Dark Energy Not Detected at Small Length Scales

According to Newtonian theory, the fate of the universe is clear: either the universe will keep expanding at an ever decreasing rate, or, if there is enough mass, it will eventually collapse in on itself. But, there is evidence that the rate of expansion is increasing. To explain this, phycisists have postulated the existence of a substance called dark energy that exerts a repulsive force counteracting the effects of gravity. According to cosmologists, the effects of dark energy should be observable as a short range force detectable at length scales around 85 µm.

PhysicsWeb (registration required, PRL, Pre-print) is reporting that a team from the Center for Experimental Nuclear Physics and Astrophysics (CENPA) at the University of Washington "found that Newton's law of gravity holds to a high degree of accuracy at distances as small as 55 µm." While this result does not rule out dark energy, it does provide a significant restriction on the range and type of interaction possible.

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