As far as humans can tell, space is infinite; it has no end or borders. Scientists believe that space will always seem infinite to humans for two reasons. First, our investigation of space has never found an edge (or any indications of an edge). Second, measurements show that space is expanding faster and faster, which pushes the edges of the universe ? if there are any ? ever farther out.Know More
Space is continuing to expand (meaning that all the galaxies are speeding away from the center of the universe) because of the Big Bang's momentum and because of a substance called dark energy. Dark energy occupies the seemingly empty parts of the universe, but it has a strong negative pressure, pushing things away from each other even faster than they would move as a result of the Big Bang. This makes it difficult for humans to measure the farthest reaches of space.
In addition, anything traveling through space ? including humans' investigative tools, techniques and measurements ? is limited to the fastest possible speed: the speed of light. Because nothing can travel faster than light, there is a limit to how far scientists can explore or understand the universe. The size of the observable universe (the part astronomers could potentially study) is approximately 45.7 billion light-years across.Learn more about Universe
Giant elliptical galaxies form early in the life of local galactic clusters as members of the group pass close by each other and begin to merge, according to John Dubinski for the Canadian Institute for Theoretical Astrophysics. In any sizable galactic cluster, some galaxies near the core of the group gravitationally interact with each other, exchange material and eventually fall together to form the core of the central elliptical giant.Full Answer >
It is impossible to know what lies beyond the universe. Our modern technology can only detect the light that has had the time to reach us, making it impossible to even estimate the size of our universe.Full Answer >
In science, if something isn't directly observable it can't be "discovered." There is only indirect evidence of black holes. The existence of black holes has been a topic of speculation for hundreds of years, but John Wheeler is credited with coining the term, "black hole," in 1969.Full Answer >
Whether humans are the only intelligent life to have evolved in the universe cannot be answered with certainty, but a probability can be assigned to the proposition. Accurately estimating the number of advanced civilizations in existence is done by assessing the number of opportunities for intelligent life to evolve and contrasting that with the improbability of various stages in the development of a civilization.Full Answer >