Basically almost everything is held by gravity in space. Some astronomers believe some galaxies as held by black holes. But is that really the case? The short period of growth of the universe started of as the Big Bang about 13.7 billion years ago. After the Big Bang the universe started to cool of, starting protons and neutrons, hydrogen, helium, lithium and more. Stars, planets, galaxies started to form during the process. According to the European Space Agency's Herschel Telescope have discovered the brightest galaxies say to be the most important. The Herschels Telescope has very sensitive mapping that can locate thousands of galaxies. When the universe was still forming, the universe led to planets collapsing, asteroids running into planets, and galaxies colliding.
What if galaxies collided? Last but not least we have, why's if two galaxies were moving towards each other, would they explode? It is scientifically proven that according to the new study, that larger galaxies consume smaller galaxies. But we don't know that for a fact yet. You might be thinking galaxies are just stars and more who run into each other but galaxies have black holes in the centers. Scientists and astronomers are waiting for this moment to happen. Some galaxies can even have a mass of our own Sun. Some Galaxies have so strong black holes we have yet to discover what would