Proving and Improving the Platonic Representation Hypothesis with JEPAs

Abstract: Whether models trained on different modalities converge to the same representation of the world is central to AI. The Platonic Representation Hypothesis (PRH) conjectures that they do as they scale, but without a proof it offers neither a guarantee nor a recipe. We turn the hypothesis into a theorem. First, we prove a \emph{Platonic Representation Theorem}: Joint-Embedding Predictive Architectures (JEPAs) trained separately on any number of modalities learn the same representation up to one rotation whenever their positive pairs are two observations of one scene--\emph{good views}--and their misalignment is bounded otherwise. Second, we show that next-token prediction is a JEPA with \emph{bad views}, parts of a single document, which explains why LLMs align with vision only through scale. Third, we validate the theory from 145k captions to the texts of 940M web images, and uncover a scaling law of alignment that predicts unseen runs within seed noise. Good views need 42 times fewer training samples than next-token prediction on the same corpus to reach the same alignment, and a 109M-parameter text JEPA aligns with DINOv2 and CLIP's image encoders better than every LLM we evaluated, up to 72B parameters, and than CLIP's text encoder: next-token prediction is a remarkably inefficient route to platonic representations. As a showcase, one rotation turns separately trained encoders into an image captioner (CIDEr .838 on COCO). Even that rotation needs no pair: on the latest pair-free benchmark, our text JEPA beats every zero-shot accuracy reported with LLMs up to 8B parameters, e.g., 64\% against at most 56\% top-5 on ImageNet-100. Positive views, and not scale alone, are thus the lever to build platonic representations.

• The paper proves the Platonic Representation Theorem, showing that independently trained Joint-Embedding Predictive Architectures (JEPAs) with shared positive-pair distributions can recover a common world representation if the minimization is unique up to orthogonal transformation.
• LeJEPA's JEPAs can factor between views to address JEPA responses. However, in initial theories, JEPAs apply only to good views, which lie between pairs of independent observations of common world states, and not bad views, which are pairs from corrupted views.
• The empirical results of this paper demonstrate that existing alignment techniques fail to address more subtle cases of JEPA alignment, like good views vs. bad views, The theoretical bounds derived also confirm this conclusion, as only good view results in sufficiently aligned encoding dimensions.

From hypothesis to theorem

The paper addresses a central question in multimodal representation learning: under what conditions do independently trained encoders for different modalities recover the same representation of the underlying world? The Platonic Representation Hypothesis (PRH) proposes that sufficiently capable models converge toward a shared representation, but prior formulations were primarily empirical or restricted to substantially idealized contrastive settings. “Proving and Improving the Platonic Representation Hypothesis with JEPAs” (2610.39302) recasts the question in terms of the positive pairs used by Joint-Embedding Predictive Architectures (JEPAs).

The paper’s central claim is that scale is not the primary determinant of cross-modal alignment; the decisive factor is whether positive pairs correspond to multiple observations of the same world state. The authors distinguish:

• Good views: two observations of the same scene or world state, such as two captions of one image or two frames of one video.
• Bad views: two corruptions of one observation, such as masked spans of one caption or crops of one image.
• Next-token prediction: interpreted as a special case of a bad-view JEPA, because its positive relation is between a prefix and its continuation within a document rather than between independent observations of a shared scene.

The theoretical contribution is the Platonic Representation Theorem. In an idealized finite-world setting, if independently trained JEPAs use the same positive-pair distribution over world states and their minimizers are unique up to rotation, then all modalities recover the same world representation up to a modality-specific orthogonal transformation. Thus, the PRH is not asserted as an emergent consequence of unlimited scale: within the stated assumptions, it follows from shared positive-pair structure.

Spectral formulation of JEPA representations

The analysis begins with a finite set of world states $z$, a modality-specific rendering $g_m(z)$, and a positive-pair distribution $\pi_m$ over state pairs. The encoder minimizes a prediction loss between positive embeddings together with a rotation-invariant anti-collapse term. Whitened mean-squared error and spectral contrastive objectives fall directly into this framework; VICReg and Barlow Twins do so in appropriate whitened limits. The analysis also relates to the spectral theory of self-supervised learning developed in prior work (2610.39302).

The crucial reduction is that an injective rendering changes only the coordinates in which the objective is written. After composing the modality encoder with the inverse rendering, every modality-specific optimization problem becomes an optimization problem over world states. If all modalities share the same positive-pair distribution, they therefore optimize the same objective.

