So far Inflationary expansion has been the for-runner in explaining the begining of the universe, though not an experimentally tested theory it predicts the shape of the universe to be flat. It works well because of the predicted amount of material in the universe(5% solid matter 25% dark energy 70% dark matter). If this theory is correct we will know the universe is completely flat everywhere. Or is it? This same situation has happened before. A thousand years ago everyone knew the earth was flat, the only difference is that they didn't have mathematical equations that explained why. In a few hundred years from now will it be proven that the universe is spherical or is the universe truly flat?

Although i understand the term "flat" when it comes to the universe, it makes no sense to try and give a 3 dimensional universe the term "flat" as opposed to spherical, which implies that the shape is the only answer you are seeking. a "flat" universe is one that starts with a big bang (wether or not inflation is your explanation of how it got so big) and proceeds to expand forever untill it fades away into oblivion. a spherical universe is one that starts with a big bang, expands and then contracts to a big crunch. So far as i know all observations point to an expanding universe that is accellerating, which would give correct assumption to a "flat" universe, and untill otherwise observed, i see no reason why it would change

the universe is 3-d (debatably 4-d) so why why would it be flat (2-d)

I don't think your correct in assuming that space is flat.....I believe Hawkings and Einstein agree (as do most physicists) that space is "curved". Space is folded, bent, twisted, etc.......due to gravitational forces pulling on the "fabric"........

Dr. Strangehug Im talking about space as a whole. Only 5% of the universe is made up of objects with enough mass to warp and curve the fabric. The rest of the universe is almost uniformally flat.

We know alot about the geometry of space and time, but everything we know about space and time may be useless when we truly start probing the secrets of the universe. Like a painting seen on microscopic levels, the concepts of space and time may just be part of a much larger, much different system of nature.

What do you mean by "flat"? Are you suggesting that all the galaxies and such are distributed in a space geometry like a cereal box? That is, that the galaxis can expand left or right a great distance but only up or down to a much more limited degree?

That doesn't make any sense.

i think the universe is a sphere.

if the big bang did in fact happen, and in order for the universe to be flat, the explosion would have only gone in two ways.

plus, everything in the universe would be in a linear form. we wouldn't have planets revolving around stars. nothing would move, and if anything did move, it would only be able to go back and forth.

it would seem as though it is an expanding (inflating) sphere but, what is meant by 'flat' here is that if you were to go to the boundary on one side (of this universe) you would not curve back and reappear on the opposite side as if it was a globe (like earth)

And, BTW, there is not enough matter in the universe to curve the space of it so much it would curve back to itself. So in my opinion it is flat and so far inflationary - until proven otherwise.

Dark matter and dark energy are thusfar only speculations! Antimatter however is not but it is not what its name would suggest - it still has MASS not 'antimass' (and therefore would count towards the curvature of space). Antimatter is not the opposite of matter (it only has some opposing properties ie. charge for electrons-/positrons+).

ok i see what you mean. basically, we are inside of a glass ball.

but the question is if you were to reach the edge of the universe, say at the very outside of the "sphere" what would prevent you from going further out? what would be a boundry? would it be like running into an invisable wall?

the boundary is actually radiation/light/expanding space travelling (from the initial BB) outwards. So the boundary itself is travelling at the speed of light out. Going beyond the boundary is a paradox because you cannot travel faster than light to even catch up to the boundary and if you were to go beyond - no light or space exists to see what there is - paradox

PS. Any such boundaries or beyond are UNIMAGINABLE only the concept of them is imaginable

so this would indicate the the universe is constantly expanding, correct?

all evidence gathered so far suggests so ie. all galaxies are moving away from each other & accelerating (not slowing down)

some believe this is caused by 'dark matter' in between galaxies that repel matter but this does not explain the acceleration. To explain acceleration using 'dark matter' your 'repelling' force would have to be related in such a way as to repel MORE the further matter is away from 'dark matter'. If this is the case then I am being INFINITELY repelled by all 'dark matter' in the universe - but all I feel is gravity, dough.

so all we can do for now is speculate based on our observations...

The only possible explainations are a flat inflationary expansive universe, or that the big bang is still in its begining phase of explosion. Other than that i dont have a damn clue.

i don't see any other possible explaination either, considering the explosion was extremely massive. in zero gravity there would be nothing to slow down the outward force generated from the blast.

After doing some research......I found that NASA confirms that the common thought is that space is "flat" so to speak....what kinds of implications does this have? Right now I can only see how it might affect our theories of the expanding universe....we'll be long gone by then anyways........My question is thus........are we expanding into something? If we're expanding surely we must be expanding INTO something, correct?.....Or.....are we creating as we're expanding.........maybe dark energy is out there.....pulling the universe along......who knows...what are ya'lls thoughts on this?

I believe it's expanding into nothing. Kinda weird but if you think about it 'something' only makes sense inside our universe so there is no something that our universe is actually expanding into. OR you could say it is expanding into something but that something is actually the space of our universe just created

Outside the universe questions such as where, how far, how long, when, why HAVE NO MEANING because there is nothing to relate them to - not even the universe.

