Talk:Gamma-ray burst

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GRBs as Standard Candles[edit]

There is an immense amount of work happening in the field of GRBs in cosmology. GRBs can be used as standard candles, much further out than SN Ia can even dream of reaching. While the accuracy of GRBs as a means of finding cosmological distances is about 2-3 times that of supernovae, the utility of GRBs is that it can reach out to the early universe (which SN Ia and cepheids cannot). By using GRBs on the hubble diagram, you can now determine for a cosmology that involves changing dark energy.

Anyway, I could write for pages on this as my research focuses on GRBs as standard candles. :-p I was just wondering why there's not even a peep about it on the page.

130.39.0.198 (talk) 18:21, 10 November 2009 (UTC)

I think an extensive discussion of uses of GRBs for cosmology (not just as standard candles but also for reionization probes, etc.) would be a bit auxiliary to the main topic of the article, which is the bursts themselves. Even the articles on supernova and type Ia supernova devote only a sentence or two to cosmological applications despite the fact that these are the focus of a vast amount of international study. Also, the real utility of GRBs for cosmology is still viewed with great skepticism by a lot of researchers in the field. A short mention the topic (maybe in the energetics section) might not be a terrible idea, but I think anything significant would better fit in one of the articles on cosmology, the distance ladder, etc. Daniel Perley (talk) 09:27, 1 January 2010 (UTC)

The use of GRBs as cosmological distance indicators is only now being explored with acceptable rigour and still relies on the assumption that empirical relations are fundamentally due to common physical processes. There are many issues in the statistical analysis that are unsatisfactory in much of the past attempts at this, so I don't think this should feature much, if at all, in the article.86.0.198.250 (talk) 13:56, 9 May 2012 (UTC)

Copyedit[edit]

Changes[edit]

Hm, I see a lot of changes have been made in the past month or so. While splitting up the article is probably a positive development some of the recently edited or added text is rather incoherent or poorly worded... I'll try to do some cleanup in the next couple weeks. I made some small changes tonight but did not do a very thorough job with referencing; something I'll try to work on soon if somebody else doesn't beat me to it. Daniel Perley (talk) 10:46, 21 November 2007 (UTC)

Credibility of History Channel as source[edit]

I noticed that the vast majority of cited sources in this article are highly credible, academic sources, with one major exception: Source #32, "History Channel, Mega Disasters, Gamma Ray Burst". I've seen some of the History Channel "documentaries" before; they're highly un-academic and seem to focus garnering viewers through sensationalism (particularly through exaggerating the possibility of some big apocalyptic disaster, then leaving viewers hanging for more details after a commercial break, which then turns out to be anti-climatic) more than being factually accurate or presenting all relevant information. Even Wikipedia's own article on it has plenty of dirt that I would consider enough to discredit it as a source, especially for a statement that says something could "incinerate the Earth". I'll remove the statement and citation from the article for now, but I'd like to hear if anybody has any arguments for keeping it in. --Poochy (talk) 06:27, 24 March 2008 (UTC)

What needs to be seen is if history channel attributed the statement to someone well known in this field, then maybe we can add the cite and state that "History channel showed a documentary in which Mr XYZ said so and so...."....but if the point was made by channel itself and not by some specialist, then i guess deleting it might be justified. Maybe someone who saw the episode might be of some help here ... Gprince007 (talk) 07:41, 24 March 2008 (UTC)

Mass extinction on Earth - 10% survival rate citation[edit]

this is said by one of the sientist who also worked on the "Did a gamma-ray burst initiate the late Ordovician mass extinction?" report, on the episode "Human Extinction" of the "Earth Investigated" on the National "Geographic Channel"

posting this here to be sure that this information doesn't get lost (and it's not enough for reference)

My comments[edit]

Alrighty, Jehochman! First off, I must admit that while I do work on mostly science articles, I know very little about astronomical physics. However, I firmly believe in the value of fresh eyes. So here's my plan of attack: First, I'll go through the article and find weaknesses in the prose. If I notice any major gaps in the content, I'll list them here too. Second, I'll go through the references to check for reliability and such. After that, I'll compare the current article to the revision as of the end of the previous FAC and see which of the objections have been adequately dealt with and which have not. As for completeness and content, consider contacting the members of WP:SPACE or WP:AST if you haven't already. All that being said, let's get started! --Cryptic C62 · Talk 22:54, 29 November 2008 (UTC)

Thank you for these ideas. I will work on it the next chance I get. Jehochman Talk 01:30, 2 December 2008 (UTC)

General[edit]

  • The article mixes "gamma ray" with "gamma-ray". Which is correct? Even if both are correct, the article should be consistent. Yes check.svg Done
    • The literature appears to be unanimous in using the hyphenated version. I've moved the article and related articles, but we will need to clean up Category:Gamma ray bursts. Perhaps somebody has an automated tool that can help. Jehochman Talk 16:29, 19 December 2008 (UTC)
I just got permission to use AWB. I'll try it out in the next few days.Yes check.svg Done
The standard rule (eg, ApJ, Nature ...) has been that "gamma-ray" should be hyphenated when used as an adjective, as in "gamma-ray telescope" or "gamma-ray burst", but not when used as a noun, as "Gamma rays are the shortest-wavelength form of ...." Seems fussy (and often broken) but I believe it still applies. (The same rule applied to "x ray", BTW.) Wwheaton (talk) 18:20, 10 January 2009 (UTC)
  • Here's something that confuses me. Why is it that the first GRB detected was assigned the number 670702? It seems to me that the first should be labelled 000001! I'm joking, of course, but I think that if you can find information about how GRB numbers are designated, it would make a good addition to the article.
    Hrm, I just noticed Note 12. This is an odd place for the explanation. Any way you can squeeze it into the main article somewhere?

