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.

Features and problems subsections order

I care a lot about wikipedia article sections and subsections being organized in a logical order. With respect to 'Features and problems' subsection, I think we ought to either have an alphabetical order or a going-from-more-significant-features-slash/problems-to-the-less-important-ones order. I prefer the latter. Currently, the order seems to vaguely be the latter, but not quite. For example, while 'Horizon problem' and 'Flatness problem' are the first subsections and seem like the most important features/problems, 'Globular cluster age' seems like the least important issue (because it's pretty much been resolved and never really posed much of a problem for the theory), but it doesn't go last.

I'm curious what you guys think about what the subsection order should be. If we go with the important-to-less-important issues idea, then I think the order should be something like this (based on what the subsections currently say, although admittedly I'm not too knowledgeable on these issues):

Horizon problem, Flatness problem, Dark energy, Dark matter, Magnetic monopoles, Baryon asymmetry, Globular cluster age.

What are your thoughts on this issue? Would you prefer alphabetical? Etc. Byelf2007 (talk) 12 April 2012

Simplifying the lede

I think it this point the lede (and in particular the first paragraph) is more complicated than it needs to be. Given the mass appeal of the subject, we should be aiming to make the lede accessible to as large an audience as possible. In the process we should be looking to see if we can make the lede a bit shorter as it is a bit longish. (At a glance there is some detail there that is need absolutely necessary. I have made a start at reducing the huge amount of wikilinks in the lede, which hamper readability (we do not need to link every other word). Similarly, there were way to may references for some single facts which I trimmed.

One suggestion would be to have one or two sentences after the first sentence that summarize the core of the ideas behind the Big Bang theory. For example,

The main idea is that the universe is expanding. Consequently, the universe was denser and hotter in the past. In particular, the Big Bang model suggests that at some moment all matter in the universe was contained in a point. Modern measurements place this moment at approximately 13.82 billion years ago, which is thus considered the age of the universe.

I am not quite happy with this yet, but it does put into focus the main idea behind the BB: the universe is and was expanding. I am not quite sold on inlcuding the singularity bit, partly because the singularity falls outside the Big Bang theory per se. However, some how including the fact that the big bang theory suggests the universe (as we know it) has a beginning seems desirable.TR 14:02, 15 April 2014 (UTC)

That sounds good. Be careful with removing too many links; the lede section admits a higher density of wikilinks, as any jargon term should be either explained or linked to. Diego (talk) 14:59, 15 April 2014 (UTC)

help with sentence

The lede currently contains the following sentence:

The Big Bang theory offers a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background, large scale structure, and Hubble's Law.

I feel that this sentence may not be helpful to the general reader who will have no clue what there phenomena are based on the jargon used to refer to them. However, I am stuck on thinking how to improve it. Any ideas?TR 12:09, 2 May 2014 (UTC)

My feeling is that since these topics are all explained in the article and all but one of them are linked in the lede (perhaps linking 'abundance of light elements' somewhere would help, but I'm not quite sure of the best target) it's fine as is. The lede is meant to be a summary of the article, and we can't go into too much detail. The current version tells the reader that the BBT explains lots of observations and lists the main ones, allowing them to follow those up if desired or read on to find out more. That seems OK to me. Olaf Davis (talk) 12:37, 2 May 2014 (UTC)

I mostly agree. It is OK, but it is not very good or excellent (which is what you want from an FA). It is this sort of sentence that makes articles like this one inaccessible for many lay readers. So, if we can find a better alternative that would be a good thing. If we can't it also not too big a deal.TR 13:00, 2 May 2014 (UTC)

FWIW - first sentence of paragraph seems ok to me as well - but then - seems the entire paragraph could be better (esp second "sentence"?) - seems "readability" of the paragraph could be better also - perhaps replace the paragraph with equivalent content from an earlier version? =>

copied from an earlier version:

