What if the universe is a four-dimensional ball?

[Fraxtil]

I've been thinking quite a bit about the non-observable universe lately. I began to notice quite a few similarities between the entirety of the universe and Earth. A few centuries ago, people believed that the Earth was a flat, two-dimensional surface with edges, like a piece of paper or a 2-by-4. Today, of course, we know that the Earth is a three-dimensional sphere. This leads me to wonder if we have an equally naive concept of the universe's shape. Today, most people believe that the universe is a large three-dimensional glob or sphere with boundaries, similar to a balloon or an amoeba. However, there is a growing amount of evidence that the universe is infinite or boundless. I'd prefer to think of the latter term. We know that if you walk in a straight line across the Earth, you'll eventually arrive where you started. What if the same principle applied to the universe? Perhaps the universe is a giant four-dimensional hypersphere, so that if you were to travel in a straight line through the universe you would eventually come back to where you started?
It's been theorized that the universe has more than three spacial dimensions. I'm taking this theory to the next level by suggesting that the fourth dimension doesn't simply give it depth, but rather gives it a shape. Any criticism/alternate theories?

[Zora_S_Kenneth]

I'd think that those quantum physicists would have figured it out by now. "Earth is flat" theory came out of observation but no proof. We have obtained proof by confirming the existance of dark energy that is responsible for expanding our universe. (Dark energy may also be a string, but that's an unproven theory).

[Condog]

I think out universe does have four dimensions. The first three are the x, y and z axes of space, whic allow us to move freely through 3 dimensional space. The fourth is time, which progresses in a straight line at a fixed rate (Although it might technically be possible to move backwards on the time axis via faster than light travel).

So while I agree that it does have four dimensions, I don't think it is cyclic in nature. You would just keep going forever.

[wolfgang]

Yes, time is usually considered to be the fourth dimension. But a universe with more dimensions than we perceive is quite possible.

String theory relies on the existence of qute a few extra dimensions I believe. Although my memory is very vague at this point because I watched that documentary several years ago. There was one guy who said extra dimensions would explain why gravity was such a weak force, because it might be the only fundamental force (gravity, strong nuclear, weak nuclear and electromagnetism) which acts throughout all dimensions.

[rambo5252]

what if it was like a game and when u got to the end of the universe you appeared at the other side =/
or if you reached the end of it you had to turn around and go back becuase you cant go forward beceause their is absolutly nothing on the other side?
or if we are just a video game that other people are playing, like the sims
or what if a new big bang destroyed out universe as a new universe opened up
ok im done now lolz

[t̷s͢uk̕a͡t͜ư]

Okay, let's clear a few things up...
Mathematicians, physicists, and all the other similarly trained people, abstract their own dimensions as they believe helps them work with whatever they're working on better. Particle physicists, for example, frequently use a phase space of 8 dimensions (x position, y position, z position, time, momentum in x direction, momentum in y direction, momentum in z direction, kinetic energy). The point I'm trying to make is that you can arbitrarily tack on additional information as another dimension just about anywhere, and the fact that we can do that does not describe anything objective about the way the universe functions. We can slap on color and temperature on to that 8-dimensional vector if we thought it was relevant, but that doesn't mean that in all of natural law across the universe the 10th dimension is color. In fact, you can make a few calculations about 3-dimensional physical space a bit easier if you abstract one or more physical dimensions. But this doesn't mean that reality actually has more than 3.
So if that's where you're coming from, there's no reason for you to believe that there are more than 3 physical dimensions if all you're going by is that it's possible to describe such a vector space mathematically.
And all these people saying that time is the fourth dimension should technically be saying that physicists usually find it convenient to make time the fourth dimension. Fun Fact: the universe does not actually care about how humans attempt to comprehend it, and while functional for exploring the universe for humans, the universe may not actually hold to any human conceptions of "dimension."

Unless you're talking about parallel universes or something, in which case I'll just leave before I get angry.

[smartalco]

We have obtained proof by confirming the existance of dark energy that is responsible for expanding our universe.

Dark energy is still a theory.

I forgot what else I was going to rant about...

[Lightning55]

I think out universe does have four dimensions. The first three are the x, y and z axes of space, whic allow us to move freely through 3 dimensional space. The fourth is time, which progresses in a straight line at a fixed rate (Although it might technically be possible to move backwards on the time axis via faster than light travel).

So while I agree that it does have four dimensions, I don't think it is cyclic in nature. You would just keep going forever.

Time is a figment of the human mind created in order to organize themselves.

We have obtained proof by confirming the existance of dark energy that is responsible for expanding our universe.

Dark energy is still a theory.

I forgot what else I was going to rant about...

