References

The literature anchoring the stack.

Every axis-value, every constant, every cell on the table traces to a published source. Grouped by domain. Means-tested for v0.2; forty-four substrates surveyed.

I · Physics & information theory

The thermodynamic floor of the Eᵂ axis and the speed-limit ceiling of the τ axis.

  1. Shannon, C. E. (1948). A Mathematical Theory of Communication. Bell System Technical Journal 27.
  2. Landauer, R. (1961). Irreversibility and Heat Generation in the Computing Process. IBM Journal of Research and Development 5.
  3. Bérut, A., Arakelyan, A., Petrosyan, A., Ciliberto, S., Dillenschneider, R., & Lutz, E. (2012). Experimental verification of Landauer's principle linking information and thermodynamics. Nature 483.
  4. Hong, J., Lambson, B., Dhuey, S., & Bokor, J. (2016). Experimental test of Landauer's principle in single-bit operations on nanomagnetic memory bits. Science Advances 2.
  5. Margolus, N., & Levitin, L. B. (1998). The maximum speed of dynamical evolution. Physica D 120.

II · Computer architecture & silicon memory

The substrates that placed silicon at every classical-memory coordinate.

  1. von Neumann, J. (1945). First Draft of a Report on the EDVAC. University of Pennsylvania.
  2. Forrester, J. W. (1951). Digital Information Storage in Three Dimensions Using Magnetic Cores. Journal of Applied Physics 22.
  3. Wanlass, F., & Sah, C. T. (1963). Nanowatt logic using field-effect metal-oxide semiconductor triodes. IEEE ISSCC.
  4. Wilkes, M. V. (1965). Slave Memories and Dynamic Storage Allocation. IEEE Transactions on Electronic Computers EC-14.
  5. Dennard, R. H. (1968). US Patent 3,387,286 — single-transistor DRAM cell.
  6. Masuoka, F. et al. (1987). NAND flash memory architecture. IEDM Technical Digest.
  7. Wulf, W. A., & McKee, S. A. (1995). Hitting the Memory Wall: Implications of the Obvious. ACM SIGARCH 23.
  8. Strukov, D. B., Snider, G. S., Stewart, D. R., & Williams, R. S. (2008). The missing memristor found. Nature 453.
  9. Burr, G. W. et al. (2008). Phase change memory technology. IBM Journal of Research and Development 52.

III · Associative & distributed memory

Content-addressable substrates from Hopfield through modern hyperdimensional computing.

  1. Hopfield, J. J. (1982). Neural networks and physical systems with emergent collective computational abilities. PNAS 79.
  2. Amit, D. J., Gutfreund, H., & Sompolinsky, H. (1985). Spin-glass models of neural networks. Physical Review A 32.
  3. McEliece, R. J., Posner, E. C., Rodemich, E. R., & Venkatesh, S. S. (1987). The capacity of the Hopfield associative memory. IEEE Transactions on Information Theory 33.
  4. Kanerva, P. (1988). Sparse Distributed Memory. MIT Press.
  5. Kanerva, P. (2009). Hyperdimensional Computing: An Introduction to Computing in Distributed Representation with High-Dimensional Random Vectors. Cognitive Computation 1.
  6. Ramsauer, H. et al. (2021). Hopfield Networks Is All You Need. ICLR 2021.
  7. Bricken, T., & Pehlevan, C. (2021). Attention Approximates Sparse Distributed Memory. NeurIPS 2021.

IV · Cognitive psychology of memory

The canonical decomposition of human memory across a century of psychology.

