Talk:Big Bang

IMPORTANT: This is not the place to discuss how you think the universe began, or to discuss whether or not the Big Bang model is correct. This page is for discussing improvements to the article. The article is about the Big Bang model, with content based on information presented in peer-reviewed scientific literature about it or other appropriate sources. See Wikipedia:No original research and Wikipedia:Talk page guidelines. If you wish to discuss or debate the validity of the Big Bang please do so at BAUT forum or talk.origins.

Misnomer (incorrect name) for Big Bang

Just think we should emphasize that "The Big Bang is not an explosion of matter moving outward to fill an empty universe". This is already in the article, but not clear enough -a lot of people incorrectly think the Big Bang is an explosion 129.180.175.166 (talk) 06:14, 16 September 2014 (UTC)

While, yes, the name "Big Bang" is a misnomer, the problem with this suggestion is that it's still officially called the "Big Bang," and Wikipedia can not rename it without running afoul of Wikipedia's own rules against original research and inappropriate synthesis. Where would you add more emphasis to better explain how it's not actually an explosion?--Mr Fink (talk) 15:46, 16 September 2014 (UTC)

I suggest that since it is a general consensus of the field that time and space expanded rather than there being a single point of an detonation, that the words explosion be replaced with expanded or expansion. By definition the requirements for an explosion do not exist within the Big Bang.--digitalbeachbum 11:13, 9 October 2014 (UTC) — Preceding unsigned comment added by Digitalbeachbum (talk • contribs)

Isn't that already explained in the article?--Mr Fink (talk) 15:33, 9 October 2014 (UTC)

I am confused by this statement. The only occurrences of the word "explosion" in this article, are in sentences saying (in various forms) that the big bang is not an explosion. What is it exactly that you are suggesting?TR 15:53, 9 October 2014 (UTC)

visible universe

Since the big bang theory only accounts for 4.9% of the universe (i.e. ordinary matter), shouldn't the statement in Wikipedia :

"The Big Bang theory is the prevailing cosmological model for the early development of the universe."

be modified to end with:

"the development of 4.9 % of the universe (i.e. ordinary matter)"? — Preceding unsigned comment added by 99.234.204.140 (talk) 16:40, 19 September 2014 (UTC)

no.TR 16:45, 19 September 2014 (UTC)

Why do you think that the Big Bang theory only accounts for ordinary matter ? How do you think dark matter originated ? Gandalf61 (talk) 16:20, 9 October 2014 (UTC)

Incorrect statement about the Big Bang model needs correction

The article incorrectly states "the Big Bang model suggests that at some moment all matter in the universe was contained in a single point". This is merely a popular misconception about the Big Bang model, is contrary to authoritative sources about the Big Bang model, and should not be further popularized.

According to http://map.gsfc.nasa.gov/universe/bb_concepts.html

Please keep in mind the following important points to avoid misconceptions about the Big Bang and expansion:

• The Big Bang did not occur at a single point in space as an "explosion." It is better thought of as the simultaneous appearance of space everywhere in the universe. That region of space that is within our present horizon was indeed no bigger than a point in the past. Nevertheless, if all of space both inside and outside our horizon is infinite now, it was born infinite. If it is closed and finite, then it was born with zero volume and grew from that. In neither case is there a "center of expansion" - a point from which the universe is expanding away from an origin point. In the ball analogy, the radius of the ball grows as the universe expands, but all points on the surface of the ball (the universe) recede from each other in an identical fashion. The interior of the ball should not be regarded as part of the universe in this analogy.

Furthermore, according to http://map.gsfc.nasa.gov/universe/uni_shape.html

We now know (as of 2013) that the universe is flat with only a 0.4% margin of error. This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe.

Another source, Anthropic Bias: Observation Selection Effects in Science and Philosophy (Studies in Philosophy), by Nick Bostrom, page 51:

A widespread misconception is that the open universe in the standard big bang model becomes spatially infinite only in the temporal limit. The observable universe is finite, but only a small part of the whole is observable (by us). One fallacious intuition that might be responsible for this misconception is that the universe came into existence at some spatial point in the big bang. A better way of picturing things is to imagine space as an infinite rubber sheet, and gravitationally bound groupings such as stars and galaxies, as buttons glued on. As we move forward in time, the sheet is stretched in all directions so that the separation between the buttons increases. Going backwards in time, we imagine the buttons coming closer together until, at “time zero”, the density of the (still spatially infinite) universe becomes infinite everywhere.