Dark energy is what I would call "negative space" The more it absorbs, the less space it takes up. Dark energy is energy that we can detect by its influence on other objects, but that we cannot detect itself.

I believe the fourth dimension is the hole through places. It would be like a shortcut to all of the past, present, and future. It could travel through to the past in the same spot. It could transfer you 10000bahcaltumophicillion miles across the universe in the same second, or 500 years into the future.

The main concept is that we as humans with our pathetic minds are probably not able to comprehend enough dimensions to see the entire universe.

[DemonzLunchBreak]

Time is a figment of the human mind created in order to organize themselves.

lolwut

Dark energy is what I would call "negative space" The more it absorbs, the less space it takes up. Dark energy is energy that we can detect by its influence on other objects, but that we cannot detect itself.

I... what? Do you know anything about physics at all, or are you just making shit up? Energy is not space. Energy is not "negative space." "Negative space" is meaningless.

Dark energy is the theoretical energy that causes the expansion of the universe.

I believe the fourth dimension is the hole through places. It would be like a shortcut to all of the past, present, and future. It could travel through to the past in the same spot. It could transfer you 10000bahcaltumophicillion miles across the universe in the same second, or 500 years into the future.

It's nice that you believe this. Do you have any reason whatsoever to think that this is true? Could you explain to me how this constitutes a dimension?

[blue_tetris]

When I read this on Vent for the first time, I shat out loud.

"A few centuries ago, people believed that the Earth was a flat, two-dimensional surface with edges, like a piece of paper or a 2-by-4."

Wahahahaha. The earth was two-dimensional? Crazy. I wish I could have lived back then, when the third dimension didn't exist.

Moreover, because we were initially wrong about the shape of the earth, he suggests that we must be wrong about the shape of the universe. Like that's how logic works.

[t̷s͢uk̕a͡t͜ư]

When I read this on Vent for the first time, I shat out loud.

"A few centuries ago, people believed that the Earth was a flat, two-dimensional surface with edges, like a piece of paper or a 2-by-4."

Wahahahaha. The earth was two-dimensional? Crazy. I wish I could have lived back then, when the third dimension didn't exist.

Moreover, because we were initially wrong about the shape of the earth, he suggests that we must be wrong about the shape of the universe. Like that's how logic works.

You're wrong because I once read this book and there was a character in it who was wrong.

[origami_alligator]

1. I thought gravity was considered the proof of a 4th dimension? Something about looking at how the direction in which light travels is not always a straight line when passing around a gravity source.

2. The universe may also be a giant one of these.
And that if you go all the way through the universe in any and every direction you'll end up back at the same place you started after a while. (Obviously a really long while.) I don't know what that has to do with anything but just thought I'd point it out.

3. Time is a measurement of change, Zora. Humans did not "imagine time and then it became real!!!" we just gave it a name, like we do with most everything we observe. When everything stops changing you let me know and I'll say time doesn't truly exist.

[Condog]

When everything stops changing you let me know and I'll say time doesn't truly exist.

But if time stops, then he wouldn't be able to tell you you're wrong. And he wouldn't even know that you were wrong. And you wouldn't know that you're right!

[t̷s͢uk̕a͡t͜ư]

1. I thought gravity was considered the proof of a 4th dimension? Something about looking at how the direction in which light travels is not always a straight line when passing around a gravity source.

wat

2. The universe may also be a giant one of these.

wat

And that if you go all the way through the universe in any and every direction you'll end up back at the same place you started after a while.

wat


Please contribute only if you aren't just making random shit up, kthx.

[Izzy]

The fourth is time, which progresses in a straight line at a fixed rate (Although it might technically be possible to move backwards on the time axis via faster than light travel).

I measure my dimensions with a ruler.

[乳头的早餐谷物]

1. I thought gravity was considered the proof of a 4th dimension? Something about looking at how the direction in which light travels is not always a straight line when passing around a gravity source.

Gravitational time dilation?

[Condog]

The fourth is time, which progresses in a straight line at a fixed rate (Although it might technically be possible to move backwards on the time axis via faster than light travel).

I measure my dimensions with a ruler.

You can measure your dimensions how ever you like, it's not going to change anything.

[jean-luc]

I will postulate that there are 3 spatial dimension. It is convenient to denote time as the 4th dimension, so I will do so for the post, but with the understanding that time is linear only by our perception (as we look at the quantum level, we find that time no longer behaves in a nice orderly linear fashion). For the purposes of the following theory, I will not accept that there are additional spatial dimensions.

