Talk:Cosmic inflation/Archive 5

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When "prediction" is used instead of "retrodiction"

When "prediction" is used instead of "retrodiction", this appears to be an issue throughout cosmology as reflected here on Wikipedia. Might it help the credibility of cosmology with the public to systematically distinguish when something is actually a prediction, as compared to a retrodiction? For example, if I produce a climate model that better predicts the climate ten years out, as compared to the other popular models, my model gains credibility. But for the most part, all the models "predict" the climate from ten years ago. That's not as impressive because we software developers are pretty good at getting our software to generate required outputs, and that says very little about the predictive ability of our work. (I was a programmer in the McDonnell Douglas Helicopter Co simulation department in the 80s for the AH64 Apache Helicopter.) For example, if the big bang model "predicts" the initial abundances, but that is really a series of repeated retrodictions designed to meet the required observed abundances, then for many people, that builds less credibility for the model than would an actual prediction. So, might it help with credibility for Wiki's many cosmology articles to employ "retrodiction" where appropriate? Bob Enyart, Denver KGOV radio host (talk) 18:00, 17 January 2020 (UTC)

Retrodiction? Never heard this term before. 192.88.124.40 (talk) 16:53, 3 March 2020 (UTC)

I've heard it, but am not sure it applies here. It's perfectly possible to predict about the past, because even if things have already happened, that doesn't mean one already knows about them. A theory might predict that if a particular inquiry is made about the past, a certain answer will be obtained. I wouldn't advocate the use of the word ‘retrodict’ for a general audience anyway, there are are usually better words to use like ‘explain’ for example, depending on the specifics. — Preceding unsigned comment added by 77.61.180.106 (talk) 05:57, 15 January 2021 (UTC)

I've gone back through the article searching for the word ‘predict’ and I think he's right after all. The article contains a number of instances where I can see even at a glance that the word ‘predict’ is probably used wrongly and the entire article should be screened to make sure that every instance of ‘predict’ actually refers to new data that was obtained after the relevant theory was constructed. — Preceding unsigned comment added by 77.61.180.106 (talk) 06:05, 15 January 2021 (UTC)

Semi-protected edit request on 27 May 2021

Add a reference https://arxiv.org/abs/1306.4213. From: sometimes called the exotic-relics problem, says that if the early universe were very hot, a large number of very heavy To: sometimes called the exotic-relics problem, says that if the early universe were very hot, a large number of very heavy Rainspires (talk) 20:38, 27 May 2021 (UTC)

 Not done. Source (arXiv) is a considered unreliable, author does not seem to be subject-matter expert. ◢  Ganbaruby!  (talk) 03:44, 28 May 2021 (UTC)

The first author has published peer-reviewed papers on magnetic monopoles and cosmological implications thereof in reputable journals (see his arxiv history: EPJC, PRL, ...) and is a professor of physics at the University of Valencia, one of Spain's most prestigious. While this particular paper is not (yet?) peer-reviewed, he certainly qualifies as a subject matter expert. (I am not in any way affiliated or acquainted.) Advolvens (talk) 23:06, 9 June 2021 (UTC)

The existence of heavy magnetic monopoles with masses above $10^{16}$ GeV is one of the prediction of GUT theories. Rainspires (talk) 18:25, 9 June 2021 (UTC)

ArXiV is a reliable source for the provenance of the paper. The authors are SMEs and both are working with high profile international collaborations in the field. I don't have the background to judge their work, but surely when a full professor published in excess of 200 papers there is some credibility. --Shmuel (Seymour J.) Metz Username:Chatul (talk) 01:24, 10 June 2021 (UTC)

References

Vaas book

The book by Rudy Vaas appears on Google Books with a publisher, an ISBN, etc: [1]. It's also on Amazon: [2]. However, it doesn't appear to be actually available for purchase anywhere, and I don't find a copy in a quick search of a couple of university libraries, so it must be a very limited run. The information on the Google Books link should give us what we need to properly cite. --Amble (talk) 17:27, 11 April 2022 (UTC)

@Amble: I don’t see it even searching Worldcat. It’s supposedly by Springer, the publisher still exists an everything else they’ve ever published is recorded in their website. And per WP:SAYWHEREYOUGOTIT people are getting it from this draft version, not the published version (if that is anything more than just an ISBN). Umimmak (talk) 18:33, 11 April 2022 (UTC)

OK, apparently having an ISBN doesn't mean much, and you're right, Springer doesn't show it. Do the Google Books and Amazon pages get automatically populated from the ISBN even if no book is published? The draft seems to be cited in various papers as a chapter of the book (even though there doesn't seem to be a book). Perhaps it's best in that case to manually format the citation instead of using a template. --Amble (talk) 18:56, 11 April 2022 (UTC)

I mean, I thought was fine the way I had it before, using |type=Unpublished draft manuscript, was fine? But I think the best thing to do is to find something else Steinhardt has written (outside of SciAm) that speaks to him becoming a critic of the idea? Unless this particular draft manuscript is particularly influential, it seems strange to even cite in the first place? And perhaps, ideally, a secondary source noting how he has become a critic? Umimmak (talk) 19:45, 11 April 2022 (UTC)

I edited believing that there actually was a book, based on the ISBN, Google Books page, and Amazon listing. But there doesn't seem to actually be a book after all. I'm happy to revert. --Amble (talk) 19:50, 11 April 2022 (UTC)

Hypothesis / Theory

The first introductory sentence of the article calls the Cosmic Inflation a "theory", making a false impression that it is an established scientific fact. There is still a debate about the validity of this hypothesis in the scientific community. Calling something a Scientific theory requires a much higher level of validation and experimental/observational testing. The phrasing is also in contrast with articles in other languages: German, French, Italian and Russian versions in different ways, but all mention the hypothetical nature of the subject at the outset.

