A big bang in an infinite flat universe?

[bascule]

If the big bang was an explosion of space, then how could it give birth to an infinite flat universe? Wouldn't the space have to explode into... infinite more space?

[Daecon]

What do you mean by "flat", though?

[Royston]

I think Bascule means 'flat' as in definition not structure, before the advent of curvature that came with GR. However, there's no need for space to explode into anything, because space (space-time) is 'the anything'...if that makes sense, sorry it's poorly phrased.

[Daecon]

Hmm... if the M-Brane theory is accurate, then our 4D Universe was created by the collision of some other Brane dimensions, and the Big Bang explosion was the process of that collision.

 

This lead to the creation of our reality and everything we hold dear.

[bascule]

I think Bascule means 'flat' as in definition not structure

 

The overall curvature of space can be positive, negative, or flat. If space has positive or negative curvature, it will be closed. If it's flat, then it will be infinite.

 

However, there's no need for space to explode into anything, because space (space-time) is 'the anything'...if that makes sense, sorry it's poorly phrased.

 

As far as I can tell that statement holds true for a closed universe with positive or negative curvature. However if the universe is infinite flat then how can something which is infinite explode?

[Royston]

So were talking about a Euclidian universe...which can be defined as a 'flat' universe. Just double checking you weren't talking solely about dimensions et.c

 

As you well know the three scenarios so far are all plausible...whats more interesting is that a 'flat' universe agrees with cosmic inflation, and yes it holds infinites. Basically if the universe is 'flat' it will yield enough mass to stop expansion after an infinite amount of time. You may be interested in 'phase transition' which explains the early repelling force that kick started inflation.

 

That's all I know...so far, an infinite universe has no need to start again by exploding into another infinite, because it is infinite...is that right ? Feel free to rip this apart, I'm under the weather today so not thinking to clearly.

 

I think the problem is there shouldn't be infinites, and why there is a lot of concentration on implementing curvature, and why there's all these mysterious goings-on in black holes, and everything agreeing with thermal dynamics and so and so on. Maybe someone with more knowledge could tell you if it's plausible or not...I think this is one of those 'what if' questions though, which (probably eat my words now) that I'm not sure anybody can answer.

[Martin]

If the big bang was an explosion of[/i'] space, then how could it give birth to an infinite flat universe? Wouldn't the space have to explode into... infinite more space?

 

Hi bascule, part of what puzzles people about the big bang and related matters is that it has to do with stuff that is current research or where the measurements are not yet accurate enough.

 

Your questions can be PARTLY answered, but it will leave an unsatisfactory sense of incompleteness that talking can't cure.

 

1. I agree that the universe looks spatially flat, if you look at a large enough piece of it. Or else ALMOST flat. Astronomers have this number Omega that they measure and they get values like 1.01 +/- 0.01.

If Omega = 1 exactly then the U is spatially flat. Which contains the idea of infinite as the most likely (but not the only possible) realization.

But if, say, Omega = 1.01, then the U has to be FINITE with a slight curvature. and we dont know which it is----exactly 1 or just a bit over.

 

2. space doesn't need some surrounding space to expand INTO

space simply expands.

 

To answer your question

Wouldn't the space have to explode into... infinite more space?

The answer is no. It would not need any space to expand into.

 

That is just a feature of the mathematical model used to represent space (and time) in Gen Rel. It doesnt need any surrounding to contain it.

 

3. Astronomers are constantly trying to measure Omega more accurately. Eventually they may get it down to something like, say,

 

1.005 +/- 0.0025

 

that would be GREAT! What a relief! Then we would know that the U was NOT spatially flat and that no way could it be infinite. At least the usual sigma confidence interval would be from 1.0025 to 1.0075.

so it would be almost but not quite flat, and it would have a very slight positive curvature (analogous to a very large sphere) and would be FINITE.

 

But until they can orbit an accurate enough instrument and until they actually get some measurement like that, then we can't decide---we have to keep both possibilities in mind----definitely a nuisance but complaining does no good

 

4. As far as the big bang goes. The mathematics do not require the universe to be a point, or even to be finite, at the moment expansion begins.

There is a misconception caused by popular writing where it is called an "explosion". But as far as the math goes the UNIVERSE CAN START OFF SPATIALLY INFINITE AT THE MOMENT IT STARTS TO EXPAND. there isnt any problem with this.

 

To answer your other question:

If the big bang was an explosion of space, then how could it give birth to an infinite flat universe?

