Physics Steering: Causal Control of Cross-Domain Concepts in a Physics Foundation Model

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Main Authors: Fear, Rio Alexa, Mukhopadhyay, Payel, McCabe, Michael, Bietti, Alberto, Cranmer, Miles
Format: Preprint
Published: 2025
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_version_ 1866917109895790592
author Fear, Rio Alexa
Mukhopadhyay, Payel
McCabe, Michael
Bietti, Alberto
Cranmer, Miles
author_facet Fear, Rio Alexa
Mukhopadhyay, Payel
McCabe, Michael
Bietti, Alberto
Cranmer, Miles
contents Recent advances in mechanistic interpretability have revealed that large language models (LLMs) develop internal representations corresponding not only to concrete entities but also distinct, human-understandable abstract concepts and behaviour. Moreover, these hidden features can be directly manipulated to steer model behaviour. However, it remains an open question whether this phenomenon is unique to models trained on inherently structured data (ie. language, images) or if it is a general property of foundation models. In this work, we investigate the internal representations of a large physics-focused foundation model. Inspired by recent work identifying single directions in activation space for complex behaviours in LLMs, we extract activation vectors from the model during forward passes over simulation datasets for different physical regimes. We then compute "delta" representations between the two regimes. These delta tensors act as concept directions in activation space, encoding specific physical features. By injecting these concept directions back into the model during inference, we can steer its predictions, demonstrating causal control over physical behaviours, such as inducing or removing some particular physical feature from a simulation. These results suggest that scientific foundation models learn generalised representations of physical principles. They do not merely rely on superficial correlations and patterns in the simulations. Our findings open new avenues for understanding and controlling scientific foundation models and has implications for AI-enabled scientific discovery.
format Preprint
id arxiv_https___arxiv_org_abs_2511_20798
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Physics Steering: Causal Control of Cross-Domain Concepts in a Physics Foundation Model
Fear, Rio Alexa
Mukhopadhyay, Payel
McCabe, Michael
Bietti, Alberto
Cranmer, Miles
Machine Learning
Artificial Intelligence
Computational Physics
Recent advances in mechanistic interpretability have revealed that large language models (LLMs) develop internal representations corresponding not only to concrete entities but also distinct, human-understandable abstract concepts and behaviour. Moreover, these hidden features can be directly manipulated to steer model behaviour. However, it remains an open question whether this phenomenon is unique to models trained on inherently structured data (ie. language, images) or if it is a general property of foundation models. In this work, we investigate the internal representations of a large physics-focused foundation model. Inspired by recent work identifying single directions in activation space for complex behaviours in LLMs, we extract activation vectors from the model during forward passes over simulation datasets for different physical regimes. We then compute "delta" representations between the two regimes. These delta tensors act as concept directions in activation space, encoding specific physical features. By injecting these concept directions back into the model during inference, we can steer its predictions, demonstrating causal control over physical behaviours, such as inducing or removing some particular physical feature from a simulation. These results suggest that scientific foundation models learn generalised representations of physical principles. They do not merely rely on superficial correlations and patterns in the simulations. Our findings open new avenues for understanding and controlling scientific foundation models and has implications for AI-enabled scientific discovery.
title Physics Steering: Causal Control of Cross-Domain Concepts in a Physics Foundation Model
topic Machine Learning
Artificial Intelligence
Computational Physics
url https://arxiv.org/abs/2511.20798