ħ ≫ 1); nothing is labelled until you ask.
Not every frontier node tests a crack. Nodes marked “Method” (VUV combs, attosecond interferometry, Rydberg sensing, spin squeezing, muon g−2) extend measurement capability; nodes marked “Engineering” (the three fusion routes) advance hardware. Forcing them onto a crack would present engineering progress as experimental test, so they are left unlinked and the card says so.
Sources and conventions
The branch split and the three-layer structure follow the “scale across, established / cracks / exploration down” layout. Node content is compiled from public reviews and experimental reports across these branches in 2024–2025. Checkable figures include:
- Particle physics: Standard Model gauge group SU(3)C×SU(2)L×U(1)Y, tested down to about 10⁻¹⁸ cm; SMEFT as the systematic framework for beyond-Standard-Model searches; LHCb precision targets on selected decay parameters through 2025–2028.
- Cosmology: SH0ES local expansion rate H₀ = 73.2 ± 1.0 km/s/Mpc, persistently at odds with early-universe inference; JWST observations of fully formed galaxies and massive central black holes at z ≈ 14; DESI DR2 plus supernovae favours evolving dark energy at the ~3-sigma level, still undecided.
- Condensed matter: iron-based topological superconductors and Majorana zero-mode control; topological phases in twisted WSe₂ and twisted graphene; neutron scattering signatures of magnetic excitations and nematic order in cuprates and iron pnictides.
- AMO: VUV/EUV frequency combs for precision spectroscopy of few-electron atoms; Rydberg field sensing; attosecond interferometry reconstructing electronic phase on a sub-cycle scale; spin squeezing beyond the standard quantum limit.
- Quantum information: bosonic qubits with about 160× reduction in bit-flip errors through squeezing; heterogeneous architectures cutting physical-qubit requirements by about 138× under detailed resource accounting; stabiliser error detection on silicon devices; superconducting surface codes below threshold; qLDPC boundary constructions aimed at planar devices.
- Plasma and complex systems: magnetic, inertial and magneto-inertial fusion running in parallel; on the non-equilibrium side, subsystem resetting, cluster tomography in active matter, and the KPZ / Kuramoto universality classes.
A comparable atlas
The closest existing work is Quanta Magazine's Theories of Everything, Mapped, an interactive map built by Emily Fuhrman with text by Natalie Wolchover. The two cut differently: Quanta centres on problems, each fanning out into candidate solutions as a network; this page centres on branch × layer, answering where a problem sits and who is working on it. Go to Quanta to see how many solutions a crack has; come here to see which branch an experiment belongs to and which layer it occupies.
Data and official sources
- Particle Data Group · Review of Particle Physics 2025 — the authoritative compilation of particle-physics and cosmological parameters, with dedicated reviews on dark matter, dark energy, the CMB, inflation and tests of gravitational theory.
- Towards the map of quantum gravity — a taxonomy of quantum-gravity approaches. This page lists five main routes; that paper resolves them further.
- CERN · The Standard Model — the official particle content and interactions, the first block of the foundation layer.
- Nobel Prize in Physics 2012 — experimental confirmation of the Higgs mechanism, which completed the Standard Model spectrum.
- Nobel Prize in Physics 2015 — neutrino oscillations, the observation that forces an extension of the Standard Model.
- Nobel Prize in Physics 2011 — the supernova discovery of accelerating expansion, where the dark-energy problem starts.
- DESI · Dark Energy Spectroscopic Instrument — the survey currently testing whether the dark-energy equation of state evolves.
- NASA · James Webb Space Telescope — official source for the high-redshift galaxy and black-hole observations.
Layers and status are editorial, not an official rating by any agency or collaboration. “Foundation” does not mean “fully settled” — the Standard Model and ΛCDM both sit there while explicitly being effective theories. “Crack” does not mean “the theory is wrong”; it marks a confirmed phenomenon whose mechanism has no agreed answer. Where the field is still divided, competing routes are listed side by side rather than collapsed into one narrative. Compiled 2026-10-25.