An experiment using the Earth itself as a source of electrons has narrowed down the search for a new force-bearing particle, placing tighter limits on how big the force it carries can be.
As an added bonus, if the new particle is real, it will shed light on processes and structures inside Earth, say study researchers from Amherst College and the University of Texas at Austin. The experimental results appear in the Feb. 22 issue of the journal Science.
The new force of nature carries what is called long-range spin-spin interaction, said lead study author Larry Hunter, a physicist at Amherst. Short-range spin-spin interactions happen all the time: Magnets stick to the fridge because the electrons in the magnet and those in the fridge's steel exterior are all spinning around in the same direction. But longer-range spin-spin interactions are more mysterious.
The force would operate in addition to the four fundamental forces familiar to physicists: gravity, electromagnetism, and the strong and weak nuclear forces. Some physicists think this new force exists because extending the Standard Model of particle physics — a theory that defines the physics of the tiniest particles — actually predicts as-yet undiscovered particles that would carry it.