Will the universe expand forever ?

I think the balloon analogy is excellent for demonstrating the overall expansion, but isn't ideal for galaxy collisions. 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... [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.

Drj312's response is correct, but even without those factors an unlimited expansion would not disprove gravity. For simplicity we will disregard such exotic things as dark energy. Gravity is dependent on mass. The more mass in the universe the greater the overall amount of gravity. If there is enough mass (and therefore gravity) then the expansion of the universe will slow and eventually stop. The universe will then begin to contract again. If there is insufficient mass then there will not be enough gravity to overcome the expansion. Despite the existence of gravity the universe will continue ... [More]

There are some very speculative ideas about the future of the universe. One suggests that phantom energy causes divergent expansion, which would imply that the effective force of dark energy continues growing until it dominates all other forces in the universe. Under this scenario, dark energy would ultimately tear apart all gravitationally bound structures, including galaxies and solar systems, and eventually overcome the electrical and nuclear forces to tear apart atoms themselves, ending the universe in a "Big Rip". On the other hand, dark energy might dissipate with time, or even become at... [More]

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 around wit... [More]

I really like your idea and believe it has merit. I wouldn't call it a theory yet, but the idea itself is as sensible as many other ideas that match with the known universe. I'd even dare to say that with my limited scientific knowledge on the whole thing, that it makes more sense than many other hypotheses that have floated around. You might actually be onto something! But then again, you might not... It's certainly not something I would brush under the rug as preposterous though. I don't study this subject matter myself, and don't know if anyone has ever proposed such a thing before. But if ... [More]

So, even if the Universe continues to expand, new galaxies will form around black 'holes' or even merge into giant-galaxies. 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 a... [More]

The Fandango Theory Hey I like the sound of that! It isn't a theory until it's backed up by empirical data. At present it is at best the The Fandango Hypothesis, as a hypothesis is a proposed explanation for observed phenomena.

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. 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... [More]

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