The answer is EASY, the big bang is just the moment expansion started. the initial condition, or rather the condtion at that moment could very well have been an infinite, spatially flat, universe. So the big bang could EASILY have given birth to an infinite spatially flat U, simply because that is what was already present----it was what expansion started with.

 

but if Omega is ever so slightly bigger than one, and the universe is not flat, but instead is slightly positive curved, and FINITE, then that means that at the moment it started expanding it was already finite.

 

WHICHEVER IT IS NOW, finite or infinite, IT ALREADY WAS WHEN IT STARTED EXPANDING

 

5. I think the most important theoretical research being done now is exploring, using computer simulations among other tools, what conditions were like IMMEDIATELY BEFORE THE BIG BANG.

 

the old 1915 Gen Rel model breaks down at the moment expansion starts but an improved version of quantum cosmology appears not to break down and so one can investigate the prior phase before expansion started.

 

This is very new work. I can get some links. One shouldn't expect the issues to be settled. Like any theory, predictions have to be derived from it and then tested. Do you want some links to recent work?

[Daecon]

What if the universe is both positively curved along the X axis and negatively curved each along the Y axis, leading to a kinda "saddle" shaped universe?

[guardian]

Well, thank you Martin. Your post pretty much answers the questions I posed in post #176 in the 'Where does space end...' thread in this forum section that seems to have been overlooked and perhaps buried by the next poster. I should have posted it as a new topic I suppose.

 

So we can still hold onto the hope that perhaps space is minutely curved and perhaps closed as long as we get a positive Omega value. Even though it is very close to 1, it CAN be said that the possibility of a closed ALMOST infinite universe still exists. Couldn't this minute curvature (translating to a larger curvature earlier on in the universe) be responsible for the reason we have mainly matter and not anti-matter as the norm? Couldn't this also be responsible for the CP symmetry violation?

[bascule]

[b']WHICHEVER IT IS NOW, finite or infinite, IT ALREADY WAS WHEN IT STARTED EXPANDING[/b]

 

I guess my question then becomes how does something which is infinitely large to begin with expand?

[Martin]

...

 

So we can still hold onto the hope that perhaps space is minutely curved and perhaps closed as long as we get a positive Omega value. Even though it is very close to 1' date=' it CAN be said that the possibility of a closed ALMOST infinite universe still exists. Couldn't this minute curvature (translating to a larger curvature earlier on in the universe) be responsible for the reason we have mainly matter and not anti-matter as the norm? Couldn't this also be responsible for the CP symmetry violation?[/quote']

 

you are asking intelligent questions, G. but rather than me trying to answer (e.g. about why matter is dominant over antimatter, and if this is connected somehow to the possible finiteness of the U) I think you have to research that one yourself.

 

People have offered explanations for matter dominance which do not depend on spatial finiteness, they would work in spatially flat U, as long as you have symmetry violation. So I think your idea is that the symmetry violation in the Standard Model may arise somehow from the slight curvature of space!!! I don't see how it would work and I don't know enough to properly evaluate the idea. I think there is no known way that could happen but there is plenty of room for new physics in the future and who knows they might be connected.

[Martin]

I guess my question then becomes how does something which is infinitely large to begin with expand?

 

Hi bascule,

I don't see the problem. Why shouldnt something that is infinite expand?

 

think of a simple infinite line marked with dots, say, every 6 inches.

a straight black line with white dots---half a foot apart---stretching out to infinity in both directions

 

so you are standing looking at this line, and amazingly enough it begins to expand in the sense that the dots are slowly getting farther apart

 

now they are nearly 7 inches apart and the line is still stretching out

 

after a while you come back and see they are over a foot apart!

 

the important thing when something is expanding is that points in it get farther and farther apart from each other

 

the thing that is expanding may have NO definite OVERALL SIZE, because it may be infinite, so it has no well-defined length or other dimension. BUT IT CAN STILL SWELL UP as long as points in it keep getting farther apart.

 

is that OK bascule?

 

If you want, think of it as just a semantic verbal thing. when I say EXPAND that is what I mean, like the raisinbread dough is rising and the raisins are getting farther apart----and I dont care whether the dough is infinite or finite, I just look at a local bit of it and I see it is expanding.

 

You can have a more restrictive definition of the word "expand" and then you would describe the universe differently.

 

I like my concept of expansion because it is loose and general and applies in both the finite and the infinite case. And that's good because at present WE DON'T KNOW YET which case we are in. We do know it's expanding but we don't yet know if it is finite or not. So it is convenient to have a concept of expansion that applies to both the possibilities.

[guardian]

Thanks Martin, I will source some of the proposed explanations for these observables, any idea of a good source?

