‘Chameleon’ forces remain elusive in a new dark energy experiment
A hypothetical fifth force that morphs based on its environs didn’t turn up
![photo of a levitating force sensor in gold amid red-hued light](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2022/08/082522_EC-chameleon-particles_feat_rev.jpg?fit=1030%2C580&ssl=1)
A levitating force sensor (shown) found no hints of a fifth force predicted by “chameleon” theories that aim to explain the dark energy that is causing the universe to expand at an increasing clip.
Han Xie