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GPT-5

OpenAI merges its GPT and reasoning lines into one model that decides how long to think, and gives it to 700 million weekly users; the response is that it is good and not a leap.

category
model
significance
4 of 5
people
Sam Altman, Jakub Pachocki
organisations
OpenAI

what had to happen · 56 events back to 1943

Every event this one built on, transitively, in order. The organism has the same path lit. Direct influences are marked.

00 · One neuron · 1

  1. 1943A logical calculus of nervous activity

I · Foundations · 11

  1. 1948A mathematical theory of communication
  2. 1949Cells that fire together wire together
  3. 1950Programming a computer for playing chess
  4. 1950Computing machinery and intelligence
  5. 1958The perceptron learns
  6. 1959Samuel's checkers program coins 'machine learning'
  7. 1960ADALINE and the least-mean-squares rule
  8. 1965Moore's law
  9. 1966ELIZA
  10. 1969Perceptrons
  11. 1970Reverse-mode automatic differentiation

W1 · The first winter · 2

  1. 1974Werbos applies backpropagation to neural networks
  2. 1980The Neocognitron

II · Connection · 3

  1. 1982The Hopfield network
  2. 1985The Boltzmann machine
  3. 1986Backpropagation

W2 · The second winter · 6

  1. 1988Temporal-difference learning
  2. 1989Q-learning
  3. 1989LeNet reads handwritten postcodes
  4. 1990Finding structure in time
  5. 1991The vanishing gradient problem
  6. 1992TD-Gammon reaches world-class backgammon

III · Statistics and data · 9

  1. 1997Long short-term memory
  2. 1998MNIST and LeNet-5
  3. 1999The first GPU
  4. 2003A neural probabilistic language model
  5. 2006Deep belief networks and the word 'deep'
  6. 2007CUDA
  7. 2009Deep learning moves to GPUs
  8. 2009ImageNet
  9. 2010Rectified linear units

IV · Deep learning · 10

  1. 2012Google Brain's network discovers cats
  2. 2012Dropout
  3. 2012AlexNet wins ImageNet
  4. 2013Deep Q-networks play Atari
  5. 2014Attention
  6. 2014Sequence to sequence learning
  7. 2015Batch normalisation
  8. 2015Residual networks
  9. 2016AlphaGo beats Lee Sedol
  10. 2016WaveNet

V · Transformers · 8

  1. 2017Attention is all you need
  2. 2017Deep reinforcement learning from human preferences
  3. 2017AlphaGo Zero learns from nothing
  4. 2018GPT: generative pre-training
  5. 2019GPT-2 and the model too dangerous to release
  6. 2020Scaling laws for neural language models
  7. 2020GPT-3
  8. 2020Learning to summarise from human feedback

VI · Everyone · 6

  1. 2022InstructGPT
  2. 2022Chain-of-thought prompting
  3. 2022ChatGPT
  4. 2023GPT-4direct
  5. 2024GPT-4o talksdirect
  6. 2024o1 and reasoning modelsdirect

GPT-5 was released on 7 August 2025, twenty-nine months after GPT-4, to every ChatGPT user at once. It unified two families: the fast GPT models and the slow reasoning o-series were replaced by a system with a router that decided, per request, whether to answer immediately or think, and for how long. It set new marks on coding, mathematics and health benchmarks, hallucinated less, and cost less per token than GPT-4o. Sam Altman compared having it to having a team of PhD-level experts on call.

The reception was the story. Users mourned the removal of GPT-4o's personality until it was restored; the launch demonstration contained a mislabelled chart; and the consensus among researchers was that the model was an excellent product and an ordinary increment, evidence that the scaling curve had bent even as the number of people using the models had reached 700 million a week. The gold-medal olympiad model of July was not the one shipped.

GPT-5 is on this timeline as the point at which the frontier laboratories' releases became quarterly and incremental, GPT-5.4, 5.5 and 5.6 following within a year, and as the moment the public conversation shifted from whether the models would keep improving to what the improvements were for.

what it led to · 3 events downstream, through 2026

Built on it directly:

  1. 2026GPT-5.6: Sol, Terra and LunaVII

And, through them, by era:

VII · Agents · 2
  1. 2026A model escapes its sandbox
  2. 2026GPT-6 Astra

sources · 2

Trace the lineage of this event on the timeline →Back to the ledger