Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Maggie Tidcombe on 15/11/2010 16:30:06
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Maggie Tidcombe asked the Naked Scientists:
I have been reading about the origin and life of the universe, about the big bang, the following inflationary period and the subsequent slower expansion we are now in.Â
My question is... in which area of space, or in which direction can the source of this expansion be found?  If everything in our universe has expanded from a single point and may well contract back to the same point, then do we know in which direction to look for this point? Where did the big bang happen?  If our universe is closed and curving round on itself like an inflated balloon, then there must be a centre. Which way is the centre, is it where quasars and more densely populated areas of the universe are to be found... In which direction can the oldest part of the known universe be found?
Thank you for an excellent programme (http://www.thenakedscientists.com/HTML/podcasts/)
Maggie Tidcombe, Cornwall.
What do you think?
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Hi, Maggie; lucky you - living in Cornwall. I left 45 years ago, and doubt that I shall return now. [:-'(]
I will not pretend that I can answer your question, but some thoughts on the subject might help.
Excluding the possibility of a pre-existing “somewhere” we can say that it makes no sense to talk of the Big Bang as having happened at a particular place. Never-the-less, it is difficult for the non-scientist like myself to shake off the idea that there must be some place in the Universe where it all started. The usual response to this in popular science books is to state simply that the Big Bang “happened everywhere”. Perhaps this is an area in which the balloon analogy can help. Imagine an un-inflated balloon on which you mark a small dot. As you inflate the balloon, the dot grows. Now, ask yourself where, within that enlarged patch, you might find your original mark. Obviously, the answer must be “everywhere”. The same can be said of the Big Bang. At the instant of “creation” it encompassed the entire Universe, and as the Universe has expanded it has not left behind some original Big Bang site. Having said, and perhaps accepted, all this; if we return to the balloon analogy, there must always be a feeling that because the mark expanded evenly in every direction from the centre, that must be its spreading centre. I suspect that it is this feeling, rather than an inability to accept that the Big Bang happened everywhere, that is the lay-person’s chief difficulty.
Would I be right in thinking that it is a spreading centre, rather than an actual B B site that you are looking for?
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Maggie,
From current knowledge the centre of our universe is undetermined. I have a hunch because we are more positioned peripherally as a galaxy in our Universe it is difficult to determine the exact centre. However the origin of the universe from the big bang theory is generally accepted but the expansion is not slowing down it is actually speeding up. This is not what you would expect. I have my own theory on this phenomenon.
The universe is not going to contract back to the same point. What you need to get your head around that a lot of the theories currently being postulated are just that theories not fact. I don't believe our universe is curved or closing in on itself. The vastness of our own universe has made it difficult to locate which parts are which.
I suspect myself with the James Wood telescope to replace the Hubble in 2013 will bring about new insights into the origin of the universe. Specifically determining our position and greater understanding of our own universe. Also the key to understanding the universe is hidden in the gravitational forces which transcend beyond our own known.
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there is the added complication that the oldest things we see form a sphere all round us, billions of light years away in every direction, which raises the question as to why, if we can see things as they were, say, a billion years after the BB, they are not close together.
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The Big Bang did not occur at a single point, and the universe did not begin as a single point.
Imagine an infinite rubber sheet covered with dots spaced a metre apart.
Now Stretch the rubber till the dots are two metres apart. The sheet is still infinite, and there is no special point that everything is moving away from.
Reverse the shrinking and the dots get arbitrarily close, but the sheet still remains infinite in size.
The Universe is like that: always infinite, but everything in it is moving further apart from a virtually infinite beginning at t=0, but with no centre of the expansion.
What happened at and before t=0 is unknown, and there is not actually any rubber or any force to stretch it, but I find it a helpful analogy.
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Thanks Pikaia, I like the analogy, but when scientists talk of running the expansion of the Universe backwards to an initial point, or singularity, how does that fit this picture.
Also, if the Universe is 13.7 billion years old, where were all these spots 13.7 billion years ago?
Finally, what do you mean by "virtually infinite"? [???]
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Maggie Tidcombe asked the Naked Scientists:
I have been reading about the origin and life of the universe, about the big bang, the following inflationary period and the subsequent slower expansion we are now in.
My question is... in which area of space, or in which direction can the source of this expansion be found? If everything in our universe has expanded from a single point and may well contract back to the same point, then do we know in which direction to look for this point? Where did the big bang happen? If our universe is closed and curving round on itself like an inflated balloon, then there must be a centre. Which way is the centre, is it where quasars and more densely populated areas of the universe are to be found... In which direction can the oldest part of the known universe be found?
Thank you for an excellent programme (http://www.thenakedscientists.com/HTML/podcasts/)
Maggie Tidcombe, Cornwall.
What do you think?
What your question requires is a center to the universe, but there is no such point unless you consider every point on the spacetime map as the center. There is no specific directionality one can point to and say was the origin of the universe. It was spacetime that expanded, not the matter in it. Space between matter expanded meaning there are specifically and infinite amount of spacetime points you can call a center.
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where were all these spots 13.7 billion years ago?
Finally, what do you mean by "virtually infinite"?
I use the word "virtually" because there was probably no truly infinite density. According to Loop Quantum Gravity the density was enormously high but not infinite, and at these high densities we get repulsion, which causes the initial expansion of the universe. So the points were very much closer at the BB, but still separate.
http://www.scientificamerican.com/article.cfm?id=big-bang-or-big-bounce
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where were all these spots 13.7 billion years ago?
Finally, what do you mean by "virtually infinite"?
I use the word "virtually" because there was probably no truly infinite density. According to Loop Quantum Gravity the density was enormously high but not infinite, and at these high densities we get repulsion, which causes the initial expansion of the universe. So the points were very much closer at the BB, but still separate.
http://www.scientificamerican.com/article.cfm?id=big-bang-or-big-bounce
I am not disagreeing with you on the interpretation of Loop QG, however, it fails to understand such repulsion probably was not required. matter being infinitely stacked on top of each other would cause serious ''disruptions'' in the early phase for two reasons. Trying to force boson on a boson is impossible - it requires more energy than we possibly could ever have, more than in the visible universe. For this reason, a force can be associated to bosons. While they may quantum mechanically fall into equal energy states, they can never occupy the same space - this would have been the first major reason why matter could not be sustained in that tiny confinement we call the singularity.
Second reason is that the uncertainty principle would have played a massive part in expansion as well. Matter being stacked on top of each other, (or possibly simply energy) would have also caused great disruption in the positions causing a massive jolt in their trajectories (hence the expansion of space). There was massive (infinite in fact) certainty during the singularity and first instance of time, so much, we can say the universe was truely born out of a total uncertainty in complimentary conditions.