According to theory, the universe has been ever expanding since the Big Bang. Is the force from that initial event the only cause of the expansion of our universe?

 

Also, if that happens to be true. Would the force of gravity slow the universe's expansion to a point where it stops all-together?

 

since gravity affects matter in an infinite distance in all directions, would it not be true that the universe would begin to contract?

 

Lastly, because gravity would be the only force affecting all the galaxies, would they over time condense into an infintesimally small and dense black hole, recreating the initial conditions for the Big Bang?

"In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Dark energy is the most popular way to explain recent observations and experiments that the universe appears to be expanding at an accelerating rate."

http://en.wikipedia.org/wiki/Dark_energy

TO LEPTON - You wrote:

 

"According to theory, the universe has been ever expanding since the Big Bang. Is the force from that initial event the only cause of the expansion of our universe?"

 

ANSWER: No. The Universe has recently been observed to be expanding faster and faster, not slowing down as once believed. No one knows why and just use the term 'dark energy'.

 

"Also, if that happens to be true. Would the force of gravity slow the universe's expansion to a point where it stops all-together?"

 

ANSWER: The point is now moot since the universe is expanding faster and faster, not slower and slower as once believed. However, even when it was believed the universe was slowing down from the force of gravity, the unanswered question was whether it was slowing down enough to reverse direction. It is not an issue any longer.

 

"since gravity affects matter in an infinite distance in all directions, would it not be true that the universe would begin to contract?"

 

ANSWER: Gravity does not affect matter at infinite distances or instantaneously. It is limited in both distance and effect by the speed of light. For instance, nuclear fission reduces the mass and gravitational force of the core matterial. The reduced gravity is not instantaneously felt by solars systems many light years away. The reduced gravity effect travels at the speed of light.

 

"Lastly, because gravity would be the only force affecting all the galaxies, would they over time condense into an infintesimally small and dense black hole, recreating the initial conditions for the Big Bang?"

 

ANSWER: The universe is expanding faster and faster, not slower and slower. We don't know why. But clearly, gravity is not the only force acting on the galaxies. At least for now, there is no possibility of a big crunch. I believe this could change, however, if 'dark energy' is just another instance of temporary 'inflation'.