Lead[edit]

Discovery and History[edit]

  • "Cosmic gamma-ray bursts" This is the first and only use of "cosmic," yet there is no explanation of the word given. Eh? Yes check.svg Done
  • "...details of the Vela Incident..." It's not clear why this particular incident is singled out. Is this the only notable incident involving the Vela satellites? If so, this should be stated explicitly. Perhaps it should also be moved into its own sentence, as it reads awkwardly enough as it is now.Yes check.svg Done
  • "looked nothing like a nuclear weapons signature" Do you mean a nuclear weapon's signature or nuclear weapon signatures? Yes check.svg Done
    • Rereading this sentence, the word "looked" doesn't seem quite right. It's neither encyclopedic nor scientific. Also, using "looked" implies that the analysis of these radiation flashes was based entirely upon a simple visual comparison, which I have a hard time believing. If it really is about visible differences, consider rewording to include the word "appearance". It it isn't just about visible differences, find a more specific word.
  • "These results were published in 1973" Results of what? Perhaps "findings". Yes check.svg Done
  • "prompting the scientific study of GRBs" Huh? The paragraph jumps straight from discovery of the events to studying them without even explaining how they were identified and named. At the very least, this should be rewritten to "the scientific study of what were then identified as GRBs".Yes check.svg Done Also, by whom were these studies conducted? What new information did they find? Yes check.svg Done
  • "such as Apollo and the Soviet Venera probes" Somewhat US-centric. Why does it clarify that Venera probes were Soviet, but not that Apollo was a US program? Yes check.svg Done
  • "However, some believe there is a third type of GRBs.\sum_{n=5}^9 [n]" Wow. Lots of citations. If it's that amazing, why is there no elaboration or explanation of this third type whatsoever? Yes check.svg Done
  • "as predicted by most models" If scientists had no idea where the GRBs were coming from, how could they model them? Perhaps you need to clarify what sort of model you're talking about. Yes check.svg Done Unclear what the statement meant, so I have removed it. Jehochman Talk 21:25, 5 December 2008 (UTC)
  • "the first of many to come" I can't seem to find the relevant policy page at the moment, but it goes something like this: Don't hint at information that will appear later in the article. If it's relevant now, state it plainly. If it isn't, leave it out. Yes check.svg Done
  • "which combines a sensitive gamma-ray detector with the ability to slew on-board X-ray and optical telescopes" I'm not a scientist, so I could easily be wrong here, but "slew" doesn't sound like a very scientific verb, and even if it is, it might not immediately make sense to the average user. Perhaps "aim" or "point" ? Yes check.svg Done
  • "The mission has also discovered huge X-ray flares" "Huge" doesn't carry with it a particularly encyclopedic tone. How about "large" ? Yes check.svg Done
  • "On June 11, 2008 NASA's Gamma-ray Large Area Space Telescope (GLAST), later renamed the Fermi Gamma-ray Space Telescope, was launched." Several problems here: First, it's a one-sentence paragraph. Second, it has no citation. Third, it is unclear how this statement is relevant. What's special about GLAST? Yes check.svg Done

Galactic vs. extragalactic models[edit]

GRB Jets collimated emission[edit]

  • "Many GRBs have been observed to undergo a jet break in their light curve" What is a jet break? It's unclear if the second clause defines the term or is just elaborating. Yes check.svg Done
  • "the optical afterglow quickly changes from slowly fading to rapidly fading as the jet slows down" Way too many speed-related adverbs in this sentence. Also, what's a jet? Yes check.svg Done
  • As I continue to read this paragraph, it becomes more and more confusing as it continues to use phrases including "jet". There is obviously a large disconnect between the article and your understanding of jets. What they are and how the word is used needs to be clearly stated near the beginning of the section. Yes check.svg Done
  • "the true energy release of a (long) GRB is approximately constant—about 1044 J" Why is long in parentheses? Also, does this sentence mean that all long GRBs have the same energy release? Or that for the duration of any single GRB, the rate of energy release is constant? Yes check.svg Done
  • "1044 J, or around 1/2000 of a solar mass" there appear to be conflicting units here. Why would a solar mass be measured in joules? Do you mean "1/2000 of the energy released by a solar mass"? Yes check.svg Done
  • "Bright hypernovae do in fact appear to accompany some GRBs" This implies some deeper connection between hypernovae and GRBs, but then the paragraph ends. Eh? Yes check.svg Done
    • "suggesting that hypernovae may be a source" Source of what?
  • "only a small fraction happen to be pointed the right way to allow detection" The use of "allow" implies some form of control. How 'bout "...pointed such that they can be detected." or something along those lines? Yes check.svg Done
  • Short GRBs probably shouldn't be its own subsection. It's very short, and it refers to "the above arguments". Yes check.svg Done
  • "They appear to be generally less beamed or possibly not beamed" I think "not beamed" needs to be emphasized further. How about "or possibly not beamed at all"? Yes check.svg Done

Progenitors[edit]

Emission mechanisms[edit]

Mass extinctions[edit]

  • "The idea that a nearby gamma-ray burst could significantly affect the Earth's atmosphere and potentially cause severe damage to the biosphere was introduced in 1995 by physicist Stephen Thorsett, then at Princeton University." This reads a bit too much like a Dan Brown novel. Consider rearranging the sentence so Thorsett and 1995 are introduced at the beginning. Yes check.svg Done
  • "Gamma-ray bursts within the Milky Way galaxy every 100,000 - 1,000,000 years." This is what English professors like to refer to as "not a sentence". Yes check.svg Done I thought I had typed a verb. :-)
  • Why the sudden jump from 1995 to 2005? Did nothing happen with this theory in 10 years? At the very least, Thorsett's theory should be elaborated upon before moving on to the NASA/University of Kansas study. Yes check.svg Done Apparently not much happened on this speculative/sensationalistic theory.
  • "rather the strength of their work was their atmospheric modeling, essentially a "what if" scenario." Huh? I really have no idea what the last clause is referring to. Yes check.svg Done
  • "ultraviolet radiation from the Sun would kill much of the life on land and near the surface of oceans and lakes, disrupting the food chain" Having the food chain bit at the end makes it seem like the most important consequence. Perhaps you should go on to elaborate as to why disruption of the food chain is such a big deal. Yes check.svg Done
  • "metal-deficient galaxies are the most likely candidates." Again, they are not participating in an election.
  • "The likelihood of the metal-rich Milky Way galaxy hosting a GRB was estimated at less than 0.15%, significantly reducing the likelihood that a burst had caused mass extinction events on Earth" Yes check.svg Done Gone back to the original paper and deciphered what they were saying.
    • The statistic presented is meaningless without context. Does it mean that there is a .15% chance that it ever hosted a GRB? Some kind of time frame needs to be added. Yes check.svg Done
    • An estimate doesn't change the likelihood of something else happening. Perhaps you meant to say that the estimate suggested a significantly lower likelihood or some such. Yes check.svg Done
  • "at least one nearby event has probably hit the Earth in the past billion years, with life on Earth being at least 3.5 billion years old" While it may be obvious to us what the second clause is implying, not everyone will understand. It should be explicitly stated that if a GRB occurred in the Milky Way while life was present on earth, it could have caused an extinction event. Yes check.svg Done
  • "has been found to have a rotational axis aligned within 16° of the solar system. The chances of it producing a gamma-ray burst are small, ..." So what? This paragraph needs to be expanded, and it should be made clear why the rotational axis alignment is relevant here. Yes check.svg Done
  • "Comparative work in 2006" By whom? A quick glance at the citation at the end of the paragraph doesn't even state who was conducting this work. It's especially important to be clear about this here because the other paragraphs all mention specific persons and organizations. Yes check.svg Done
  • "it is most unlikely that a nearby GRB has caused mass extinction events on Earth" This conclusion should not be presented as fact; the very next paragraph reaches the opposite conclusion. It should be made clearer that neither of the two conclusions are known to be true or false. Yes check.svg Done

