This podcast covers the biggest AI shifts in 2025-2026. Two AI researchers argue that progress now comes less from bigger models and more from letting models 'think longer' during inference (the stage where they generate answers). They highlight DeepSeek R1, a Chinese model that matched GPT-4 with far less computing power, showing China's engineering edge. They also note that AI agents (programs that automate tasks) are entering production for low-risk jobs like customer service and code review, but still can't make autonomous decisions. A key warning: the current Transformer architecture might not lead to true AGI.
This report discusses the frontiers of AI technology in 2026, with core themes covering LLMs, coding, Scaling Laws, China's AI development, AI Agents, GPUs, and AGI. The central argument is that the AI field has achieved significant technological breakthroughs over the past year, including the matur
Nathan Lambert (Head of Post-Training at Ai2, author of The RLHF Book) and Sebastian Raschka (author of Build a Large Language Model (From Scratch)), two machine learning researchers, systematically reviewed the key advances in AI from 2025 to 2026 on the Lex Fridman podcast. Core judgment: Scaling Laws have not broken down, but the focus has shifted from pre-training scale to post-training and inference-time scaling—"2025 is the year of post-training, and 2026 will be the year of inference" (Nathan Lambert).
Nathan Lambert believes the most significant change in AI over the past year is that post-training methods have evolved from "icing on the cake" to "core engine."
RLHF (Reinforcement Learning from Human Feedback) underwent a transformation in 2025 from a "tuning trick" to "systematic engineering." Lambert points out that the release of DeepSeek R1 in late 2024 was a watershed moment—it proved that pure RL (without supervised fine-tuning) can enable models to learn chain-of-thought reasoning without requiring large amounts of human-annotated reasoning data. "R1 told us that you can let models learn how to think on their own through RL, without massive amounts of human-annotated reasoning data." (Nathan Lambert)
Sebastian Raschka adds technical details: The core difference between reasoning models and standard LLMs lies in "thinking tokens"—the model generates an internal reasoning process before outputting the final answer. This brings two key changes:
Extrapolation: Lambert predicts that by 2026, a "Reasoning-as-a-Service" business model will emerge, with API pricing distinguishing between "thinking time" and "output time." Falsification signal: If the commercial adoption of reasoning models lags behind expectations (e.g., enterprise customers are unwilling to pay for "thinking time"), this trend may be overestimated.
Both guests agreed that Scaling Laws remain valid, but the definition of "scale" is being rewritten.
The traditional view holds that Scaling Laws mean "larger models + more data = better performance." However, Raschka pointed out that the key finding in 2025 is: data quality matters more than data quantity, and post-training scaling is becoming the new growth curve.
| Dimension | Traditional Scaling (2023-2024) | New Scaling (2025-2026) |
|---|---|---|
| Primary Stage | Pre-training | Post-training + Inference |
| Key Variable | Parameter count, training data volume | RL training steps, inference compute |
| Bottleneck | Data wall | Inference cost, evaluation methods |
| Representative Breakthroughs | GPT-4, Claude 3 | DeepSeek R1, OpenAI o3 |
Lambert proposed a counterintuitive view: the growth rate of model parameter scale is slowing (the largest open-source model in 2025 has about 400B parameters, similar to 2024), but "effective compute" is still growing exponentially—because the thinking time during inference can be extended indefinitely. "A 70B reasoning model may outperform a 400B non-reasoning model on complex problems because it has more time to 'think'." (Nathan Lambert)
Uncertainty: Raschka cautioned that the sustainability of inference-stage scaling depends on hardware efficiency. If GPU computing costs do not decline fast enough, the economics of inference scaling could become a bottleneck.
The two guests share a highly consistent view on China's AI ecosystem: 2025 marks a critical turning point for China's AI, shifting from "following" to "running in parallel."
Core evidence chain:
1. Model capability: DeepSeek R1 achieves or surpasses GPT-4 levels in mathematical reasoning (MATH-500 score of 97.3%) and coding (HumanEval pass rate of 92.7%), with training costs estimated at roughly 1/10 of the latter (based on publicly available information)
2. Open-source ecosystem: The number of models released by Chinese teams on Hugging Face grew by 300% in 2025, with a significant improvement in quality (no longer merely "Chinese-optimized versions")
3. Application deployment: China's penetration rates in AI customer service, code assistance, education, and other scenarios are higher than those in the U.S. (Lambert cites data: AI customer service handling rates at top Chinese e-commerce platforms have reached 85%, compared to approximately 60% in the U.S.)
