Dark energy Definition and 553 Threads

http://space.newscientist.com/article/dn13975-dark-energy-imaged-in-best-detail-yet.html Ever since accelerated expansion was observed in 1998 some people (like e.g. David Wiltshire) have been working hard to think up alternative explanations that could account for the observations without...

I was curious if dark energy will one day tear everything apart in the universe. Since dark matter is what keeps everything in the universe in place and not scientist have found out that the acceleration of the universe is caused by dark energy, so basically one day it will overcome the dark...

The people that are interested in Holography and dark energy probably know better than me on how to search for papers on Holographic dark energy. The following papper discusses ALL dark energy models EXCEPT Holography Dark Energy. This thread is related to We are in a Schwarzschild black...

http://arxiv.org/abs/0803.1987 Is dark energy from cosmic Hawking radiation? Authors: Jae-Weon Lee, Hyeong-Chan Kim, Jungjai Lee (Submitted on 13 Mar 2008) We suggest that dark energy is the Hawking radiation from a cosmic horizon. Despite of the extremely low Hawking temperature this dark...

Hello everyone! I am writing a paper for a final in a basic Cosmology course in college. I chose my topic to be Dark Energy. I am wondering, does anyone here have any good links or sources that I may consult and reference in writing my paper? There is no specific aspect I am focusing on...

Has anyone read this paper? Shifting the Universe: Early Dark Energy and Standard Rulers Authors: Eric V. Linder, Georg Robbers Comments: 6 pages, 3 figures Subjects: Astrophysics (astro-ph) The presence of dark energy at high redshift influences both the cosmic sound horizon and the distance...

I once read that dark energy(it may be dark matter,I am a bit confused), is ripping apart the universeand was awarded as the best theory of some year. What is this dark energy(/matter) and waht is it to do with the ripping of the universe??

When people cite the dark energy fraction informally (without errorbar) and other basic parameters they often have been saying something like Hubble 71 dark energy 73% dark matter 23% baryonic 4% If I remember right, those are the default values used in the calculator at Ned Wright's website...

http://arxiv.org/abs/0803.0982 Dark Energy and the Accelerating Universe Joshua Frieman (Chicago/Fermilab), Michael Turner (Chicago), Dragan Huterer (Michigan) Invited review for Annual Reviews of Astronomy and Astrophysics; 53 pages, 18 figures (Submitted on 7 Mar 2008) "The discovery...

http://www.ciw.edu/news/dirty_space_and_supernovae

I know next to nothing about either concept, but that does not stop me from asking: Have physicists/cosmologists considered dark energy possibly being associated with creation of new space? Or are they totally unrelated? Or even opposite concepts?

http://www.sciencedaily.com/releases/2008/01/080110194502.htm Results of the simulations, carried out by Durham University's world-leading Institute for Computational Cosmology (ICC), tell researchers how to measure dark energy -- a repulsive force that counteracts gravity.

There must i guess be places where neither gravity or dark energy dominate, places where the pull of gravity equalls the push of dark energy, if that is so, then would these places be a good place for dust to gather?

http://www.abc.net.au/science/articles/2007/12/21/2124258.htm He makes some interesting claims:

This has probably been posted elsewhere within the forums but I'm unable to find a thread relating to it. Could some one explain how the existence (and the expected eventual increase) of dark energy doesn't violate the first law of thermodynamics? regards Steve

Dark Energy and the Hubble Constant Authors: H. Arp Comments: 3 Figures, 7 pages Subjects: Astrophysics (astro-ph) Dark energy is inferred from a Hubble expansion which is slower at epochs which are earlier than ours. But evidence reviewed here shows $H_0$ for nearby galaxies is actually...

arXiv:0711.4810 Title: Dark Energy in Light of the Cosmic Horizon Authors: Fulvio Melia Comments: Submitted to MNRAS Subjects: Astrophysics (astro-ph) Based on dramatic observations of the CMB with WMAP and of Type Ia supernovae with the Hubble Space Telescope and ground-based...

So I'm running a superhero game on another forum and I am trying to keep comic book physics to a minimum. Problem is...I've never taken a physics class (I'm a high school student, I've taken Biology and Chem but Physics is next year). I was wondering how dark matter and dark energy work and...

This paper came out on the arxiv a few weeks ago. I've not had a chance to read it fully yet, but it looks like an interesting paper. http://arxiv.org/abs/0710.5307 Here's an article in the news section of Nature on the same topic: Bursting Dark Energy's Bubble.

First of all, I don't really know much of physics so it may very well be something silly and laughable... but I just find somewhat interesting, and from the layman's point of view at least, not worse than some ideas that I see from people from the field, such as the hypothesis of darwinian...

I attended a seminar today in which a new theory of dark energy was discussed. I'm not sure which forum to put this in, since it includes a lot from other fields, but since it is regarding dark energy, cosmology seems the best place. Here's a link to the paper...

I've been wondering, is it possible to model both the Hubble redshift and dark energy as a gravitational field which gets strong the further away you look? For example, we know that light from distant galaxies is red-shifted, which is equivalent to a photon having climbed out of a gravitational...

It would be really funny if this paper of William Nelson and Mary Sakellariadou turned out to be right. And I can't see any reason it couldn't. http://arxiv.org/abs/0709.1625 Dark energy from corrections to the Wheeler-DeWitt equation William Nelson, Mairi Sakellariadou (King's College...