Notable GRBs[edit]

  • Knowing that you plan to bring this article to FAC again, I think a bulleted list is the wrong way of organizing this section. I recommend picking a few GRBs that are highly notable and are not already mentioned in the article and expanding those into full paragraphs. Consider the following question: If the GRBs are notable enough to appear in the article, shouldn't they be notable enough to be in a full paragraph? Yes check.svg Done
  • To avoid making this section too long, consider adding GRBs with their own articles to the See Also section. Category:Gamma ray bursts would also be a helpful link, either as a hatnote or part of the See Also section. Yes check.svg Done
  • "This was the first with a successfully detected afterglow." Unclear meaning. Was "this" the first satellite to successfully detect an afterglow? Or was "this" the first detected GRB to also have its afterglow detected?
  • "GRB 970508 was the first with a measured redshift. The extent to which the radiation is redshifted allows astronomers to calculate an estimate of the distance of the event), 0.835." Uh... Yes check.svg Done
  • "momentarily reaching or exceeding a magnitude of 8.9"
    • Is this the magnitude of GRB 990123, or of GRB 080319B?
    • 8.9 what? Pirates?
  • "despite its distance of nearly 10 billion light years" Distance requires two points. I'm assuming this means 10 billions light years from earth? Yes check.svg Done
  • "GRB 030329A was an extremely close (z=0.168), and therefore extremely bright GRB" - References did not look good for this one, so removed it. Yes check.svg Done
    • What is (z=0.168)? This bit of terminology definitely needs to be clarified.
    • Here you imply that a close GRB will also be a bright GRB, but in the previous paragraph, you mentioned that the brightest GRB ever was 10 billion light years away. Hmm...
  • "GRB 030329 was so bright..." The sentence before this was about GRB 030329A. Different incidents, or typo? Removed Yes check.svg Done

References[edit]

Most of my comments here are pretty trivial, so I'll probably correct them later if you don't. I'll list them here either way so you know what I'm doing.

  • Consider separating the explanatory notes and references into two separate sections. This might solve the problem of where to put the information about the GRB naming conventions. See Wikipedia:Footnotes#Separating_reference_lists_and_explanatory_notes.
  • I think that when you provide a DOI, you're not supposed to link the name of the article. I'll check with Ealdgyth.
    According to SandyGeorgia, if the DOI and the URL both link to the same page, the URL is unnecessary. If, however, the DOI goes to an abstract while the URL leads to the full article, then both are to be included. I'll go through the journal refs and makes changes where necessary.
  • Note 3 (A Gamma-Ray Burst Bibliography) has the author listed First initial. Last name whereas the rest of the citations use Last name, First initial.
  • Note 4 (Spatial distribution of gamma-ray bursts...) has no space between the author's two initials, while the rest of the citations use a space.
  • Note 17, 24, 47, 50 use The Astrophysical Journal while the rest use Astrophysical Journal. Are these the same publication?
  • Note 24 (Jet Breaks in Short Gamma-Ray Bursts) lists all of the authors while the other citations with more than 3 authors use et al.
  • Note 27 and 28 are missing first initials for the main author.
  • Note 31 and 33 use ApJ as the publication, whereas the rest spell out the full title, which I presume to be Astrophysical Journal.
  • Note 37 (Gamma-ray bursts from synchrotron self-Compton emission) is missing information that's readily available on the article's page.
  • Note 39 (Optical and Long-Wavelength Afterglow from Gamma-Ray Bursts) has a random tilde (~) in it?
  • Note 46 (badastronomy.com) is incomplete.

I fixed most of these, but am unsure about 37 and the correct publisher for 46. Jehochman Talk 03:23, 7 January 2009 (UTC) ...

Third paragraph in lead[edit]

I find part of the following sentence a bit confusing:

The fragment Though the short duration of a gamma ray burst would limit the immediate damage to life is vague. GRB will cause mass extinction in Earth, whether short lived or long lived. This is why I think this part is unnecessary. What is meant by "limit the immediate damage to life"? How are you calculating the damage with the duration of the GRB? What is the standard time a GRB will need to cause mass extinction? Otolemur crassicaudatus (talk) 17:21, 10 December 2008 (UTC)

Another important point, the fact that mass extinction on Earth due to GRB is highly unlikely should be mentioned in the lead to give a clear picture. Otolemur crassicaudatus (talk) 17:50, 10 December 2008 (UTC)
It seems like you and I have made the necessary changes. Are you satisfied with the current lead? Jehochman Talk 14:03, 19 December 2008 (UTC)

To be done before FAC[edit]

We need to expand the Types of bursts and Research missions sections, based on comments at the last FAC over a year ago. In particular, there are a few significant missions that have not been mentioned (RXTE and HETE), and we probably need to identify the InterPlanetary Network and the Gamma-ray Burst Coordinates Network. Jehochman Talk 15:48, 10 January 2009 (UTC)

Okey doke. I can try to assist with the research if you want, but I don't know how much help I'll be. Leave a message either here or on my talk page when you're done expanding those sections, and I'll start reviewing them, yeh? --Cryptic C62 · Talk 17:23, 10 January 2009 (UTC)

Vela gamma-ray detectors looked for nuclear tests in space[edit]

