The End of the Universe - big crunch or big bang?

Scientists working at the Sudbury Neutrino Observatory (SNO) in Ontario, Canada have finally revealed the fate of the Universe ...

They have managed to calculate the mass of the elusive neutrino particle and have concluded that the combined mass of the colossal amount of neutrinos in our universe is not enough to halt a universal expansion. The universe is therefore destined to expand forever until it becomes a cold, dark place devoid of all signs of life.

What is a neutrino anyway?
Technically, a neutrino is a lepton with zero charge, half spin and an extremely small mass that only interacts with other particles through weak interaction. Its existence was originally postulated by Wolfgang Pauli to account for the missing energy in beta decay. It is thought that neutrinos make up a large portion of the dark matter in our universe. Neutrinos come in one of three types: electron, muon or tau.

The physicists working on the project were trying to explain the problem of the missing solar neutrinos. The nuclear reactions fueling the Sun emit a vast quantity of electron neutrinos, but experiments find that only a fraction of the expected amount of electron neutrinos reach Earth.

The experiments at Sudbury proved that neutrinos can oscillate between the different types, accounting for the discrepancy in the amount of electron neutrinos. This interesting discovery is far-reaching in that in implies that the direct evidence for solar neutrino transformation also indicates that neutrinos have mass and, by combining this with previous information, it is possible to set an upper limit on the sum of the known neutrino masses. According to Scott Tremaine, professor of astrophysical sciences at Princeton University, "This is the final clue we need to determine the fate of the Universe".

Missing Mass
In order for the universe to halt expansion and eventually contract into a 'Big Crunch', the mass of the universe must be above a certain value. The stars and galaxies in the universe detectable by our telescopes and instruments only account for a small fraction of this total mass, an assertion clearly supported by indirect evidence, e.g. the rotation of galaxies.

Therefore neutrinos were thought to make up a large fraction of the dark matter in the universe. But with an upper limit on their mass, the total mass of the universe cannot reach the critical level, so our universe will surely expand into infinity with all its remaining consequences.

Consequences
If the 'Big Crunch' model is discarded, the universe is predicted to expand into a diffuse, dark nothingness during the consecutive degenerate, black hole and dark eras. Planets will detach from stars that will in turn evaporate from galaxies. The proton will decay, all stars will run out of fuel and be engulfed by black holes that will radiate all their masses and leave the Universe a vast, cold, sterile place.

Update to article:
The Ontario research is not a final say, however. A new force called 'dark energy' is known to push galaxy clusters apart and its composition is unknown. That too could affect the universe's fate. In addition, astrophysical constants like the fine structure constant (alpha) slowly change over time. At some point, a constant like α or some particle’s mass may decay past a critical point and universal matter would disintegrate. Whatever happens will not happen during our lifetimes or our children's and thus there is no need to worry – even though scientists can create a black hole capable of swallowing Earth.

Author: Astronomy Today Staff