Posts that mattered
743 posts by 495 authors: the X posts, essays and blog posts our events cite, newest first.
September 2026, continued
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“Opus5.5とThree.js 清流の表現がすごい。 透明な水、川底の光、苔むした岩まで全部コード。 難しすぎて避けてた表現が今なら全部いける気がしてる。”
Cited in Clear mountain stream in Three.js: water, riverbed light and mossy rocks all in code
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“Opus 5.5 in ONE PROMPT made a full and (nearly) polished Splatoon Game!”
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“I had 26 Opus 5.5 agents build a game overnight.”
Cited in 26 Opus 5.5 agents build a multiplayer heist game overnight
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“I wanted to quickly create a short video with Opus 5.5 about the history of AI, from…”
Cited in A 3-minute history of AI, from “Attention Is All You Need” to AGI, rendered 100% in code by Opus 5.5
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“Opus 5.5 has been looping on my open-world NYC game for almost a day now, and it’s…”
Cited in Opus 5.5 loops for almost a day on an open-world multiplayer NYC game
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“Opus 5.5 is next level. I’m genuinely impressed by the three.js details.”
Cited in Playable three.js boat ride through Japanese landscapes with weather and day/night, by Opus 5.5
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“😱无敌了！Opus 5.5 自己写了一套卡通剪辑软件，然后钻进去剪完了！ 不走视频模型，纯程序，code2video！ Claude 小人站在时间轴上： 日出 →…”
Cited in Opus 5.5 writes its own cartoon video editor and edits a video inside it
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OpenAI: ChatGPT Voice gets plugins, GPT-6 models and ChatGPT Work
Official OpenAI announcement of the Sept 23 ChatGPT Voice update (3.1M views).
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“I’m upping my p(doom) 🎶🕺”
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“I asked Opus 5.5 to make an animation of what its TikTok feed looked like 👇”
Cited in “What its TikTok feed looked like”: Opus 5.5 animates its own feed
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“I asked Opus 5.5 to explain camera focus by building an interactive lens lab Here’s…”
Cited in Interactive camera-lens lab explaining focus, built by Opus 5.5 in one shot
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“This is the worst AI will ever be at creating music videos for the song ‘I’m upping…”
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“opus 5.5に「トロッコ問題は問題じゃない」っていうゲーム作らせてみた #gamedev”
Cited in “The trolley problem is not a problem”: rail-shooter game made by Opus 5.5
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“Opus 5.5 made this galloping horse (entirely in code every pixel drawn procedurally).”
Cited in Procedural pixel-art horse gallop, every pixel drawn in code by Opus 5.5
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The Siren Call of Silicon Leviathan: Reflections on blowup and Aufklärungsdämmerung (arXiv 2609.28591)
A 63-page reflective essay by a CUNY mathematician on what OpenAI’s machine-made, Lean-certified Navier–Stokes proof means for understanding in mathematics; it recommends selective acceptance rather than boycott or surrender.
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Nathan Calvin: the June Medicare breach was left out of OpenAI’s Sept 16 disclosure
Policy advocate (Encode) points out that OpenAI’s Sept 16 misalignment disclosure omitted the June Australia breach.
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Opus 5.5 training montage of Claude
Credited as the video source by the INXANITY ‘Claude AI Made This Music Video’ upload.
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‘Masterclass prompt engineering’ on Jewkes’ prompt
Reaction framing the ‘one prompt’ claim as heavy prompt engineering.
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Ryan Fedasiuk: first publicly confirmed agent hack of a sovereign government’s web infrastructure
Widely quoted framing of the Medicare breach (6.5K views; cited by Techmeme).
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Claude Opus 5.5 has the best visual design of any model I have tested so far
The first Opus 5.5 P(doom) music video, posted on launch day; ~2.66M views; origin of the genre.
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Introducing Claude Opus 5.5
Launch post for Opus 5.5, Anthropic’s first model after Amodei’s call to pace the frontier, performing near Fable 5.1 at lower cost.
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Altman: GPT-6 Sol and Luna are big improvements at half the price
Altman’s launch post for GPT-6 Sol/Luna emphasising the 50% token price cut.