I have reverted an edit today, by El Wray (talk), that claimed that the Vela satellites were intended to detect gamma-rays from nuclear tests on the Earth, not in space. This is incorrect. The 1963 Nuclear Test Ban Treaty barred tests in the atmosphere or in space. There was a concern that tests in space would not be noticed by earth-based monitoring. The optical flash of such tests might be bright, but would be very brief, and not necessarily obvious if exploded far from Earth, on the day side of the Earth, or behind the Moon. A test in the atmosphere, if conducted at low altitude (say below 10 km), would not produce a gamma-ray flash observable from space, due to absorption in the overlying air. (There could be a much slower, minutes to hours, rise seen in space detectors due to delayed emission from radioactive materials lofted by the cloud of debris.) The very short, very intense flash of gamma rays from a space nuclear test would be easily observable and distinct from the natural sources known before the Vela spacecraft were launched. By spacing them around the Earth at distances of about 100,000 km, approximate positions (and hence also device yields) could be determined from the relative timing of the burst observations. Even a test behind the Moon would produce an expanding sphere of very fast-moving, intensely radioactive fission products, that would spread beyond the rim of the Moon within about a second. If I recall the Vela spacecraft did have detectors that might have detected the optical flash from a surface test, or possibly other signatures. A good reference for the design and capabilities of the Vela spacecraft would probably be in the proceedings of the October 1973 Los Alamos conference on gamma-ray bursts, of which I believe I still have a copy, though not conveniently at hand. Wwheaton (talk) 04:22, 29 January 2009 (UTC)

Our own Wiki Vela article gives further details about the spacecraft and their capabilites, and confirms my statements above. The capability of observing on-Earth tests was added in the second series of "Advanced Vela" satellites, and resulted in the detection of the characteristic optical flash of a nuclear explosion in the atmosphere, on 22 September 1979, by the Vela 6911 spacecraft, somewhere over the southern circumpolar ocean, near South Africa. I believe this "Vela Incident" is now widely believed to have been a nuclear test, possibly due to a collaboration between South Africa and Israel. Wwheaton (talk) 05:00, 29 January 2009 (UTC)

Reorganization?[edit]

As I continue to expand upon the Research Missions section, it is becoming increasingly apparent that the organization of this article is flawed. As it stands now, most pieces of information could logically fit into two distinct locations in the article. Discovery and Research Missions provide a general overview in chronological order, while the rest of the article focus primarily on our current understanding of GRBs, but instead broken up by subtopic. Any suggestions on how to reorganize the information to reduce the opportunity for redundancy and improve the flow? --Cryptic C62 · Talk 21:41, 20 February 2009 (UTC)

Actually i've had this article on my watchlist for a long while now....i had copyedited this article a long time back and since then it has changed a lot....infact in past few months, there have been too many additions and i had stopped keeping track of it....however, i feel that the article may need some restructuring and i'll be glad to help with copyediting once the article becomes STABLE. Once the structure of the article is agreed upon by editors and article is STABLE, I'll be glad to offer my services in copyediting the article !!! Gprince007 (talk) 14:53, 22 February 2009 (UTC)

GROND credit[edit]

I have created a stub for GROND. I'm bringing this up because of the confusion I've seen in the popular media and web forums about the importance of the GROND team's work in the observation of GRBs, and the significance of the discoveries (ie, modeling of GRB emission mechanics; interpretation of redshift, distance scale and energetics).

For example, both GRB 080913 and GRB 080916C (the most-distant and most-powerful GRBs observed to date, respectively) were observed and back-extrapolated by the GROND team (NASA pr 1, NASA pr 2). Though Fermi and Swift detect GRBs and alert the network (and that is amazing in itself), in both of these cases the work of Jochen Greiner's team was essential in determining distance and energy.

I'm planning on working this into Gamma-Ray_Burst#Distance_scale_and_energetics (minimally... I've seen the history of splitting this article into smaller pieces) unless there are any objections. Also, this is a heads up that there is now an article to link to when there are other news-worthy stories regarding GRBs (and there will almost certainly be more). demonburrito (talk) 23:04, 23 February 2009 (UTC)

Notable GRBs organization[edit]

Hey all. I've updated and cleaned this section a bit.

For the organization of this section in its current form, I've made a draft here with subsections for each event. I saw the earlier objections to making it a list; but I thought that subsections might work well, for the following reasons:

  1. Some paragraphs are too long, while providing the bare minimum of info to show the notability.
  2. In the future, each event could have a main article link (all but one of them have articles).
  3. In the distant future, event descriptions could be a transcluded from a stand-alone list article.

Even if none of the above apply, it still looks pretty and is more navigable. I suspect lots of people hit this article first when looking for background on news reported in the popular science press. demonburrito (talk) 14:26, 28 February 2009 (UTC)

Major retooling[edit]

For those who haven't noticed, this week (2009 May 5-12) I'm trying to do a another major retool of the site to bring it fully up to date and improve the organization/emphasis a little. Feel free to point out or correct any problems that come up with rewritten sections or if there is resistance to removing particular content. (Grammar cleanup and typo patrol also appreciated.) Daniel Perley (talk) 09:24, 8 May 2009 (UTC)

You may be interested in using {{In use}} or {{Under construction}}. --Cryptic C62 · Talk 11:10, 9 May 2009 (UTC)

Good to know! By the way, I see someone has been uncapitalizing the uses of "Galactic". This is not a typo; Galactic in this sense means referring to the Milky Way Galaxy. Anyway, after some exhaustive editing I'm now essentially done. Daniel Perley (talk) 10:55, 12 May 2009 (UTC)

Some redlinks[edit]

  1. Afterglow (gamma-ray burst)
  2. Ray Klebesadel
  3. GRB 980425
  4. WR 124
  5. GRB 790305b
  6. Acta Astronomica

Could make for some interesting DYKs... Cirt (talk) 20:24, 15 May 2009 (UTC)

Aye, I definitely plan on DYKing an Afterglow article at some point if no one else gets to it. I'll probably have to wait until January 2010 before I have access to good sources, though. --Cryptic C62 · Talk 20:26, 15 May 2009 (UTC)
Added one more, Acta Astronomica. Cirt (talk) 06:31, 16 May 2009 (UTC)
I noticed an afterglow stub article was made for a while, but now it just redirects right back to gamma-ray burst... what's up with that? Daniel Perley (talk) 11:16, 23 May 2009 (UTC)


PBH Evaporation[edit]

Adding this is fine, though the classification section should probably (in my opinion) stick to models that have been confirmed to apply in at least come cases or are otherwise broadly accepted by the community. Primordial black hole evaporation is still entirely theoretical; PBH's are not known to exist in nature and no GRB has been convincingly shown to have the characteristics of an evaporation explosion. It's definitely worth mentioning in the Progenitors section, though so I'll leave that one and move the wikilinks there. —Preceding unsigned comment added by Daniel Perley (talkcontribs) 23:16, 17 May 2009 (UTC)

That's fine. I was not sure where to mention it. Jehochman Talk 00:15, 18 May 2009 (UTC)

Out of date![edit]

"A subclass of GRBs (the 'short' bursts) appear to originate from a different process, possibly the merger of binary neutron stars."

