If you don't live in a big city in Poland, you can observe many stars at night. Did you ever wonder how would look our sky in the next millions of years if we would count only on existing proven astrophysical theories and calculations? It would be absolutely empty. All celestial bodies in the galaxy are rotating around the biggest black hole in the middle of galaxy (in Milky Way this black hole is 6.4 billion times heavier than our sun) with such speed that the gravity generated by galaxy’s observable matter could not possibly hold them together. This leads us to conviction that something we cannot see is at work and is giving galaxies extra mass, generating the extra gravity that galaxies need to stay intact. Something, that will ensure us that our sky will remain the same as it was a million years ago. The official name of this strange and unknown matter is the “dark matter”. Unlike normal matter, dark matter does not interact with the electroma...