Could it have been the Big Leak and not the Big Bang?

[Robert P]

As I understand it the big head scratcher regarding the BB is how did it get set in motion?

How about the notion that regarding our universe, it didn't expand from an inert pinpoint but is instead a breach in the "wall" of an even larger system - i.e. essentially like a volcanic eruption. Of course it still raises the question of where the larger system came from.

I assume this notion has been raised before. What would make this implausible?

 

[phinds]

As I understand it the big head scratcher regarding the BB is how did it get set in motion?

How about the notion that regarding our universe, it didn't expand from an inert pinpoint but is instead a breach in the "wall" of an even larger system - i.e. essentially like a volcanic eruption. Of course it still raises the question of where the larger system came from.

I assume this notion has been raised before. What would make this implausible?

Your concept that the BB was a point in space is incorrect so the rest of your post is based on a false premise.

 

[Arman777]

As I understand it the big head scratcher regarding the BB is how did it get set in motion?

How about the notion that regarding our universe, it didn't expand from an inert pinpoint but is instead a breach in the "wall" of an even larger system - i.e. essentially like a volcanic eruption. Of course it still raises the question of where the larger system came from.

I assume this notion has been raised before. What would make this implausible?

Also in a such a case universe wouldn't be homogeneous and isotropic. But its homogeneous and isotropic so it rules out any type of "point explosion"thing.

 

[PeterDonis]

As I understand it the big head scratcher regarding the BB is how did it get set in motion?

Where did you get this understanding from?

 

[Robert P]

Where did you get this understanding from?

Are you serious? Every illustration and description I've ever seen. The whole notion that all bodies seem to moving away from a common point.

From the Wikipedia article on the singularity:

"General relativity is used to predict that at the beginning of the Universe, a body containing all mass, energy, and spacetime in the Universe would be compressed to an infinitely dense point."

 

[Robert P]

Your concept that the BB was a point in space is incorrect so the rest of your post is based on a false premise.

See my response above to PeterDonis. I'm curious where YOUR concept comes from and what it is since it's apparently radically different than the commonly promoted notion of the BB.

 

[Ibix]

See my response above to PeterDonis. I'm curious where YOUR concept comes from and what it is since it's apparently radically different than the commonly promoted notion of the BB.

From a cosmology textbook, I should imagine. Unfortunately, pop-sci descriptions of cosmology are generally badly wrong. For example, the pictures you posted should not be taken at all literally (edit: and the Wikipedia quote is just wrong - a common issue, I'm afraid).

The core of cosmology is that, on very large scales, everything is the same everywhere. That immediately precludes the idea that there was a single point from which the universe expanded because that wouldn't have been the same as elsewhere. Another way to look at it is, if the universe is infinite in extent now (as we believe) then it must always have been infinite.

The scale factor of the universe used to be smaller, yes. Stuff used to be closer together, more dense and hotter. But there was always infinitely much of it spread out over an infinite volume. There is a problem at the start, where our models say the scale factor goes to zero. That most likely means that our models break down somewhere, though, and we hope quantum gravity will help there.

 

[PeroK]

See my response above to PeterDonis. I'm curious where YOUR concept comes from and what it is since it's apparently radically different than the commonly promoted notion of the BB.

The BB theory is essentially an incomplete theory. It takes us back to a time when the universe was very dense, but it cannot take us back to the very beginning.

If you look more closely at the Wikipedia quotation it says:

General relativity is used to predict that at the beginning of the Universe, a body containing all mass, energy, and spacetime in the Universe would be compressed to an infinitely dense point."

That begs the question of whether in this respect General Relativity is a complete description of the universe. Given this "prediction" it doesn't take a lot to imagine that there might be something yet to find out.

In any case, the popularised assumption that everything came from a single point is physically and mathematically problematic, to say the least.

 

[Arman777]

See my response above to PeterDonis. I'm curious where YOUR concept comes from and what it is since it's apparently radically different than the commonly promoted notion of the BB.

The problem in this picture is, you are looking the universe "from the outside".

There's no such thing. The universe is infinite hence, there can't be the a place where you can draw such thing or even think something like this.

The fundamental wrong of the pic is this concept. Hence, we can think that the picture cannot give a true description about what really happens.

 

[phinds]

... The universe is infinite ...

Maybe, maybe not, but that should not be stated as a fact since it is not known to BE a fact, just the most likely theory.

 

[phinds]

... I'm curious where YOUR concept comes from ...

From actual science, rather than pop-sci misrepresentations. Your misunderstanding on this point is VERY common and will go away as you do more reading in actual science.

 

[Arman777]

Maybe, maybe not, but that should not be stated as a fact since it is not known to BE a fact, just the most likely theory.

I am not the only person that claims it. Ibix also claimed that in his post also I am sure I can find many others. And current obervational data shows that universe should be inifinite and flat.

 

[phinds]

I am not the only person that claims it. Ibix also claimed that in his post also I am sure I can find many others. And current obervational data shows that universe should be inifinite and flat.

"Should be" and "is" are not the same thing. I acknowledge that many people here on PF, all of whom know more physics than I do, say that but I believe that their saying it IS infinite is really just shorthand for saying something like "we don't know for sure that it is infinite but is seems to be based on current evidence". Calling @PeterDonis who has made the statement several time as I recall.

 

[Ibix]

"Should be" and "is" are not the same thing. I acknowledge that many people here on PF, all of whom know more physics than I do, say that but I believe that their saying it IS infinite is really just shorthand for saying something like "we don't know for sure that it is infinite but is seems to be based on current evidence". Calling @PeterDonis who has made the statement several time as I recall.