Are these possibly one and the same, or are they completely different concepts? It seems like both are credited for the expansion of the universe, depending on who is doing the talking. dilletante

[FONT="Trebuchet MS"] Hi , I am rather new to this (well just found the site today) and I was wondering weather any of you knew the answers to my questions? I have searched the internet for any theories on the questions bit without and success, and I would like to hear your views. My first...

So we don't really know what DE is quite yet, but because it is a form of energy density, does it bend space to produce gravity like other, more dense, concentrations of it (like mass)? On a universal scale, does dark energy curve spacetime? I'm thinking this is an untestable idea, since it...

A nice review of Dark Matter and Dark Energy, including discussions of the CMB and Inflation, arrived today at the arXiv: http://arxiv.org/abs/0706.2986 I think some people here would find it quite interesting.

Could Dark Energy and Dark Matter be ...? Time? I am sure that there is hundreds of reasons why this could not be possible but, it seems to me that there is some kind of synergy in this hypothesis. Imagine for a moment that time is a form of energy that we have not yet managed to quantify...

Wiltshire casts doubt on existence of "dark energy" Wiltshire is a minority voice in cosmology, but one worth listening to. Speculation about a "dark energy particle" would be in vain if the appearance of acceleration can be traced to classic GR effects, which is what he tries to do. Wiltshire...

This poll is a companion to the one Wallace posted recently: https://www.physicsforums.com/showthread.php?t=168166" Just as there is a certain ambiguity in that poll, so too there is ambiguity in this one. For example, you may feel that the relevant astronomical data themselves are clear -...

I have been removed from this forum for previous "crackpot" ideas. However, I would appreciate a review of the one presented below. I submit it to this subforum because it is based on superstring theory. Selectrons as the particles of Dark Energy Consider the creation of particle pairs in...

This has come up in a few threads as a side question, but I'd like to have a central discussion on this issue. The question I have is what evidence do you think will be needed to elevate the existence of Dark Energy to the same kind of level as the existence of things in the standard model...

http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.2499v1.pdf This seems interesting, has anyone an idea about this research ?

Would there be any way to discover dark energy, dark matter, if the only observable body was the galaxy you lived in?

So there has been a few threads over the last few days where the whole issue of dark energy and/or the cosmological constant has been discussed in the context of whether it is a valid 'solution' to GR or if it violates some principle of relativity or even insults Einsteins 'legacy', whatever...

Could the impetus for the ever-expanding universe lie in an exotic, long range repulsion between primordial matter and antimatter (as in the term cosmon)? If so, it might be possible to calculate the abundance of antimatter at a given distance and direction by variations in redshift from the...

This is my second question. As I understand the currently popular explanation for the accelerating expansion of the universe, it is based on the hypothetical existence of a uniformly distributed form of expansionary energy. Again, as I understand expansion, it is not the movement of bodies...

Dark Energy Discovery [NASA Teleconference 16 Nov] The latest fad among cosmologists... :rolleyes: via Asymptotia Looks like cosmology is accelarating. :biggrin:

1) Assuming that one day physicists will be able to extract energy from the Quantum field, would this energy extraction deplete the field in accordance with conservation of energy laws? 2) If one accepts the notion of the Multiverse, are separate Universes therein sharing a common Quantum...

The Higgs field, the inflaton field, the cosmological constant, quintessence,... are all mentioned as possible candidates in explaining dark energy (expansion of space). My questions are: 1. In what exactly do these possibilities differ from each other? 2. Are there other candidates in...

An interesting paper on the ISW effect appeared on Arxiv today. It complements WMAP results affirming dark energy and might be important: http://www.arxiv.org/abs/astro-ph/0607572 A high redshift detection of the integrated Sachs-Wolfe effect Authors: Tommaso Giannantonio (ICG, Portsmouth)...

Greetings, I've never liked the idea of Quintessence (although I admit I don't understand it fully). 1. As for Dark energy, what are the leading theories on how it may be caused? 2. Also, I have an idea about a possible cause for the Universe's acceleration. Perhaps, the fringes of the...

Dark energy: Mystery of the Millenium T. Padmanabhan http://arxiv.org/abs/astro-ph/0603114 This is an impressive paper, based on a talk and quite readable. :smile:

Hi Friends, I just want to know how many of you believe that there is dark matter and dark energy in the universe and how many of you believe that there is something wrong with our understanding of gravity.

This should throw another spider into the web: http://www.physicsweb.org/articles/news/10/2/4/1 As far as I can tell, this is not MOND, is it? Zz.

I apologize in advance if this is the wrong forum for this thread... My overall question is: What specifics, if any, do we know about the "dark" stuff - ie dark energy and dark matter? Specifically: Do we know anything about what the darkstuffs are made of (either experimentally or...

Google scholar has 651,000 results for dark matter and 521,000 results for dark energy, more than i could read in a life time, can anyone suggest the hot pappers on these subjects.

It is good practice to calculate the dark energy density. I remember doing it a few years back and later posting the result here at PF. As I recall it was about 0.6 joule per cubic kilometer----so if you were being not overly finicky and giving a rough approx, it was about HALF a joule per...

Following close on the heels of new study shows Dark Matter isn't needed? Relativty explains it? we have Back-Reaction: A Cosmological Panacea which does for Dark Energy what General Relativity Resolves Galactic Rotation Without Exotic Dark Matter tries to do for Dark Matter. It now seems...

Detailed observations of distant Type 1a supernovae, by two independent teams, are what got astrophysicists and cosmologists salivating about 'dark energy' (and the many possible physical processes that could give rise to it). Systematic effects (including mis-identification) are, of course...