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Notes

or theory

#+BEGIN_SRC text BLOCK A — What Orch OR claims, why it is controversial, and the present status

Claim in one line Orch OR says conscious moments arise when coherent quantum states in neuronal microtubules undergo objective reduction at a gravity-set threshold, with neural processes “orchestrating” the build-up and readout of those states. Hameroff & Penrose 2014. oai_citation:0‡ScienceDirect oai_citation:1‡PubMed

Physics backbone Penrose’s Objective Reduction ties collapse time to the gravitational self-energy of the superposed mass distribution: τ ≈ ℏ / E_G. The idea is that spacetime cannot consistently support large mass superpositions beyond τ, so collapse is intrinsic, not observer-driven. Penrose 1996. oai_citation:2‡ADS

Biological implementation Hameroff and Penrose place the putative qubits in tubulin states within microtubules, propose network-level “orchestration” via cytoskeletal coupling and gap-junction synchrony, and link Orch OR event rates to EEG bands that correlate with conscious report. Hameroff & Penrose 2014. oai_citation:3‡ScienceDirect oai_citation:4‡PubMed

Key supportive claims Reports of room-temperature electrical or vibrational resonances in isolated microtubules are cited as compatible with long-lived coherence and anesthetic sensitivity, although independent replication and mechanistic attribution remain contested. Sahu et al. 2013 Hameroff & Penrose 2014. oai_citation:5‡ScienceDirect

Main objections from physics and biology

  1. Warm-wet brain decoheres too fast for useful quantum computation. Tegmark estimated 10^-13–10^-20 s, far below neural timescales. Tegmark 2000. 2) Microtubule conformational qubits and required isolation lack firm evidence in situ. Reimers et al. 2014. 3) Gravity-related collapse models face experimental bounds from tabletop and astroparticle data that squeeze parameter space. Bassi 2021 Jones 2024. oai_citation:6‡Physical Review Links oai_citation:7‡PubMed oai_citation:8‡AIP Publishing

Rebuttals from proponents Recalculations argue Tegmark’s model used unfavorable assumptions and that structured water, cytoskeletal phases, and metabolic driving could lengthen decoherence to neurorelevant windows. This keeps Orch OR “not ruled out,” though still unproven. Hagan et al. 2002 Hameroff & Penrose 2014. oai_citation:9‡Physical Review Links oai_citation:10‡ScienceDirect

Bottom line in 2025 Orch OR is a bold, testable synthesis of gravitationally induced collapse with cytoskeletal biophysics, yet it remains outside mainstream neuroscience due to weak in vivo evidence and strong decoherence constraints. The gravitational-collapse pillar is actively probed in non-biological systems, which indirectly pressures Orch OR regardless of microtubule debates. Bassi 2021 Jones 2024. oai_citation:11‡AIP Publishing oai_citation:12‡Physical Review Links #+END_SRC

#+BEGIN_SRC text BLOCK A — Factual notes on Orch OR (concise, test-focused)

One-liner Orch OR posits that transient quantum states in neuronal microtubules are “orchestrated” by biology and terminate via gravity-related objective reduction events, each event corresponding to a conscious moment. Hameroff & Penrose 2014. oai_citation:0‡ScienceDirect

Physics backbone Objective Reduction sets collapse time by τ ≈ ℏ / E_G, where E_G is the gravitational self-energy of the superposed mass distribution; collapse is intrinsic and observer-independent. Penrose 1996. oai_citation:1‡SpringerLink

Biological implementation (claimed) Tubulin states inside microtubules serve as qubits; cytoskeletal networks and possibly gap junctions “orchestrate” build-up and readout; Orch OR rates are linked to neurophysiology such as gamma rhythms. Hameroff & Penrose 2014. oai_citation:2‡ScienceDirect

Key predictions that tie biology to physics

  1. Microtubules should support mesoscopic coherence long enough to reach OR thresholds relevant to perception. 2) General anesthetics should disrupt the putative microtubule quantum channels. 3) Independent tests of gravity-related collapse should converge on parameters compatible with neurorelevant timescales. Hameroff & Penrose 2014. oai_citation:3‡ScienceDirect

