Mysterious "Fifth Force" May Exist

We know about the four fundamental forces of nature: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force. They govern all physical interactions in the universe. But scientists believe there's a mysterious "fifth force" as well, Science Daily reported. A NASA physicist says we might need to look closer to home, not just at distant galaxies, to find evidence of the new fundamental force of nature. In a paper published in Physical Review D, Dr Slava G Turyshev of NASA's Jet Propulsion Laboratory argues that precision experiments within our own solar system could reveal a "fifth force" tied to dark energy and dark matter. The four already known forces don't fully explain the universe. Gravity works beautifully for planets, but it can't account for why galaxies hold together or why the universe's expansion is accelerating. That gap is usually filled by "dark matter" and "dark energy". But no one knows what they are. It might be evidence of a fifth force.