Speed of sound in methane under conditions of planetary interiors
Bibliographic record
Abstract
We present direct observations of acoustic waves in warm dense matter. We analyze wave-number- and energy-resolved x-ray spectra taken from warm dense methane created by laser heating a cryogenic liquid jet. X-ray diffraction and inelastic free-electron scattering yield sample conditions of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mn>0.3</a:mn><a:mo>±</a:mo><a:mn>0.1</a:mn></a:mrow></a:math> eV and <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mn>0.8</b:mn><b:mo>±</b:mo><b:mn>0.1</b:mn></b:mrow></b:math> g/<c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msup><c:mi mathvariant="normal">cm</c:mi><c:mrow><c:mo>−</c:mo><c:mn>3</c:mn></c:mrow></c:msup></c:math>, corresponding to a pressure of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:mo>∼</e:mo><e:mn>13</e:mn></e:math> GPa. Inelastic x-ray scattering was used to observe the collective oscillations of the ions. With a highly improved energy resolution of <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:mo>∼</f:mo><f:mn>50</f:mn></f:math> meV, we could clearly distinguish the Brillouin peaks from the quasielastic Rayleigh feature. Data at different wave numbers were utilized to derive a sound speed of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:mrow><g:mn>5.9</g:mn><g:mo>±</g:mo><g:mn>0.5</g:mn></g:mrow></g:math> km/s, marking a high-temperature data point for methane and demonstrating consistency with Birch's law in this parameter regime. Published by the American Physical Society 2024
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".