New calculations have shown that the average human gets hit by a particle of dark matter about once a minute. Dark matter, which is supposed to make up about 80% of the matter in the Universe, hasn’t been directly observed, but scientists have seen its apparent gravitational effect on galaxies and even larger galaxy clusters.
Scientists think that Weakly Interacting Massive Particles, or WIMPs, would have only a weak effect on baryonic matter, typically zipping through most of the universe, including people. However, they can collide with atomic nuclei on occasion, and new research shows that such collisions might occur more than previously thought.
Katherine Freese, a professor with the Michigan Center for Theoretical Physics, at the University of Michigan, states that these collisions happen once a minute. The research was published through arXiv and has been accepted for publication in the journal Physical Research Letters.
WIMPs were created at the dawn of the Universe, much like other forms of matter. However, they don’t interact much with baryonic matter. If two particles strike each other, they annihilate, turning their mass into energy. As the Universe expanded and cooled, WIMPs spread out so far that they no longer collided. Models suggest that billions of WIMPs are streaming through Earth and its people every second.
The results of the new calculations show that oxygen and hydrogen atoms are more likely to be struck by WIMPs. Since humans are made up of large quantities of water, the human body has a lot of potential for WIMP interactions.
The collisions inside the human body aren’t dangerous.
Reference: “Dark Matter collisions with the human body” by Katherine Freese and Christopher Savage, 24 September 2012, Physical Research Letters.