Talk:Dark energy

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Frequently asked questions

The total amount of dark energy increases as space expands. Doesn't that violate conservation of energy?

Conservation of energy is not well-defined in curved spacetime, since the stress-energy tensor does not transform cleanly under change of coordinates.^{[FAQ 1]}

References

1. ^ Michael Weiss; John Baez (2017). "Is Energy Conserved in General Relativity?". math.ucr.edu. Retrieved 16 December 2021.

The section 'Evidence of existence' lists as one of the bullet points the 'theoretical need' for another type of energy given a flat universe. Basically its saying that without Dark energy our math doesn't work. That may be true but since when is that evidence of existence? It is a clue at most. 2A02:A44A:1378:1:F590:F6F0:A753:FA0 (talk) 09:22, 24 October 2024 (UTC)Stijn de Witt[reply]

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Dark Energy.

(+) DARK MATTER AND ATOMS

(-)DARK ENERGY

ATOMS:- FINISHED GOODS

DARK MATTER :- SUPPORTING MATERIAL

DARK ENERGY:- WASTE

CALCULATION :- 72%-23%+5%= 44% (DARK ENERGY). THE HUGE AMOUNT OF DARK ENERGY(72%) IS ATTRACTING THE SMALL AMOUNT OF DARK MATTER(23%) AND ATOMS(5%). . — Preceding unsigned comment added by RajnishGuunwal (talk • contribs) 12:44, 12 December 2012‎

Introduction

A more updated review on dark energy should be cited in the introduction. I suggest the book ^[1]

^ Amendola, Luca; Tsujikawa, Shinji (2010). Dark Energy. Theory and Observations. Cambridge University Press. ISBN 9780521516006.

It could also serve as citation for several of the "citation needed", e.g. the possible failure of general relativity.— Preceding unsigned comment added by 2.246.99.116 (talk • contribs) 07:50, 18 October 2014‎ (UTC)[reply]

Observational skepticism section

IMO this should be its own section instead of a subsection of Theories of Dark Energy. Most articles of scientific theory for theories not already well-established have their contravened sections more conspicuous. It could probably use more content too but we've at least touched on the first of the Sarkar papers. We should probably expand the section with the V3 of their latest paper, "Evidence for anisotropy of cosmic acceleration" - https://arxiv.org/abs/1808.04597

Misc feedback

As a non-physicist I found myself disliking this article more and more. I kept re-reading it trying to answer basic questions, and could not. Maybe I am simply not understanding what anyone reading the page ought to be able to understand, but here are some thoughts anyway.

The first sentence treats dark energy as an established fact of the universe, and the second sentence seems to obfuscate the fact that dark energy is a component of one theory (lambda CDM). Immediately I am not clear that the people working on dark energy, or at least the people working on this wikipedia page, are differentiating between evidence for accelerating expansion of the universe, and evidence for dark energy. The two are not the same thing. The history of discovery section is more like "here are some things that are like dark energy". Try substituting "pink unicorn" for "dark energy" in the first few sentences to get an idea of how this looks. The vagueness, lack of clarity, and relative sparsity of treatment of counterarguments in the article makes the it look like a house of cards, and/or a mishmash of things that are hard to blend into a coherent whole. There's nothing wrong with having an opinion, but let's please be objective and clear.

Anyway here are some suggestions: (1) explicitly state whether it is known that dark energy exists, (2) make clear the difference between evidence for accelerating expansion, and evidence for dark energy (a possible explanation of the accelerating expansion, if that is actually what is meant by dark energy), (3) make clear which theories dark energy is present in and which it is not, (4) change the title of the "In Philosophy of Science" to something that is more clearly a criticism of dark energy, and put this criticism very close to the front of the document, if there is significant skepticism of dark energy in the physics community. Put another way, do you really want to emphasize in this section "In Philosophy of Science" that dark energy's main role in Merritt's discussion is to serve as an example? Or is this a possibly valid criticism of dark energy? What are the responses to this criticism? "Lack of scientific consensus"???, (5) explain the relation between "energy" in "dark energy" and energy in the sense of more every day physics, e.g., the conservation of energy, (6) explain more clearly the history of the concept of dark energy with clear separation of the concept of dark energy as an explanation for accelerating expansion of the universe (or whatever dark energy is supposed to do), and accelerating expansion of the universe (or probably more precisely, observations made of the universe), (7) consider moving some material into other pages. if dark energy is a super important wikipedia page then maybe the article should be only a few pages long. 2601:600:877F:DD20:BC4F:ED64:C1C8:C377 (talk) 04:47, 11 March 2024 (UTC)[reply]

