Talk:Planck epoch

Question about durations shorter than Planck time
Why is it meaningless to speak of durations shorter than Planck time?

Because the laws of time and space are virtually meaningless at a duration shorter than a Planck Time. Let me put it to you this way. There are fundamental constants that govern the size of particles, such as the size of electrons and protons. Also, there are laws governing our universe for large objects (General Relativity) and the universe at the small scale (quantum mechanics). These laws however have inherent contradictions of one another since they govern two aspects of the same universe, thus, there is no unifying principle that can link quantum mechanics to general relativity. The Planck time at the beginning of the universe deals with a moment in history where the laws of quantum mechanics and general relativity existed in the same realm with one another (at the Planck Length). As we have no explanation by which to unify these different principles then it is meaningless to speculate on the universe's beginning at a duration shorter than the Planck time. HuronKing


 * Yes great! I agree. It's so incredible nobody replied. Please note this void sentence..."promise to push back our 'cosmic clock' further to reveal quite a bit more about the very first moments of our universe's history, hopefully giving us". So someone promise us something... full of hopes. That's religion. BTW, wikipedianers, will you please take in account this criticism?83.103.38.68 (talk) 13:43, 18 August 2008 (UTC)

Expecting to edit here
I expect to do some writing/editing here, after adding some content to Planck scale article, and finding it's more appropriate to expand this entry instead. Current research in Planck scale dynamics is shifting from the particle physics to the astrophysics arena, with recent WMAP results and other experiments coming online. Many links also exist for Planck Era, from various educational websites. This article could now be greatly expanded, although little could be said here 3-5 years ago. I will do what I can to make this a more informative and meaningful entry, without adding too much fluff. JonathanD 04:33, 8 October 2006 (UTC)

Question about Unification of Forces at Planck Time
A question for Yevgeny: Can you cite any references which call into question the idea that the fundamental forces were unified at the Planck time? Some sources suggest that unification could have taken place later, or at a larger dimension than the Planck length, but I have found none who express doubt that the forces are unified during the Planck epoch. In fact; all I've read implies that this is the defining quality of that cosmological era. Do you have any references that state this is not true? I will cede that there may have never been a Planck era, but by definition it is that time when all the forces were unified. The question is not whether this is so, but how long it remained that way. If supersymmetry works (or is proven) it would show that the universe could grow by a factor of 1000, after the Planck time, and still remain unified before symmetry breaking forced the beginning of inflation. Please comment. JonathanD 22:33, 21 October 2006 (UTC)


 * All physicists hope that it's possible to provide a unified description for all forces of nature. You would agree with me, however, that nobody has even approximately shown that such a unification actually occurs. (Of course, if it does exist, it would be reasonable for it to happen around the Planck scale, where all the interactions have a comparable strength.) Yevgeny Kats 22:53, 21 October 2006 (UTC)


 * A strange question. "Unification" is a shameless way of admitting that the more we go towards the Big Bang, the more it is impossible: "How can it ever explode-expand as it was infinitely dense?" Reply: "Let's postulate physical laws changes!!". So theunification wil occour EXACTELY when needed by this flawed model. Waiting a new Galileo.83.103.38.68 (talk) 15:31, 18 August 2008 (UTC)

Adding References Section to Article
I hope to add a references section to the article, before day's end. I would ask all editors to the Planck epoch entry to carefully note syntax. The detail of each reference is embedded in the main text for each topic section, but shows up below in the References section below.

Thanks,

JonathanD 21:06, 22 October 2006 (UTC)

When does the Planck Epoch start???
This page says that the epoch begins at 0 and ends at 10-43 seconds or 1 planck time. However http://dictionary.laborlawtalk.com/Timeline_of_the_Big_Bang says that it BEGINS at one Planck time and ends at 10-35 seconds. So im just wondering which source is true.82.2.211.133 14:18, 12 November 2006 (UTC)
 * The second timeframe you refer to describes the Grand Unification Epoch; the second epoch of the universe.24.21.139.41 07:02, 14 May 2007 (UTC)

"String theory has yielded meaningful insights" ?
What mathematician have you been talking to? Because last time I checked (which was just now) string theory has led to absolutely nothing, because it has no experimental basis at all. It doesn't even qualify as science, since it lacks predictive value.

Argument from mathematical elegance is ridiculous. --76.209.59.227 16:05, 3 February 2007 (UTC)

"Primodrial Neutrino detection less than useful" ?
I'm not entirely sure why the ice cube neutrino detector would be expected to provide any insight on this epoch, as all the primordial neutrinos would be expected to have energies approaching that of the microwave background radation. No known method is present for detecting such low energy neutrinos, least of all several tons of antarctic ice. In addition, its likely that neutrinos provide information only extending back to the electroweak or at most the GUT era, as the interaction energies were high enough in those epochs to be 'optically' opaque to neutrinos. Citation or links should be provided or this should be deleted.