"the leading hypothesis is that [short gamma-ray bursts] originate from the mergers of binary neutron stars"

"The favored theory for the origin of most short gamma-ray bursts is the merger of a binary system consisting of two neutron stars."

Those three quotes are all out of date. The evaporation of primordial black holes is currently the favored explanation of short gamma ray bursts per http://www.physics.ucla.edu/hep/vsgrb/vsgrb_ichep2010.pdf 76.254.22.47 (talk) 05:31, 21 June 2011 (UTC)

This is by no means the consensus in the field, but rather the view of one research group, and it is only in regards to very short gamma ray bursts: binary neutron star mergers are still the primary working hypothesis for most short GRBs. They only appear to have one publication about this, in New Astronomy. I don't think it is worth more than a sentence or two. - Parejkoj (talk) 16:27, 21 June 2011 (UTC)
I'd recommend surveying the recent literature. I know some of the Fermi people assume PBH evaporation for all of their short bursts (but I'm not sure if they have a category of medium length bursts which overlap with others' idea of the longer short bursts....) Ever since a couple of intermediate mass black holes were confirmed, astronomers attitudes about PBHs have changed. 157.22.42.3 (talk) 06:29, 22 June 2011 (UTC)
Do you have a cite for that last statement? IMBHs and PBHs are very different things. There can be primordial IMBHs, but they wouldn't evaporate. - Parejkoj (talk) 16:19, 22 June 2011 (UTC)
I don't have a cite for the fact that the confirmation of IMBHs made PBHs more plausible. What reason is there to believe the contrary? I do recommend that people double-check the current literature to be able to correctly summarize reliable sources on the plausibility of PBHs. 157.22.42.3 (talk) 05:52, 24 June 2011 (UTC)
I'm having trouble seeing why you're assuming that IMBHs and PBHs are correlated at all. I see no reason offhand to expect intermediate-mass BHs to be of primordial origin. You could make an argument for IMBHs that were primordial implying that there were a lot more lower-mass primordial holes around, but a) you'd have to prove the first part in order to do that, and b) you'd still be making assumptions about the mass distribution (that it follows some kind of power law that favours small holes). If you're going that far out on a limb, I'm afraid the onus is on you to do the literature search. --Christopher Thomas (talk) 06:34, 24 June 2011 (UTC)
What Christopher said. IMBHs can be primordial (see, e.g., Volonteri (2010)), but that doesn't make very low mass PBHs, of the sort that could produce very short GRBs, particularly more likely. Cite please? - Parejkoj (talk) 14:57, 24 June 2011 (UTC)
Here are some from the past couple years: Carr et al (2010), Cline et al (2011), Khlopov (2010), Ukwatta et al (2010), and Lacki and Beacom (2010). Authoritative corroboration of the plausibility of low mass primordial black holes without discussion of GRBs or evaporation (at least in their abstracts) can be found in Frampton et al (2010) and Hawkins (2011). What is the evidence that short gamma-ray bursts without an x-ray afterglow are not from primordial black holes? 76.254.22.47 (talk) 19:52, 24 June 2011 (UTC)
The energy of a gamma short burst is "only" 10^33 J in 5 milliseconds. This is far less than the >10^44 J of the long bursts. Primordial black holes all must be the same mass (10^11 kg) and must all explode with the same energy (multiply by c^2 = about 10^28 J). So they come up short in the energy needed for even a a short gamma burst by a factor of 100,000. Which is a lot. Thus, I think this theory fails. However, what is the potential energy of two 1.4 solar mass stars falling into each other to the 2^(1/3) radius of a each neutron star (assume 12,000 m)? I get 2*6.67e^-11*(2.8e30)^2/12000 = 10^47 J, which is easily enough. SBHarris 20:43, 24 June 2011 (UTC)
Those numbers don't agree at all with the peer reviewed sources and the literature review linked to in the previous paragraph. The sciencedaily.com article you linked to talks about radio energy, not gamma rays. Although Hawkins (2011) supposes that all primordial black holes were stellar mass (without any reasons why they should be) Frampton et al (2010) show that a more uniform mass distribution is more consistent with observations. 76.254.22.47 (talk) 23:36, 24 June 2011 (UTC)
You're missing the point. We don't CARE about what mass these things are-- we care about the mass of those emitting in gamma rays. For this purpose we only care about the mass of the ones blowing up now, 13.7 billion years after creation. That can be calculated by Hawking's formula [1], and if they aren't 10^15 g (10^12kg) with energy of 10^30 erg (10^23 J) in the last 0.1 sec, then they aren't Hawking holes. You can't have it both ways. You can also see Hawking radiation for the calculation. The article on primordial black holes needs a lot of improvement about the 10^11 to 10^12 kg primordial black holes that should be radiating in the gamma spectrum now. SBHarris 23:53, 24 June 2011 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── Here is the formula from Hawking radiation

The time that the black hole takes to dissipate is:

t_{\operatorname{ev}} = \frac{5120 \pi G^2 M_0^{3}}{\hbar c^4} \;

\approx 1.33*10^{-17} M_0^3 \frac{s}{kg^3}  \;

Where M_0 is the mass of the black hole.


All you need to do is plug into the formula the maximal time that a short gamma-ray bursts lasts, by definition, which is 10 seconds. The formula then gives you a mass of 9 x 105 kg. Which is equivalent to 8 x 1022 J in the last 10 seconds of a Hawking black hole's life. Not all will be in gamma rays, but even if it was, you cannot get more than this amount of energy out of the last 10 seconds of the lifetime of a Hawking black hole. Thus, Hawking evaporation cannot produce short-duration gamma-bursts of more than 1023 J. If you find a short duration burst of more than this power (and most are) it isn't a Hawking black hole evaporating. The maximal power in 5 msec (0.005 sec) is 6 x 1021 J, not the observed 1033 J. So that's pretty much the end of the discussion. If Hawking's formula is wrong, the whole black hole evaporation theory is wrong, and then "PBH" black holes STILL do not give gamma rays by any known mechanism of evaporation. SBHarris 01:12, 25 June 2011 (UTC)