Representative supportive lines (contested) Computational and model-based work reports anesthetic binding to tubulin and correlated changes in collective terahertz-scale dipole dynamics, consistent with a microtubule target for anesthetic action. Craddock et al. 2015; 2017. oai_citation:4‡PubMed oai_citation:5‡Nature

Core objections from physics and neuroscience A) Warm-wet brain decoheres far faster than neural timescales per order-of-magnitude estimates (~10⁻¹³–10⁻²⁰ s). Tegmark 2000. B) Microtubule coherence mechanisms such as Fröhlich condensation lack in-situ evidence; energetic and structural hurdles are emphasized. Reimers et al. 2009. C) Gravity-related collapse models face stringent external bounds that squeeze parameters needed for neurorelevance. Bassi et al. 2013. oai_citation:6‡Physical Review oai_citation:7‡PubMed

Rebuttals from proponents Re-estimates argue Tegmark’s assumptions overstate environmental coupling and that structured water, lattice symmetries, and metabolic driving could extend decoherence toward neurorelevant windows. Hagan et al. 2002. oai_citation:8‡Physical Review

Non-biological tests that press the gravitational-collapse pillar • Underground germanium X-ray searches set the strongest CSL bounds for r_C ≲ 10⁻⁶ m and rule out parameter-free Diósi–Penrose via a required mass-density cutoff increase. Donadi et al. 2021 Nature Physics; EPJ C. oai_citation:9‡arXiv oai_citation:10‡SpringerLink • Space mission inertial sensing constrains CSL rates and pushes DP cutoffs above nuclear scales; rotational re-analyses tighten mid-scale bounds. Helou et al. 2017; Altamura et al. 2025. oai_citation:11‡Physical Review • Review consensus: non-interferometric platforms (radiation searches, bulk-heating, precision mechanics) currently set the sharpest limits; remaining parameter wedges are narrow. Carlesso et al. 2022. oai_citation:12‡Queen’s University Belfast • High-mass matter-wave interferometry shows robust coherence for >25 kDa molecules, excluding parts of collapse space. Fein et al. 2019. oai_citation:13‡Universität Wien • Neutrino baselines: momentum-diffusion versions mapped to Penrose-style collapse are excluded by IceCube given realistic wave-packet widths; no decoherence observed. Jones 2024; IceCube 2024. oai_citation:14‡Physical Review oai_citation:15‡Adsabs

Status of anesthetic evidence There is evidence that anesthetics bind to cytoskeletal proteins, with modeling and spectroscopic work implicating tubulin; however, direct in-vivo demonstrations that such interactions quench neurorelevant microtubule coherence, as required by Orch OR, remain unestablished. Craddock et al. 2015; 2017. oai_citation:16‡PubMed oai_citation:17‡Nature

What would strongly shift the balance

  1. Replicated, in-tissue microtubule interference or phase-coherent spectroscopy tied to behavior and anesthetic dose–response. 2) A gravity-related collapse signal consistent across radiation, mechanics, and interferometry that lands in a window compatible with Orch OR timescales. Hameroff & Penrose 2014; Carlesso et al. 2022. oai_citation:18‡ScienceDirect oai_citation:19‡Queen’s University Belfast

Bottom line in 2025 Orch OR remains a bold synthesis with testable physics. The gravitational-collapse leg is being actively constrained by non-biological experiments, ruling out parameter-free DP and heavily limiting CSL near canonical r_C; no in-vivo microtubule coherence at neurorelevant scales has been demonstrated. The viable space for an Orch OR-compatible collapse dynamics is narrow and under pressure. Donadi et al. 2021; Helou et al. 2017; Carlesso et al. 2022. oai_citation:20‡arXiv oai_citation:21‡Physical Review oai_citation:22‡Queen’s University Belfast #+END_SRC