Agree with this. We model space as infinite (or finite but unbounded in the case of a closed universe), and we have no idea what a bounded space would look like. What's beyond it, if anything? And all of our experimental evidence is consistent with these models. But we can't see to infinity - so there could be funny stuff happening beyond our sight that would change our models if we were aware of it.

I don't say that's particularly likely, but it's always worth keeping in the back of your mind the idea that any of our scientific models can, in principle, be invalidated by future more precise measurements.

Just to note, I did say if the universe is infinite in my previous post. I admit I slipped somewhat later on, and I didn't draw attention to the fact that the cosmological principle is (effectively) a rule of thumb rather than an absolute truth.

 

[Arman777]

Okay I agree, I should use "should" instead of "is". But it still doesn't change the main idea. Even universe is flat and have finite topology, we can't image universe as an outside view. Since there's no such think as "outside of the universe".

 

[phinds]

Okay I agree, I should use "should" instead of "is". But it still doesn't change the main idea. Even universe is flat and have finite topology, we can't image universe as an outside view. Since there's no such think as "outside of the universe".

I certainly agree w/ that and did not mean to imply otherwise

 

[newjerseyrunner]

Those images that you showed I thank are where a lot of misconceptions come from. It shows a large universe crunched down to a point. But that is meant to represent a sample of the universe, of which there are (likely) infinite. Expansion appears to be a scalar effect, not an explosion. If you scale an infinite object down, no matter how far you go, it's still infinite.

That said, the universe appears to be infinite in three dimensions, but the universe has (at least) four. The fourth dimension of time does calculate down to a point about 13.8 billion years ago. Of course, there are also plenty of models that can make sense of a before time.

 

[Nik_2213]

Now I'm confused...

Perhaps banging higher-dimensional branes together will not suffice as hand-wavium, after all !

 

[jbriggs444]

The universe is infinite hence, there can't be the a place where you can draw such thing or even think something like this.

Not on topic for this thread, but I've seen this misconception a few times and want to address it. "Infinite" is not a synonym for "all-encompassing". You can have a thing that is infinite and still view it from outside. Take, for example, a birds-eye view from above an infinite two-dimensional plane.

The term "universe" by itself does mean something all-encompassing. There is no outside, regardless of whether it is finite or infinite.

 

[Arman777]

Not on topic for this thread, but I've seen this misconception a few times and want to address it. "Infinite" is not a synonym for "all-encompassing". You can have a thing that is infinite and still view it from outside. Take, for example, a birds-eye view from above an infinite two-dimensional plane.

The term "universe" by itself does mean something all-encompassing. There is no outside, regardless of whether it is finite or infinite.

Yes I agree and I already claimed that on my post #15

 

[Robert P]

From a cosmology textbook, I should imagine. Unfortunately, pop-sci descriptions of cosmology are generally badly wrong. For example, the pictures you posted should not be taken at all literally (edit: and the Wikipedia quote is just wrong - a common issue, I'm afraid).

If you feel you can back that up with valid citations you should correct the Wikipedia article.

 

[Ibix]

If you feel you can back that up with valid citations you should correct the Wikipedia article.

Go ahead if you like (although @PeroK makes a good point about all the caveats rendering the final clause irrelevant to reality). See e.g. chapter 8 of Sean Carroll's lecture notes https://www.preposterousuniverse.com/grnotes/

 

[Robert P]

If you feel you can back that up with valid citations you should correct the Wikipedia article.

Go ahead if you like (although @PeroK makes a good point about all the caveats rendering the final clause irrelevant to reality).

I'm not sold on the notion that the concept outlined in that Wiki article doesn't accurately reflect current theory but you seem to be. I'm not a necessarily a cheerleader for Wikipedia but what I've seen of that article is in line with impressions I've gotten elsewhere.

I'm also aware that all notions on the topic of "where it all came from" are speculation. There's no one on this planet who knows.

 

[Ibix]

Go ahead if you like

Just to amend that slightly, the problem is that any natural language description of what's actually going on is going to be open to misinterpretation somehow. So while I could probably write something that clears up this particular issue, it would not clear up all issues and may raise others. If precision like that were easy then pop-sci descriptions wouldn't have the flaws I'm carping about!

Basically the solution is for everyone to realize that if they can't follow the maths they don't really understand the theory.

 

[PeterDonis]

Every illustration and description I've ever seen.

Illustrations, descriptions, and Wikipedia articles are not valid sources. What textbooks or peer-reviewed papers have you read? If, as I suspect, the answer is "none", then go read some. You can't learn actual science from pop science sources. (And, btw, you marked this thread as "I", which indicates an undergraduate-level understanding of the subject matter. You can't get that from pop science sources or Wikipedia.)

The whole notion that all bodies seem to moving away from a common point.

Which is not what the actual model used by cosmologists says. So if you got that notion from Wikipedia and pop science sources, which it appears you did, that just illustrates what I said above: you can't learn actual science from pop science sources.

 

[PeterDonis]

I'm not sold on the notion that the concept outlined in that Wiki article doesn't accurately reflect current theory

Unless you've read some actual textbooks or peer-reviewed papers that describe the current theory, you have no valid basis for an opinion.

I am closing this thread since the OP is based on a misconception. @Robert P if you have any valid sources--textbooks or peer-reviewed papers--that support your understanding, please PM them to me.

 

[PeterDonis]

If you feel you can back that up with valid citations you should correct the Wikipedia article.

Correcting Wikipedia articles is a tedious, frustrating, and thankless process of whack-a-mole. That's why many knowledgeable people don't bother--it's not worth it. And it's why we don't consider Wikipedia a valid source here at PF. If we refer to Wikipedia articles, it's only in cases where we know based on valid sources that the article's presentation is reasonably accurate.