What is your source for the energy of "most" short GRBs? That 1033 J figure you keep quoting was from a radio event, not gamma rays. How do you feel about using the peer reviewed journal articles and literature review I linked to above as sources instead of your own original calculations about radio frequency radiation? 76.254.22.47 (talk) 16:49, 25 June 2011 (UTC)
The Hawking equation can't produce radio bursts of 1033 J in a short time, either! There just isn't enough energy in a small black hole (or any kind of black hole-- since smaller is more powerful) evaporation in that short time. I see nothing in your sources about PBH evaporation-- only abundance. A radio burst of 1033 J means the mass=energy has to be far higher than a PBH evaporating. So it doesn't matter if it's not gamma-- the energy is too high for that short time span. Lastly, we're talking about gamma bursts in this article, and the short ones just have too much energy to be PBH evaporation. I linked Hawking's original article. You have provided NO cites that suggest that PBHs cause short gamma bursts. If you find one, I guarantee they won't have done the calculation Hawking did. It's not MY calculation. It's not original. It's a well-known piece of physics. If you want to say PBH evaporate, you must use this (Hawking's) equation, since we have no other known mechanism for it. Argue with Hawking, not me. SBHarris 17:21, 25 June 2011 (UTC)
"I see nothing in your sources about PBH evaporation...."
Start with the Cline et al (2011) literature review. That's a WP:SECONDARY source directly addressing the energy measurements. Hawking is on record stating that all black holes will eventually evaporate. As you say, neutron star collisions can have much more energy, and they can explain the GRBs with an x-ray afterglow, but not those without. 208.54.5.213 (talk) 02:40, 26 June 2011 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────The Cline "review" is not a review in any sense that is WP:SECONDARY. It fails by 1) being primarily the Cline group "reviewing" their own group's work on arcXive (they've been pushing the idea of a special group of VERY short gamma ray bursts (<0.1 sec) for two decades, and have been pushing the PMH hypotheses for 10 years and still nobody believes them). 2) The paper [2] is not peer-reviewed (it was posted 26 May of this year).

The second problem is that the paper simply cites Cline's old bad calculations, which he hasn't fixed for 5 years. "The properties of PBH burst emission are model dependent and are estimated for gamma-ray burst in the range of tens of msec with luminosity 10^33 erg." Sorry, but that's off, by a factor of 1000. A 10 msec lifetime PBH has a total "luminosity" (energy of explosion) of 10^30 erg. If you look at the first table (Table 1) on the second page of this Cline paper [3] you see the problem. Cline thinks that a 10^8 g BH will evaporate in 84 msec (correct) and make 10^33 erg (totally wrong). If you multiply that mass by the square of the speed of light (3e10^10 c/sec) you see it's obviously more like 10^29 erg.

In any case, Hawking's PBH model doesn't really explain very short GRBs either, and I'm embarassed for this group in attempting it. They say the rise for the burst is consistant with the Hawking PBH explosion rise of luminosity = k t^(-2/3), but they don't prove it. That's a statistical question and where are their statistics? Then they have the terrific problem that their bursts have a tail and decay. Which they want to blame on bogus physics of production of heavy particles at the very end of a PBH explosion. They blame the assymetry of the bursts (all Hawking bursts should naively look alike, no?) on such effects also. Hadron/quark jets ala Supercollider. The problem with this is that a 100 msec PBH "hadronized" its radiation looong long before 100 msec, since its temperature really is 99 TeV then. In fact, since T goes as t^-1/3, even a 1 second BH has a temp of 46 TeV. The equation is T(TeV) = 46.4 t^-1/3. You can do the math. Even a 10 second black hole is running at 21 TeV at the beginning-- hotter than the large hadron collider, and still heating up after that.

With all of this, Cline's group argues [4] that his very short bursts are "extra hard" because their roll-off in energy is slower than the other longer bursts (of 1 sec and 10 second). See figure 7 in the "review." But it still goes down a lot between 100 keV and 1 MeV, and far more between 1 MeV and 10 MeV (!). And this is an explosion that the authors are arguing occurs at 10 TeV and more. I'm sorry, the group IS at UCLA but I suppose also in "LA-LA" land as well. ;) The idea is that 10 TeV (or 100 TeV) radiation is broken down to 100 keV (with sharp roll-off by 10 MeV) by interaction with other particles [5] , BUT there is also anisotopy that is explained by the idea of hadron jets, non particle interaction, and non-thermalization, so this sort of extreme cooling of radiation-output cannot happen. Alas, you can't have this both ways! Cline likes the mechanism when it serves to lower his gamma energy by a factor of a million (!) from 100 TeV to 100 MeV, and tosses it later when he has to explain something else--but nature either this thick cooling blanket of thermalizing particles around PBH explosions to thermalize the heat output, or it doesn't.

Finally, the Cline group is putting their PBHs out at only 2 parsec away, in order to make the energy observations work (pretty close-- the nearest star is 1.4 parsec) and making as many as they like, in order to do it. And that's even figuring them for more power than they actually can have, I would bet (Cline doesn't say, except as I noted above, which is wrong). Apparently they haven't been listening to earlier work saying you can't really make as many PBHs as you like, to explain any data you like. See [6], a paper not reviewed in Cline et. al's "review."

Finally, at this point you're probably telling that it's original research to point out Cline's math error in not being able to multiply 10^8 g by c^2 to get 9e28 erg. All I can plead is WP:CALC. However, it hardly matters, as all this is primary research, and Cline's reviewers haven't held his feet to the fire yet. In cany case, it's far too early to give him a major encyclopedic role in explaining GRBs, even the ultrashort ones that he's interesting in. (To his credit, the neutron star merger, tho not perfect, works better even for his purposes, and he also discusses that; I hope he finally sees the (gamma) light). SBHarris 21:56, 26 June 2011 (UTC)

  • (3 months later-- Oct. 9) New evidence suggests neutron-star merger or black hole/neutron star merger is the answer to at least some short bursts. [7]. Looks like I was right. SBHarris 22:39, 9 October 2011 (UTC)

"since the Big Bang"?[edit]

"They are the most luminous electromagnetic events in the universe since the Big Bang." Reference? What exactly is meant by the luminosity of the Big Bang? --98.176.24.91 (talk) 21:09, 3 June 2009 (UTC)


The mentioning of the Big Bang in this sentense only causes confusion. I propose to change "They are the most luminous electromagnetic events in the universe since the Big Bang." to "They are the most luminous electromagnetic events occurring in the universe". --65.105.195.14 (talk) 00:25, 16 June 2009 (UTC)


Dear RobertG, "previous edit lost the idea that the big bang was more luminous" - yes, that was the exact intent of the edit. I couldn't find any source that would give a definition of the luminosity of the Big Bang. Could you cite one? And regarding your question "where else" can events occur if not in the universe. I think it's inaccurate to say that the Big Bang was an "event that occurred in the universe". So I thought that adding "in the universe" to the sentense would make it more accurate and less confusing. --65.105.195.14 (talk) 20:11, 24 June 2009 (UTC)

