The last podcast that I listen to dealt with the shape of space and that the universe is flat. I was wondering if the universe could actually be a sphere with a size so large that to use it appear flat much like the earth does with a view of the horizon. Our galaxy is just part of the crust o the sphere universe which would be thin compared to the dimensions of the sphere itself. The rapid expansion of space could have made it so the the distances to other reaches of the universe are so distant that not light or any other ray could be detected? Just wondering if anyone has thrown this out there and if it has be shown wrong yet by math/physics?

What they mean by "flat" is that it's generally isotropic, particular as you include larger dimensions for comparison. Only locally (that's a very relative term) does it "clump" into smaller things like galaxies and galactic clusters. There are a couple much larger gaps and clumps, but for the most part, it's flat.

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

As I understand it, yes, the 'shape' of space could be spherical, but so large as to appear flat over that portion of the universe we can observe. (I believe the observations are that the universe is flat within 2% margin of error.)

But... the 'sphere' is a two dimensional analogy of our three dimensional space. Try to think not of the whole sphere (its volume), rather just it's surface. Then try to extrapolate that two dimemsional spherical surface shape to higher dimensions, three, four, more.

Don't worry you can't. No one can. Even the experts can't visualise that 2d sphere surface in higher dimensions, they use mathematics instead.

Once you're ok with that, you can see that our real 3d space isn't the crust of a large hollow sphere. And it isn't necesarily a sphere. Maybe a cube, donut, soccer ball etc.

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If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

To make it easy, Flat just means that 2 parallel lines going in any direction will stay parallel. The shape can be many things.

It is flat in 3 dimentions. Not just 2 like a piece of paper.

Hard to wrap your head around I know...but when it clicks, you will totally get it.

It can't really be spherical, because lines around the surface of a sphere do not stay parallel. They intersect at the poles and are widest at the equator. To have this shape, the universe would have to have 2 starting points.

Please don't say it can't be spherical EvilEye. By Occam's Razor it must be spherical as the simplest possible solution. This is Q/A after all and if you want to go shooting down the big bang there is the ATM for that

How is it ATM?

The accepted Shape thus far is a Taurus. (where lines do stay parallel)

how can the universe have a shape at all? I just don't understand, and am not formally educated in this area, i just can't help to think about it. Having a shape implies that there is a center and edges. Having a shape also implies that there must be something "containing" this shape. I just can't grasp any possibility other than an infinitel universe void of any type of shape. Is this a silly idea? it just bothers me constantly....

Have a look at this website - it is a good introduction to the concept of the shape of space.

Nice link Speedfreek.

Hi Evil Eye. As I understand it the observations are that the universe is flat to within 2% - which leaves the possibility the universe could be negatively or positively curved (and very large - but that wouldn't be a surprise). Having said that, the consensus seems to be that it is flat, and it would seem there's a 98% chance thats correct. A lot of the research goes over my head though...

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If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

It's like a splinter in your mind, no?

Hang around this forum and it will start to make sense. Mostly.

Just say the word if you would like more links, I'm happy to share my favorites too. And, there's a whole thread of links here:

http://www.bautforum.com/questions-a...urces-web.html

And of course Fraser and Pamela's podcasts:

http://www.astronomycast.com/

It seems to me the most likely 'something' to contain the universe would be a higher dimension(s) - so compare our universe (three dimensions) to the surface of an expanding balloon (two dimensions) in your living room - the higher dimension is your living room (and the air inside the balloon). Thats just my lay opinion though.

Scientists think we may even see real evidence of other dimensions when the Large Hadron Collider fires up later this year.

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If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

Er, I drive a Taurus. Methinks you mean a torus. Makes me hungry for a donut.

ok....yes.

Presumably "torus" means the overall topology is S1×S1×S1, which could be locally flat. Then again S3 is also special, could it also be locally flat?

S1? S3? Please explain.

S1 is a circle, S2 is a sphere, S3 is a hypersphere.

I have the same problem as reenpeery, why can't we just base an idea on that space i.e. the black void of nothing between matter and energy is nothing more than that, an infinite void which could be populated with matter and energy way beyond what we can detect. Or the outer most edges of what we can detect are exactly that the edge of our universe. Is our universe defined by this boundry? ( if it exists ) and the rest is an infinite void? or are we trying to define it as the whole of space? which may be just nothing. I do understand that we detect a background radiation emitting from all directions but this may only show that we are unable to detect further out than the bubble of matter and energy which we are a part of. assuming that there is a way to detect beyond this?

Hey Cosmocrazy,

that would certainly be a lot easier. But space isn't nothing. The best theories and observations we have come up with (Big Bang cosmology, and chuck in inflation too) strongly suggest space as we know it (and time for that matter) began with this initial hot dense state called the Big Bang.