For whitened squared-distance JEPAs, the population minimizer is characterized explicitly. Let $\mu_1,\mu_2,\ldots$ denote the eigenvalues of the normalized positive-pair operator, excluding the constant eigenfunction. A $k$-dimensional encoder recovers the first $k$ eigenfunctions, and the optimum has value

$2\sum_{i=1}^{k}(1-\mu_i).$

When the eigengap $\mu_k-\mu_{k+1}$ is positive, the minimizer is unique up to an orthogonal transformation. This spectral gap is not merely a technical convenience: it identifies the directions that are stable under perturbations and explains why alignment empirically concentrates in leading principal directions.

The resulting theorem states that for any number of modalities, if they share a positive-pair distribution and the minimizer is unique up to rotation, then there is a common world embedding $h^\star$ such that each learned encoder satisfies

$f_m^\star \circ g_m = Q_m h^\star,$

for some orthogonal matrix $g_m(z)$0. Any two modalities can therefore be aligned with a single rotation. The theorem does not cover predictive JEPAs with nontrivial action-conditioned predictors, non-injective or lossy renderings, finite-sample optimization, or the full uniqueness properties of LeJEPA’s SIGReg objective. The authors explicitly retain uniqueness under the full-distribution constraint as an assumption.

Misaligned positives impose a quantitative limit

The exact theorem requires identical positive-pair distributions, which real modalities rarely satisfy. The paper therefore derives a robustness result based on eigenspace perturbation. If two modalities induce kernels $g_m(z)$1 and $g_m(z)$2, their post-rotation representation mismatch is bounded by the norm of the kernel difference divided by the eigengap of the second kernel:

$g_m(z)$3

This is a Davis–Kahan-type result: alignment improves when positive-pair kernels are similar and when the relevant spectral subspace is well separated. Conversely, small eigengaps make representations intrinsically sensitive to differences in views. The empirical check uses 300 randomly generated finite worlds, and the observed error lies below the theoretical bound in every case; the largest ratio of error to bound is 0.18.

Figure 1: The measured post-rotation representation mismatch remains below the kernel-mismatch bound across randomly generated finite worlds.

The implication is that cross-modal alignment cannot be repaired solely by increasing model capacity when the modalities optimize materially different positive relations. A modality may be perfectly optimized for its own kernel and still fail to align with another modality because the learned eigenspaces encode different relational structures.

The paper also establishes that the rotation itself is identifiable from $g_m(z)$4 paired states in general position, using orthogonal Procrustes. In contrast, first- and second-order statistics of unpaired whitened embeddings cannot identify the rotation, because every orthogonal transformation preserves those statistics. Higher-order geometry can nevertheless identify the map on finite datasets, which motivates the paper’s pair-free experiments.

Good views suppress modality-specific nuisance

To formalize the distinction between observations and world states, the authors introduce a modality-specific nuisance variable $g_m(z)$5. An observation is $g_m(z)$6, where $g_m(z)$7 is the shared scene and $g_m(z)$8 includes factors such as wording, viewpoint, lighting, or authorial style.

A good-view JEPA forms positive pairs from independently sampled observations of related world states:

$g_m(z)$9

with independent nuisances. A bad-view JEPA forms two corruptions of the same observation, causing the pair to retain correlated nuisance information.

The paper defines the scene-explained fraction of an encoder through the covariance of its conditional mean given the world state. For centered and whitened encoders, it proves that alignment error between two modalities is lower-bounded by the amount of embedding capacity spent on modality-specific nuisance:

$\pi_m$0

A representation that is entirely a function of the world state has $\pi_m$1. Any nuisance-dependent directions reduce the maximum possible cross-modal agreement, regardless of the quality of the rotation.

For the spectral objective, good views recover state-only directions under an eigengap condition. Bad views instead allocate dimensions to nuisance whenever the nuisance correlation preserved by the corruption exceeds the correlation of the world’s $\pi_m$2-th direction. This yields a precise explanation for why two masked versions of one caption can preserve lexical and stylistic properties that are irrelevant to image alignment, while two independent captions of the same image share scene information but not the particular wording of either caption.

The empirical measurements support this mechanism. On Flickr, using 32 principal directions, the scene-explained fractions are:

Text objective	Scene-explained fraction
Good-view JEPA	0.804
Bad-view JEPA	0.655
Next-token prediction	0.608

The corresponding image–text alignment errors increase in the same order. The result is important because it connects an abstract nuisance bound to a measurable property of trained encoders: bad-view and next-token objectives encode more modality-specific variation, and that variation is precisely what cannot be removed by a cross-modal rotation.