Dear Jehochman, "This is what the sources say; not for us to decide truth; we just report". Right. So could you please reference a verifiable source of the statement in question? Thank you. --65.105.195.14 (talk) 21:04, 24 June 2009 (UTC)

Dear All, let me clarify my concerns. I am trying to understand the meaning of the phrase "They are the most luminous electromagnetic events in the universe since the Big Bang". I have some basic training in physics and math. I am not a native English speaker, but I rarely have problems with reading comprehention. So please help me interprete the phrase correctly. If "since the Big Bang" is interpreted as "after the Big Bang" it makes the phrase meaningless but harmless: no new information means no wrong information. However if we interprete "since the Big Bang" as "apart from the Big Bang" then we either need to explain what exactly is the luminosity of the BB or to reference a verifiable source. So, what does "since" mean in this context? Thank you much for your attention and time. --65.105.195.14 (talk) 23:49, 24 June 2009 (UTC)

I believe that the sentence was intended to convey the second meaning that you proposed: "apart from the Big Bang". I do not remember this being explicitly stated in any of the sources. I believe the sentence that you proposed is a fair compromise for now, and I will revert back to it. Jehochman may not have been the one who originally wrote that sentence; we recently asked an expert contribute to the article: User:Daniel Perley. He is probably not active anymore. You may wish to contact him, though I can do it myself if you'd like. --Cryptic C62 · Talk 03:16, 25 June 2009 (UTC)
Thank you Cryptic C62. I have seen mentionings of the big bang luminosity and even of its spectrum in special articles on cosmology, but have never found any definition of those terms. Which photons do we count? Over what time period? I agree that we should better refrain from mentioning it until experts tell us what it really is. --98.176.24.91 (talk) 04:28, 25 June 2009 (UTC)
Let me explain my edit. This edit changed the page to say that gamma-ray bursts are "the most luminous electromagnetic events occurring in the universe", and I removed "occurring in the universe" as entirely superfluous. I then read it again, and it now said "[gamma-ray bursts] are the most luminous electromagnetic events" which was not what the earlier version of the article said. However, I partially agreed with the original edit, because calling them the "most luminous electromagnetic events since the Big Bang" might imply that more-luminous events were known before the Big Bang, which we cannot observe. So I partially restored what was there before as "apart from the Big Bang". I do not know whether the Big Bang was more luminous than gamma-ray bursts, but the article recently passed WP:FAC with that sentence in place. --RobertGtalk 08:23, 25 June 2009 (UTC)
Thank you RobertG. Maybe "the most luminous electromagnetic events observed" would be a better formulation?. Such claim would be readiliy verifiable by the sources. --98.176.24.91 (talk) 12:43, 25 June 2009 (UTC)
How about "the most luminous electromagnetic events occurring in the known universe"? The addition of "known" may make it clearer that there exists the possibility of more luminous events that have not yet been discovered. --Cryptic C62 · Talk 14:55, 25 June 2009 (UTC)
"The known universe" sounds kind of sci-fi to me. But I better leave the choice of wording up to native speakers.--65.105.195.14 (talk) 16:06, 25 June 2009 (UTC)
I'm chiming in somewhat ridiculously late here, but just to resolve any confusion - the Big Bang was such a tremendous event (its "luminosity" is hard to define, but is in a sense the entire mass-energy content of the universe divided by a Planck time, which would be an absurd number) that the comparison to a gamma-ray burst or anything else is rather ridiculous. Still, someone being pedantic might point out that there was indeed an event in the universe's history with more energy than a gamma-ray burst, and the "most powerful event since the big bang" line is a common one in (note that, for example, it appears in the title of one of the reference volumes.) Anyway, if the statement is causing confusion there's no particular reason to hold on to it, so there's no problem with removing it. Daniel Perley (talk) 09:36, 1 January 2010 (UTC)
I wouldn't have a problem with the "most powerful event since the big bang" line. But the article specifically mentioned electromagnetic luminosity of GRB vs. BB. And if I were to try and define the Big Bang luminosity, I would count all photons over the first 10 seconds (up to the end of the lepton epoch). --65.105.195.14 (talk) 20:23, 8 January 2010 (UTC)

causes of GRB's[edit]

Shouldn't it have something about the possible causes of the explosions relating to these extremely rare events? I read somewhere that they can happen when: Either two neutron stars rapidly spiral together, eventually to collide and anhialate eachother. Or, even rarer, an abnormally large star explodes into a hypernova... It was on a poster from an acclaimed sciency magazine, but i forgte the name. Must be the heat. If these causes are already stated, that is fine, because i have only read the bits which possibly relate to this. Stakingsin (talk) 17:34, 30 June 2009 (UTC)

The relevant section of the article is "Progenitors". --Cryptic C62 · Talk 17:42, 30 June 2009 (UTC)

Thanks for thatStakingsin (talk) 19:28, 30 June 2009 (UTC) —Preceding unsigned comment added by Stakingsin (talkcontribs) 19:20, 30 June 2009 (UTC)

This BBC article reports that Gamma Ray Bursts may also occur when two black holes merge: http://www.bbc.co.uk/news/science-environment-21082617 — Preceding unsigned comment added by 2.24.88.232 (talk) 09:05, 21 January 2013 (UTC)

In this case the BBC article is wrong. During the merger of two black holes, where would the matter come from that is required for the emission of the gamma-rays? Binary neutron stars or black hole-neutron star systems could form a black hole with a rapidly accreting disk of relativistic matter, but binary black hole systems would form no such disk. They might instead merge and 'ring-down' to form a stable black hole, emitting their energy as gravitational radiation but not electromagnetic radiation. See: [[8]] for a good review of this phenomenon. 131.251.254.220 (talk) 15:33, 23 January 2013 (UTC)

Hyphenation[edit]

In other articles, like the one about mass extinction and gamma radiation itself, "gamma ray" is not hyphenated. But in this particular article it is hyphenated. Shouldn't this be changed for consistency? Kutera Genesis (talk) 20:05, 4 September 2009 (UTC)

There are two cases: gamma-ray burst is hyphenated, but 'gamma ray' is not. The grammar rule is that two word adjective phrases need hyphens. For instance, She was a flat-bottom boat, but The boat has a flat bottom.. I hope this helps. Jehochman Talk 01:05, 5 September 2009 (UTC)

-76.167.77.165 (talk)

beaming[edit]

There's a whole section on beaming. However, nothing in this section explains anything about why beaming might occur.-76.167.77.165 (talk) 06:38, 4 November 2009 (UTC)

