Is the universe smaller than we think?

[Moonhawk]

I was thinking about the size of the universe the other night and the "surface of an expanding balloon" analogy.

If we use that analogy - it follows that if we travel in a straight line for long enough - we'll end up back where we started.  The same is true of light etc.

If the universe were small enough and light could have travelled right across the universe and ended up back where it started (perhaps multiple times) - then it follows that if we looked out into space - we would actually see multiple versions of our own galaxy from earlier and earlier periods in it's history.

So my question is - is there anything in the theories of cosmology that rule this out.  Are the galaxies we see in the hubble deep field actually unique galaxies or are they in fact earlier versions of the galaxies in local galaxy clusters and are we actually seeing an infinity mirror type effect.

[ronin]

Just that the universe is not a rubber balloon and that stars/galexies/space outside the hubble radius are moving away from us at faster then the speed of light. So the light could never in effect get to the other side to loop back round.

There is a difference between the size of the universe and the observable universe, we can "define" the age and the observable size but not the actual size.

[Tiny Small]

The observable universe is 92 billion ly across. The stars and subsequent light can not travel faster than c, however, the space between can expand at whatever rate it sees fit. The universe is not governed by c, but everything in it is. No exceptions.

[ollypenrice]

But does the curvature of the universe require light from the MW to go 'all the way round' and so fall outside the observable universe or could it be curved round in a smaller radius and so find its way back to us and be observable?

Olly

[andrew s]

But does the curvature of the universe require light from the MW to go 'all the way round' and so fall outside the observable universe or could it be curved round in a smaller radius and so find its way back to us and be observable?

Olly

It could but the evidence so far is that the universe is flat Olly

Regards Andrew

[kalasinman]

If we accept the OPs conditions, then the light would have to travel billions of years to return. As the light spreads as it travels, intensity would be quite low and by then everything will have continued to move, so point of origin isn't there any more.

[symesie04]

Skymapper has mapped a fair amount of the observable universe. If the the OP theory was true then surely what we would see in the map is a serious of repeated patterns altering only slightly to allow for the passage of time. In fact what is seen is a completely random formation of galactic clusters, random in shape, pattern, size, position, types and individual sizes etc. This would surely in itself the notion that the universe is not a small self contained curve?

[Cath]

I'm sure that at this stage in human evolution, what ever it is we say the universe is most likely has little bearing on what it actually is

But then that's currently of no help to us with our current learnings, so best we continue on the path we're on.

I know, I know. I really shouldn't, but sometimes I just can't resist

[Ptarmigan]

I know, I know. I really shouldn't, but sometimes I just can't resist

Life is just full of little temptations isnt it 

I keep suggesting that the universe is not expanding,

it is just our measuring sticks that are shrinking,

but no one payes me any heed

[Cath]

Life is just full of little temptations isnt it 

I keep suggesting that the universe is not expanding,

it is just our measuring sticks that are shrinking,

but no one payes me any heed

lol

Their once was a man who I think once suggested that all could well be 'relative'

[acey]

There have been various cosmological models where one would see multiple images of the same thing (try googling "hall of mirrors universe"). Searches have been made for multiple galaxy images - none found. There have been similar models that would lead to repeating patterns in the cosmic microwave background - again, none found, though for a while there was a suggestion that they might have been.

[ollypenrice]

Apparently when Aldous Huxley was given a chance to look through the 100 inch Hooker by his friend Edwin Hubble, Huxley asked if he was going to get a view of his own backside in the thing... 

Olly

[Moonhawk]

There have been various cosmological models where one would see multiple images of the same thing (try googling "hall of mirrors universe"). Searches have been made for multiple galaxy images - none found. There have been similar models that would lead to repeating patterns in the cosmic microwave background - again, none found, though for a while there was a suggestion that they might have been.

Multiple galaxy images would be difficult to find though because of the timescales involved.  

If the light took 1 billion years to do a circuit - a galaxy could would look very different each time you see it because you are effectively looking back in time.  You won't see your galaxy as it appears now - you will see it as it appeared 1 billion, 2 billion etc years ago.  When you also consider that the galaxies are moving and that light can be bent via gravitational lensing too - that only complicates the issue as each image of our galaxy could appear in a different location too.

[Cath]

The fact that we have several differing ideas on what the structure of the universe might be tends to tells us that we simply do not know.

Our current method of explaining away that what we see as being the matter in the distant parts of the universe moving away from us at relative speeds that far exceed the speed of light is to say that space itself is expanding. I'm sure that the reality of what really is going on here, will, at the end of the day, turn out to be far more weirder than our currently ever so limited and simplistic visualizations/thought processes can currently deal with.

[kalasinman]

Eagerly awaiting the restart of CERN, one physicist said that the Standard Model was a nice neat theory that he hates, as it doesn't explain 96% of matter, or gravity. He described the common feeling of researchers there that they wanted to "break physics". Could be exciting times ahead.

[andrew s]

Eagerly awaiting the restart of CERN, one physicist said that the Standard Model was a nice neat theory that he hates, as it doesn't explain 96% of matter, or gravity. He described the common feeling of researchers there that they wanted to "break physics". Could be exciting times ahead.

Indeed, we certainly need some good observations to take physics forward. I have grown more and more frustrated with current theory of everything and cosmology theorist's who are only guided by whim and their feelings and verry cross at those who wish to redefine science to avoid any attempt at critical predicions and observation!

Rant over regards Andrew