# How to Test a Flat-Earth Claim

A claim becomes useful when it can be tested. The goal is not to win a shouting match but to turn a vague assertion into a prediction that can succeed or fail.

#### Step 1: State the Claim Clearly

“The horizon always rises to eye level” is testable. “They are hiding the truth” is not, unless it comes with specific evidence.

#### Step 2: Identify the Prediction

Ask what should happen before looking. If a model can explain every possible result afterward, it is not doing scientific work.

#### Step 3: Control the Variables

For visual claims, record distance, height, lens, date/time, weather, temperature gradient and location. For astronomy claims, record latitude, direction, time and date.

#### Step 4: Compare Models

The question is not “Can I invent a story?” The question is which model predicts the observation more simply, consistently and quantitatively.

#### Step 5: Keep the Result

Good experiments should be logged, even when they do not support your expectation. Reality is allowed to be inconvenient.

## Claim Lab Worksheet

Use this worksheet before debating a claim:

1. **Exact claim:** Write one sentence without sarcasm.
2. **Flat prediction:** What should we observe if the claim is true?
3. **Globe prediction:** What should we observe if Earth is spherical?
4. **Measurement plan:** What tools, locations, times, heights, and distances are needed?
5. **Failure condition:** What result would make you less confident?
6. **Repeatability:** Can someone in another location check it too?

## Example: “We Should Feel Earth Spin”

**Flat-style claim:** if Earth rotates, people should feel a violent motion. **Prediction to test:** Earth’s rotation should produce a large outward acceleration. **Measurement:** calculate centrifugal acceleration and compare it with gravity. **Result:** at the equator the effect is real but tiny, reducing apparent weight by roughly a third of one percent.