[Martin]

Thanks Martin, I will source some of the proposed explanations for these observables, any idea of a good source?

 

the short answer is NO, I dont have a good book or website---I think what you are asking about is the Standard Model of particle physics

(why are there these and these kinds of particles, why are there 3 of this and 4 of that etc.)

 

I will tell you who my current hero is in particle physics. it is a young australian guy at Adelaide University

 

here is a paper that he wrote this year:

 

http://arxiv.org/hep-ph/0503213

A topological model of composite preons

Sundance O.Bilson-Thompson

9 pages, 3 figures

 

here is a video of him giving a talk at a place in Canada called Perimeter Institute.

it is worth watching if you have a fast connection and can download it within a reasonable time.

 

http://streamer.perimeterinstitute.ca:81/Mediasite/Viewer/Viewer.aspx?layoutPrefix=LayoutTopLeft&layoutOffset=Skins/Clean&width=800&height=631&peid=2e5425f4-3f47-4e5a-a86a-804a6d499b17&pid=e949d11b-a1a5-4365-a152-7e2014cb3867&pvid=1&playerType=WM64Lite&mode=Default&shouldResize=true

 

there are two ways to get the video, try this one and if it doesnt work tell me and I will tell you the other way, if you want

[padren]

If you want' date=' think of it as just a semantic verbal thing. when I say EXPAND that is what I mean, like the raisinbread dough is rising and the raisins are getting farther apart----and I dont care whether the dough is infinite or finite, I just look at a local bit of it and I see it is expanding.

[/quote']

 

That would require interaction out from some source right? I mean, a ripple effect, spreading at some finite speed no larger than c, pushing the raisins farther apart, but taking an Exceptionally Long Time to reach Really Far Away and would never impact anything at Infinity And Beyond...

 

Oi my brain hurts.

 

Ok, I don't know a lot about this topic but I have to ask about infinite space, since there is something that just doesn't sit right with me.

 

If I have a red object and a blue object, there is some sequence of cause and effect that led to the different colorations, and for any two anythings to have distinct characteristics, those objects must have some distinct property that is either red or blue in this case.

Some difference in the energy that created the two objects was required to create the difference between the two.

 

The reason I am mentioning this, is because when you have space, I can hold a hotdog 2 feet from me or 3 feet from me, and to me, that tells me there is a difference in the space at 2 feet and at 3 feet - that the space there has quantifiable differences (like blue or red), and it must have taken energy to create that difference.

To create infinite space, in my mind, would be like something creating enough atoms for infinite mass to exist, which would never make sense in terms of cause and effect, because it would take an infinite amount of energy to make an infinite number of particles with unique attributes and some quanta of mass, and probably an infinite amount of time.

 

If this is the sort of question that I wouldn't ask if I was more well read - can you recommend any good books? I find it somewhat perplexing.

[Martin]

Guardian, about that talk. It was given 16 November 2005. some of it is very recent work.

 

the first 3 or 4 minutes is Lee Smolin talking about other seminar talks and then he introduces Sundance---who is the tall gangly young guy

 

the good thing about Sundance model is it SIMPLIFIES the standard model and explains why there are this many quarks and that many leptons and so on.

 

it has very few basic components ("pre-ons") which are combined to produce the known quarks and also electrons and neutrinos.

 

so there are just these two things, which pair up in 3 possible ways, and those three then combine to make all the particles we know about. (pretty fantastic.) and JUST those, not any others!

 

part of this depends on the rules of combination, which he talks about in the lecture.

 

part of the talk is with slides, that he had prepared before, and part he doesnt have slides for and was going to the blackboard drawing smudgy chalk pictures and rubbing them out and redrawing etc.

 

impressive guy.

 

I will tell you who my current hero is in particle physics. it is a young australian guy at Adelaide University

 

here is a paper that he wrote this year:

 

http://arxiv.org/hep-ph/0503213

A topological model of composite preons

Sundance O.Bilson-Thompson

9 pages, 3 figures

[guardian]

Martin, I have actually read a paper about preons and such. Cannot remember the detail, I will have a look again and refresh my memory, thanks for the links & the info.

 

I am quite well versed with the St. Model however what I am looking for is a credible (non-cooky) explanation for the domination of matter in the U and perhaps a similar explanation of why CP symmetry violation occurs. Swaying off topic here a little - but it's all good.

[Martin]

Martin' date=' I have actually read a paper about preons and such. Cannot remember the detail, I will have a look again and refresh my memory, thanks for the links & the info.

