Space.

[kris]

After reading a topic about this somewhere else. It got me to thinking. When does space end? How far can one travel before there is no more universe? If there is an end, what is it like? What then begins? And how do we know if it even ends?

[NismoDrifts]

hmmmm thinking about that has hurt my head........

i suppose it doesnt end.........but thats the easy way out

some people tend to believe that it starts over, but how does something thats 4-dimensional (or more) start over!?

other beliefs are that the big bang happens, the universe expands to a point, falls back in on itself, explodes again, expands, one big cycle...but that doesnt answer your question

well, i gave it my best shot......

another question, how do we define universe? its supposed to be all existence, but if we can go beyond it, we're existing somewhere, and that somewhere is existence, so that just negated itself, so the only thing i can think of is that it doesnt end

haha that probably made no sense at all, i cant find my glasses and i cant focus on anything right now

[MBTN]

I try to catch things like this on TV. The last time I saw something about this scientists said that the universe is shaped like a ribbon that folds under itself. SOt of like this shape:

_________
_________)

What also is mind boggling is what is the blackness that we see?

[NismoDrifts]

Well, blackness is lack of light...............sure theres stuff out there, its just too far for the light to reach at the time, so we see black, and, how does something 3-dimensional curve in on itself? not saying youre wrong or anything, im just really interested by this stuff

[SickLude]

I dont think the universe ends. Its like time, its infinite. I consider everything the univere, such as people, earth, space. i also believe in the hereafter, or life after death, heaven and hell. Therefore, the universe is ever-present. To me, its kinda like imagination...it just dosent stop.

[ric]

i really dont think you can say for sure. i mean when you try and picture it in your head you will always have an end at any given point because the human mind cannot picture infinity. sure you can draw an infinity symbol but sit back and actually try to picture the concept of it in your mind. not to mention infinity within infinity, it doesnt necessarily have to become larger. my whole belief in supreme powers is based only on the concept of infinity and how it applies to space, or everything for that matter. supposedly space itself is void of anything, so how could you attempt to picture something from nothing.. i believe the human mind itself is the limiting factor on understanding things of this sort. we rely on what einstien said about technology surpassing humanity to get our ideas, i believe once evolution alters us to the point of humanity surpassing technology we may be able to understand space, and infinity and a host of other things


one of my older childhood idea's on the universe was that the universe was a particle of a particle of a particle that made up a sub atomic particle of an atom that made up bla bla bla of another being in which his universe was a particle of a particle and so on and so on never ending. seems rediculous but i was 9 or so and who knows ya know?

[GSr32]

OK, now here's something that will spook you.

If the universe is infinate, never ending, then in theory there is infinate stars, infinate planets, infinate earths. I mean if out of all the universe and beyond, we exist, surely there is others, and more.

My head hurts

[YogsVR4]

Originally posted by i like naked girls
one of my older childhood idea's on the universe was that the universe was a particle of a particle of a particle that made up a sub atomic particle of an atom that made up bla bla bla of another being in which his universe was a particle of a particle and so on and so on never ending. seems rediculous but i was 9 or so and who knows ya know?

You just described Cosmology.

[darkness]

damn trying to think about something that big is making my brain hurt.

[fritz_269]

Originally posted by NismoDrifts
Well, blackness is lack of light...............sure theres stuff out there, its just too far for the light to reach at the time, so we see black, and, how does something 3-dimensional curve in on itself? not saying youre wrong or anything, im just really interested by this stuff

Good call on the blackness.

The universe is not necessarily three dimensional. It may only look that way from our very narrow perspective. I think MBTN's 'ribbon' is an idea that came out of string theory, which posits that there are something like 15 dimensions. If you look at a sheet of paper pefectly on edge, it looks like a line. If it were fixed in front of your eyes like that for a long time - you'd probably believe it was a line. But it's not, it's a plane, you just have to get a new perspective to see it. We haven't quite figured out how to get a new perspective to see the dimensions proposed by string theory, but lots of smart folks are working on it.

