Just like the Big Crunch and the Big Freeze, the Big Rip is a theory that speculates about how could the death of the universe be. Unlike the first two theories, which depend on the matter density in the universe, the theory of the Big Rip, proposed by Robert R. Cadwell, is based on dark energy.
According to the current observations, it is thought that the latter is formed by about 70% of dark energy (plus a 25% would be dark matter, which is invisible for us, and the remaining would be formed by the type of matter we are formed of, and that we can see). It is this energy, present in all the universe, responsible for its expansion, which is increasingly faster.
What does the theory propose?
The theory of the Big Crunch holds that a moment will arrive in which the amount of dark energy will be so elevated that the universe will end up tearing itself up.
In the first place, a billion years before the end, galaxies will separate the ones from the others, as is already happening nowadays. Then, gravity wouldn’t be strong enough to maintain galaxies gravitationally bound, and 60 billion years before the end, only isolated stars, with their planets around, would exist in the universe. However, even the latter would end up disappearing. Approximately 3 months before the end of the universe, the solar systems would lose their gravitational cohesion.
During the last minutes, stars and planets would decompose. At this moment, the universe would only be formed by single atoms, but it wouldn’t have been all over. Atoms would end up being destructed in a fraction of a second before the end of time and only radiation would be left over. The universe would be like instants before the Big Bang, but with an enormously big size, and an infinitely small density.
When it is thought it will occur?
As I have already said, the quantity of the existent matter in the universe is much lower than the quantity of dark energy. For this reason, and because dark energy produces an opposite effect to gravity, the theory of the Big Rip is one of the most accepted theories speculating about the death of the universe.
The authors of this theory estimate that the end of the universe, caused by the so-called Big Rip, will take place in about 50 billion years.