Next-token prediction as a bad-view objective

The paper offers a deliberately strong reinterpretation of autoregressive language modeling. With context representation $\pi_m$3, target-token embeddings $\pi_m$4, and a linear softmax head, the next-token loss decomposes as

$\pi_m$5

The first term is a prediction term, while the log-partition term acts as an anti-collapse component independent of the target token. In this sense, next-token prediction has the structural form of a two-encoder JEPA: a context encoder predicts a target-token encoder, and the positives are prefix–continuation pairs drawn from one document.

The distinction from good views is structural. A prefix and its continuation share document-specific wording, discourse style, and authorial conventions. Contexts that predict the same frequent token may also become implicit positives, creating narrow connections through common lexical events rather than direct connections between descriptions of the same scene. The paper argues that this produces a sparse and noisy approximation to a world-state kernel. More data and model scale can improve the approximation, but they do not change the positive relation itself.

The identification result is also weaker than the JEPA result: next-token optima are invariant under arbitrary invertible transformations of the context and token representations, not merely orthogonal transformations. If the conditional token distributions can be represented exactly, the logits satisfy

$\pi_m$6

which is invariant under $\pi_m$7 and $\pi_m$8. Thus next-token prediction does not intrinsically identify a common Euclidean geometry, whereas whitened JEPAs can identify one up to rotation under a spectral gap.

The authors appropriately describe the application of the good/bad-view theorem to next-token prediction as heuristic rather than a direct corollary: the theorem assumes one encoder and a spectral JEPA objective, while autoregressive language modeling uses two representations and has $\pi_m$9 rather than orthogonal invariance. The experimental results nevertheless strongly support the proposed interpretation.

Controlled experiments on Flickr and video

The first experimental comparison uses Flickr30k, where five captions are available for each image. Text encoders share architecture, initialization protocol, data, and training schedule; only the positive construction changes. The comparison includes caption-view JEPAs, masked-span JEPAs, and next-token prediction. The image encoder is trained separately and never sees text.

On 1,000 Flickr test pairs, a single rotation fitted on validation pairs produces the following results:

Text objective	Mutual 10-NN	R@1	R@5
Good-view JEPA	0.062	0.044	0.133
Bad-view JEPA	0.047	0.027	0.095
Next-token prediction	0.042	0.021	0.077
Random initialization	0.010	0.001	0.011

The good-view model retrieves the correct caption first at 44 times chance. Training next-token prediction on pairs of captions from the same image barely changes performance, from R@1 0.021 to 0.023. This is a particularly important control: having access to image-level grouping is not sufficient; the grouping must be used as the positive relation of the JEPA objective.

Figure 2: Cross-modal alignment rises substantially faster and reaches a higher level for caption-view JEPAs than for masked-span JEPAs or next-token prediction.

Alignment is concentrated in leading spectral directions. After rotation, the correlation is approximately 0.70 in the first text principal direction and decreases toward 0.1 by the 60th direction. This agrees with the perturbation analysis, although the authors note that low-variance directions can also exhibit lower measured correlation because of estimation noise.

Figure 3: The strongest cross-modal correlations occur in leading, spectrally separated embedding directions.

The ablation study identifies trimming as the most consequential implementation choice. Using entire captions as views reduces R@1 from approximately 0.246 to 0.185, a reduction of roughly one quarter. Other changes, including masking rate, number of views, batch size, and schedule, generally alter the mean by no more than the seed variability. Gradient clipping is important for stability: several runs collapse abruptly without it, whereas clipping prevents most observed collapses.

Figure 4: Trimming, which removes observation-specific wording while retaining shared content, is the dominant alignment-related ablation.

The video experiment tests whether both modalities benefit from good views. On MSR-VTT, where each clip has multiple frames and captions, good views on both sides achieve mutual 10-NN alignment of 0.067, compared with 0.039 when both image and text models use bad views. Good text views alone produce 0.059, while good image views alone produce 0.043. Frozen DINOv2, whose own positives are image crops, aligns better with the crop-trained image JEPA than with the frame-trained one. This supports the kernel-matching prediction: alignment is highest when the positive relations used by both encoders agree, even when that relation is not the most semantically desirable one.

Figure 5: Good views improve alignment on both the image and text sides of a video–caption task, while DINOv2 favors an image JEPA with matching crop-based positives.

Data coverage and the alignment scaling law

The paper’s coverage theorem separates two effects that are often conflated: the positive-view mechanism and the distribution of training data. A bad-view objective may eventually connect descriptions of the same scene through overlapping corruptions, but weak overlaps require dense sampling. Strong corruptions can instead connect different scenes through shared nuisance, imposing an alignment ceiling that additional data cannot remove.

