A thought occurred to me: Big Bang and a finite universe

The non amateur stuff. Hawking, black holes, that sort of thing

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Crisis
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A thought occurred to me: Big Bang and a finite universe

Post by Crisis »

I've never studied astrophysics before, but recently, I've become interested, and I've decided to begin writing down my thoughts on the state of the universe.

Early this morning, a thought occurred to me. I'm going to go ahead and assume that this thought is either wrong, unfounded, or just something everyone has come to realize over time. Either way, I've decided to put it forward for your thoughts:

The Finite Cosmos: Limitation through the Big Bang theory.


The universe, though an apparently infinite space, cannot be such. The Big Bang theory of the creation of the universe through an explosion, an intense reaction that spawned the series of events leading to our universe in present day, is often accepted as more than theory, almost fact. If we consider Big Bang theory, we must consider that all matter propelled outward from the center of the explosion must be in constant motion, whether away from this nucleus or back toward it – two very possible states of our universe.

However, it is sometimes thought that our universe is an infinite expanse. This thought clashes with Big Bang theory quite blatantly. The state of the universe prior to the Big Bang could be compared to a deflated rubber balloon. Following the explosion, the newly born universe would be forced into constant expansion, or at least, constant motion. The balloon in this analogy would have been filled with its first breath, and as air would continue to flow into the balloon, so would the universe continue to expand.

The universe would resemble this balloon in that it would have a limit to its space. Air trapped within the balloon is restricted to the inside of the rubber balloon. The balloon itself serves as a model for the boundaries of our own universe, as it is a boundary for air.

The balloon (if we assume it is a balloon that can be inflated a very great deal) will continue to expand as long as air continues to flow. For our purposes, we will assume that the universe is still in a state of expansion at a constant rate, as the air into the balloon. In this sense, it is feasible that the universe will expand continuously, however, following this logic, the universe is not, was never, and will never be an infinite space.
Cliff
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Post by Cliff »

Dear Crisis
I have had a general interest in astronomy quite a long time and became a bit more interested in cosmology in the last few years.
I agree with you that it does sometimes seem to said that the Big Bang Theory is the be all and end all of explaining things but it may not be actually right. However, I am not sure but I think you may be taking the "balloon analogy" too far. As I understand things the "balloon analogy" is only a very simplistic way of trying to explain some aspects of the "Big bang Theory" to laymen like me.
I personally cannot get my mind round 99 percent of the things I read about cosmology, and even probably about 98 percent of ordinary astronomy. So there is no way I could give you any definitive answers.
Best wishes from the Grumpy old Codger Cliff
Crisis
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Post by Crisis »

Dear Cliff,

Thank you for your input - I did realize I'd said the word "Balloon" far too many times, for one, and yes, I did kind of make comparisons between the two a bit much. I couldn't think of a better analogy at 1 AM. :lol:
Cliff
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Post by Cliff »

Dear Crisis
For ordinary folk like me, I think cosmology is fantastically weird.
As far as I am concerned cosmology is certainly interesting but I can only read what the experts tell us and just accept what seems OK to me.
However, since I feel a bit out of my depth in many areas of cosmology, I keep it a bit at arms length and tend to concentrate on some the simpler aspects of amateur astronomy which satisfy me. Although I am always on the look out for new projects to try. And I must admit that I enjoy a little contoversial discussion from time to time.
Best wishes from the Grumpy Old Codger Cliff
Crisis
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Post by Crisis »

Dear Cliff,
Don't we all enjoy a little controversial discussion? For me, I'd probably be better off focusing on something a little easier to handle than cosmology, but something about it just fascinates me. I wonder if they make a "For Dummies"? That'd be perfect for me. :lol:
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Post by joe »

Dear Crisis,

There are two aspects of your picture of the expanding balloon analogy that are not quite right but often when trying to visualise something abstract the use of reality can easily confuse as well as enlighten.

The first thing is that there is no nucleus as you put it, the universe IS the nucleus. There is no "air" being put into the balloon as it is simply the "deflated balloon" or singularity that is expanding.

The second point is that when visualising the inflating balloon/expansion of the universe analogy you have to bear in mind that we are refering to THE SKIN OF THE BALLOON ONLY . The universe is the skin of the balloon but.... with one dimension taken out. The air inside does not exist. From this you can see that the skin of the balloon is not the leading edge of the universe. This is why when someone uses this analogy they always preface it with a warning that it is a crude one.

