Talk:Accelerating expansion of the universe

How to distinguish?

How does one distinguish between a universe whose expansion is accelerating at a flat rate, and a universe whose contraction is accelerating at a flat rate and is faster then the speed of light? If someone can find that information, it should be on this page I think.

This article needs a History section

When was an "Accelerating Universe" theory first postulated? When was it first expected? Etc. —Preceding unsigned comment added by 71.10.67.171 (talk) 23:42, 8 August 2010 (UTC)

OR

It seems obvious that the acceleration of our particular Universe is proof positive we live in a Multiverse consisting of matter and antimatter with a total mass of zero caused by unknown factors/distortions within infinite 3D space. Due to the vast distances, relative slowness, and dispersion of photons we are unable to view the other Multiverses (in fact we cannot even see the other side of our own) but that certainly does not mean the other Multiverses (or the other side of our own) do not exist or we also would not exist. Some of the matter being expelled from our Universe (where forces such as Big Bang momentum, dark energy negative pressure, and the weak gravity of other Multiverses overpowers counterforces such as the collective gravity of our own Universe) will eventually go into other Multiverses' upcoming Big Bangs, just as some matter from previous others contributed to our Universe's most recent Big Bang just 14 billion Earth years ago (a virtual nanosecond in infinite time) as part of a perpetual cycle. Theorists should move beyond the age old question of "What created the Universe" as this is passe and dated -- instead they should focus on what factors/distortions trigger the generation of offsetting matter/antimatter regardless of the scale as all else directly follows from that. -- MFPrice1

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—Preceding unsigned comment added by MFPrice1 (talk • contribs) 01:57, 26 January 2009 (UTC)

Hm. This is a bit out of my field, but isn't inflation theory another possible model for the accelerating universe phenomenon? -- April

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This is out of my field as well, but if the rate of expansion is constantly accelerating, does this open up the possibility that the universe always existed? I mean, if you reverse time this would mean the universe never shrinks out of existence because the rate of contraction would slow down 69.234.200.38 (talk)

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—Preceding unsigned comment added by 69.234.200.38 (talk) 03:39, 23 January 2009 (UTC)

Yes, but that's included in non-zero cosmological constant (which presumably caused inflation).

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Wrong, sorry. The present non-zero cosmological constant/quintessence can be thought of as a form of inflation, but it probably has no relation to the inflationary scenarios (they are not theories, because they are too vague!). The inflationary scenarios generally talk about inflation when the Universe was about 10^(-33) seconds old, long before the microwave background epoch.

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See the special edition of
Scientific American, Volume 12, Number 2
Title: The Once and Future Cosmos
It is readable, detailed, and current.
Randal Leavitt 00:40 Oct 13, 2002 (UTC)

Acceleration

Does anybody know what is the value of the acceleration of Hubble's constant in terms of dH/dt. There is an obscure relativistic effect that partly simulates the accelerated expansion of space. For our universe this simulated part would be of order of 2x10^-36/s/s. I wonder how close this theoretical value is to the observed one. If close enough it might mean that the whole acceleration is just an illusion produced by subtleties of Einsteinian gravitation. Jim 20:41, 13 Jul 2004 (UTC)

I'm not sure. It should be relatively trivial to get from Friedmann's equation (or rather a derivative of it) given Omega_m of .3 and Omega_lambda of .7 I think. You could always give it a go yourself and see how it comes out. Otherwise I'd suggest tracking down the original Type 1a supernova paper that suggested an accelerating universe. EddEdmondson 20:02, 14 Jul 2004 (UTC)

I wrote to Ned Wright about it and he gave me the value of $(dH/dt)/H_{0}^{2}$ in terms of $\Omega _{m}$, $\Omega _{\Lambda }$ which comes out as -0.45. It might mean that the whole acceleration is an illusion since the theoretical Einsteinian prediction of the effect is -1/2 (11% off) and the accuracy of $H_{0}^{2}$ alone is 8%. Jim 16:56, 13 December 2006 (UTC)

Expanded

I think that this article could stand to be... Expanded. Mr. Billion 06:10, 5 Mar 2005 (UTC)

I recently expanded the dark energy article. They are nearly the same topic. --Joke137 15:55, 5 Mar 2005 (UTC)

Redirect to dark energy?