I believe space is being created as the universe inflates ie. as the radiation travels outward space is kinda 'dragged' with it. Just my thoughts.

I believe that space is curved.

A book I am reading has an interesting concept on this (called Parallel Worlds by Michio Kaku). Alan Guth assumes If the universe underwent a turbocharged hyperinflation at the instant of it's birth, astronomically faster than the one believed by most physicist, he could solve a host of deep cosmological questions. It became an idea that would come to revolutionize cosmology. (which recent data from the WMAP satellite are consistent with it's predictions.) If Alan Guths theories turn out to be correct it solves the flatness problem. Data has shown that the curvature of the universe is remarkably close to zero, in fact maybe closer than perviously believed. This could be explained if the universe, like a ballon that is rapidly being inflated, was flattened out during the inflation period. We, like ants walking on the surface of a ballon, are simply too small to observe the tiny curvature of the ballon. Inflation has stretched space-time so much that it appears flat.

Hi,All very interesting stuff here I'm quite interested in astronomy and cosmology,though a lot of it is a bit mind boggling
One thing that bothers me at the moment,and I apologise if it's slightly off topic.
If the universe is expanding and galaxies are moving away from each other,how come the galaxy Andromeda is moving towards us and in xbillion years will collide with the Milky Way??
Thanks

It could have possibly collided with a different galaxy in the past, thus shooting it off towards our direction.

During the BB, objects ricocheted off each other, causing rotation of gas clouds and such. They probably remained in a constant, neverending spin, hence making it easier to bounce off in different directions when they collide.

Is kinda like when you have two billiard balls, and if you have one person at the either end, and you both push the balls down the table and the collide, they bounce off, usually they come back in the direction of the thrower. But if you spin them while throwing them and they collide, they usually go off to the side. Now, mutiply the two billiard balls by a trillion and thats basically had at the BB. So, its easy to see how two objects can eventually run into each other.

Thanks,I see what you're getting at,but galaxies aren't solid objects,in fact there is more space in galaxies than matter.I read somewhere that they reckon Andromeda will just merge with the Milky Way without too much fuss and probably not affect the solar system at all!!
Don't know if I quite believe it or not.
Anyway,my point is that surely galaxies can't 'bounce' off each other,but due to gravity,they become as one.

it isnt a shape ASSUMING that there is ONE universe.if there is only one universe, it is an infentesimal sphere. it goes on in EVERY direction forever.

IF there is more than one universe, then it is most likely a sphere.

IT CONFUSES ME!!!

this could well be true *throws another coal on the fire* but, consider this...
A balloon/earth is a very poor analogy to curved space ie. if you move UP instead of forward/backward you lose your curvature however, in curved space this does not happen. Curved space means that if you move in ANY direction for long enough you will eventually come back to the same spot. Put differently, if I could look far enough in ANY direction I would see the back of my head!

The implications of this are that EVERYTHING exists between my face and the back of my head....is that possible?

ie. face - galaxy a - galaxy b - galaxy d - etc. - back of my head
face - galaxy h - galaxy i - galaxy j - etc. - back of my head

imagine a circle of diameter x, dot in the middle is your face and the circumference line (all of it) is the back of your head - everything exists in between - so I am the center of MY universe and you are the center of yours if space truly curves back to itself

sry for the double post but 'edit' is freezing up,

I've been pondering this...


and I believe I have an answer (still speculation but makes sense). Andromeda is the NEAREST MAJOR galaxy. BTW, there are other galaxies (smaller & closer) that are already merging (to a degree) with our Milky Way. Because Andromeda is major it would stand to reason that its gravitational forces with respect to our galaxy may have overcome the separation momentum & hence the closeness, the mass and ultimately gravity is bringing it closer.

Now, having said that, it also stands to reason that there are many more galaxies undergoing the same phenomenon however the distances & difficulty of measuring this phenomenon from our Milky Way have made it difficult to identify these clearly. But ultimately if there is enough distance between galaxies the momentum of their velocity overcomes the gravity between them.

"Dark matter" is the same thing as a "finagle factor" was when I was in college . . . that which is made up to make calculations come out right when at first they don't. They call it "dark matter" because they are unable to see it, or detect it in any way.

Well um... like a magnet? If you're a iron particle, or something influenced by magnetism, at the magnetic northpole, and you leave the northpole in any direction, the magnetic field will always guide you to the southpole of the exact same magnet.

Even nothing has a name for it. nothing is void, nothing is not darkness nor light, it is something else. Even empty space is something, it has length, width, and depth. The answer to the question of what exists outside the universe is usually expected to be nothing. But, since noone knows what exists beyond what we see who's to say that there isnt just another form of something? Possibly a place where the normal laws of physics do not apply and our intuition is meaningless.

where you are born after you die, people ride bicycles backwards and even if you kill george bush he just keeps coming back... just like he was cloned by aliens to be super retarded.