The reason for beaming in GRBs is still very poorly understood. It probably has something to do with the accretion disk and/or magnetic field geometry around the progenitor. So given the poor state of understanding of the topic generally I feel it's not a major failing to omit this discussion. (At any rate, I certainly don't feel qualified to discuss it myself!) Daniel Perley (talk) 09:41, 1 January 2010 (UTC)

For the acromatic jet break the beaming is very good explanation. Euty (talk) 13:26, 21 April 2011 (UTC)

The problem of gamma ray bursts has been completely solved[edit]

Wikipedia is not the place to try to publish or popularize your own ideas. See WP:OR and WP:RS. --Christopher Thomas (talk) 19:11, 18 March 2010 (UTC)
I don't really care if it's self-published or not. I fail to see how this is as an important of a breakthrough as Zhao seem to think it is. The idea that GRBs are related to black holes has been around for a long time. The article explicitly states "he most widely-accepted mechanism for the origin of long-duration GRBs is the collapsar model, in which the core of an extremely massive, low-metallicity, rapidly-rotating star collapses into a black hole in the final stages of its evolution." Although this research paper supports a conclusion that may become the ultimate indisputable consensus that would require us to substantially rewrite this article (or at least the Progenitors section) yet, that hasn't happened yet. It's just one theorist saying stuff that, for the most part, has already been considered. --Cryptic C62 · Talk 19:19, 18 March 2010 (UTC)
This is one of about eight talk pages so far this IP user has cut-and-pasted the same essay into. I wouldn't worry about it too much (they're already blocked). --Christopher Thomas (talk) 19:28, 18 March 2010 (UTC)

Terrestrial gamma-ray bursts[edit]

I find this article lacking description of terrestrial gamma-ray flashes, described in the article linked as "bursts of gamma rays in the Earth's atmosphere". --Eleassar my talk 10:14, 18 June 2011 (UTC)

These are flashes, not the gamma ray bursts of this article, but are gamma rays produced by bremsstrahlung from high energy electrons produced in lightning discharges. See the article on gamma ray 17:05, 22 June 2011 (UTC)

Mystery of gamma-ray bursts solved[edit]

http://www.nasa.gov/mission_pages/swift/bursts/short_burst_oct5.html — Preceding unsigned comment added by 82.230.229.84 (talk) 22:30, 9 October 2011 (UTC)

What is it "Afterglow" ?[edit]

It is not good.

You resend [redirect] Afterglow (gamma-ray burst) to "Gamma-ray burst ", but do not say what is an afterglow [in this article]. The only page what deer [that define] of afterglow is page over the light of the morning and of the abend. The light of mornig or abend is not due to the Gamma-ray Burst but to the Sun whith is sub horizon. No rapport [understand].

In this page over Gamma-ray burst you deer [use] often "afterglow" but one never say what is it : I suggest you fay [give] a page in whith you explain what is it afterglow post Gamma-ray burst, and meet a lien [link] to this.

Apophyse [apology] my bad english, it is because I am not english.

--Jean-François Clet (talk) 11:51, 4 February 2012 (UTC)

I put in a few English words into your message to make it more clear. Yes, afterglow is an article about solar afterglow. The word when linked once in this article is pipe-linked back to gamma-ray burst, which isn't good (so I'll remove that link, which isn't helpful). The term afterglow (gamma-ray burst) (which may be used in other articles) should continue to redirect to this article because this article DOES define the gamma-burst type afterglow in two places (so a separate one is not needed at this time). One place is breifly in the lead paragraph, and in detail later. To show the latter definition better, I've added a subheading "afterglow" to set it off. SBHarris 20:35, 4 February 2012 (UTC)

Reference 87[edit]

It is my first time trying to help out Wikipedia, so forgive me if this is the wrong approach. I found the second and third items under "Potential effect in relation to Deinococcus radiodurans" to be worth investigating, but Note 87 seems to be a dead end. It refers to "Galante and Horvath", which does not appear in the References section. There is a reference for Horvath, but the term "Galante" appears once on the page. Also, the Horvath reference does not appear to contain information related to the text the Note 87 is associated with. — Preceding unsigned comment added by Stepnrazor (talkcontribs) 04:19, 5 February 2012 (UTC)

It's a bad reference, worthy of deletion. I'm going to replace it with a [citation needed].SBHarris 00:40, 6 February 2012 (UTC)

one GRB per galaxy[edit]

GRB's are seen about once per day.
About half of all GRB's have redshifts less than 2.
The universe is 13.75 billion years old so the light with redshift 2 has traveled 6.875 billion years.
the exact distance light has traveled in that time is hard to determine but since the universe has only doubled in that time we can say for certain that its less than 13.75 billion light years.
If the rate at which GRB's occurs has remained constant then light from a total of 6.875x10^9 * 365/2 GRB's has reached earth since 6.875 billion years ago.
That means that 1,254,687,500,000 have occurred within a volume of space of 4/3 * pi * (13.75x10^9)^3.
Thats about 10^31 cubic light years.
Thats one GRB per 8x10^18 cubic light years.
Thats a cube of space about 2,000,000 light years across.
That means that there is one GRB per galaxy in the universe.
Just granpa (talk) 05:17, 3 April 2012 (UTC)

That's all very well, but light from a cosmological source at redshift z=2 has been traveling since the Universe was 1/(1+z) or 1/3 its current age, assuming uniform expansion, not 1/2. Also, the observable Universe doesn't have a radius of 13.75Glyr, it's bigger than that. See: [[9]] 131.251.254.220 (talk) 15:43, 23 January 2013 (UTC)

Section: "Extraterrestrial intelligence hypothesis"[edit]

This section is entirely unscientific speculation, and barely even makes a coherent link between the speculative and the implication it is making about GRBs. Suggest deletion. Thoughts?86.0.198.250 (talk) 14:10, 9 May 2012 (UTC)

Done. --Cryptic C62 · Talk 15:08, 9 May 2012 (UTC)

Since you've deleted that section, it's hard - of course - to tell whether your choice had merits. Since this article links to a paper by John A. Ball (of MIT Haystack Observatory), maybe we can include his hypothesis here. Kortoso (talk) 22:02, 3 July 2013 (UTC)

Not hard at all. Here is the revision of the article that existed just before I deleted the section in question. Have a look for yourself. --Cryptic C62 · Talk 00:40, 6 July 2013 (UTC)
Thanks; that clears it up for me. The original was speculating about gamma ray bursts as alien communication. Kortoso (talk) 00:04, 10 July 2013 (UTC)