"One of the parameters used to describe the universe is Ω (the Greek letter omega), defined to be the ratio of the total gravitational potential energy to the total kinetic energy.
Since the universe has mass and hence gravity, it must have gravitational potential energy as well. The expansion of the universe represents motion, so the universe must have kinetic energy as well. As the universe expands, the gravitational potential energy will change. At the same time, gravity will slow the rate of expansion so that the amount of kinetic energy will change as well. Generally the
two energies will not change in the same sense or by the same amount so that Ω will change with time. A value of Ω < 1 means that the kinetic energy is greater than the gravitational potential energy. Conversely, a value of Ω > 1 means that the gravitational potential energy exceeds the kinetic energy. If a big-bang universe began with Ω < 1, then Ω will decrease in value. The minimum value is zero. If on the other hand Ω > 1 at the beginning of the universe, then Ω should have increased in value. Therefore, over billions of years the value of Ω should have dramatically changed from its initial value. For several decades all data have suggested that while Ω is indeed less than 1, it is not much less than 1. The sum of all visible matter in the universe produces an Ω equal to about 0.1. The prospect of dark matter pushes the value of Ω closer to 1.
The fact that Ω is very close to 1 today suggests that the universe began with Ω almost, if not exactly, equal to 1. If Ω were only a few percent less than 1 initially, then the evolution of the universe since the big bang should have produced an Ω dramatically less (many orders of magnitude) than 1 today. How close to 1 did the value of Ω have to be at the beginning of the universe to produce the universe that we see today? The value depends upon certain assumptions and the version of the big bang that one uses, but most estimates place the initial value of Ω equal to 1 to within 15 significant figures. That is, the original value of Ω could not have deviated from 1 any more than the 15th place to the right of the decimal point. Why should the universe have Ω so close to 1? This problem is called the flatness problem. The name comes from the geometry of a universe where Ω is exactly equal to 1. In such a universe space would have no curvature and hence would be flat. There are several possible solutions to the flatness problem.
One possible answer to the flatness problem is that this is just how the world happens to be. While this is not a physical impossibility, it does raise some troubling questions, at least for the atheist. It seems that the initial value of Ω could have been any number, but only a very small range in values could have led to a universe in which we exist.
If Ω were too small, then the universe would have rapidly expanded to the point that the density would have been too low for stars and galaxies to form. Thus there could have been no planets and no life. Ergo, we would not have evolved to observe the universe.
If on the other hand the value of Ω were initially too large, the universe would have ceased expanding long ago and contracted back to a “big crunch.” This would not have allowed enough time for us to evolve. Either way, we should not exist. Therefore the correct conditions that would have allowed our existence were present in the universe from the beginning." UnvierseByDesign
Since the universe has mass and hence gravity, it must have gravitational potential energy as well. The expansion of the universe represents motion, so the universe must have kinetic energy as well. As the universe expands, the gravitational potential energy will change. At the same time, gravity will slow the rate of expansion so that the amount of kinetic energy will change as well. Generally the
The fact that Ω is very close to 1 today suggests that the universe began with Ω almost, if not exactly, equal to 1. If Ω were only a few percent less than 1 initially, then the evolution of the universe since the big bang should have produced an Ω dramatically less (many orders of magnitude) than 1 today. How close to 1 did the value of Ω have to be at the beginning of the universe to produce the universe that we see today? The value depends upon certain assumptions and the version of the big bang that one uses, but most estimates place the initial value of Ω equal to 1 to within 15 significant figures. That is, the original value of Ω could not have deviated from 1 any more than the 15th place to the right of the decimal point. Why should the universe have Ω so close to 1? This problem is called the flatness problem. The name comes from the geometry of a universe where Ω is exactly equal to 1. In such a universe space would have no curvature and hence would be flat. There are several possible solutions to the flatness problem.
One possible answer to the flatness problem is that this is just how the world happens to be. While this is not a physical impossibility, it does raise some troubling questions, at least for the atheist. It seems that the initial value of Ω could have been any number, but only a very small range in values could have led to a universe in which we exist.
If Ω were too small, then the universe would have rapidly expanded to the point that the density would have been too low for stars and galaxies to form. Thus there could have been no planets and no life. Ergo, we would not have evolved to observe the universe.
If on the other hand the value of Ω were initially too large, the universe would have ceased expanding long ago and contracted back to a “big crunch.” This would not have allowed enough time for us to evolve. Either way, we should not exist. Therefore the correct conditions that would have allowed our existence were present in the universe from the beginning." UnvierseByDesign
Through faith we understand that the worlds were framed by the word of God,
so that things which are seen were not made of things which do appear.
Hebrews 11:3