But, even if it is three dimensional, it can curve in on itself if space itself is curved. One of the older and still quite useful theories that comes out of general relatitivity (i.e. space is curved by gravity) is that the universe is finite in size, but has no edge. If I get in a rocketship and fly as straight as I can for a very very long time, I'll end up exactly where I started. Consequently, no matter where I am, I can look around and convince myself that I'm at the exact center of the universe! (And no, that's not because I have a big ego )

Picture a big sphere - this contains all the matter and energy in the universe (which is finite since the sphere is finite). Now, imagine that if you headed out of one point on the edge of the sphere, you would instantly be transported to the diametrically opposite point where you would now be entering the sphere.

This is just like the old video game Asteroids, where when your ship went off one edge of the screen it immediately reappeared on the opposite edge, still traveling in the same direction. You have a two dimensional screen which is a distorted representation of the surface of a three dimensional toroid (doughnut shape) -- but note that everything happens within just two dimensions; there is no third dimension in Asteroids, but it's quite useful to picture the ship traveling on the surface of a three dimensional object.

That's very similar to how the universe space is curved. It's only got three dimensions, but if you picture it as a sphere - when you exit one side, you come right back in the opposite side. We have a three dimensional universe that is a distorted representaion of some four dimensional object. If you could picture four dimensions, you could picture it easily (but you probably can't... ). So just like Asteroids with only two dimensions, there are only three dimensions in the universe, and it's just useful to picture us traveling on the surface of a four dimensional object.

It may take a little head scratching, but if you think about it, no matter which way you look, it always appears that you are in the center...

Upshot - the universe is finite and has no edges because space is curved. You simply can not ask the question "What's beyond the edge?" - it simply has no meaning in this universe.

Of course, this is all based on a specific interpretations of General Relativity resulting in a spherical or toroidal topology for the universe. There is no absolute consensus on this, and many experiments recently have been pointing towards a local hyperbolic geometry of space, and perhaps an overall hyperbolic topology as well (which would be an infinite universe). We'll see...

Cool stuff eh? :smoker2:

PS> Here's a good article: http://www.sciam.com/1999/0499issue/0499weeks.html

[MBTN]

COOL!

Aren't there theoretically an infinite number of dimensions?

[fritz_269]

Originally posted by MBTN
COOL!
Aren't there theoretically an infinite number of dimensions?

In math, you can use as many dimensions as you feel like. But if you're doing physics - there are only four dimensions in space-time that have any real meaning.

That's one of the big upsets about string theory, these mathematicians have invoked a whole bunch of new dimensions without fully describing what they physically represent. It's all very confusing right now. It may turn out to be a good theoretical model for the universe, or it may turn out to be absolutely pointless bunk. But they're definitely going about it in a very backwards way that is generating a lot of controversy: Do the math first, then try to fit the data. Most of science tries to get the data first, then try to fit the math.

[NismoDrifts]

thanks for the read fritz hahahah asteroids rocked

[NismoDrifts]

we cant really define any of these other dimensions can we? coz we cant really experience much outside of our 4 lil dimensions.......

......whoa, now im thinking about what it would like to be a 2d creature on a piece of paper, what do you do if the paper gets ripped and your house is on the other side?!?!?!!!

[fritz_269]

Originally posted by NismoDrifts
we cant really define any of these other dimensions can we? coz we cant really experience much outside of our 4 lil dimensions.......

At the moment, no. But there is certainly no proof that we won't discover another dimension. One that's just not so obvious. It may take some very special equipment to see. Or maybe we'll never actually see it, but we'll be able to infer its existence through its effects on the dimensions we can see...

......whoa, now im thinking about what it would like to be a 2d creature on a piece of paper, what do you do if the paper gets ripped and your house is on the other side?!?!?!!!

Your fabric of space gets ripped, your universe gets smaller, and you'll never see your home again.

There's a classic book called "Flatland: A Romance of Many Dimensions." by Edwin A. Abbot. Published in 1880, it recounts the adventures of a character who lives in two-dimensional space, and watches him discover the existence of a third dimension and even reason out a fourth... It's a great little philosophical treatise that points out just how limited out perspective can be, not only in geometry, but in life in general. It's only about 100 pages and it's a quick and easy read, even quite funny. I highly recommend it. www.amazon.com has got it for just $9!