A new analysis has revealed that a force tied to dark energy could still be hiding in the solar system despite near-perfect local tests of Einstein’s theory of general relativity.
It turns the gap between local gravity tests and the universe’s larger behavior into a search for the faint traces that force might still leave behind.
Where it disappears
Around the Sun, planetary motions and spacecraft signals agree with Einstein so closely that any extra pull would have to survive there as a tiny residue.
From that precise record, physicist Slava Turyshev at NASA’s Jet Propulsion Laboratory (JPL) showed that the hidden force could persist locally without leaving an obvious trace.
Rather than disappearing outright, the force shrinks into a weak remnant that current instruments can miss while familiar gravity still governs the solar system.
That limit leaves the solar system looking less like a rejection of the force than a place where only its weakest traces could remain, pushing the question toward whatever suppresses it.
Why density matters
Far from stars and planets, matter thins out, and theories that add a fifth force – an extra interaction – can produce larger effects.
In these ideas, the environment changes how the added field behaves, so the force can act more freely in emptier regions.
That hiding is called screening, and it lets the universe look odd at large scales while nearby planets keep following familiar paths.
Once screening enters the story, a null result in the solar system becomes part of the model, not the end of it.
Chameleon in sunlight
One route uses chameleon screening, where the added field changes with local density and grows harder to notice as matter piles up.
Near the Sun, that setup can squeeze the effect into a thin outer shell instead of spreading it across the system.
Turyshev calculates that this leftover signal could still affect light travel time and free-fall if instruments improve enough.
That makes chameleon-like models frustrating but testable, because they predict a weak residue rather than perfect silence.
Gravity hides itself
A second route, Vainshtein screening, suppresses the extra force through the surrounding gravitational field itself.
Instead of changing the force directly, the local environment chokes off its effects until a large boundary called the Vainshtein radius is crossed.
One account places the Sun’s Vainshtein radius near 400 light-years, or roughly 2.4 quadrillion miles (3.9 quadrillion kilometers), large enough to include nearby stars.
If that picture is right, near-term missions would struggle to see anything there, even if the extra physics exists.
Cosmic surveys guide
The best clues now come from Euclid, a European space telescope studying large-scale cosmic structure.
On the ground, the Dark Energy Spectroscopic Instrument (DESI) has built a 3D map from millions of galaxies and quasar spectra.
Those surveys watch gravity in sparse regions where a screened force should leak out more clearly than it does near the Sun.
Their role is not to settle the case nearby, but to narrow the local signals a solar-system mission should chase.
What counts locally
The team argues that local experiments help only if they target signals a screened model still allows.
One candidate is Shapiro delay, the slowing of light or radio signals as gravity bends spacetime around a massive body.
Turyshev estimates that a spacecraft signal passing near the Sun could probe departures from Einstein at about two to five parts per million.
That is precise by any normal standard, yet still far above what a heavily Vainshtein-screened force would leave behind.
Other narrow windows
Another opening comes from the Einstein equivalence principle, the rule that gravity pulls different forms of matter the same way.
Atom interferometers in space, upgraded lunar laser ranging, and linked optical clocks could catch mismatches or oscillations that navigation misses.
Turyshev forecasts sensitivity near one part in 100 quadrillion for some free-fall tests and threefold to tenfold gains for clock searches.
Each option looks for a specific leftover signature, which is exactly what screened theories require before an experiment can really fail them.
Missions drive discovery
None of that will happen by accident, because Euclid and the Dark Energy Spectroscopic Instrument watch the distant universe, not the solar gravity well.
A serious local search would need mission plans built around a falsifiable prediction, a clear signal model, and purpose-made instruments.
That is why the work favors a guardrail-and-discovery program: tighten limits, then escalate when one anomaly survives scrutiny.
Without that trigger, a costly flagship mission risks repeating the same answer in finer detail.
A harder standard
The argument also cuts against a common instinct in physics, which is to assume that more precision alone will solve a mismatch.
Here, precision matters only after theory tells researchers exactly where screening leaves a measurable residue.
That puts the burden on models that link cosmic observations to local leftovers instead of treating the two arenas separately.
If such a model survives, the solar system becomes a place to reject weak ideas and sharpen stronger ones.
What comes next
The work recasts a frustrating mismatch between cosmic behavior and local precision tests as a narrower problem of screened remnants and mission design.
That does not make a new force likely, but it shows how dark energy, dark matter, and solar-system physics might meet.
The study is published in Physical Review D.
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