Will the universe expand forever ?

I wasn't really trying to explain HOW the galaxies move, indeed my analogy was deliberately over simplified... as is yours. What I was trying to show was that there can be independent motion, and hence collisions, even within an expanding space/time. The reality is that galaxy movement is far more complicated as there is a layer of complexity which neither of our analogies take into account. Galaxies do not, in fact, wonder around independently on the whole, but are parts of clusters. These are groups of galaxies which are gravitationally tied together. The galaxies are free to move aro... [More]

I don't really understand why they don't take into account the creation of matter from energy. I mean, going back to the singularity that became our universe today, it didn't contain all the matter that is here today. The first element thought to have come into being was Hydrogen, and later other electrons bonded with helium to produce Helium etcetc. Even then, also, there were no stars but slowly the universe became full of them. So, even if the Universe continues to expand, new galaxies will form around black 'holes' or even merge into giant-galaxies.

Unless gravity isn't a force, but a by-product of space/mass. For reasoning that gravity is not uniform nor does it exist where there is no great collection of mass (more gravity inside a solar system than there is surrounding it.) I say it's not uniform, as for example, out suns gravity is strongest inside of itself, and weakest towards the edge of our solar system. At the same time, on Earth gravity is strongest away from the equater and weakest at the equater. Even Einstien and other major players in the field of Physics see gravity as an illusionary-force. Perhaps if there w... [More]

http://en.wikipedia.org/wiki/Dark_energy Ten years ago we did not know about dark energy and its effect accelerating the expansion of the universe. Ten years from now, or 100 years from now it's possible we may understand the fate of the universe to be quite different than we do today.

Sorry Waspie_Dwarf, I wasn't trying to say you were wrong by any means. And you're right, my analogy is definitely over simplified. The difference between using ants on the surface of an expanding balloon and the marbles is that the ants can independently change direction, stop, and start up again, without an outside force impacting those "decisions". Marbles dumped out on the floor don't "decide" where to go, they simply interact with the other marbles, the floor, and the walls due to basic physics. I was merely offering an alternate simplified way of exp... [More]

Thanks, its been on my mind for a while, I think im going to look into it further. Hey I like the sound of that!

No they won't. There is only a finite amount of matter in the universe. It is not constantly being replenished. As stars burn out and die they have used up their nuclear fuel... it can never be used again. Eventually there will be no more left for new stars. The Second Law of Thermodynamics states that entropy increases with time in a closed system. The universe is such a closed system. In effect this means that as the universe continues to expand it will become colder and colder, until it approaches absolute zero. As it approaches absolute zero no further chemical or nuclear reactions ... [More]

It isn't a theory until it's backed up by empirical data. At present it is at best the , as a hypothesis is a proposed explanation for observed phenomena.

That is possible, however it will not change the fact that expansion of the universe has been measured more and more accurately. We now know that the expansion is accelerating, no new discoveries are likely to change that. We may understand better why it is happening. We may discover some phenomenon that means we can get rid of the need for dark energy from our explanations. We may have a better understanding of what the consequences of a universe which expands forever are... but the speed at which the universe is expanding is a measurable quantity, it not going to be changed by any new dis... [More]

http://www.youtube.com/watch?v=GSMjtNRKepU&feature=related