I would like to directed this page to the dark energy article. The only information on this page which isn't in the general review in dark energy is the stuff about zero point and eternal intelligence, which might as well go into the pages that are being referred to. I think pages like ultimate fate of the universe, cosmological constant or quintessence (physics) could be useful as independent pages, but I can't really see anything going in here that wouldn't belong either in dark energy or a more specialized page on cosmology with Type Ia supernovae. --Joke137 18:11, 7 Mar 2005 (UTC)

Negative pressure

As a layman i have to ask what is negative pressure? Does it have anything to do with gravitational repulsive material? -- Orionix 00:56, 10 Mar 2005 (UTC)

It has everyting to do with it. See cosmic inflation.--Michael C. Price ^talk 08:14, 8 December 2006 (UTC)

Inflation, then decceleration, THEN acceleration

A recently-verified fact that is often ignored is that the universe was deccelerating by gravitational attraction up until about 5 billion years ago. This was preceded, in theory, by a period of rapid expansion called 'inflation', and followed by the current acceleration caused by the 'funny energy' in space. Thus the expansion of the universe goes through three radically different epochs: 1. A fraction of a second of rapid acceleration immediately after the Big Bang. This inflation is the small epoch of expansion that lasted from 10^-43 seconds to 10^-35 seconds after the Big Bang, and caused space to expand faster than the speed of light, 2. A period of about 10 billion years of decceleration by gravitational attraction before matter was dilute enough to be dominated by the antigravitational effect of the 'dark energy', 3. The current epoch of about 5 billion years in which 'dark energy' rules over gravitational attraction. In this third period, the 'dark energy' creates an outward push called 'negative pressure' much like the air in blowing up a balloon. See my book http://empyreanquest.com/science/cr/cosmrep.htm Cosmic Acceleration: Hounding The White Whale of Cosmology free online. Philip Petersen, PhD

Arrogantly, (since I have no training in this field) I say that even if there was not a big bang, space would still be here. Space is', just as God is', and in my opinion space was not created by a big bang but merely the "field" in which the bang banged. The cosmologiocal constant and space and God and ether was and always will be there or.......HERE.

Certainly there would be no galaxies or visible creation without a bang, but space would still exist. The exasperating question arises of : "Well, if there was nothing to experience or exist in space and no one to experience it, how do we know space was there prior to the bang? It would be impossible to measure space without any contents but space would still exist, MERELY AS SUBJECT, SINCE NO OTHER SUBJECT WOULD BE THERE TO SEE IT AS AN OBJECT. This question is a paralell to the other very silly question of "if a tree falls in the woods and no-one hears it?... did it make a sound?" ...and... the even sillier postulated answer given by the so-called "wise and educated" of "No, it did not". How absurdly preposterous by anyone posessing of common sense! Although it made no resonation in the ear of the dummy who provided the ill-accepted answer ... I am sure it made a sound in the ear of the innocent and simple-minded, little woodpecker who made his nest there.

In fact, space, being infinite, is not measurable... by the very definition, only opne object to another. But space is not an object. It is merely subject. Singularity, (since we are in need of a word to represent the time before a 3-D creation and the condition within a black hole) was the existence at that time before the big bang, YES...but space was already here and space has to be infinite in all directions. Obviously, the reason is this: If there was a boundary to space...then what is beyond the boundary? And...any boundary that may be there would be permeated with the cosmological constant AND/OR ether, being one in the same.

I correlate all this cosmology with my own finite understanding of an infinite being...i.e. God. Not the jealous God of the Bible but that Omniscient, Omnipresent and Omnipotent God. Ether, or the cosmological constant is "His" very body and/or mind and what we percieve is "His" thoughts/creations from "His" infinite mind which creates merely from thinking it (whatever it is) into being... and it is done immediately. His omnipresence is apparent in the fact of the cosmological constant which is everywhere, not only between objects in space but within and outside the creation as well.

When I was young, that term was "ether"... not ether like what is sniffed to wake up the unconcious but ether as in that ungraspable thing that is in everything but not contained by it. Ether is the mind or body of God in which all things exist.

I never hear the term "ether" used any more. I do not know why not. It is much easier to say than cosmological constant and therefor comprehension easier.

Instinctively yours.

66.56.17.250 21:32, 3 March 2007 (UTC)

Alternative theories

There should probably be a mention of other theories, such as ones that say the acceleration is an illusion. I've heard at least one which was corroborated by data, something about our solar system being located in an area of low density of matter which causes light to redshift. Cannot cite source. In my layman's opinion, which is governed by common sense rather than infinitely complex math, the illusion theory involving differential densities makes alot more sense. But as I say, I'm no physicist.

