NASA scientist proposes screening hides fifth force in solar system despite cosmic evidence

NASA scientist Slava Turyshev says a hypothetical fifth force of nature may be detectable within the solar system if experiments are designed to account for environmental screening effects.

How screening could hide a fifth force in dense environments

Turyshev’s research at NASA’s Jet Propulsion Laboratory focuses on the “Great Disconnect,” where cosmic-scale observations suggest dark energy or modified gravity, but local solar system measurements show no deviation from Einstein’s gravity. He proposes that screening mechanisms, such as the chameleon model, could cause a fifth force to weaken in high-density regions like the solar system, making it undetectable by current instruments despite its presence.

Why local tests show no anomaly despite cosmic evidence

In low-density regions of the universe, such as intergalactic space, the effects of dark energy or a fifth force become more apparent, influencing the expansion of the cosmos. However, within the solar system, the high density of matter suppresses these effects through screening, meaning that planetary orbits and spacecraft tracking data appear consistent with standard gravity, even if a fifth force exists.

What experimental precision could reveal

Turyshev argues that overcoming the screening effect requires experiments designed with extreme precision and selectivity, targeting conditions where the force might be less suppressed. Such efforts could bridge the gap between cosmological anomalies and local null results, potentially uncovering new physics without contradicting established solar system dynamics.

What is the chameleon model?

The chameleon model is a theoretical framework in which a hypothetical fifth force changes its strength based on the local density of matter, becoming stronger in low-density regions and weaker in high-density environments like the solar system.

Why haven’t we detected this force before?

Current instruments may not be sensitive enough to detect the fifth force in high-density areas where screening suppresses its effects, even if it exists and influences cosmic-scale phenomena like the universe’s expansion.