The universe is an amazing place from what we observe. The distances are truely mind numbing to even attempt to grasp in some meaningful way. To give an idea of how mind numbing I offer you this YouTube clip.
Near everything we observe is going away from us. That is lacking a few such as the Andromeda Galaxy.Andromeda Galaxy
Everything can be measured as how fast we are departing from each other through red shift. The typical rule of thumb is the farther away an object, the faster is it moving away. Anything going away from us has it's light red shifted. The furthest objects we have detected through the Einstien Ring has been red shifted into the infrared part of the spectrum. The Einstein ring is a quirk of gravity, predicted but until fairly recent modern times never observed. Einstein ring
Anything approaching us has it's light blue shifted. There are not many galaxies that are blue shifted we find. The Andromeda Galaxy is blue shifted because we are due for a collision with it in about 4 billion years. You might want to circle that year on your calender so as not to miss it.
We've gone through several ideas over time as to the nature of the Universe and what that might mean to us. During Medieval Ages the universe was thought to be filled with Aether. A material that filled all space so that light and gravity had something to transport it along.
At some point the idea of the Big Crunch came along. The Big Crunch was that if there was not enough energy to continually push the universe in expansion that one day it would run out of energy and reverse direction. All mass and objects headed back to a center point. Sort of like when you throw a ball in the air and it comes back to earth. Others felt that there might not be enough gravity to oppose expansion and it might continue on forever.
A term was created called The Omega Factor (Ω). The idea here was that if the Ω factor was 1 or greater, the expansion of the universe would never stop. If it was less than 1 then the Big Crunch was the ultimate fate of the universe. At the time dark energy and dark matter were not named but something was realized not accounted for. The Ω factor eventually came out to be slightly larger than 1, meaning there will be no Big Crunch. Instead the fate of the Universe will be continued expansion, at an ever increasingly faster rate. If humans are around there will come a time when no stars are visible in the Universe. That everything will be so far apart, reaching another star system won't be possible, given the science we know today. This will occur before the ultimate end of entropy. Entropy being the loss of all energy to where there is nothing left of moving molecules or enough energy to see light, nor heat. Again relativity will stretch that time a bit longer, due to the slow speed of light traveling. Probably for many millions of years afterwards possibly billions, that last beam of light will continue in space until it finds something that blocks its photons.
The universe will end with a whimper, not a bang.