I think that if it were true that the cause of the red shift is that we reside in a low density area, then the amount of red shift would be nearly constant, independent of the distance of the source (except for a few sources very close to us). But the amount of red shift increases with the distance of the source, which means the light from distant sources must have done most of its red shifting before it got close to us. It can't be explained by a local phenomenon. SEppley (talk) 18:02, 10 April 2011 (UTC)

Also, let's keep religion out of discussions on physics unless we're talking about metaphysics. (Directed at 66.56.17.250 above) 69.90.51.160 (talk) 06:48, 31 March 2009 (UTC)

I happen to be a physicist and I even know how to prove with a few lines of high school math and with the principle of conservation of energy that it is really an illusion. Not only acceleration but the whole expansion. But then it is not a "theory" but a hard fact and so it can't go by the name "alternative theory". It is just a conclusion from Einstein's theory of gravitation which is so far proved right.

Unfortunately there is a lot of folks making good living out of the idea that the universe is expanding and that energy can be created from nothing (since it is a necessary condition of expansion). Apparently it is more desirable idea if so many folks prefer it to the old and boring "Einstein's universe", which is not even expanding and only looks like expanding with accelerating expansion which acceleration I can calculate from first principles, saving a few billions, and it comes out as it is observed :).

In about 50 years when all attempts to create energy from nothing fail, scientific journals start publishing papers saying that nobody ever expected that energy can't be created, and some professor gets Nobel Prize for showing why the acceleration, and even the expansion itself, are illusions.

The funny thing is that my friend Mike Guillen predicted over 25 years ago (when I was his student and I showed him the proof), that he is glad that I got such a nice result but it won't be published for the next 15 years since it would hurt too many scientists who decide what stuff may be published. So after 25 years I have to be more conservative in my predictions. Jim (talk) 22:46, 24 August 2009 (UTC)

Clearly the article is misleading where it begins by claiming acceleration is an observation. The actual observation is the higher-than-expected red shift of extremely distant supernovae. The so-called corroborating observations do not corroborate acceleration; they only corroborate the presence (in the early universe, at least) of much more mass (energy) than is accounted for by non-homogeneous dark matter; that extra mass/energy isn't necessarily repulsive. Acceleration is merely one theoretical explanation of the high red shift, and since acceleration is rather remarkable and unexpected--implying a counter-intuitive repulsive force--there may be better explanations. The article ought to describe acceleration as a theoretical explanation, not an observation, and should delve into why other explanations are considered unsatisfactory. The acceleration theory is on shakier ground than the big bang theory that explains the ordinary Hubble red shift. Also, since the extremely distant supernovae emitted the light a very long time ago, perhaps the acceleration (or whatever is the cause of the high red shift) was a property of the early universe and only occurred a long time ago, maybe an effect of inflation. SEppley (talk) 18:02, 10 April 2011 (UTC)

To elaborate on the last sentence in my comment above: Assuming the cosmological principle is correct, then accelerating expansion would also affect light emitted from sources not quite as far away as the recently observed extremely distant supernovae. Does the amount of red shift of the light from nearer sources show any evidence that the rate of expansion is increasing, or is it consistent with the opposite conclusion: that the rate of expansion is less now than it was when the light from extremely distant supernovae was emitted? Also, where I wrote above that "perhaps the acceleration was a property of the early universe" I should perhaps not have called it acceleration, since a greater rate of expansion long ago is consistent with decelerating expansion (after the end of inflation). SEppley (talk) 12:21, 29 October 2011 (UTC)

I skimmed the catalog cited by citation 46 of the Redshift article, which catalogs articles containing alternative explanations of the red shift. The catalog, published in 1981, doesn't list the articles' content beyond their titles, unfortunately. None of the titles appears to mention the notion that the red shift might be explainable by a changing rate of the passage of time. Both special and general relativity describe how time passes at different rates due to velocity or gravity, so this notion doesn't seem a priori nonsensical. Has this possibility been ruled out? Is it equivalent to expansion of space since space & time together comprise spacetime, or would some consequences be different? SEppley (talk) 16:06, 29 October 2011 (UTC)

Gravitational Lensing?

I do not understand why gravitational lensing would show how the universe is expanding... Can anyone give me some clarification on that? Marx01 ^{Tell me about it} 06:01, 7 August 2009 (UTC)

It does not need to be related to the expansion but the more "evidence" for the expansion the better. Only real evidence for expansion is the Hubble redshift but it happens also in static "Einstein's universe" if energy is conserved and, what is even worse, approximately in the same amount as observed. It is caused by dynamical friction of photons and the theoretical value of the Hubble constant in static universe resulting from dynamical friction is c/R where c is speed of light and R is "Einstein's radius of universe" (radius of curvature of space), about 4 Gpc. So the Hubble redshift is not a very reliable evidence of expansion since many folks (especially physicists) think (and rightfully so) that energy is conseved. Luckilly they don't know enough physics, especially Einstein's, not to believe in expansion at all. So they have to be hit with "more evidence" to stop doubting the expansion and continue to agree on their tax money being spent on financing scientists (as opposed to "science").

