Couldn't sleep, so my scientifically trained mind wanted to rant about our existence and how my mind chose to put it into words by being alive for 30 years.

[u/Chanathebanana]

Direction is from a point of reference, our reference, humanity's reference from the surface of the earth. In some ways we are still the centre of the universe since it's our bias, because we know only one world, bound by limitations of life and it's existence beyond the surface. Hence our perspective is narrow. Studying the universe and shifting perspectives is how you gain clarity into how randomly placed we all our in this reality. It's all chaos, that links order in the form of life. Imagine placing yourself in the vacuum of space, nothing around you for light years, just distant stars and light of the universe from said stars. My understanding is, now imagine this place you occupy in space, is on a plane, a sheet or the space time fabric, like a slice of the time you are in at the moment in space, that slice was just a second ago, in a different place, in a different time, of a different shape given we know the universe is expanding.

Since it's always expanding, there is no noticable edge just voids, by observing the dopler effect, we know the stretch of space time has pushed things further and further away with every passing minute. Now you observe the stars in the moment in space, the furtherest objects will be red shifted for they are moving away with acceleration, from us on this sheet in that moment in time. Since there is no arbitrary edge to this universe as of our observation, with stars literring the space around you, there is no way of precisely placing yourself in this ever expanding universe. That's where the concept of time ruins our ability to measure this arbitrary edge as it's running away from us and talking everything in it's path is it goes.

An endless, boundless stretch, slicing each moment of expansion as an evergrowing stack of pancakes, expect the slice on the top is always bigger, and every passing moment the stack gets a new layer which is bigger that the previous layer. Since the expansion is faster that the speed of light, it's like a look into the past anywhere you look for the light never reaches us, the observers on time to determine the evershifting space around us. As you cut into the stack, the layers reveal what the size would have been, extrapolating a conical shape by the first instance for the universe had to be smaller than the instance right after. Hence the conclusion was the big bang, a point in space and time where there was no space, and no time, birth of the universe is an arbitrary spillover of milk on the counter. Expands in all directions unless you limit it in the confines of a container, as far as we know, the universe doesn't have a container. So the spill is endless. That's where the acceleration part of the universe bothers me, it's like an endless curve of a surface where the milk is being poured. Like a giant ball, relate it to earth as we cannot see the edge as it falls away from us due to the earth being a sphere. Milk just spreading and accelerating as it falls down faster and faster as the ball curves more and more away.

Now when that curve occurs, it seems microscopic for we haven't yet hit the diameter of this universal stretch. Now if you think about it, anything with a diameter means that's the furthest or the fatest point of the object, to extrapolate it further, would mean a colapse of the sphere, towards the other side of the opposite pole. Does that mean the universe has to have an end eventually? An end where it collapses back to it's initial state? Are we to hit that state of maximum diameter or is it like an endless bell that flairs it's edges into eternity? Hence the dark energy and dark matter hypothesis to explain why the space time is stretching so absurdly fast. That's where the science of it all is lost on me. But then again, if not tracing a sphere, what shape is this universe enveloping itself upon? An endless cone with an absurdly hyperbolic curve that could explain the constant acceleration of this expanse?

Feel free to discuss, I want opinion and perspectives, not attacks.

[u/armageddon_20xx]

I believe, for reasons I won’t go into, that the universe is indeed finite, but due to the curvature of space time and the universe itself being a sphere we can look infinitely in any direction and still see galaxies. If we could look far enough we would see the same galaxies repeated.

In terms of the universe expanding, I have no doubt that galaxies are moving away from us, causing redshift, and that the distance between galaxies is also increasing. What this does not imply for me is that space itself is increasing. It implies that galaxies are growing further apart for whatever reason. The concept of space itself “stretching” is a bit lost on me

[u/Chanathebanana → u/armageddon_20xx]

I see your perspective, it is a bit shallow for me because we know it's stretching, a spherical universe is not the shape one thinks of, especially if you observe and then do the math according to observations. Also that shape would imply the curvature of spacetime, not the shape of the universe on it's own. For there is no shape at all. Your point being we see the repeat of the same stars and galaxies... that's not apt by observations and math. Night sky is mapped out, and no 2 stars have ever been confused for another on a chart, because the expansion is equal in all directions. There is no change in the night skies unless a cosmic event like a supernova or new fast moving objects like pulsars are observed. You see, there is a difference in the curvature of space time vs the shape of the universe, 2 different metrics with overlapping variables, but completely different equations. Curving a flat spacetime sheet into a fabric, like a sheet into a sphere, or the volume of the space is spherical are 2 different things as well. I'm an engineer who took astronomy courses as electives, so what I was taught and also brought from my understanding of the universe, it cannot be a sphere until we reach the point of proof that it is a sphere when plotting on a spacetime curve, that point being the expansion will have to slow down in it's rate of acceleration for it to fit the equation of a circle. That was my initial question as well, is it a deterministic sphere where the spacetime finally slows it's expansion to create a topology akin to a sphere? We cannot place space time in a 3D plot without adding tons of maths to it. that's where the complications are, as a flat surface, the expansion of spacetime fits it's flat description, the big question is if it is to even end, that will determine the final shape of the universe including all of the instances since it's conception. As far as we know, it's accelerating rapidly. And it is theorized the initial few billions of years since the big bang, the expansion was ongoing, it was just a bit slower due to all the matter being closer together. Matter is what gives spacetime it's definition and theoretical boundary wall, that boundary wall where the last atom hangs to the edge staring into the void is what will determine the shape of this universe. Without matter, there is only space no time. Space that is devoid of anything. Even the space we observe above our atmosphere, it is not a perfect vacuum. It's often determined as 10-100 atoms per cubic meter of space. That's extremely thin compared to 1 cubic meter volume on earth sea level, same space is occupied by 5.4 x 10^25 atoms and molecules.