Lambert specifically emphasized DeepSeek's "efficiency innovation": They achieved near-top-tier performance with fewer GPUs and smaller models, forcing U.S. companies to rethink the "compute scaling" strategy. "DeepSeek proves that if you push engineering optimization to the extreme, you don't need 100,000 H100s to build a world-class model." (Nathan Lambert)
Risk warning: Raschka points out that China's AI still lags behind the U.S. in fundamental research (e.g., new architecture design, theoretical breakthroughs), with current advantages primarily in engineering optimization and the application layer. Falsification condition: If U.S. export controls tighten further (e.g., restricting access to H100 alternatives), China's AI catch-up pace could slow significantly.
Nathan Lambert argues that 2025 marks the year AI Agents transition from the "demo phase" to the "production phase," though they remain far from "autonomous decision-making."
Lambert proposes a classification framework:
Key data: Citing internal data, Lambert notes that Ai2's Agent system reduces manual review time by 40-60% in code review scenarios, but "fully autonomous" code submissions (requiring no human review) still account for only 5-10%.
Raschka adds technical challenges: The biggest issue with current Agent systems is "error accumulation"—a single step's error amplifies along the reasoning chain, rendering the final result unusable. He predicts that the breakthrough direction in 2026 will be the "verifier"—a model specifically designed to check the correctness of each step an Agent outputs.
Extrapolation: Both guests agree that Agent commercialization in 2026 will focus on "low-risk, high-repetition" scenarios (e.g., customer service, data entry, code review), while "high-risk decisions" (e.g., medical diagnosis, financial trading) will still require human-in-the-loop.
The two guests hold clear disagreements on the timeline for AGI.
Nathan Lambert (Optimist): Believes AGI could be achieved by 2027-2029, provided GPU compute costs decline by over 50% annually. He cites an analogy: "If the H100 in 2025 is a steam engine, then the Blackwell in 2027 is an internal combustion engine—an order-of-magnitude efficiency improvement."
Sebastian Raschka (Cautious): Argues that the very definition of AGI is problematic, and the current architecture (Transformer + RL) may not be the right path to AGI. "We might be looking for nails with a hammer—Transformers excel at language tasks, but does that mean they can solve all intelligence problems? I am skeptical." (Sebastian Raschka)
Shared acknowledged uncertainties:
| Position | Analyst View | Key Data |
|---|---|---|
| DeepSeek R1 | Highly positive (innovation benchmark) | MATH-500 score 97.3%, training cost approximately 1/10 of GPT-4 |
| OpenAI o3 | Acknowledged (industry leader) | Significant improvement in reasoning capabilities, but specific data not disclosed |
| NVIDIA H100 | Neutral (computing bottleneck) | Lead time 6-9 months, training frontier models requires 50-100 GWh |
| Leading Chinese E-commerce Platforms | Not explicitly stated (application case) | AI customer service handling rate 85% (approximately 60% in the US) |
1. "2025 is the year of post-training, and 2026 will be the year of inference" (Nathan Lambert) — The focus of AI development is shifting from pre-training scale to post-training methods and inference-stage compute scaling.
2. "DeepSeek has proven that if you optimize engineering to the extreme, you don't need 100,000 H100s to build a world-class model" (Nathan Lambert) — China's efficiency innovation in AI is reshaping the global competitive landscape.
3. "We may be looking for nails with a hammer — Transformers excel at language tasks, but does that mean they can solve all intelligence problems?" (Sebastian Raschka) — A fundamental challenge to the current AI architecture's path toward AGI.
4. Agent three-tier framework (Nathan Lambert): Tool calling (mature) → Multi-step reasoning (available in 2025) → Autonomous decision-making (expected 2027+), with current Agent systems still exhibiting a 10-20% error accumulation rate.
5. "A 70B reasoning model can outperform a 400B non-reasoning model on complex problems" (Nathan Lambert) — "Thinking time" during inference is becoming a new performance lever; model parameter growth is slowing, but effective computation continues to scale exponentially.
6. "We may be looking for nails with a hammer" (Sebastian Raschka) — A fundamental challenge to whether the Transformer + RL architecture can lead to AGI, arguing for exploration of new architectures (e.g., state-space models, neuro-symbolic systems).
7. Data quality > data quantity (consensus among both guests) — The key finding in 2025 is that carefully curated 100B tokens are more valuable than randomly collected 1T tokens; data engineering is becoming central to model competitiveness.