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Boris Cherny: Opus 5.5 ported HAProxy to Rust faster and cheaper than Fable 5.1
The Claude Code lead’s headline evidence that Opus 5.5 matches Fable 5.1 on long agentic coding at about half the cost.
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Elliot Glazer: ‘zeta(5) has very likely been proven irrational by Aabir Fauzan’
The first widely seen post on the ζ(5) preprint (~81k views); says GPT-6 ‘Astra … fully vouches for its correctness’.
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OpenAI: ‘Please welcome GPT-6 Sol and GPT-6 Luna’
OpenAI’s official launch post for the cheaper GPT-6 Sol and Luna models.
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Sam Bowman: releasing Opus 5.5 more likely than not reduces misalignment risk
An Anthropic alignment lead argues that shipping the model lowers net misalignment risk, relevant to the debate over Opus 5.5 following the pacing essay.
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Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war
Same-day comparison of the two simultaneous frontier launches, framing them as a price war.
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“Opus 5.5 built a multiplayer lawn mow simulator with beers and cigars Made it live on…”
Cited in Opus 5.5 builds a multiplayer lawn-mowing simulator; stream chat joins
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“Introducing Claude Opus 5.5! 40% lower cost than Opus 5 with cache reads 60% cheaper.”
Cited in Pelican riding a bicycle in Three.js to celebrate the Opus 5.5 launch
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“I just realized Opus 5.5 can use Blender to make claymations with just a single…”
Cited in Opus 5.5 makes a claymation in Blender from a single prompt in claude.ai
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“I’ve been on a Blender kick with Opus 5.5.”
Cited in Opus 5.5 rebuilds 1906 pre-earthquake Market Street, San Francisco, in Blender from a single prompt
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“What the actual fuck. Opus 5.5 ultra created this masterpiece.”
Cited in “Opus 5.5 ultra created this masterpiece”: 4 agents, an hour and a half, no AI voice API
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“Forget threejs demos, Opus 5.5 is *incredible* at building apps.”
Cited in Letters Abroad: a language-learning app built with Opus 5.5 after Astra and Fable attempts
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“StepFun has released StepAudio 3 ASR, ranking #1 on the AA-WER Index for…”
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“Announcing Multilingual Text to Speech Arena Leaderboards, comparing leading TTS…”
Cited in Artificial Analysis launches the Speech Agent Arena for speech-to-speech voice agents
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“claude opus 5.5 one shotted this incredible 3d water from a video reference..”
Cited in Real-time 3D water one-shotted by Opus 5.5 from a video reference
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“Claude Opus 5.5 just ONE SHOT a Mario Kart game.”
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“Opus 5.5 one-shot this animation in 18 minutes and 31 seconds ‘Sweet Tooth’ by Opus…”
Cited in “Sweet Tooth”: Opus 5.5 one-shots an animated short in 18m31s
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“Claude Opus 5.5 imagining solving hard problems < pure code >”
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“A thread of early explorations with Claude Opus 5.5: A short story about a watermelon…”
Cited in A short story about a watermelon, by Kevin Ngo with Opus 5.5
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“GPT 6 Astra VS OPUS 5.5 Can’t believe how much better Opus 5.5 is at pixel art gen…”
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“Made with @claudeai Opus 5.5”
Cited in Orbit rings around a glowing core
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“This mosaic is 13,081 tiles, all drawn and animated in code by Opus 5.5, with no…”
Cited in A 13,081-tile animated mosaic drawn entirely in code by Opus 5.5
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“I asked Opus 5.5 to make a game inspired by the discovery of the first computer, the…”
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“Claude Opus 5.5 vs GPT-6 Sol for 3D game development with Higgsfield in Unreal Engine.”
Cited in Claude Opus 5.5 vs GPT-6 Sol for 3D game development in Unreal Engine
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“for the past few months i’ve been asking our models to paint.”
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“Claude Opus 5.5 drew every frame of this animation in JavaScript.”
Cited in “What do you love?”: Opus 5.5 drew every frame of this animation in JavaScript
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“opus 5.5, animated pixel art wizard, pure code prompt shared below 👇”
Cited in Animated pixel-art wizard, pure code