Elements and matter are consistently the same throughout the universe. Matter is theorized to have originated in an initial explosion where the simplest element, hydrogen, was formed. As hydrogen spread out through empty space gravity "clumped" the hydrogen gas into large massive clouds. When the clouds were massive enough, and pressure in the center of the clump was sufficient, hydrogen atoms began to fuse together in a nuclear fusion reaction to create helium. A star is born. When all the hydrogen has fused into helium, the fusion reactions stop, cooling and collapse occurs, and when pressure is sufficient helium then begins to fuse into other elements. Lithium elements to Iron elements are formed in this second stage. As helium is used up and elements are created and thrown into space, the star cools and collapses again. This final stage creates so much pressure as it cools that the star rebounds and explodes, creating the remaining elements found in the universe and sending them out into space traveling near the speed of light. Elements are formed from the stars, a "common origin."