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A thought
Posted Jan 24, 2003
I woke up in the middle of the night a couple of days ago and probably half asleep decided to write something to do with an essay I was researching for at the time. So I wrote about the end of the universe and what will happen, not that it matters because we won't be around to see it but tell me what you think about it.
The Future of the Universe
The future of the Universe. The fate of all matter and energy on a cosmological timescale of many billions of years. According to the consensus in present day cosmology, the universe was born in a gigantic explosion called the big bang and is still expanding today. Its ultimate fate depends on how much matter it contains. Gravitation – The pull of each piece of matter on every other- is slowing the expansion. If there is enough matter in the universe (more than the so-called “critical density”) the expansion will eventually halt and then reverse. Everything in the universe will fall together and be crushed in a “big crunch” the reverse of the big bang. In these circumstances, the universe is aid to be closed. It is not possible to say how far in the future the big crunch could be.
During the collapsing phase of a closed universe, Galaxies would begin to merge about a year before the big crunch. The cosmic background radiation would become hotter as it was compressed by the shrinking of the universe, and would eventually become hotter than a star, so that the stars would dissolve into a sea of hot particles. An hour before the moment when the big crunch would occur, if the collapse were to continue smoothly, giant black holes at the centers of the galaxies would begin to touch one another. As they did so, the rest of the collapse would occur in a fraction of a second. It is possible that this sudden collapse would cause a “bounce”, creating a new expanding universe, born phoenix like from the ashes of the old one.
If the universe is of less than the critical density, it is said to be open, and it will carry on expanding forever. About a million million years from now, all star making material will have been used up, and from then on galaxies will start to fade as stars die out and are not recycled. Some stars will end up as black holes, others as cold balls of matter, in which over enormous periods of time (10^33 years or more) even the protons may decay into radiation and positrons (the positive counterparts to electrons). Neutrons, the other major component of ordinary matter, also decay into electrons and protons, so that ultimately all of this matter will have been converted into radiation, electrons and positrons, which will annihilate one another to leave more radiation. Black holes also “evaporate” eventually, emitting radiation as they do so. Nothing would be left in an open universe but radiation.
Observations published by two teams of scientists in 1998 have given weight to the likelihood of an open universe. Both teams were measuring the red shift of type 1A supernovae in distant galaxies and the results they obtained indicated that the galaxies were fainter and therefore further away, than standard models predicted, suggesting that the expansion of the universe, far from slowing down, is actually accelerating. This observation had two important implications: firstly that the expansion of the universe has been slower in the past than it is now, meaning that the universe is older than previously estimated and secondly that an active repulsion, or anti-gravitation is functioning with an ever increasing force proportional to the increasing volume of space in the universe. No theory as to how such a force might act has yet been tested.
We do not know which of these will be the ultimate fate of the universe because it is very difficult to measure its density today. If there is enough matter in the universe to make it closed, most must be in the form of unobservable dark matter, hypothetical material that is unlike the matter we are familiar with. However this would not affect the scenario just described. If there is no dark matter, then the universe is certainly open. It is also possible that there is a precisely the critical density of matter in the universe, in which case it is said to be flat. In this case the universe would expand ever more slowly, never quite coming to a halt, and hovering for eternity on the point of collapse.
This would require a precise ratio of ordinary matter to dark matter. However according to some theories, exactly this ratio was produced in the big bang.
A concerted effort is under way to detect the dark matter that is believed to exist. Studies of motions of galaxies show that their movements are slowed by unseen matter, accounting for at least part of the suspected matter. Some dark matter undoubtedly exists in the form of large numbers of brown dwarfs, masses of gas of less than one tenth of the mass of the sun, too small to shine as stars, which began to be discovered in the mid-1990s. But these relatively “conventional” objects will probably not account for all of the missing mass.
Physicists are searching with particle accelerators for a whole range of conjectured kinds of elementary particle, which, if they exist, would form an undetected ocean underlying the universe with which we are familiar.
As we are not capable of measuring the mass of the universe no definite conclusion can be made as to what the future of the universe is.
and that is as far as I got but if I have any more midnight inspirations I'll post then here.
Discuss this Journal entry [46]
Latest reply: Jan 24, 2003
Christmas
Posted Dec 19, 2002
The end of another year, anyway pop open a bottle of bubbly because I have a feeling 2003 will be better, heres to hoping.....
Discuss this Journal entry [1]
Latest reply: Dec 19, 2002
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