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Michelson-Morley Experiment (1887)

Objective:
The aim was to measure the Earth's motion through the luminiferous ether, a medium through which light was thought to propagate.

Experimental Setup:
An interferometer was employed to compare the speed of light in perpendicular directions, expecting to detect the "Earth's supposed motion" through an "ether wind."

Result:
The experiment yielded a much smaller effect than anticipated—about 1/6th of the predicted value—resulting in a "null result."

Interpretations and Reactions

1. Detection of Ether:
- The small effect suggested that the light did not behave as initially predicted, but it did not disprove the ether's existence. It implied that the Earth's motion through the ether might be different from what was expected.
- The smaller effect still supported the interaction with the ether, contradicting the immediate conclusion that the ether was nonexistent.

2. Reevaluation of Predictions:
- Scientists reexamined their framework to account for the reduced effect, leading to various alternative hypotheses within the ether framework.

Alternative Hypotheses and Post-Hoc Reasoning

1. Lorentz-Fitzgerald Contraction:
- Lorentz proposed that objects contract in the direction of motion through the ether, which would explain the reduced effect observed. This hypothesis used post hoc reasoning to reconcile the null result with the expectation of a moving Earth, preserving the heliocentric model while supporting the ether theory.

2. Ether Drag Hypothesis:
- It was suggested that the ether might be dragged along by the Earth, reducing the relative motion detectable by the interferometer. This hypothesis also utilized post hoc reasoning to maintain the assumption of a moving Earth.

3. Non-Moving Earth:
- An alternative view suggested that the Earth might not be moving relative to the ether, which would account for the smaller observed effect. This interpretation aligned with the detection of the ether but challenged the heliocentric model and did not rely on post hoc reasoning.

Einstein's Special Relativity and Fallacies

1. New Framework:
- Introduced in 1905, Einstein's theory of special relativity posited that the speed of light is constant in all inertial frames of reference, eliminating the need for the ether. While this was a new concept, it did not disprove the ether but rather offered an alternative that made the ether redundant within the theory.

2. Illogical Fallacies in Relativity:
- Circular Reasoning: Special relativity’s assertion that the speed of light is constant in all frames was based on assuming that light’s speed is constant. This assumption was used to derive further implications of the theory, creating a circular argument where the premise and conclusion are interdependent.
- Ad Hoc Hypotheses: To address inconsistencies and experimental results, Einstein introduced additional postulates without direct empirical evidence. For instance, the theory's reliance on relativistic effects like time dilation and length contraction were added post hoc to account for observations not directly explained by the initial framework.
- Ignoring Contradictory Evidence: Einstein’s theory did not address all anomalies. For example, the theory did not initially account for certain astronomical observations. The later introduction of dark matter can be seen as an attempt to fix these gaps without revising the core assumptions of relativity.

3. Dark Matter and Post-Hoc Reasoning:
- Inadequacies in Relativity: Special relativity faced challenges in explaining cosmic phenomena, such as the rotation curves of galaxies. The postulation of dark matter was introduced to explain these discrepancies.
- Illogical Justifications: The concept of dark matter was used to address inadequacies within the relativistic framework rather than revising the theory itself. This approach involved introducing a new, unobservable component to justify inconsistencies, which can be seen as a form of ad hoc reasoning.

1987 Air Force Experiment

Objective:
To replicate the Michelson-Morley experiment using modern technology and test the Earth's motion through the ether.

Technological Advancements:
Utilized advanced lasers and interferometers for enhanced precision.

Result:
The results aligned with the original experiment, showing no significant anisotropy in the speed of light and reinforcing the findings of a smaller-than-expected effect.

Reassessment of Predictions

Given the smaller-than-expected effect:

1. Scientific Methodology:
- The detection of a smaller effect supports the presence of the ether and necessitates a reevaluation of predictions about Earth's motion through it. Scientists explored modifications to ether theory and alternative hypotheses.

2. Heliocentric and Relativistic Claims:
- The results suggested inaccuracies in heliocentric predictions regarding Earth's motion through ether, prompting reassessment rather than altering the theory. The use of post hoc reasoning in alternatives like Lorentz-Fitzgerald contraction and ether drag highlighted efforts to align with the moving Earth model. Similarly, Einstein's introduction of dark matter addressed gaps in relativity's predictions through post hoc adjustments, demonstrating the ongoing complexity and challenges in scientific interpretation and theory adaptation.

Conclusion

The Michelson-Morley experiment did not disprove the ether but detected a smaller-than-expected effect, supporting its presence. This led to the reconsideration of predictions and exploration of alternative hypotheses within the ether framework. Einstein’s special relativity employed illogical fallacies such as circular reasoning and ad hoc hypotheses to address inconsistencies, and the subsequent introduction of dark matter was a post hoc fix to further reconcile discrepancies in the theory. This highlights the intricate nature of scientific theory development and the role of post hoc reasoning in reconciling experimental results with theoretical models.