FOR the purpose of astronomy and the study of the very large scale, scientists often define the universe as having the size that it would have assuming that material has spread at the speed of light since the big bang. Since the big bang was an estimated 13.7 billion years ago, the universe is presumably a sphere 13.7 billion light years in radius. The edges are not, however, well defined. Only a limited quantity of material (only light, by current theories) would travel to the fringes of the universe. Density of objects, and the size of objects, increases as you approach the center.
Assuming that only one 'big bang' has occurred, we may conclude that 13.7 b ly away, there is true nothing, for infinity. This line, 13.7 b ly out, is thus the 'outer curtain' of 'reality' or 'creation'.
This theory is, of course, dependent on there being only one big bang event. If we theorize that the big bang is an event that can occur in multiple places at multiple times, then there must be infinite quantities of matter, infinite distances away. The gaps between universes may be immense, but nonetheless there is matter on the other side of the gap. I personally find this likely.

Assuming multiple big bangs occur (and thus an infinite number of big bangs) there is matter outwards for infinity, although the gaps between universes in which there is nothing may be unfathomably immense. 'Reality' or 'creation' is thus of infinite size. The ramifications of this infinite size are interesting to consider.

---

Now I will postulate that there are more than 3 spatial dimensions, many of which we do not perceive, but exist nonetheless.

IN this case, it is very difficult to predict exactly how the universe works, spatially. I would think (although this is completely unfounded, it is only personal opinion/hope) that space is of infinite size, and that additional dimensions may be exploited to permit faster-than-light travel.

---

I would propose that in any of these cases, 'space' is of infinite size. What is limited is the amount of space that actually contains 'stuff'. If reality is of limited size, then there is a point where space continues on infinitely, but there is absolutely nothing in it. Therefore it can be actually be said not to exist - but the potential for space is still present.

[blue_tetris]

The universe is a cantitruncated 24-cell polychoron.

[Zora_S_Kenneth]

@smartalco ages ago: Dark energy is just a theory, yes

@Condog more recent: I think that Izzy is trying to say that he has no idea how to measure time. Apparently he hasn't heard of a stopwatch. But due to the formula for time dilation via increased velocity, weird things start happening past c including the dilation going off in to imaginary numbers...
...so we can't necessarily travel back in time that way. Dang, I can't use my car to travel in time (sans flux capacitor).

@blue_tetris: What.

[blackson]

The earth is a sphere, I was reading a book on it a couple nights ago. A little more information-

There are three future cones that are popular with the universe. One, is where the universe expands at a linear rate, and keeps growing. Two, is where the universe expands just fast enough so that the gravity has no effect on it, and thus, keeps growing. The last one however, is when the universe doesn't quite expand past the point where gravity can not effect it, and shrinks, all the way back to an infinintly dense mass (ring any bells?). The universe was stated as a sphere (it's a rather recent book 2007, this may have been disproven since). Let's say you are traveling the circumfrence at the speed of light of this enormous ball. In scenario #3, you would NEVER get back to the point you started before the universe contracted back into it's smallest form.

*Awaits replies*

[blue_tetris]

The earth is a sphere, I was reading a book on it a couple nights ago.

..... ^ _> ~

[t̷s͢uk̕a͡t͜ư]

The earth is a sphere, I was reading a book on it a couple nights ago.

..... ^ _> ~

[Nexx]

Dark energy is what I would call "negative space" The more it absorbs, the less space it takes up. Dark energy is energy that we can detect by its influence on other objects, but that we cannot detect itself.

I... what? Do you know anything about physics at all, or are you just making shit up? Energy is not space. Energy is not "negative space." "Negative space" is meaningless.

Hilarous.

All you guys talking about the universe being spherical make sense to me, but then again I know jack about physics. However, in A Brief History of Nearly Everything (of which I've read only the first 4 pages), Bill Bryson said something to the effect of "you can't travel to the edge of the universe. This is not because it would take an incomprehensible large (if not infinite) amount of time to reach the edge of the universe, but that's true too. It's because"... something about space time bending and you would never be able to get to the end. (I don't really remember because I didn't understand it and he chose not to explain it further, which is contrary to his stated principles in the introduction) And he also said something to the effect that space doesn't exist outside of the edge of the universe, which is at least consistent with something my friend who majored in physics was trying to tell me once about space and time not existing (as we know them) before the Big Bang. But yeah, as you can probably see, I have absolutely no grasp on either the idea of space curving or of space not existing. Or really anything else in this field.

Nonetheless, what I am trying to say is that I think GForce might not be far off the mark, but I can't be sure as I don't understand this stuff.

[blackson]

The earth is a sphere, I was reading a book on it a couple nights ago.

>:[

Universe*

"...something my friend who majored in physics was trying to tell me once about space and time not existing (as we know them) before the Big Bang."

I think what he means, is that anything that happened before the Big Bang (maybe another world and life) would not change the future of the universe. Once the universe condenses, all past events are forgotten.