There may be implications that a Technical Section Template could warrant at least one or possibly two locations. I am far too hesitant on when that is applicable, given such varying degrees of intellect on the internet. I do agree that some information in this article could be communicated better. I would attempt to edit some sentences, but such a page like this is daunting to a user like myself with not many edits, in addition to the scrutiny this article comes under. It is also worth noting this is a Class-C article Content assessment which means it would benefit from items being rewritten per the Grades/Quality Scale Xiberion (talk) 08:10, 30 March 2024 (UTC)[reply]

Dark Energy is a barely 25 year old concept, the details of which are still being fleshed out. It is generally believed by astronomers to be the cause of the universe's accelerated expansion.

The first paragraph of the article treats Dark Energy very much like what it is, speculative/hypothetical science that we are only beginning to understand. Dark Energy *is* the accelerating expansion of the universe. from my understanding, "Dark Energy" is the term used to describe all observations that the universe's expansion is actually accelerating, and that we observe a large missing fraction of the energy density of the universe.

From there we can start making speculations as to what is present, a field or a particle or substance or fluid of some kinds. Lambda CDM is the current theoretical working model of the cosmological makeup of the universe. It's the current model with scientific consensus, and it predicts practically all the observable effects we see in our universe. Not all astronomers sign on with it, and there are alternative theories/models to work with, but the current standard model is Lambda CDM, and it is the model with general scientific consensus among the astronomy community.

now, Lambda CDM cosmology is the current theory with scientific consensus as to the shape/structure/time evoluton/energy and mass content of the universe. Lambda CDM predictions produce practically all effects we observe in the unive.chnology.

The section on scientific philosophy reads really janky. I don't agree that dark energy is some magical ad hoc hypothesis that's supposed to discredit falsifying evidence, and i don't think astronomers created it as such. we have models for how the universe is created based on the evidence we see, and we use those models to make prediction, and those predictions hold valid on wide scales across the universe.

this article could definitely use some work. it was challenging to work through and understand, but it is currently in agreement with other pages around wikipedia and does explain Dark Energy fairly well. 2600:6C47:A03F:C443:65DD:BFC6:330:DB15 (talk) 14:59, 2 April 2024 (UTC)[reply]

Your leading comment here is actually the best explanation I've found so far. I won't take the liberty myself but I think this would be a great lead for the wiki. "Dark Energy is a barely 25 year old concept, the details of which are still being fleshed out. It is generally believed by astronomers to be the cause of the universe's accelerated expansion." 70.79.145.68 (talk) 05:34, 15 September 2024 (UTC)[reply]

Dark Energy is Flawed or Nonexistent?

Seems recent studies suggest that Dark Energy thinking is seriously "Flawed"^[1] - or that Dark Energy doesn't even exist at all^[2]^[3] - if interested, my related pubished NYT comments may be relevant^[4] - in any case - Worth adding to the main "Dark Energy" article - or Not? - Comments Welcome - Stay Safe and Healthy !! - Drbogdan (talk) 13:45, 5 April 2024 (UTC)[reply]

Yes, I think dark energy will go the way of “the aether.” Far more believable is that expansion is due to the merger of universes. 174.205.98.225 (talk) 19:53, 1 July 2024 (UTC)[reply]

NOTE: A related discussion has been centralized on "physics Wikiproject", and can be found at the following link => "Wikipedia talk:WikiProject Physics/Archive April 2024#Dark Energy is Flawed or Nonexistent?" - iac - Stay Safe and Healthy !! - Drbogdan (talk) 22:19, 8 April 2024 (UTC)[reply]