The Big Bang is a well-tested scientific theory which is widely accepted within the scientific community because it is the most accurate and comprehensive explanation for the full range of phenomena astronomers observe. Since its conception, abundant evidence has arisen to further validate the model.< ref>Feuerbacher, B.; Scranton, R. (25 January 2006). "Evidence for the Big Bang". TalkOrigins. Retrieved 2009-10-16.</ref>< ref>Wright, E.L. (9 May 2009). "What is the evidence for the Big Bang?". Frequently Asked Questions in Cosmology. UCLA, Division of Astronomy and Astrophysics. Retrieved 2009-10-16.</ref>

hope this helps in some way - Enjoy! :) Drbogdan (talk) 13:00, 2 May 2014 (UTC)

Big bang vs black hole, universal expansion vs light speed

I have 2 questions which do not seem to be explained:

1. How does the early universe, or significant portions of it, avoid being considered a black hole?

2. It appears that the outward spread of light is not the same as the expansion of the universe. If the outward spread of light does not effectively cause the universe to grow, then where does the light go (I know I didn't express that well)? Hmm, I guess this is answered by the universe wrapping around.

Scott McNay (talk) 03:11, 18 April 2014 (UTC)

The short answer to your first question: "because it expands" or "because it is not dense enough".

The slightly longer answer is that expansion of spacetime and gravitational collapse are two competing effects with in the case of our (visible) universe expansion winning. The condition for the visible universe to collapse or keep expanding is exactly the question whether the density is lower or higher than the critical density as discussed in the section on the future according to the Big Bang.

It is of course possible that in some regions the density was big enough to win out from the expansion. This regions would have collapsed to form primordial black holes.

The second question, just seems a matter of confusion about what is meant with "expansion". The universe is not expending into anything.It is space itself that is expanding. As far we can tell the universe is completely homogenous, consequently there is no such notion as "outward". In particular there is no outward spread of light. (At any point, there is about same amount of light travelling in any direction. Well, at least if you average over a large enough scale.) The article attempts to address this in the section title "FLRW metric".TR 09:52, 18 April 2014 (UTC)

A conceptual fallacy?

I miss a discussion about the following problem:

A universe only can be said to expand if it has a finite inside dimension –which in increases in time.

Not to mention that Big Bang cosmology in speaking about its age, asserts that the universe lives in a time realm not of its own making, doesn’t a (finite) inside dimension imply a finite outside size –even though it obviously cannot be measured from the outside as space and time, the meter and second aren’t defined outside of it?

Put differently, what is the significance of statements about the size and age of the universe if by definition there is nothing outside of it with respect to which its size and age matters, physically?

Can someone explain how a universe can have particular properties and evolve as a whole if there is nothing outside of it with respect to which it can have properties, can interact with and express such properties?Antonquery (talk) 03:11, 28 April 2014 (UTC)

You'd have better luck asking this at the Science Reference Desk, which is meant for general questions. This page is for discussion about how to improve Wikipedia's article about the Big Bang. Adrian J. Hunter^{(talk•contribs)} 05:05, 28 April 2014 (UTC)

These are questions that taking a course on differential geometry will answer.TR 08:09, 28 April 2014 (UTC)

You might want to investigate the Milne model.166.137.101.164 (talk) 09:46, 1 July 2014 (UTC)Collin237

Before The Big Bang Information?

To start, I do not know much about cosmology (verging on nil) and was looking for something at the beginning of the Big Bang article that would mention some alternative besides there’s nothing then poof the universe (the article hints at an alternative by using “prevailing cosmological model”) . Never the less, I still will ask a very simplistic question that someone should have already asked (and put some place on Wikipedia for me to read), since the universe is 13.8 or so billion LY in each direction and still expanding, doesn’t this seem to follow the same concept of a supernova or other cosmological things exploding but on a larger, “universal” scale? In other words, is there something bigger than the universe (a non sequitur since nothing bigger than the universe?) that our universe is expanding in? If so, then where would such a link or information be found if not in the “See Also” section or at the beginning of the article? Please use small words when you explain how wrong I am on this request and where to find this info in Wikipedia. Septagram (talk) 20:51, 16 June 2014 (UTC)

@Septagram - FWIW - several possible articles that *may* be relevant to your question => "Multiverse" and "Roger Penrose#An earlier universe" - in any case - Enjoy! :) Drbogdan (talk) 22:24, 16 June 2014 (UTC)