The strangest objects in the Universe are "black holes". These are formed when a certain kind of star contracts towards nothing. As it does so, the material in the star becomes more and more dense and its gravitational field gets stronger and stronger. Eventually the star's force of gravity is so strong that nothing, not even light, can escape from it. Anything near the star is sucked into it and disappears. It becomes, in fact, a kind of invisible vacuum cleaner.
Strange as this may seem, an American scientist has produced an even stranger idea. He suggests that , as black holes can only get bigger, because nothing can escape from them, the whole universe might eventually consist of a multitude of black holes which might then combine into one universal black hole containing everything. The Universe will have sucked everything into itself !