Unless there is a request for additional authoritative sources confirming that what the wikipedia article states is a misconception about the Big Bang model, I will proceed with making the necessary correction. Thank you, Vanyo (talk) 02:28, 18 October 2014 (UTC)

The statement is not actually inaccurate. All the universe WAS contained in a single point, that single point also being the sum total of space too. I think there was a talk page discussion about this very issue a few years back in the archives.Farsight001 (talk) 05:26, 18 October 2014 (UTC)

For each of those "reputable"sources you can find sources treating the initial singularity as a single point. So who is wrong? Nobody. The dimensionality of singularities in GR is notoriously ill defined. Being a singularity the geometry of the initial time slice is not defined at all. The best you can do is define a topology on it. Here you have a choice. You can complete your open manifold by a single point or by a point for each comoving coordinate. (There are more choices, but those are not isotropic or homogeneous).

If you choose for a spatially infinite initial slice, however, you end up with a very unintuitive result. Because, the FLRW metric is spatially homogeneous and isotropic and contains matter, it has a preferred time slicing. This allows for a canonical definition of the geometry of the initial slice. In this geometry, the geodesic distance between all points on the initial slice is zero. Hence it is not what anybody intuitively would call "infinite". (In fact, the natural topology induced by this induced metric is the trivial topology. If we then insist on the topology being Hausdorf as well, then this implies that the initial slice consists of only a single point).TR 12:23, 18 October 2014 (UTC)

Do those sources that describe it as a single point (or anything spatially finite) address whether or why they're assuming the universe today is spatially finite? (but of course unbounded) ... Or are they just repeating a popular misconception about the theory? Do they argue that the question of a finite or infinite universe is settled? Do they argue that an infinite universe can expand from a point? I'd like to see a source that addresses those question with a different conclusion than the sources I cited. I know there are many that repeat the hypothesis of a pointlike singularity while seemingly oblivious to any of that. Vanyo (talk) 19:28, 18 October 2014 (UTC)

No they do not, because they do not assume that the universe today is spatially finite. Going from your response, I am guessing you did not understand the explanation I gave before. More simply put, it is simply the question: What is zero times infinity? (With the answer being depends.)TR 20:09, 18 October 2014 (UTC)

The wording is a little bit poor, I must agree. To state that "all matter in the universe was contained in a single point" conjures up images of something with and outside as well as an inside. Perhaps the word "occupied" might be more appropriate? nagualdesign 01:27, 19 October 2014 (UTC)

Indeed, the wording can probably be improved. However, to me "occupied" conjures up even more strongly the possibility of there being other points. The whole point is that at the Big Bang singularity all of space (and its contents) is reduced to a single point. The emphasis here is that this is not a single point is space, but that space is a single point (at t=0). I had a go at making this more explicit in the lede.TR 13:03, 20 October 2014 (UTC)

LEAD TOO LONG -- Too complex

I am sorry to come here and say this, But I read a lot of Leads on Wikipedia and this one is a MONSTER. It is too big, too much non-essential detailed information that belongs in the body, not the lead per WP:LEAD. As often is the case people work on these articles so long that they stop being critical. But when I read this lead it is heavy and too much. 1/2 this info does not belong in a lead. Actually I find it hard to read because of how it is written. --Inayity (talk) 19:35, 8 December 2014 (UTC)

Yes, this is often a problem. I think that a short lead gets written, then added to, and added to, etc. Some leads evolve into monsters. Just taking a quick look, I'd say that the entire paragraph on history can be deleted. That material appears below, and all an interested reader has to do is scroll down a bit. In general, it is helpful to reflect on just what is necessary for a lead. It can be a learning experience on its own. I'd concentrate just on what the BB is, not how we came to understand the BB. But, of course, some editors may disagree. Still alive, Grandma (talk) 19:43, 8 December 2014 (UTC)

History section is critical to the topic and should not be deleted from the lead. Consider that some people will only read the lead, and that it should stand as a miniature article with all the relevant parts. Diego (talk) 21:39, 8 December 2014 (UTC)

