But the answers are hidden in cosmic rays. Every second, our Earth is bombarded with billions of charged microscopic particles, including those from unknown hidden matter. Some of these particles can have extremely high energy, sometimes even billion-times higher than the a particle generated by CERN - the largest particle accelerator on Earth. These particles are called cosmic rays, and the more energy these particles have, the rarer they are. The cosmic particle with the highest energy is very difficult to detect: in a whole century, only a single one per square kilometer is detected. In order to increase the probability of such detection, it is necessary to build a larger detector. Is it possible to build one with the size of a continent, the whole Earth, or even bigger? People from the CREDO project want to achieve just such an ambitious idea.