You might not consider it a legitimate reason but scientists need to eat too so sometimes they are forced to do such things, even if they don't want to just to survive. You are given brain not to believe in everything they tell you. You may also appreciate that some are honest enough to tell you the whole story. And it's better that such things go on in astronomy than in civil engineering since, as my astronomy teacher used to say "the beauty of astronomy is that in astronomy, unlike in civil engineering, one may be 100% wrong and no one is hurt". Jim (talk) 23:34, 24 August 2009 (UTC)

Preloaded Debate from User Talk Page

I've removed everything that could be interpreted as original research. The remaining text is copied from the cited New Scientist articles. Those articles contain references to peer reviewed publications.--Systemizer (talk) 18:11, 12 September 2009 (UTC)

Hello, first of all, you didn't remove anything from your text. Your edits are exactly the same as the text that was removed before. Second, your claim that they are no original research is simply wrong, it's also not coming from New scientist as many parts are referenced by this site eschatopedia.webs.com which is nowhere near a reliable source status. --McSly (talk) 18:49, 12 September 2009 (UTC)

Hello. Nothing comes from eschatopedia. It is cited because it contains quotations from the same New Scientist articles. The text is copied and pasted from the cited New Scientist articles based on the work of Craig Hogan, director of Fermilab's Center for Particle Astrophysics in Batavia, Illinois--Systemizer (talk) 18:59, 12 September 2009 (UTC)

Hello again. First a couple of technical things. Please always use the edit summary field to tell other editors what you do because without that, it's hard to tell what's going on. Also make sure to use the "this is a minor edit" checkbox properly, this edit [1] and that edit [2] were most definitely not minor. One last thing. I'd like you to be aware of the 3 revert rule as you have reached your limit on all 3 articles in dispute.

Now, sorry but you edits still don't work. First you removed the links to the eschatopedia.webs.com website but the referenced text is still there. So we are clear, when there is a problem with a source because it's not reliable, the source AND the text need to be removed, not only the source, that would be too easy. Second your additions are still full of original research which is not acceptable. Let's take an example. Here is your current addition for Doomsday event [3]. I guess the link to doomsday event comes from this sentence: "Thus, when the blurring reaches a threshold level, the Planckian pixels of space will dissolve, which will put an end to the universe's locality". Well I read the 2 sources you provided for this and nowhere in them is a mention or a hint or anything really related to "disolve", "end of the universe's locality" or "threshold level". So here is my question, since nothing is mentioned in the source, how did you come up with that sentence exactly ? While you think about it, I'm going to remove the text as obvious original research. Any re-addition of this sentence (or anything resembling) without proper reliable source will be summarily reverted. --McSly (talk) 20:14, 12 September 2009 (UTC)

"Blurring" and "dissolution" are synonyms. "Blurring" is optical dissolution. Pixels cannot become blurred ad infinitum—this is obvious and cannot be regarded as original research.--Systemizer (talk) 20:30, 12 September 2009 (UTC)

no there are not. And what about "end of the universe's locality" and "threshold level". You need to find a reliable source stating exactly that. And don't use synonyms, quote what the source says, not your interpretation of it. So yes what you did is clear, obvious original research. --McSly (talk) 20:36, 12 September 2009 (UTC)

Wikipedia does not prohibit using synonyms. To become blurred means to become less distinguishable: blur 1) to make or become vague or less distinct (Collins English Dictionary). A sufficiently blurred thing becomes indistinguishable, "dissolves." A pixel is the elementary locus of space. Absence of loci means absence of locality.--Systemizer (talk) 20:52, 12 September 2009 (UTC)

Oh that was a nice dodge there. First, thanks for confirming that "blurring" and "dissolve" are in fact not interchangeable. I will add that this edit [4] pushes you even further into original research territory. Which brings us to the main point. If all these words are synonyms, why don't you just quote the article instead of spending time looking up definitions in the dictionary or arguing with me. Sure the use of synonyms in not prohibited, but accurately citing a source would be much better, so why don't you do it ? and the answer is obvious, because the source doesn't say anything about doomsday scenarios, doesn't say anything bout the locality principle, or any kind of threshold. That's why you can't do it, because that part is complete original research. But anyway, I'm done here for now since we are not getting anywhere. I'm sure other editors will give some feedback and I'm not really worried about the final outcome. --McSly (talk) 21:35, 12 September 2009 (UTC)