In the synthetic experiments, good views align world states exactly from one observation per state. Weak bad views require increasing sample density, with the required view reach decreasing approximately as $\mu_1,\mu_2,\ldots$0, where $\mu_1,\mu_2,\ldots$1 is the number of samples per state. When the data distribution causes positive connections to cross between classes, alignment remains capped even as the number of samples grows.

Figure 6: Weak positive relations require increasing data density, whereas cross-scene mixing imposes a ceiling that more data cannot eliminate.

The empirical scaling law models Flickr R@1 as a function of samples seen, the fraction $\mu_1,\mu_2,\ldots$2 of good-view examples, and the number of unique images. It fits 45 grid cells with RMSE 0.007 and predicts 85 previously untrained runs with RMSE 0.0093. Two independent seeds of the same run differ by RMSE 0.0096, so within the fitted range the law predicts unseen configurations approximately as accurately as rerunning a configuration with another seed.

Figure 7: Alignment grows approximately linearly in the logarithm of samples seen, with a higher growth rate as the fraction of good views increases.

The law is empirical rather than derived from the coverage theorem. Its exponents are poorly identified, and it fails for very long training runs with good views, where repeated passes over the same data cause it to overestimate performance. The result should therefore be read as a useful interpolation model for one training recipe, not as a universal scaling law.

Scaling beyond language-model baselines

The largest experiments use Recap-DataComp, where each web image is associated with an alt-text and two LLaVA-generated recaptions. The text JEPA never observes pixels, but the grouping of texts by image defines good views. This distinction is essential: the recaptions contain information distilled from an image–text model, so the data are not entirely independent of multimodal supervision.

With a 33M-parameter text JEPA, WIT-1024 alignment rises from 0.034 on Flickr captions to 0.108, 0.111, and 0.125 when trained on texts from 2.16M, 10M, and 50M web images. A 109M text JEPA trained on texts from 940M images reaches 0.184 with DINOv2 ViT-B, compared with 0.154 for Qwen2.5-72B. The same good-view JEPA reaches 0.507 in linear CKA on WIT, compared with 0.418 for Qwen2.5-72B.

Text encoder	Parameters	WIT mutual 10-NN	WIT CKA
Qwen2.5-7B	7B	0.118	0.353
Qwen2.5-72B	72B	0.154	0.418
CLIP text encoder	—	0.124	0.339
Good-view JEPA	109M	0.184	0.507

The claim is deliberately narrow but strong: for the evaluated alignment metrics and vision encoders, a 109M good-view text JEPA exceeds every tested LLM up to 72B parameters, as well as CLIP’s text encoder and all-mpnet-base-v2. It does not establish that the JEPA is a better LLM or general-purpose representation; it establishes that next-token prediction is substantially less sample-efficient for the specific objective of agreeing with independently trained visual representations.

The sample-efficiency comparison is especially pronounced. On the same corpus, a good-view JEPA reaches WIT alignment 0.109 after 21.6M training samples, whereas next-token prediction reaches 0.111 after 900M samples. The good-view model therefore requires 42 times fewer samples, 14 times fewer text tokens under the stated view construction, and 435 times fewer unique images to reach comparable alignment.

Figure 8: Good-view JEPAs outperform bad-view JEPAs and next-token prediction across data scales, encoder sizes, and frozen vision-model families.

The result is robust across DINOv2, MAE, I-JEPA, and CLIP image encoders. The exact absolute scores depend strongly on the vision representation, but the ordering remains consistent: good-view JEPA, next-token prediction, then bad-view JEPA. This is consistent with the theory’s emphasis on agreement between positive kernels rather than on any particular image objective.

Composing independently trained encoders

The paper demonstrates that the learned alignment can be used compositionally. A text decoder is trained only on text-JEPA embeddings and captions. At inference time, a frozen image embedding is mapped into the text-JEPA space using a single orthogonal or orthonormal-row linear map fitted on paired data. No network is trained on image–caption pairs.

On Flickr, the resulting captioner reaches CIDEr 0.431 with a map fitted on 30,000 pairs and 0.396 with 1,014 pairs. On COCO, using a rotation fitted only on Flickr pairs, a text-only decoder, and stronger frozen image encoders, the system reaches CIDEr 0.838 with consensus decoding over 32 samples.

Figure 9: A text-only decoder can generate captions from frozen image representations after a single cross-modal linear map.

The paper also predicts decoder noise from the residual alignment error. If the mean cosine between rotated image and text embeddings is $\mu_1,\mu_2,\ldots$3, the injected Gaussian noise scale is chosen as

$\mu_1,\mu_2,\ldots$4

The transfer performance peaks close to this predicted value rather than at a freely tuned arbitrary noise level. This provides an operational consequence of the geometric analysis: the decoder should be trained to tolerate the residual error of the alignment map, not an idealized zero-error embedding.