Diego, In the spirit of moving forward, then, what do you think should be removed? Please be specific. Grandma (talk) 21:45, 8 December 2014 (UTC)

There's no need to remove anything, only to give it a better structure. I've reworked the lead using an inverted pyramid and moving some of the fluff to the Overview section, that was empty anyway. In this form, the lead provides a short introduction to the concepts of the theory without unnecessary detail, without renouncing to the historical part which will be what non-technical readers will be most interested in. The inessential concepts of what the theory is that were in the lede are now moved right below it, in the Overview section, that before was too complex to provide an actual overview of the general topic. Feel free to change some sentences between these two parts, as long as the lede still contains the few essential parts about who proposed the theory and in what century it did happen. Diego (talk) 21:58, 8 December 2014 (UTC)

Thank you, Diego, for contributing, here. I also hope other editors weigh in on the lead, working to keep it focussed. Cheers, Grandma (talk) 01:41, 9 December 2014 (UTC)

Often people are too close and cannot judge what is non-essential: In 1929, Edwin Hubble discovered that the distances to faraway galaxies were strongly correlated with their redshifts. Hubble's observation was taken to indicate that all distant galaxies and clusters have an apparent velocity directly away from our vantage point: that is, the farther away, the higher the apparent velocity, regardless of direction.[7] Assuming that we are not at the center of a giant explosion, the only remaining interpretation is that all observable regions of the universe are receding from each other.--100% this is NOT lead material.--Inayity (talk) 02:55, 9 December 2014 (UTC)

Inayity, I agree, and, personally, I'd take out all the history from the lead. History is important, yes, and I love it, but there is so much to cover in this article, and repetitious stuff can be removed. An example of a succinct lead that is related to this page on the BB is Universe. Although the universe literally encompasses everything, the lead for that article is relatively short! Cheers, Grandma (talk) 02:59, 9 December 2014 (UTC)

I have tried to make the opening flow better, please feel free to tweak, re-edit, whatever. I feel the age of the Universe and the beginning of the universe convey the same point, it is a choice which one is better but I think having both is a duplicate.--Inayity (talk) 03:21, 9 December 2014 (UTC)

You don't seem to understand the problem you've created with that removal. By removing history, you eliminate any insight about the timeframe in which the theory was created. In your version, Big Bang theory could have been one of the many theories invented by the Greek; no one could tell otherwise from the lede. The Universe is not a human creation, the theory that describes the Big Bang is, though; the lead needs to include some basics about how the theory was developed, not merely of what it says. Diego (talk) 07:42, 9 December 2014 (UTC)

But you still have to write good prose, not have orphan statements that are disconnected at out of place. In 1929 Edwin Hubble discovered evidence that all faraway galaxies are drifting away at high speeds seems orphaned. --Inayity (talk) 08:25, 9 December 2014 (UTC)

Then improve the paragraph, don't delete it wholesale. This is collaborative editing. Make an improvement that you think I could agree with, taking into account what I've said it's important to keep. Diego (talk) 08:59, 9 December 2014 (UTC)

I did not delete it wholesale, I removed excessive information. And put a notice to problem sections so we can work on them collectively. --Inayity (talk) 09:09, 9 December 2014 (UTC)

Those sentences cannot join. I think something must be added and we must look at the chronology of events, and also that last sentence in the lead I do not get it-- I understand background radiation but something needs to be clarified. --Inayity (talk) 12:39, 9 December 2014 (UTC)

Loose ends

My observations about some loose ends within the article:

1. Black body radiation of cosmic microwave background: What is the significance, specifically for the Big Bang, of the fact that this radiation follows a black body curve? This is not explained in the article.

2. How do we connect the Big Bang (per se) with the large-scale structure of the universe? Perhaps this is difficult to answer, but I don't see how an explosion from an idealized singularity results in spatial clumping of matter.

3. Some statements in the lead need some very slight elaboration. We are not looking for a long lead, but, instead, some foreshadowing of the content in the main body of the article. One thing that needs to be put into the mix of the lead is a statement about dark matter and dark energy. Can one say that with dark energy and the accelerating expansion of the universe that the Big Bang is, effectively, still occurring?

Anyway, that is my to-do list. Can some editors familiar with these topics please contribute to discussion? Thank you, Grandma (talk) 00:12, 10 December 2014 (UTC)