  1. Ebbinghaus, H. (1885). Über das Gedächtnis: Untersuchungen zur experimentellen Psychologie. Duncker & Humblot.
  2. Bartlett, F. C. (1932). Remembering: A Study in Experimental and Social Psychology. Cambridge University Press.
  3. Miller, G. A. (1956). The Magical Number Seven, Plus or Minus Two. Psychological Review 63.
  4. Peterson, L. R., & Peterson, M. J. (1959). Short-term retention of individual verbal items. Journal of Experimental Psychology 58.
  5. Sperling, G. (1960). The information available in brief visual presentations. Psychological Monographs 74.
  6. Atkinson, R. C., & Shiffrin, R. M. (1968). Human memory: A proposed system and its control processes. The Psychology of Learning and Motivation 2.
  7. Tulving, E. (1972). Episodic and Semantic Memory. In Organization of Memory, ed. Tulving & Donaldson. Academic Press.
  8. Tulving, E., & Thomson, D. M. (1973). Encoding specificity and retrieval processes in episodic memory. Psychological Review 80.
  9. Baddeley, A. D., & Hitch, G. (1974). Working memory. The Psychology of Learning and Motivation 8.
  10. Squire, L. R. (1992). Memory and the hippocampus: A synthesis from findings with rats, monkeys, and humans. Psychological Review 99.
  11. Johnson, M. K., Hashtroudi, S., & Lindsay, D. S. (1993). Source monitoring. Psychological Bulletin 114.
  12. Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences 24.
  13. Murre, J. M. J., & Dros, J. (2015). Replication and Analysis of Ebbinghaus' Forgetting Curve. PLOS ONE 10.

V · Neuroscience of memory

The biological substrate measured.

  1. Scoville, W. B., & Milner, B. (1957). Loss of recent memory after bilateral hippocampal lesions. Journal of Neurology, Neurosurgery & Psychiatry 20.
  2. Marr, D. (1971). Simple memory: A theory for archicortex. Philosophical Transactions of the Royal Society B 262.
  3. Bliss, T. V. P., & Lømo, T. (1973). Long-lasting potentiation of synaptic transmission in the dentate area of the anaesthetized rabbit. Journal of Physiology 232.
  4. O'Keefe, J., & Nadel, L. (1978). The Hippocampus as a Cognitive Map. Oxford University Press.
  5. McClelland, J. L., McNaughton, B. L., & O'Reilly, R. C. (1995). Why there are complementary learning systems in the hippocampus and neocortex. Psychological Review 102.
  6. Frey, U., & Morris, R. G. M. (1997). Synaptic tagging and long-term potentiation. Nature 385.
  7. Laughlin, S. B., de Ruyter van Steveninck, R. R., & Anderson, J. C. (1998). The metabolic cost of neural information. Nature Neuroscience 1.
  8. Nader, K., Schafe, G. E., & LeDoux, J. E. (2000). Fear memories require protein synthesis in the amygdala for reconsolidation after retrieval. Nature 406.
  9. Attwell, D., & Laughlin, S. B. (2001). An Energy Budget for Signaling in the Grey Matter of the Brain. Journal of Cerebral Blood Flow & Metabolism 21.
  10. Kandel, E. R. (2001). The molecular biology of memory storage: A dialogue between genes and synapses. Science 294.
  11. Bartol, T. M. Jr., Bromer, C., Kinney, J., Chirillo, M. A., Bourne, J. N., Harris, K. M., & Sejnowski, T. J. (2015). Nanoconnectomic upper bound on the variability of synaptic plasticity. eLife 4 — 4.7 bits per synapse.

VI · Memory-augmented neural networks & LLM memory

The recent line of work that tried to give artificial systems an explicit retention substrate.

  1. Hochreiter, S., & Schmidhuber, J. (1997). Long Short-Term Memory. Neural Computation 9.
  2. Graves, A., Wayne, G., & Danihelka, I. (2014). Neural Turing Machines. arXiv:1410.5401.
  3. Weston, J., Chopra, S., & Bordes, A. (2015). Memory Networks. ICLR 2015.
  4. Graves, A. et al. (2016). Hybrid computing using a neural network with dynamic external memory. Nature 538 — Differentiable Neural Computer.
  5. Vaswani, A. et al. (2017). Attention Is All You Need. NeurIPS 2017.
  6. Lewis, P. et al. (2020). Retrieval-Augmented Generation for Knowledge-Intensive NLP Tasks. NeurIPS 2020.
  7. Edge, D. et al. (2024). From Local to Global: A Graph RAG Approach to Query-Focused Summarization. Microsoft Research.
  8. Chung, J.-W. et al. (2026). Where Do the Joules Go? Diagnosing Inference Energy Consumption. arXiv:2601.22076.
  9. Niu, C. et al. (2026). TokenPowerBench: Benchmarking the Power Consumption of LLM Inference. AAAI 2026.