Therefore we now have a universe that is expanding but has no centre just as there is no centre to the surface of a balloon or the surface of the Earth.

The language of cosmology is essentially mathematics and while it is easy for mathematicians to speak of 11 dimensions and infinity, it is not for mere mortals like us and when trying to visualise something using our finite three dimensional brains we often feel that our instincts are right and crazy cosmologists are wrong. The idea of infinity is also a dangerous concept to try and visualise. The universe could have been a singularity that was infinite and is now expanding but it would be the infinite space that is doing the expanding not galaxies which may or may not be infinite. Space can easily be infinite (Anyone who can explain clearly Zeno's Hare and Tortoise Paradox would be welcome here) as there can be as much infinity between my ears as there is between here and the edge of the visible universe. Oh and Crisis, that reminds me, the VISIBLE UNIVERSE does have an edge, it being the distance light has travelled since the Big Bang.

Best wishes,
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davep
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Post by davep »

joe wrote:(Anyone who can explain clearly Zeno's Hare and Tortoise Paradox would be welcome here)
http://en.wikipedia.org/wiki/Zeno's_paradoxes might be of some help here.
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BIG BANG AND NON-INFINITY

Post by Vick »

The surface of the Earth is finite but being curved a person can travel around it for ever giving the impression if infinity. The universe can be similarly imagined
joe
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Post by joe »

Hi Vick,

Infinity versus the impression of infinity? I see a minefield here.
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Cliff
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Post by Cliff »

Dear Joe
I totally agree.
Assume that someone travelled round the world in these times by modern means. I think when they arrived back at their starting point they would probably easily know where they were\are because they would recognise the landscape. However suppose that someone travelled round space(assuming it to be curved in a fairly conventional sense). Perhaps arguably their journey would take so long that even if they reached the place they actually supposedly set out from, things would have changed so much in the meantime, there is no way they would be able to recognise it as being the same place. Or would they? Perhaps by the time such a journey might be possible I suppose some clever devil would be able to pedict how the place they had started from would change.
! wonder?
To be honest I suspect what I just said is really a bit of simplistic nonsense.
As far as I am concerned when it comes to talking about the vastness of space it is really beyond my understanding. I read generally what are simplified versions of what the experts know (or think they know) and try to understand it. The further I travel in my mind from Earth the less I can grasp what it's all about.
Why, people (at least supposedly grown up people) bother reading "Harry Potter " books baffles me. The night sky offers a lot more.
Best wishes from the Grumpy old codger Cliff
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Post by joe »

I suppose in an infinitely old universe you would not only have enough time walk on every square centimetre of the surface of the Earth but be able to do it an infinite amount of times. Or, you could step once on every square metre then take one of those square metres and divide it into square centimetres, then divide those into millimetres and those into micrometres, next into square nanometres, picometres, femtometres, attometres, zeptometres, yoctometres ad infinitum. A problem arises at the Plank Length 10 -35 when length doesn't make sense any more and you have to ask yourself whether infinity does either. :shock: But you still have all those other square metres to be getting on with.

PS Couldn't agree more about HP books
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davep
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Post by davep »

Cliff wrote:Why, people (at least supposedly grown up people) bother reading "Harry Potter " books baffles me. The night sky offers a lot more.
While I've never read any of those books I can confirm that it is possible for a person to enjoy fiction and the night-sky. It doesn't have to be either/or.
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Post by joe »

Yes Dave, it is a fundamental aspect of democracy (especially constitutional American) that everyone is entitled to seek pleasure, wherever and whenever it can be found ( Harry Potter included), as long as it does not interfere with the life of others. How far up the "interfere scale" does annoyance come? And if I find it pleasurable to discuss astronomy why is it never a topic of conversation at the dinner table? Rhetorical only..... it's way off topic! :(
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davep
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Post by davep »

joe wrote:And if I find it pleasurable to discuss astronomy why is it never a topic of conversation at the dinner table?:(
Wrong sort of dinner table? ;)
stella
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Thick as a plank and another planck

Post by stella »

The scientist is Max Planck.
You won't learn much about him if you google on "plank" :P
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