Re OP POV
I'm sure there are many books, vids and articles on the subject but I'll try and explain what I understand, in a proverbial nutshell.
Gravity is one of the four main forces binding things together, albeit the weakest by far. If something has mass, it has gravity and the effect on another mass is inversely proportional to the square of the distance i.e. 4x less effect at 2x distance, 9x less effect at 3x distance, etc. (Newton's Law of Universal Gravitation) Thought the force decreases dramatically with distance, it's still there, as evidenced by everything from apples to super clusters. It is a universal force on mass, an attractive force acting even between particles flung from an explosion, resulting in a rather uneven distribution of matter.. See CMB (cosmic microwave background) Stuff eventually clumped together and got hot, all due to gravity. Thus, the universe became full of stars, and everything stars have created since.
As for the demise of the universe, there are a few theories and they involve what seems to be two prize fighters contending for eternal dominance of everything; gravity pulling things together and dark energy pushing things apart. Dark energy is a yet to be defined force that is the result of observations showing that acceleration of expansion is increasing between cosmic stuff despite the current theories/numbers.
The Big Crunch will happen if the observed expansion of everything slows/stops/reverses due to gravity overcoming dark energy pushing everything apart. Eventually, gravity will let the air out of the balloon and everything will compress back to into another Big Bang, possibly an eternal cycle.
If dark energy intensifies, the acceleration of expansion will have a runaway train effect and it will eventually overcome gravity's hold on matter and the "order" it brings to what we have now. The cosmos will expand at an accelerated rate until even gravity can't keep things together. Crazy shit will happen. All matter will be eventually be stripped apart, down to atoms whose binding forces are far greater. What's called The Big Rip.
If the acceleration of expansion continues as is, a cosmic "red-out" will occur, in that everything will become so far away so fast and it's light will become so red-shifted that it disappears into the "static" of the universe's background noise, the CMB. There will be fewer and fewer stars in the sky, until there are none.
A similar but slower fate would exist if gravity and dark energy "equal" out, acceleration will slow/stop but inertia will exist and the universe will still expand slowly, forever. The universe will exist for much longer but eventually the last stars will become (theoretical) black dwarves around which circle globes of cold rock, minerals and gas.
It would follow that the last two theories are not entirely discrete and are endpoints of similar but increasingly radical curves. If acceleration continues, slows or stops, the end result is similar i.e. Big Freeze
Fascinating, eh?
Anywho, I don't have any specific references and stand to be corrected on any of this but I enjoyed the opportunity to possibly share some ideas and knowledge, such as it is. It is a discussion forum after all...