{Undent} This is the pre-loaded debate from McSly's talk page.Simonm223 (talk) 20:47, 14 September 2009 (UTC)

I have removed everything that could be interpreted as original research. The remaining text is copied from the referenced NewScientist articles and cannot be qualified as original research.--Systemizer (talk) 21:05, 14 September 2009 (UTC)

Regardless of your opinion in this matter I don't see how you think you can justify 9 reverts in 24 hours. You have been warned twice on your talk page. Even if you blank it the history remains intact. The 3RR noticeboard has a notification on it of what has gone on here.Simonm223 (talk) 21:12, 14 September 2009 (UTC)

I read over those two articles that Systemizer (talk · contribs) was claiming as refs for his statements. Whole lotta WP:SYNTH going on. Especially of note was changing a whole lot of "maybes" into certainties but the other stuff, about planckian pixels becoming "blurred" is entirely unsupported by the article. The second article, [5] says:

The information held at the boundary is not smooth, but composed of "bits", each one occupying an area that corresponds to the most fundamental quanta of distance in the universe. This is the Planck length, around 10^-35 metres – far too small for us to see the individual bits. When this information is projected into the volume of the universe, however, each bit gets magnified. That means we might just be able to see pixellation in space-time

in reference to Craig Hogan's hypothesis but, as you can see, fundamental changes were made by Systemizer with regards to the subject of the text. Furthermore both articles made it clear that while the holographic principle has been a useful contribution to superstring theory it is still, ultimately, unproven at this time, especially when applied to the cosmological boundary rather than the boundaries of black holes.Simonm223 (talk) 11:58, 15 September 2009 (UTC)

Unfortunately this seems par for the course and I cannot AGF with Systemizer. What you may not be aware of is his deleted articles. Two were speedied, two went to AfD, Wikipedia:Articles for deletion/Septennial cycle and Wikipedia:Articles for deletion/420-year cycle. Dougweller (talk) 12:19, 15 September 2009 (UTC)

On the second AfD you listed I had to keep reminding myself that it was an archived discussion and I was not to make comments in it... I don't believe in it but the Chinese zodiac lies at a confluence of a large number of my interests and I know a lot about it. It is not an analogue to the Greek system!Simonm223 (talk) 13:55, 15 September 2009 (UTC)

Para 1 made opaque

" the expansion of the universe is accelerating[1][2] since around redshift of z~0.5[3]." I've been studying astronomy my whole life and can't understand what that last part means. It'd be great to find out what redshift and z mean later in the article ... but that needs to be translated into something the average reader can understand at that point. Twang (talk) 10:54, 26 November 2009 (UTC)

The "z nomenclature" is simply a way of precisely pinning down a time period without having precise data as to when that period took place. If you want to talk about when the first vertebrates showed up you can say "about 380 million years ago" or you can say "at the start of the paleozoic." The redshift nomenclature is analogous to the second example. The value of z is defined as zero at the present, and increases (obviously) as you go backwards in time. z=1089 is when the CMB we see today was emitted, z=0.5 is when the acceleration of the expansion started, and so on.

Contestation

The evidence of the acceleration of the expansion of the Universe was established based on the observation of supernovae (Riess, 1998). By plotting the distance moduls M-m againt redshifts in log scale, the non-linearity of the plot was interpreted as an acceleration of the expansion of the Universe. However, due to the effect of the Planck's law for the energy of the photon (E = hc/lambda), the observed energy flux is reduced due to redshifts. By taking in to account this effect, the corrected distance modulus becomes: m-M = -5 + 5log(d) + 2.5 log(1+z). Therefore, one should plot the redshift adjusted distance modulus m-M -2.5log(1+z) against redshifts in log scale, and the plot becomes linear. Therefore, we cannot conclude anymore that the expansion of the Universe is accelerating. Ref: http://fr.calameo.com/books/000145333fb179c8eb6ae. — Preceding unsigned comment added by 92.107.15.227 (talk) 20:11, 15 August 2011 (UTC)

Accelerated question

Does this mean the entire Universe is in an accelerated frame of reference? Patsobest (talk) 00:46, 31 August 2012 (UTC)

Is it possible that the universe expands at an accelerated rate for a while and then the rate comes down and this goes on in a cyclical manner? — Preceding unsigned comment added by Ksunilsingh (talk • contribs) 01:15, 10 October 2012 (UTC)