Before dark energy , cosmologists generally propose two scenarios of future universe . If the mass density of the universe is greater than the critical density , then the universe would reach a maximum size and then begin to collapse . The universe then becomes denser and hotter again , and will eventually reach the Big Crunch .
Conversely , if the density of the universe is equal or smaller than the critical density , the universe will slow development but will never stop . Star formation will then stop because of all the interstellar gas in each galaxy has been consumed ; stars that there would then continue to undergo nuclear burning into white dwarfs , neutron stars , and black holes . Very slowly , collisions between white dwarfs , neutron stars , and black holes will lead to the formation of larger black holes . The average temperature of the universe will be asymptotically reach absolute zero ( Freezing the Great ) .
Moreover , if the proton is unstable , then the baryons material will disappear , leaving only radiation and black holes as well . In the end all, black holes are formed will evaporate by emitting Hawking radiation . Entropy of the universe will rise up to the level of no more other forms of energy can be obtained from the entropy . This situation is referred to as the heat death of the universe .
Modern observations show that the expansion of the universe continues to accelerate , this means that more and more parts of the observable universe will now continue past the event horizon and we will never make contact with us again . The final result of the increasing development is unknown .
ΛCDM model of the Universe contains dark energy in the form of a cosmological constant . This theory suggests that only gravitationally bound systems , for example galaxy , which would continue to be bound together . However , even this galaxies will reach heat death as the universe expands and cools .
Other alternative explanations are called phantom energy theories suggests that ultimately galaxy clusters , stars, planets , atoms , atomic nuclei , and the material will be torn apart by the development of ever-increasing , and this state is referred to as the Great slit .
Title : The future according to the Big Bang theory
Description : Before dark energy , cosmologists generally propose two scenarios of future universe . If the mass density of the universe is greater than ...