Among many particles arriving from outer space, there are ones with the extremely high energy that travel at nearly the speed of light, which is equivalent of a baseball thrown at a speed of 100 meters per second. New hypothesis for origin of those ultra-high-energy particles has been proposed, thus drawing particular attention from all over the world.
Source:
https://phys.org/news/2019-08-scientists-mystery-ultra-high-energy-cosmic-ray.html