The Black Hole Era: 1040-10100 years

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As the Degenerate Era closes, we enter the Black Hole Era. Black holes are objects that are so dense and so massive that their escape velocity is greater than the speed of light. They are the only objects that may survive proton decay. Originally, the definition of a black hole implied that anything entering the black hole horizon would be lost and its gravitational attraction would not even allow light to escape. However, developments in quantum theory have subsequently suggested that it might be possible for radiation to leak out, although the process would be so slow that it would be almost imperceptible in today's universe. However, in a universe where all other stellar objects have evaporated, a black hole would be the brightest, albeit the only, objects that exist.

Note: Just in case we forget, we are in the realm of near total speculation. In reality, science has not yet even conclusively proved that black holes exist, although there are many who would now say that there is sufficient circumstantial evidence to validate their existence.

However, today, it is generally accepted that black holes can be created when a very large star explodes as a supernova. While the normal outcome may be a neutron star, if the remnant star left by the explosion is more than about twice the mass of the sun, the object may collapse into a black hole.

Note: Again, while there is some observational evidence that black holes do indeed exist, it is possibly too early to put a figure on the total number.

Even so, some have suggested that in a galaxy of some 100 billion stars, there may be as many as a million black holes. There is also some evidence suggesting that a super-massive black hole may exist at the heart of most galaxies. If so, this black hole could have a mass that is a billion times greater than our sun. The evidence cited in support of this speculation is based on the orbital velocities of stars at the centre of the galaxy. The high orbital speed suggests that there is a huge gravitational mass at the centre, which cannot be seen and is compressed into an extraordinarily small volume.

Keeping the degree of speculation in mind, it is possible that by the black hole era, the galaxies could be reduced to a massive black hole and up to a million smaller ones, all radiating small amounts of energy. While this process would be incredibly slow, it suggests that even black holes would have a finite lifetime, which depends on their original mass. Therefore, the super-massive black holes will live much longer than smaller black holes. The following numbers give an indication of the life spans of black holes:

  • At 1 solar mass, life expectancy would be ~1065 years.
  • At 10 solar masses, life expectancy would be 1000 time greater at 1068 years.
  • At 1 million solar masses, in line with a galactic black hole, life expectancy would be ~1083 years.

While, in human terms this may appear close to an eternity, the black hole era is finite and therefore destined to end. At this point, the active life of the universe would effectively end.