...[/quote']

 

sundance preon model is new this year

but, as you suggest, there have been several OTHER preon models

going back to the 1970s and 1980s

 

in his talk, sundance gives some of the history of the earlier preon models and indicates what he changed

 

hope you get a chance to watch and listen to the talk, guardian,

it comes in a split screen format so you see the slides on the right side in synch with the speaker on the left

[guardian]

Well, wouldn't you know it - just checked my collection and that is the one I read (downloaded the pdf on 24 Nov) ...and I had a feeling that there was something incomplete about it, let me check...

 

Ah, yes, origins of gravity & "what physical process the twisting and braiding of helons represents". But all-in-all it is quite an interesting theory.

 

Come to think of it, I may have come accross it in one of your other/previous posts elsewhere here and that's why I read it.

 

I will watch the presentation, just need to get some time up my sleeve first.

[phcatlantis]

Quick question. Isn't there something wrong with the stretchy string, rubber sheet, balloon analogy if the idea we're trying to convey is that its a definition of distance, with a scale factor slapped on, not some tangible thing an 8 year old can bite on, that's expanding? There's gotta be a better way to explain this stuff.

[ecoli]

Quick question. Isn't there something wrong with the stretchy string, rubber sheet, balloon analogy if the idea we're trying to convey is that its a definition of distance[/i'], with a scale factor slapped on, not some tangible thing an 8 year old can bite on, that's expanding? There's gotta be a better way to explain this stuff.

 

Yeah, if we call a balloon space, immediately we think of a kid stretching on that balloon. But there is not "outside" to space, so that kind of thinking doesn't really work. The balloon has clear boundries separating baloon from not baloon. The same isn't true for the universe.

[guardian]

That would be 'limited' type of thinking but if you can get a good enough grasp of 'nothing' then talking about boundaries loses its meaning ie. becomes meaningless. We're used to having something beyond something and hence boundaries. If the universe is closed then that doubly dissolves any boundaries since space curves back in on itself and there is no way to reach any real or apparent boundaries.

[Martin]

atlantic and ecoli you both sound like you understand the problem of explaining space or spacetime using material metaphors. please try your hand at it next time we have a question about that. Your metaphors probably work as good as mine

 

I have a question. Who here (guardian, ecoli, atlantic...) can get this to play? How long does it take to download. With my connection it takes a wait of 2 or 3 minutes before it starts up. This is a talk given in November by Bilson-Thompson on a way of presenting the standard particlephysics model that he is working out.

 

http://streamer.perimeterinstitute.ca:81/Mediasite/Viewer/Viewer.aspx?layoutPrefix=LayoutTopLeft&layoutOffset=Skins/Clean&width=800&height=631&peid=2e5425f4-3f47-4e5a-a86a-804a6d499b17&pid=e949d11b-a1a5-4365-a152-7e2014cb3867&pvid=1&playerType=WM64Lite&mode=Default&shouldResize=true

 

when it starts the first person you see is Lee Smolin--he introduces the speaker

[ecoli]

atlantic and ecoli you both sound like you understand the problem of explaining space or spacetime using material metaphors. please try your hand at it next time we have a question about that. Your metaphors probably work as good as mine

 

Thank you Martin. Coming from a physics expert such as yourself, that means a lot. I'll continue to try my best

 

I have a question. Who here (guardian, ecoli, atlantic...) can get this to play? How long does it take to download. With my connection it takes a wait of 2 or 3 minutes before it starts up. This is a talk given in November by Bilson-Thompson on a way of presenting the standard particlephysics model that he is working out.

 

I got it to play... started playing after about, say 30 seconds on my DSL modem. It's streamed, so you don't need to wait until it finishes downloading.

 

 

when it starts the first person you see is Lee Smolin--he introduces the speaker

 

cool. Unfortunately, I can't watch it all now... far too late.

[phcatlantis]

I have a question. Who here (guardian' date=' ecoli, atlantic...) can get this to play? How long does it take to download. With my connection it takes a wait of 2 or 3 minutes before it starts up. This is a talk given in November by Bilson-Thompson on a way of presenting the standard particlephysics model that he is working out.

 

http://streamer.perimeterinstitute.ca:81/Mediasite/Viewer/Viewer.aspx?layoutPrefix=LayoutTopLeft&layoutOffset=Skins/Clean&width=800&height=631&peid=2e5425f4-3f47-4e5a-a86a-804a6d499b17&pid=e949d11b-a1a5-4365-a152-7e2014cb3867&pvid=1&playerType=WM64Lite&mode=Default&shouldResize=true

 

when it starts the first person you see is Lee Smolin--he introduces the speaker[/quote']

 

Its playing for me. What's the issue?