I suggest changing the wording completely - by calling it a "hypothesis" or a "model". Or, at least, add a clarification that it "...is a theory that hypothesizes a period of exponential expansion of space...". — Preceding unsigned comment added by Kanishev~enwiki (talk • contribs) 18:38, 14 February 2022 (UTC)

@Kanishev~enwiki

I agree. I think the most accurate description of the current situation is that it "is a collection of theoretical models that hypothesized a period of exponential expansion of space...". I hope someone would change the current language in the article.

CA2MI (talk) 17:16, 3 October 2022 (UTC)

All theories are provisional. While there is certainly research exploring alternative models, and some disturbing data from Webb, there is too much evidence supporting the old "Big Bang" and newer hyper-inflationary models to label them as mere hypotheses. --Shmuel (Seymour J.) Metz Username:Chatul (talk) 11:41, 4 October 2022 (UTC)

"three-dimensional sphere" ?

In the text "three-dimensional sphere" links to the article on "3-sphere" and I suggest to change "three-dimensional sphere" to "3-sphere" because the former suggests to actually be a 2-sphere, i.e. a 2-dimensional "equidistance-object" embedded in 3D. --46.91.59.169 (talk) 13:31, 12 October 2021 (UTC)

Singularity?

@Mokurai: A recent edit removed a reference to the initial singularity with a comment mentioning Quantum Mechanics. I believe that the literature describe the big bang from a classical General Relativity perspective, especially in the early days, and that no definitive answer will be available until there is a viable Quantum Gravity theory. Shmuel (Seymour J.) Metz Username:Chatul (talk) 12:45, 26 February 2023 (UTC)

Requested move 21 July 2024

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: moved. (closed by non-admin page mover) The Night Watch (talk) 21:03, 28 July 2024 (UTC)

---

Inflation (cosmology) → Cosmic inflation – Reasoning:

• Natural disambiguation is generally preferred over parenthetical disambiguation
• "Cosmic inflation" is natural, with widespread use in both reliable sources and popular sources, especially in titles and first mention
• "Cosmic inflation" is more concise
• "Cosmic inflation" beats "Cosmological inflation" in all measures of popularity (book ngrams, search trends, unpiped links)

Previous move discussion (2008–2009)

— Jruderman (talk) 12:57, 21 July 2024 (UTC)

• Support: per reasoning and WP:NATURAL.--ReyHahn (talk) 11:45, 22 July 2024 (UTC)

• Support I was going to complain that "cosmological inflation" is more precise, but TIL that depends on what you view this kind of "inflation" to be "of or relating to" per Commonly Confused Suffixes: -ic vs. -ical
  • inflation of or relating to "cosmos" -> cosmic inflation
  • inflation of or relating to "cosmology" -> cosmological inflation.

Since the topic is the inflation of the cosmos, "cosmic inflation". Johnjbarton (talk) 15:02, 22 July 2024 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

"after the Big Bang" ?

This article states that cosmic inflation happened after the Big Bang, but the Big Bang Wikipedia article states that inflation was part of the Big Bang and happened at the initial moments of the Big Bang. I think this contradiction arose because scientists use "Big Bang" to mean the expansion of the universe from the initial moments until now, or at least until long after inflation, but the general public conflates "Big Bang" with "inflation", or thinks "Big Bang" refers to the very first moment in time of the universe. I think it's best to stick to the scientific definition and I have changed the article accordingly. It's jarring to a reader to read "inflation happened after the Big Bang" in this article and then get curious and click on the Big Bang link which takes them to the associated Wikipedia article which then tells them that inflation was the initial part of the Big Bang. — Preceding unsigned comment added by 69.110.37.194 (talk) 04:01, 14 August 2024 (UTC)

Well it seems that sources do not agree with your claim:

• https://www.jpl.nasa.gov/news/nasa-technology-views-birth-of-the-universe
  • "Our universe burst into existence in an event known as the Big Bang 13.8 billion years ago."
• Kragh, Helge (1996). Cosmology and Controversy: The Historical Development of Two Theories of the Universe. Princeton, NJ: Princeton University Press. ISBN 978-0-691-02623-7. LCCN 96005612. OCLC 906709898.
  • "The idea of the universe originating in a singular event some finite time ago, that is, the big-bang idea..."

I think scientists refer to the 'idea' as the Big Bang theory and go on to discuss its implications, including inflation. But a finite timeline has a start and that start is called the Big Bang. Johnjbarton (talk) 14:47, 14 August 2024 (UTC)

Usage of "Big Bang" in cosmology is terribly inconsistent. Sometimes Big Bang means the initial singularity, sometimes it means the very early universe (e.g. Big Bang nucleosynthesis), and sometimes it means the Big Bang cosmological model (e.g. Big_Bang#Timeline), which describes the expansion history of the universe until now. Often it refers specifically to a cosmological model without inflation. This is usually the case when extrapolating back to define a zero time coordinate, so that we talk about time "after the Big Bang" even when describing models that don't have an initial singularity. I have heard scientific talks refer to inflation as happening "before the Big Bang" as well as "after the Big Bang" depending on which sense is meant. See [3] for some related discussion. It's often possible to reduce the ambiguity by using "Big Bang model" and "Big Bang singularity", but sometimes it's best just to avoid the term "Big Bang". --Amble (talk) 15:32, 14 August 2024 (UTC)

• If the Big Bang article actually says inflation is part of the Big Bang, then it is wrong, so that article should be fixed. Where does it say inflation is part of the Big Bang, though? (This might be better on that article's talk page, as well.) Banedon (talk) 02:37, 15 August 2024 (UTC)