Space is interesting because for us it is literally the final frontier and there is so much that we don't know, for everything we do know there are 100 more questions to be asked. For example, what is space? Is space just in fact that? Nothing but empty space? What is beyond what we cannot see? How did the big bang happen? What caused it? Even more so..what came before it? How Large is it? So on and so forth, there are an infinite amount of questions.
Well for starters Space is indeed not just empty space. Space, according to Einstein is a fabric called spacetime, meaning space and time are interlocked and one in the same. Just because you cannot see anything does not mean there is nothing there. Black holes,dark matter, dark energy. Dark energy in fact is said to take up about 70% of the observable universe and is the leading culprit as to why the universe is expanding at a startling pace. As for Size, the universe is said to be spherical and infinite and could possibly be as large as 94 billion light years across(this is just what we can see).in fact it could and in all likely case is bigger, light just has not reached far enough yet in ether direction which prevents us from seeing any further. With some 100 billion plus galaxies with some trillions and trillions of stars, you get one really large place, I once heard there could even be as many as 300 sextillion(Which is a mighty enormous number..thats a lot of zeros). So in basic terms, the universe is almost beyond our normal human understanding.
It is actually very complicated, so much in fact it can tie your brain in knots. As far as the Big Bang is concerned, people are still undecided on what actually caused the big bang. Why did it Bang?What caused it to bang? Nobody really knows, Scientists have always thought of the big bang as the starting point, as the moment of creation of everything we know of. Now Scientists are beginning to rethink this notion and are starting the thing the big bang was actually the end of something else entirely. Everybody knows that inflation is what caused the mass expansion of the universe but now behind closed door, there are more and more scientists that are questioning the big bang, as I've said, everybody knows what happened after but now people want to know what was before, what exactly caused the big bang? Well, an idea that seems to be getting a lot of seem is that we live in a multiverse that we are just one of a possibly infinite amount of other universes. The basic idea is that each universe is located on some kind of membrane and when one of these membranes come into contact with one another then they create the energy necessary to create a big bang which creates a universe which could possibly explain how our universe came into existence, with the collision of two of these membranes.
As for the death of the universe, the scientific community have pretty much come to common ground as think that the universe will end in a big chill. The universe will keep expanding forever and there will come a time(some 50 billion years from now)When everything is so far apart and light takes so long the reach distant galaxies that the remaining stars will exhaust all their remaining fuel and burn out and this will continue to go on until there is nothing left and the universe becomes a very cold and dark place. Then there is also the big rip theory and the big crunch. The big rip states that dark energy will continue to expand the universe at an accelerated pace that everything will be traveling so fast that all matter will be ripped apart, even the smallest atoms. The big crunch is almost the opposite. Gravity will eventually stop the accelerated expansion on the universe and pull everything back together into another singularity and the process will then start all over again. Which ever you decide to believe, our future looks grim no matter which way you slice it.
as far as the little bit on the expansion of mars and such and such. The universe is so massive that it does not have much of and effect on the grand scheme of things. The galaxies are held together by the super massive black holes at the center of all galaxies, dark matter also plays a key role in holding a galaxy together so they don't spin to fast and basically fall apart. Mars is in the same orbit from earth because all the plants orbit around the sun, they are all held together by the sun's massive gravity and coincidentally happen to be traveling at a nice speed which keeps them in orbit so as they don't fly off into the depths of space or into the sun itself. The suns gravity is so massive that it effects the things furthest away from us, such as the kuiper belt which extends as far out as 55-100 AU(Astronomical Units) Which is where many scientists believe that Pluto is from,Pluto is the start of the Belt which is said to be has 200 times as massive as the asteroid belt. Going even further out is the Oort Cloud. Which is approximately 50,000 AU(nearly a light year) out. This is where the Sun's gravitational influence ends.
You trying to tell me we could keep going and going and just discover planet after planet? galaxy after galaxy? And just go on forever never running into the same place? I don't buy that. There's gotta be a loop somewhere.
lol wut? Planets only exist in galaxies for the most part, much of the know physical mass that we know of exists in these galaxies, out of the galaxies are just stray space junk that are left overs from the big bang(and mostly dark energy). If you indeed kept going you would not discover "planet after planet" "Galaxy after Galaxy" The universe has only been around for some 13.7 billion years therefore it has only expanded for that amount of time. There simply has not been enough time for the galaxies and light to travel beyond a certain point(which is sometimes know as the light horizon). The universe as simply not had enough time to expand past this point. This is why we only know of the observable universe(all of which we can see up until a certain point). If you were to some how reach this point and keep going then I guess it is possible at some point you would simply arrive back at the point you start from but I think you would just keep going...and going..and going, forever, possibly never reaching anything. At some point you would become lost, seeing nothing but blackness in all directions and you would be fucked.
These things are explainable if you take the time to do some research into it. My former science teacher was obsessed with all things universe and would often explain stuff like this for much of the period and is quite fascinating and prompt me to do some research of my own. Things are more complicated than you realize, so complicated that even the most brightest and sharpest minds have difficulty comprehending much of it.
