# Learner lab record: Stress-energy source and energy-condition ledger

Course: General relativity

Name: ____________________  Date: ____________________  Group: ____________________

## Investigation question

What source components and invariant tests are required by a proposed spacetime geometry?

## Setup

Use the stress-energy laboratory. Choose one metric profile, record the inferred density and principal stresses in the declared frame, then vary one geometric scale at a time.

## Variables

| Variable | Role | Unit |
| --- | --- | --- |
| Metric amplitude and length scale | geometry inputs | declared model units |
| Energy density | inferred source | energy/volume |
| Principal pressures | inferred source | energy/volume |
| Null-energy contractions | invariant/frame-declared tests | energy/volume |

## Predict before changing controls

1. Predict how sharper geometry changes derivative-based source scales.

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2. Predict the null-energy result when density plus one principal pressure is negative.

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## Observation table

| amplitude | length scale | density | radial pressure | tangential pressure | NEC minimum | frame |
| --- | --- | --- | --- | --- | --- | --- |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |

## Analyze

1. Which source component dominates?

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2. How does the required scale respond to halving the length scale?

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3. Why must the observer frame or tetrad be declared?

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4. Does an energy-condition violation demonstrate constructibility?

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## Evidence-bounded conclusion

For geometry scale ___, the inferred source required density ___ and minimum null contraction ___ in frame ___; this establishes ___ but not ___.

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