8. China-U.S. gap in AI customer service scenarios (Nathan Lambert): China's top e-commerce AI customer service resolution rate is 85% vs. 60% in the U.S., reflecting China's stronger execution in AI application deployment, though basic research still lags.
The most notable change in 2025 is that DeepSeek's "crown" is being shared among multiple Chinese companies:
| Company | Representative Model | Characteristics | Strategic Positioning |
|---|---|---|---|
| DeepSeek | V3/R1/V3.2 | Architectural innovation (MLA, MoE) | Mysterious and low-key, backed by hedge fund High Flyer |
| Kimi/Moonshot | K2 Thinking | Creative writing, software engineering | Actively seeking Western market attention |
| Z.AI | GLM series | Academic influence | Has filed IPO documents |
| Minimax | MiniMax series | Multimodal | Has filed IPO documents |
| Qwen (Alibaba) | Qwen3 | Data quality, long context | Continuous iteration, detailed technical reports |
Key insight: Chinese companies release open-source models for different reasons than U.S. firms — due to geopolitical and security concerns, U.S. enterprises will not purchase API services from Chinese companies, making open-source the only route to gain influence in Western markets. This "influence investment" model is expected to persist for several years.
Although Chinese open-source models are rapidly catching up in performance, all three experts report that their daily usage still favors U.S. models:
Core reason: U.S. models offer a better speed-intelligence trade-off, and users have developed "muscle memory" — ChatGPT's brand recognition and long-term usage habits create a powerful flywheel effect.
Nathan's forecast:
Technical Principles:
Key Breakthroughs:
Essential Differences from RLHF:
| Dimension | RLVR | RLHF |
|---|---|---|
| Reward Signal | Objectively verifiable (math, code) | Human preference (subjective, style) |
| Scalability | Infinitely scalable (harder problems) | Saturation point exists (limited style learning) |
| Computational Demand | Continuously growing (approaching pre-training) | Relatively fixed |
| Capability Unlocking | Tool use, reasoning ability | Dialogue style, safety |
1. Mid-training: Similar to pre-training but more focused, e.g., long-context training, reasoning trajectory data
2. RLVR: Unlocks tool use and reasoning ability through trial-and-error learning
3. RLHF: Final polish, optimizing style, tone, and usability
Nathan listed over 20 open-source models on-site (without referring to notes):
China Camp: DeepSeek, Kimi, Minimax, Z.AI, Antling, Qwen
Western Camp: Mistral, Gemma, GPT OSS (OpenAI), Nemotron (NVIDIA), Olmo (AI2), K2 (Institute for Foundation Models), Aperdis, SmallLM (Hugging Face)
Key Trends:
An initiative launched by Nathan, aiming to:
Core Argument: Open-source models are the "gateway" to AI research. Whoever possesses the best open-source model holds the power to cultivate the next generation of researchers.
Sebastian’s striking insight: All mainstream LLMs are essentially variants of the GPT-2 architecture, with changes limited to:
| Component | GPT-2 | Modern Models |
|---|---|---|
| Attention Mechanism | Multi-Head Attention (MHA) | Grouped Query Attention (GQA), Multi-Head Latent Attention (MLA) |
| Feed-Forward Network | Single Dense Layer | Mixture of Experts (MoE) |
| Normalization | LayerNorm | RMSNorm |
| Activation Function | GELU | SwiGLU, etc. |
| Position Encoding | Absolute Position | RoPE, YaRN, etc. |
Key Insight: Starting from GPT-2 code, one can progressively build modern models like Qwen3 and Gemma3 by adding these "fine-tuning" components. Sebastian’s Build a Large Language Model (From Scratch) and Build a Reasoning Model (From Scratch) are based on this very concept.
How It Works:
Current Limitations:
2026 Prediction: May be used in scenarios requiring fast responses, such as code diff generation, but will not fully replace autoregressive models.
Olmo 3 achieves better performance with less data than Olmo 2, proving that data quality matters more than scale. The key factors are:
Sebastian's "Two-Pass Method":
1. First pass: Read offline with full concentration, without using an LLM, allowing the information to "settle"
2. Second pass: Use an LLM to aid comprehension, generate practice problems, and explore extended content
Nathan's "Reverse Method":
For researchers with limited computational resources:
The three experts adopt a cautious stance on defining AGI:
Despite rapid AI capability improvements, a significant GDP leap has yet to materialize. Reasons:
Conclusion: As Einstein once said — "It's not that I'm so smart, it's that I stay with problems longer." In the age of AI, this statement carries more weight than ever before.