VII · Biological non-neural memory

CRISPR, DNA archival, immune memory, slime mold, plant memory — substrates the cognitive literature does not catalog.

  1. Ishino, Y. et al. (1987). Nucleotide sequence of the iap gene… Journal of Bacteriology 169 — first CRISPR observation.
  2. Mojica, F. J. M. et al. (2005). Intervening sequences of regularly spaced prokaryotic repeats derive from foreign genetic elements. Journal of Molecular Evolution 60.
  3. Barrangou, R. et al. (2007). CRISPR provides acquired resistance against viruses in prokaryotes. Science 315.
  4. Church, G. M., Gao, Y., & Kosuri, S. (2012). Next-generation digital information storage in DNA. Science 337.
  5. Goldman, N. et al. (2013). Towards practical, high-capacity, low-maintenance information storage in synthesized DNA. Nature 494.
  6. Nuñez, J. K. et al. (Doudna lab) (2014). Cas1-Cas2 complex formation mediates spacer acquisition during CRISPR-Cas adaptive immunity. Nature Structural & Molecular Biology 21.
  7. Victora, G. D., & Nussenzweig, M. C. (2012). Germinal centers. Annual Review of Immunology 30.
  8. Hammerlund, E. et al. (2003). Duration of antiviral immunity after smallpox vaccination. Nature Medicine 9.
  9. Reid, C. R., Beekman, M. et al. (2012). Slime mold uses an externalized spatial memory. PNAS 109.
  10. Bruce, T. J. A. et al. (2007). Stressful memories of plants. Plant Science 173.

VIII · Human cultural memory systems

Songlines, the Vedic pātha system, khipu, and the classical art of memory — substrates of cultural retention surveyed by the scholars who studied them.

  1. Rhetorica ad Herennium, c. 80 BCE — first systematic treatment of the method of loci.
  2. Cicero. De Oratore, II.86, 55 BCE.
  3. Quintilian. Institutio Oratoria, XI.2, c. 95 CE.
  4. Ibn Sīnā (Avicenna). Kitāb al-Nafs, c. 1020 — the retentive faculty.
  5. Yates, F. A. (1966). The Art of Memory. University of Chicago Press.
  6. Staal, F. (1986). The fidelity of oral tradition and the origins of science. Nature 322.
  7. Hale, T. A. (1998). Griots and Griottes: Masters of Words and Music. Indiana University Press.
  8. Urton, G. (2003). Signs of the Inka Khipu. University of Texas Press.
  9. Norris, R. P., & Harney, B. Y. (2014). Songlines and navigation in Wardaman and other Australian Aboriginal cultures. Journal of Astronomical History and Heritage 17.
  10. Kelly, L. (2016). The Memory Code. Pegasus Books.
  11. Tempone-Wiltshire, J., & Yunkaporta, T. (2025). Songlines as distributed cognition: Aboriginal knowledge transmission through landscape. Pacific Asia Journal of Anthropology.

IX · Quantum memory

The structurally-empty corner: very high τ, very low C, requires active decoupling.

  1. Doherty, M. W. et al. (2013). The nitrogen-vacancy colour centre in diamond. Physics Reports 528.
  2. Bar-Gill, N. et al. (2013). Solid-state electronic spin coherence time approaching one second. Nature Communications 4.
  3. Wang, P. et al. (2021). Single ion qubit with estimated coherence time exceeding one hour. Nature Communications 12.
  4. Xu, Y.-L., Zhang, L. et al. (2025). Multi-qubit memory exceeding two hours in a cryogenic dual-type trap. Tsinghua University & HYQ Co.