Figure 10: Captioning performance peaks near the noise level predicted from the residual cosine after rotation.

The method transfers to video by averaging rotated embeddings from eight frames. Without video training, it reaches CIDEr 0.246 on MSR-VTT, above several zero-shot captioners based on CLIP encoders, although below systems trained with video–text supervision. The result is consistent with the nuisance analysis: averaging multiple observations suppresses frame-specific variation and preserves clip-level content.

Alignment without paired data

The final application tests whether the rotation can be recovered from unpaired image and caption clouds using shared geometry. The authors apply an existing cluster-matching and optimal-transport refinement procedure without modification. On the COCO protocol, the 109M good-view JEPA obtains FOSCTTM 0.018, CIFAR-10 top-1 accuracy 86.0%, CIFAR-100 top-5 accuracy 67.2%, and ImageNet-100 top-5 accuracy 64.4%.

Against a rerun of Qwen3-8B under identical conditions, the good-view JEPA matches FOSCTTM and CIFAR-10, while exceeding it by 5.5 points on CIFAR-100 and 16.8 points on ImageNet-100. Next-token prediction on the same texts is unstable and fails in half of its runs, with FOSCTTM 0.287 and CIFAR-10 accuracy 25.5%. The bad-view JEPA performs substantially better than next-token prediction but remains below the good-view model.

The result is not a contradiction of the earlier identifiability statement. First- and second-order moments do not identify the rotation, but finite-sample higher-order geometry can do so when the two encoders induce sufficiently similar structures. Good-view training improves precisely this geometric compatibility. On Flickr, the pair-free 109M JEPA retrieves the correct caption first 16.4% of the time, while all evaluated non-good-view encoders remain at or below 0.3%.

Figure 11: After training, a single rotation places independently trained image and text encoders into a shared geometry.

Figure 12: Image-to-caption retrieval is possible through one fitted rotation, with errors generally corresponding to semantically related captions.

Limitations and open questions

The theoretical claims depend on assumptions that are not satisfied exactly by the principal experiments. The theorem uses a finite world, injective renderings, matched state marginals, population optima, and minimizers unique up to rotation. Real images and captions are lossy observations, and the paper does not provide a theorem for the resulting non-injective case. The spectral uniqueness result applies to second-order whitening objectives, not directly to the full-distribution SIGReg constraint used in the experiments. The robust misalignment bound is likewise proved for spectral solutions, whereas the neural experiments use LeJEPA implementations.

The construction of good views is itself a substantive source of supervision. Flickr and COCO provide human captions grouped by image. Recap-DataComp provides image-associated recaptions generated by LLaVA, whose vision component was trained with multimodal information. When the authors remove the image-generated recaptions and use only alt-text plus a text-only paraphrase, WIT alignment falls from 0.107 to 0.060 at the smaller scale. Thus, the strongest scaling results rely on image-grouped and partly vision-derived text, even though the JEPA text encoder never sees pixels and never receives an image–text loss.

The experiments also focus primarily on text JEPAs against frozen or independently trained image encoders. Most image encoders use crop-based bad views, and scaling good-view image training is only tested substantially in video. The conclusions therefore do not establish that good views are equally easy to construct or equally effective for every modality. The paper leaves open whether the same theorem and empirical advantage hold for lossy observation models, action-conditioned predictive JEPAs, non-orthogonal representation equivalences, and large-scale image or audio systems trained entirely without externally supplied scene groupings.

Finally, the scaling law is recipe-specific, its exponents are poorly identified, and it fails outside the fitted range under repeated data exposure. The large-scale WIT comparison is also affected by sensitivity to SIGReg weighting and by the small benchmark size, although the view-based gaps are reported to exceed both seed and subsampling variability.

Conclusion

The paper’s principal contribution is to make the PRH conditional and operational. Under a shared positive-pair distribution and suitable identifiability assumptions, independently trained JEPAs recover a common world representation up to rotation. When positive kernels differ, the paper quantifies the resulting misalignment; when views preserve modality-specific nuisance, it establishes an irreducible alignment penalty.

The experiments consistently support the central prescription. Good views outperform masked-span objectives and next-token prediction, require 42 times fewer samples to reach comparable alignment, and allow a 109M text JEPA trained on web-associated texts to exceed the measured cross-modal alignment of LLMs up to 72B parameters. The strongest qualification is that good views require reliable scene-level grouping, and the largest data source includes vision-derived recaptions. Within those constraints, the paper presents positive-pair design—not scale alone—as the principal controllable variable for constructing alignable multimodal representations (2610.39302).