 * These notes at the IceCube web site say As a particle physics detector capable of detecting neutrinos with energies far above those produced at accelerators, IceCube will search for super-symmetric particles and the topological defects created during grand unified phase transitions in the early universe. Gandalf61 12:19, 15 March 2007 (UTC)

I agree with this remark, referring to the IceCube page mentioned. So I removed IceCube from the text. Bookaneer (talk) 09:01, 12 October 2011 (UTC)

How big was this thing ?
Do we know how big the universe was at this point ? The non-physicists among us need to relate this to real life if possible.. so was this super-dense/hot/whatever thing about the size of a bus ? With all this apparent inflation, I'm left with the horrible thought that most of the Universe's matter/energy/whatever is an illusion, and that there isn't really very much stuff at all and a lot of empty space : i.e. even so-called particles must be mostly space. Rcbutcher (talk) 16:30, 4 January 2009 (UTC)


 * First thing we need to do here is to distinguish between the universe and the observable universe. We don't know how big the universe as a whole is, or how big it was during the Planck epoch - all we know about is the part of the universe that we can currently observe. And this is limited by the age of the universe and the speed of light. But we can ask "How big was the region that now forms the observable universe during the Planck epoch". This source suggests a size of less than 10-52 metres; this source says about 10-50 metres. For comparison, the size of a proton is a huge 10-15 metres. Cosmic inflation increased the linear size of the observable universe by a factor of around 1050 - so, immediately after inflation, the observable universe was somewhere between 1cm and 1m across. Gandalf61 (talk) 16:50, 6 January 2009 (UTC)

THIS PAGE SHOULD HAVE A CAPTIAL E
This page SHOULD BE NAMED Planck Epoch with a capital e; can some expert fix that?


 * I think it should be lower case. I searched arχiv abstracts for "planck epoch" and got (only!) 16 hits, and it was lower case in all sixteen. -- BenRG (talk) 20:08, 1 March 2009 (UTC)

HELP FIX THE COMPLETE PLANCK VERSUS SUB-PLANCK SCREWUP FROM 2008
I am attempting to fix the total mess from 2008 that the now banned wikipedia editors created see sub-Planck and help fix all this...


 * What? Why this undue screaming? Rursus dixit. ( m bork3 !) 18:52, 28 January 2011 (UTC)

Warning: Gargish
The following statement is unacceptable and weirdly illogical, I don't know how to fix it exactly:
 * At this point approximately 13.7 billion years ago the force of gravity is believed to have been as strong as the other fundamental forces, which hints at the possibility that all the forces were unified.

The problem is that human beliefs doesn't affect the nature of reality according to most main-stream philosophies, especially, human beliefs have no effect whatsoever on whether all the forces were unified or not. Rursus dixit. ( m bork3 !) 18:52, 28 January 2011 (UTC)

There is more illogical contents. If the Planck epoch ended with Planck units coming to bear, also the Planck density must have come to bear. I.e it is not possible to talk just Planck time and Planck length but leaving Planck density out of consideration. This is because the Planck units are based on the existence of ALL natural constants which implies that once the constants were in place all Planck units were in place as well.

Consequently the today's mass/mass equivalents of the universe must have been compressed into Planck Density at the end of the Planck epoch. This inevitably means that the size of the universe at the end of the Planck epoch cannot have been 1 Planck length but must have been the mass of the universe divided by Planck density.

This leads to the question why an object of Planck density with the mass of the universe "exploded". Black holes of that density never were observed to explode. —Preceding unsigned comment added by 84.172.114.118 (talk) 02:59, 22 March 2011 (UTC)

please improve this article
i would do it myself but the problem is that I'm not really good at writting. for example in the first paragraph it says: "One could say that..." I think that's just wrong. The planck epoch is not about what "one" says. thanks anyway... 190.60.93.218 (talk) 17:11, 26 September 2011 (UTC)

“quantum effects of gravity were significant”
I am not familiar with cosmology/QFT/quantum gravity/etc., but isn’t it expectet that it will be possible to perform experiments to observe quantum effects of gravity somewhere in the not too distant future? (I mean, 100 years for example?) Thus quantum effects of gravity should be significant not only during the Planck epoch. --Chricho ∀ (talk) 19:07, 10 July 2012 (UTC)

Inconceivably hot and dense
I don't like how each word in "Inconceivably hot and dense" is a link. Can we expand this part so that each link is in its own sentence or phrase? — Preceding unsigned comment added by 99.236.14.188 (talk) 07:14, 23 January 2014 (UTC)
 * I agree - the links on "inconceivably" and "and" were rather pointless. Lead sections of articles are meant to be kept as short as possible, so instead of expanding that sentence, I have just removed two of the links. Gandalf61 (talk) 14:42, 23 January 2014 (UTC)

Quantum gravity epoch
I redirected Quantum gravity epoch here. I'm not sure if that name is widespread enough to be mentioned here, on a quick search I found one reference. &mdash;&thinsp; H HHIPPO  22:02, 28 January 2014 (UTC)