References

^ Overbye, Dennis (4 April 2024). "A Tantalizing 'Hint' That Astronomers Got Dark Energy All Wrong - Scientists may have discovered a major flaw in their understanding of that mysterious cosmic force. That could be good news for the fate of the universe". The New York Times. Archived from the original on 4 April 2024. Retrieved 5 April 2024.
^ McRae, Mike (18 March 2024). "Physicist Claims Universe Has No Dark Matter And Is 27 Billion Years Old". ScienceAlert. Archived from the original on 18 March 2024. Retrieved 5 April 2024.
^ Gupta, Rajendia P. (15 March 2024). "Testing CCC+TL Cosmology with Observed Baryon Acoustic Oscillation Features". The Astrophysical Journal. 964 (55): 55. doi:10.3847/1538-4357/ad1bc6.
^ Bogdan, Dennis (4 April 2024). "Comment - A Tantalizing 'Hint' That Astronomers Got Dark Energy All Wrong - Scientists may have discovered a major flaw in their understanding of that mysterious cosmic force. That could be good news for the fate of the universe". The New York Times. Archived from the original on 8 April 2024. Retrieved 8 April 2024.

Drbogdan (talk) 13:45, 5 April 2024 (UTC)[reply]

problem with units: : 6×10⁻¹⁰ J/m³ (NOT ≈7×10⁻³⁰ g/cm³),

J/m³ = unit of energy density = Joules per cubic meter.

g/cm³ = unit of density = Grams = per cubic centimeter.

1 Joule = 10⁷ ergs in Centimetre–gram–second system of units (CJS units).

1 meter = 10² centimeters (cm's), so 1 cubic meter = 10⁶ cubic cm's.

I'm going to delete "(≈7×10⁻³⁰ g/cm³)", because it is obviously wrong.

Can someone please provide a clear citation for "6×10⁻¹⁰ J/m³"?

I tried to review notes [1] - [5] and was unable to find a number for "energy density". Thanks, DavidMCEddy (talk) 18:17, 30 April 2024 (UTC)[reply]

Ref. 7 quotes the mass density of the universe and the fraction that is dark energy, equating to the 7×10⁻³⁰ g/cm³. The latter number is the equivalent in mass-energy. –LaundryPizza03 (d c̄) 02:43, 1 May 2024 (UTC)[reply]

I accept. Can you please restore the conversion I deleted with an appropriate note that cites [7] AND explains how Joules convert to grams to justify the equivalence. Thanks, DavidMCEddy (talk) 03:21, 1 May 2024 (UTC)[reply]

The conversion formula is E = mc². Banedon (talk) 08:19, 2 May 2024 (UTC)[reply]

[1] Michael Weiss; John Baez (2017). "Is Energy Conserved in General Relativity?". math.ucr.edu. Retrieved 16 December 2021.

[2] Amendola, Luca; Tsujikawa, Shinji (2010). Dark Energy. Theory and Observations. Cambridge University Press. ISBN 9780521516006.

[NYT-20240404do-3] Overbye, Dennis (4 April 2024). "A Tantalizing 'Hint' That Astronomers Got Dark Energy All Wrong - Scientists may have discovered a major flaw in their understanding of that mysterious cosmic force. That could be good news for the fate of the universe". The New York Times. Archived from the original on 4 April 2024. Retrieved 5 April 2024.

[SA-20240318-4] McRae, Mike (18 March 2024). "Physicist Claims Universe Has No Dark Matter And Is 27 Billion Years Old". ScienceAlert. Archived from the original on 18 March 2024. Retrieved 5 April 2024.

[ApJ-20240315-5] Gupta, Rajendia P. (15 March 2024). "Testing CCC+TL Cosmology with Observed Baryon Acoustic Oscillation Features". The Astrophysical Journal. 964 (55): 55. doi:10.3847/1538-4357/ad1bc6.

[NYT-20240404-6] Bogdan, Dennis (4 April 2024). "Comment - A Tantalizing 'Hint' That Astronomers Got Dark Energy All Wrong - Scientists may have discovered a major flaw in their understanding of that mysterious cosmic force. That could be good news for the fate of the universe". The New York Times. Archived from the original on 8 April 2024. Retrieved 8 April 2024.

[FAQ 1]

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