The very beginning, less than 10^-43 seconds, is beyond our comprehension, and may always be.

Infinity, when you think about it for a while, has at least as many mind bending problems as 'How did the Big Bang happen' so might not help that much.

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If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

Hi Steve, thanks, yes i see your point and i can see how infinity creates its own set of problems. the thing i,m struggling to understand is - from the theory of the big bang all matter energy and spacetime sprang into existance from a singularity.Before this point is beyond our comprehension, we can only assume that spacetime matter and energy did not exist and from that moment on the universe spacetime and matter/ energy inflated into the form that we observe today.ok. but if for example that "space" inflates and expands 3 dimensionally with time then surely the space between the subatomic particles expands also i.e between electrons and the nuclei of an atom. If this were the case then the four known forces of nature balance out this inflation to keep matter in the form that we observe, therefore becoming the cosmological constant? i.e electromagnetism & nuclear for the atoms and gravity for everything else?
Its probally because i can only percieve things in the 4 dimensions i know? also i'm very under-educated in the mathematical theories invovled in the physics.
But i,m learning lots from this forum!!

Yes the balance between the four forces result in the universe we observe.

The cosmological constant was cooked up by Einstein because his calculations predicted the universe must expand or contract, but he didn't trust them - he favoured a static eternal universe. The constant was a correction of sorts to counteract the predicted expansion or contraction. When Hubble showed the universe was expanding, Einstein quietly erased the cosmological constant.

But then, the expansion was observed to be accelerating. Welcome back cosmological constant. I don't think scientists have a good handle on what it is, but I've often seen references to a kind of 'vacuum energy' of space, or perhaps it is a vestige of the force that drove inflation. There seems to be some consensus the rate of acceleration varies over time.

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If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

Yes i have read about Einstein's cosmological constant and how it may now be regarded to be of possible importance. The acceleration of the expanding universe ( faster the further we look ) seems to be in much debate! i struggle with the notion of the measurements used to prove this idea to be correct the red shift measured in distant galaxies seems to conclude that this acceleration does exist, although reading through this forum alone there is much debate about this as a way of determining the expansion of the universe. I have also heard about vaccum energy, this idea seems to fit nicely to the current observations made but again has no hard evidence to back it up. Going back to the original question about the shape of the universe, the simple idea i proposed was that the energy/matter determined the size and shape of the detecable unviverse but that this universe could be expanding into a space which has no definate shape, size or substance conceivable to us (hence the apperance of an infinite empty void). using the analogy of us existing on or in an expanding bubble. the space between galaxies appears to be getting larger with time but with force of gravity the space inside galaxies remains relavtively constant. I guess if you consider space to be expanding then you must also consider space to be a fabric of some sorts rather than nothing as i suggested earlier.

'Fabric of space' is used a lot, and seems a pretty good way to think about it. Space (spacetime) has many properties, some better defined than others.

I think for now, the preponderance of evidence for expansion, means we have to run with it.

I'd dis-count arguments against expansion based around red-shift. Many I have seen mix up doppler shift due to relativity and redshift due to expansion. I don't pretend to understand (yet! ) the detail but apparently the different kinds of redshift have unique signatures and I have no reason to doubt the experts who do understand how it all works.

The other discussion you'll probably see around here will be about how co-ordinates are chosen in relativity - that sort of thing, and as I understand it are mainly about how we build our models of reality. I doubt that most of the people in those debates would want you to abandon the Big Bang yet.

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If something is in me which can be called religious then it is the unbounded admiration for the structure of the world so far as our science can reveal it... of the manifestations of the profoundest reason and the most radiant beauty, which are only accessible to our reason in their most elementary forms...
Albert Einstein

"It is not that there was an explosion and matter was thrown out from some center. Instead, space itself started expanding and all points in space started separating from each other. "

That's about the most eloquent wording I've heard yet to date!

Great link indeed, Speedfreak!

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

Uh, wouldn't that be "doughnut?"

Just a thoughtnut...

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.

I don't see why people have a problem with it being flat on a local scale, but toroidal on the complete scale.

The Earth is a sphere (sort of) on its complete scale, but a perfectly flat level works just fine on local scales.

When you have something extremely long, like a space shuttle landing runway, it is flat all along the surface, but curves with the shape of the earth.

A few NEWBIE questions

OK ... Is the shape of space completely determined by gravity?

The universe nor the shape does not exist without gravity and the warping of time space of gravity ( and possibly antigravity ). Why are we limited to S3? Is there an S4? Throwing in energy or gravity as a 5th dimension?

Basically the shape of the universe only makes sense relative to something else. So we can see the shape of the universe relative to earth.

Wouldnt the shape of the universe ( shape of time-space ) be much different if we were looking at it from the singularity of a black hole?

Why / why not would it be different?