Slava Turyshev, a physicist at NASA’s Jet Propulsion Laboratory, says a mysterious “fifth force” may be hiding in our solar system, detectable only through extremely precise experiments designed to overcome screening effects.
How screening could hide a fifth force in plain sight
Turyshev’s work addresses the “Great Disconnect” where cosmic observations suggest dark energy or modified gravity influences the universe’s expansion, yet local solar system measurements show perfect agreement with Einstein’s gravity. In dense environments like our solar system, screening mechanisms such as the chameleon model could cause a hypothetical fifth force to weaken significantly, making it undetectable by current instruments despite its potential role in cosmic acceleration.
Why local tests fail to see what cosmic surveys reveal
Although spacecraft signals and planetary orbits align precisely with general relativity within the solar system, observations of distant supernovae and galactic scales indicate something is altering spacetime behavior. Turyshev proposes that overcoming this mismatch requires experiments designed to be both highly precise and selectively targeted to low-density regions where screening effects diminish, allowing hidden forces to become observable.
What So for the search for dark energy
If screening is valid, it suggests dark energy may not be a uniform cosmological constant but a dynamic field that changes strength based on local density. This would explain why its effects dominate in the sparse intergalactic medium while remaining concealed in the crowded solar neighborhood, redirecting detection efforts toward specialized experiments capable of sensing weak forces in controlled, low-background environments.
What is the chameleon model?
The chameleon model is a screening mechanism where a hypothetical fifth force adjusts its strength based on nearby matter density, becoming strong in low-density regions and weak in dense areas like the solar system.
How could scientists detect this fifth force locally?
By designing extremely precise experiments that are selective in targeting low-density environments where screening effects are minimized, potentially revealing forces hidden in denser regions like our solar system.