Passage Summary: Physicists used to think there were only four forces, but new experiments showed gravity acting weaker than expected, leading some to propose a fifth 'pushing' force to explain the difference.

Conclusion: There exists a fifth universal force characterized by mutual repulsion between particles of matter.

Reasoning: The existence of such a force would account for experimental data showing lower gravitational attraction than current theories predict.

Analysis: To strengthen this argument, we need to provide more evidence for this 'repulsive' force or rule out other reasons why the gravity measurements were off. The argument currently relies on the fifth force as a convenient explanation for a single discrepancy. Look for an answer that shows this force appearing in other experiments or demonstrates that the equipment used to measure gravity was not simply malfunctioning. We want to move this from a convenient hypothesis to a well-supported theory.