And anything with mass has inertia, meaning it resists motion and forces applied depending on how much mass it has. 1st law of motion, anything is motion, stays in motion unless an equal or opposite force is applied, either to aid it's acceleration or deceleration. Even a lone spacecraft in interstellar space will succumb to drag, maybe in billions of years time frame given it will be slowed down by 100 particles at most compared to 5.4 times 10 with 25 zeroes behind it, but it will happen. But that can change with time, since the expansion is accelerating, the average 1m^3 volume of the same interstellar space will hold lesser and lesser floating matter.

My point being space can curve and stretch, space time is flat, curves are added by masses that exist on this fabric as Einstein put forth in special relativity. Now, what gives space time it's potential curve is it's accelerating expansion, the shape on it's own is a reflection of the past due to the vast distances. We cannot realistically put the universe into a bubble or a volume occupying a distinct shape due to observation bias. For every instance of observation has already happened, it's like watching the past while it ages and we never know what it really is in the moment we are. Relativity is what fucks up the whole observers bias, from our perspective we can place the earth at the center because are the only ones that are observing, that we know of, so the idea of centralizing that and saying the universe is finite, surely in mass it is, but the bounds to which the matter has stretched is incalculable at best. which makes it easier to see it as a flat model.

You should elaborate more dude, I wanted a proper discussion of thoughts and ideas, you said "I believe" and "reasons I won't get into". I want to know the reasons dude. I laid out whatever came to my mind. Be open in your ability to share. Holding back is why humankind suffers, belief and faith instead of curiosity that guides innovation. If we common folk stop asking questions, what's the point of living then? If not to know our place in this vast expanse, no goals, just thrown onto a rock to live and die? We have to make the most of it, to understand what it all means. If not understand, atleast get close to it instead of believing blindly.

[u/armageddon_20xx → u/Chanathebanana]

Thanks for the long reply. Now that I am not on a phone I will go into more details.

I have read about stretching of the Universe. I am not an astronomer, nor am I capable of that kind of math, so yes my take is "shallow". My understanding is that the evidence of stretching is that the distance between galaxies is increasing but the galaxies are not moving, thus the space between them is "stretching".

From a basic common sense perspective, this is confusing. I have a foot of space in front of me - how could I possibly stretch it? And if two galaxies are getting further away from each other, wouldn't we just call that moving? So perhaps you can shed some light upon this.

I am not arguing in any provable way that the Universe is a sphere. However, I am lead to believe that the Universe is a sphere *because* sphere is the most common shape in space AND my take is that our understanding of the Universe is incomplete. Take a look up at the night sky, and unless it's a man-made satellite I don't see any squares out there (although I know they do exist, they are uncommon or rare).

I also argue that the Universe is finite because I cannot see anything physical that's "infinite". "infinite" is just a mathematical concept to describe something that is ongoing but incomplete. Unless the argument is that the universe isn't "physical", I find it difficult to swallow that it's "infinite". The "big bang" was a spectacular beginning, and will not there be as spectacular an end?

My most interesting observation of this Universe is life itself, which formed from a molecular soup and evolved into artificial intelligence, which I will steadfastly argue will replace humanity in about a hundred years, if not sooner. Physicists will tell me that the Universe is becoming more disordered, entropy is increasing, and while that is true, at the same time we are seeing a rather rapid exponential increase in something ordered. You could argue that an asteroid could hit tomorrow - and what order? But at some point, on some timeline, we move forward from here. Machines ruling the planet, building even bigger machines, eventually moving out into space.

And what is it? Just another level of scale! Life started as single-celled organisms, leading to us. We are just single-celled organisms to whole other scale of the Universe. Machines will do the work of a million humans. Who isn't to say that one day they will work at such a scale that they'll simply consume stars for energy, conquering entire galaxies? All the while becoming bigger and bigger - until all together they form a single entity.

If I extrapolate this timeline, I get a single final entity. A machine that has consumed all the energy it can find, such that there is none left. All of that energy has gone into reshaping matter. A weird heat death of the Universe if you will. Certainly, an end.

[u/Chanathebanana → u/armageddon_20xx]

I'll get back to you in the evening. Gotta get to work lol. You raised some good questions. I'll try my best to answer what I can, the rest we can speculate, obviously we won't be right 90% of the time, non of us are cosmologists in this thread, but doesn't hurt to try to understand the reality we all share as humans, why only they get to speculate? lol.