Inside the proton, the ‘most complicated thing you could possibly imagine’
Physicists’ evolving picture of the proton portrays it not as three neat quarks, but as a seething, probabilistic “garbage can” of quarks, antiquarks and gluons whose detailed structure depends on how it is probed. Commenters use this as a springboard to unpack why protons and electrons have exactly opposite charges, how quark charge fractions and symmetry constraints might explain that, and where current theories (QCD, the Standard Model, grand unification) still leave deep “why” questions unanswered. The thread ranges from technical points on virtual particles and charge quantization to broader reflections on the anthropic principle, simulation arguments and the limits of reductionist explanations in fundamental physics.
Terminology, jokes, and context
- Many commenters initially misread the title as referring to software/services named “Proton” (compatibility layer, email, rocket), then pivot back to the physics.
- One physicist-quoting comment calls the proton a “garbage can,” emphasizing its messy internal structure and why hadron colliders need huge luminosity.
Protons, neutrons, and quarks
- Neutrons and protons are closely related: free neutrons decay into a proton, electron, and (anti)neutrino; inside nuclei, neutrons can be stable.
- Several comments explain beta decay and electron capture via weak interactions and W± bosons, stressing that quarks and electrons aren’t little bags that “absorb” each other but excitations of quantum fields.
- Protons are mostly up-up-down (UUD), neutrons up-down-down (UDD), but both contain seas of gluons and virtual quark–antiquark pairs, including heavier flavors (charm, etc.).
- The reported charm content of the proton is debated: theoretically expected via virtual pairs, but experimentally tricky and easy to overinterpret from data.
Charge quantization and “why is proton charge = electron charge?”
- A large subthread tackles why the proton’s +e exactly matches the electron’s −e despite very different internal complexity.
- Points raised:
- Electric charge appears quantized; stable free particles have charges in integer units of e, while quarks carry ±1/3 or ±2/3 of that unit but are never isolated.
- Some propose symmetry-based explanations (gauge symmetries, anomaly cancellation, grand unification, “charge space” cube constructions), but concede these are not ultimate answers.
- Others emphasize that the exact matching is unexplained in current theories and might be a “deep mystery” or an outcome of a deeper, unknown structure.
- Multiple people invoke the anthropic principle: only a universe with such balances allows atoms, chemistry, and observers; critics argue this can be an unsatisfying or circular “because otherwise we wouldn’t be here” move.
Anthropic principle, fine‑tuning, and metaphysics
- Lengthy back‑and‑forths debate:
- Whether fine‑tuned constants (including charge ratios) support multiverse ideas or a designer vs. being just selection effects.
- Whether “anthropic” reasoning is scientifically useful or equivalent to “God did it” with different words.
- The boundary between physics (“how”) and metaphysics (“why”), and the limits of explanation.
Quantum weirdness and models
- Several comments unpack how one particle species can transform into another via field interactions, Feynman diagrams, and “virtual” intermediates; some admit that beyond the math the mechanisms feel like “magic.”
- Others push back on pop‑sci language like “haze of probabilities until observed,” preferring to see particles as continuous field excitations that are always fuzzy, with measurement just another interaction.
- There is disagreement over how satisfying or explanatory current quantum interpretations are; some explicitly separate the highly successful predictive machinery from any story about “what’s really happening.”
Electricity, charge carriers, and protons-as-current
- A side thread clarifies why everyday electrical currents use electrons (or ions) rather than protons in solids: lattice nuclei (and their protons) are essentially fixed, while electrons can delocalize.
- In liquids and plasmas, proton or proton-like charge transport can occur (e.g., hydronium in acids, proton motive force in biology), but this is different from metallic conduction.