Talk:Gravitational singularity

message: This really is a small enough thing, and does not touch on the science, nor do I propose any change of meaning.  I suggest changing the following sentence's structure, just to make it a little bit clearer and readily understandable to the average (or maybe a bit below average) reader:
"Gravitational singularities are mainly considered in the context of general relativity, where density apparently becomes infinite at the center of a black hole, and within astrophysics and cosmology as the earliest state of the universe during the Big Bang."
This sentence is fine, really, and correct, but I believe that the following edit makes the full meaning more clear for even more readers:
"Gravitational singularities are mainly considered in the context of general relativity, where density apparently becomes infinite at the center of a black hole; and within astrophysics and cosmology, gravitational singularities are considered as the earliest state of the universe during the Big Bang."
If the person(s) with the proper authority and permissions agree, then please do make the change.  I offer this as a helpful suggestion, but I myself will not likely be back to the page at any predictable point in time and won't be monitoring any discussion that might take place.  I don't expect it to be controversial, unless I myself have misunderstood what the original sentence means.  Of course, if the sentence is subject to basic misunderstanding, that probably indicates a need for *some* edit, anyway.  *smile*  I'm glad I could help, in either case.
134.48.167.232 (talk) 07:43, 25 October 2020 (UTC)
thread_title: Suggestion for clarity in one sentence of the very first section; that section is not editable (for me, anyway)

message: Need a little more clarification for laymen: there's a bound for the amount of information in a finite region of space (Bekenstein bound, which depends on the amount of energy-mass in that region. Does it mean if there's an infinite amount of energy in a region of space then there's an infinite amount of information? Should there be an upper bound for energy-mass if Pauli exclusion principle really holds true? Also, if that's the case then singularity is ruled out?Mastertek (talk) 14:52, 23 October 2011 (UTC)
thread_title: Energy-mass limit in given finite space

message: I read this article and it is rather good although it may aquire some cleaning up. However, I did not see any mention of Naked Singularities. Would that be in a different article, is there anything about naked singularities on Wikipedia, or should I add a section on naked singularities to this article? Cheers!--The Relentless Rogue 02:32, 7 December 2006 (UTC)
thread_title: Naked Singularities

message: I have read through this article twice and there is no mention of time dilation or the ability to use a singularity - especially naked singularities - to harness energy. I think that this article needs to be completely rewritten by an expert.
194.80.112.40 10:31, 19 February 2007 (UTC)
replies: text: Time dilation is irrelevant to the topic. The ability to extract energy from a black hole has to do with physics outside the event horizon, and has no connection with the question whether there is a singularity at the center of a black hole.  — Preceding unsigned comment added by Cherlin (talk • contribs) 04:29, 6 September 2011 (UTC)
thread_title: Time Dilation

message: The article says "singularities can exist even if the curvature of space-time is finite everywhere.". Surely singularities do not exist by definition, since they have have no dimensions?  ----
Singularities exists because they have a verifiable, predictable effect on the stuff that is included in reality.  The effects of singularites have been observed many times. They may even have dimensions that are definable in another dimension than the three space and one time we are more familiar with in everyday observations..
:You two are talking about completely different things. Coordinate singularities like the North Pole and the South Pole exist at points of finite curvature. The other kind, the point mass with infinite density in a region of infinite curvature, simply does not exist, and has not been observed. Nor have any such effects been observed. If we had observational evidence of singularities, physics would be completely different from what it is today.--Cherlin 10:17, 19 October 2006 (UTC)
thread_title: Singularity existence

message: So, is this article about 'gravitational singularity' or 'spatial singularity' (as the intro puts it)? Ben Finn 11:54, 25 August 2006 (UTC)
replies: text: People get confused (look around this discussion page), so we have to make the distinction.--Cherlin 10:17, 19 October 2006 (UTC)
thread_title: Intro

message: If we have established that the singularity exists, have we established if it still exists or that it just existed? Any ideas on the arguements or counterarguements for this topic or where the arguements are at right now? (Simonapro 14:59, 29 August 2006 (UTC)
replies: text: We haven't, because it doesn't. Suppose you could put three solar masses at a mathematical point. Then the uncertainty principle says that its momentum is infinite. At this point the whole thing explodes. Now you might think that this is impossible, because neither particles nor photons can escape from a black hole. But that assumes the constant gravitational field of an unmoving black hole. What we are talking about here is all of the particles escaping at the same time in a spherical shell, leaving nothing at the center. The gravitational force inside the shell is zero everywhere, by a theorem of Isaac Newton.--Cherlin 10:17, 19 October 2006 (UTC)
thread_title:  Singularity exists or singularity existed? 

message: The answer to most of the questions above is "No". Black holes don't get entangled; they merge. There is no evidence of actual singularities in the cores of black holes or at the time of the Big Bang. The mathematical complications requested above shed no light on the physics, and I won't do them. I'll probably add some references, including one for a detailed discussion of coordinate singularities, when I get home and can get them off the shelf. [Sorry, I didn't] I look forward to the Exact Solutions page. If somebody wants to add stuff on the quantum foam catastrophe in early quantum gravity theories, I'll applaud.
Cherlin 2006 August 30
:Are you saying that the Big Bang is flawed? If so, how do you explain (1)The age of the Universe according to WMAP and (2)The second law of thermodynamics with regards to a static infinite universe. If you are saying the Big Bang is not flawed, what was before the bang? (Simonapro 19:42, 3 September 2006 (UTC)
replies: text: Excellent questions. The Big Bang theory is apparently accurate after the presumed first 10^{-44} sec or so. I am saying that we know nothing about the earlier interval from our current understanding of physics. I don't believe that there was a singularity before that. There are several theories of how a small region of spacetime could inflate into a universe. One of them is called "false vacuum". In some versions, the false vacuum region would create new inflationary bubbles with great frequency. This is one of several theories predicting that there are a multitude of what we currently think of as "universes". Probably there should be a page on several of these issues.--Cherlin 10:17, 19 October 2006 (UTC)
thread_title:  I did an overhaul 

message: Hi there. Seems like this article's in a bit of a mess.  First of all, although entitled gravitational singularity, it starts by describing singularities in physics in general (quite well too), before finally getting onto its title subject.  The formatting then breaks down such that sections and subsections aren't properly identified and separated.  Finally, it ramblingly concludes with poorly formatted "notes" and a reading recommendation.  My suggestion would be to create a new article, Singularity (physics), for the material at the head of the current article, then to tidy up the remainder so that its formatting is consistent with Wikipedia standards.  For an article that appears in a template bar on GR, it's really quite ugly at the moment.  Cheers, --Plumbago 16:09, 29 September 2006 (UTC)
replies: text: I put in the singularities in physics in general because I don't think you can make sense of this problem without a more general understanding of the ways physics has dealt with mathematical singularities in the past. We could certainly rearrange things.--Cherlin 10:17, 19 October 2006 (UTC)
thread_title:  Jumble 

message: I am not a physicist, so maybe this is a dumb question.  But the section on "Interpretation refers to "the ball of mass of some quantity."  What the heck is that?  A quantity of what?  What is a "ball of mass", some kind of round mass like a planet or a star? Mcswell (talk) 04:06, 20 June 2016 (UTC)
thread_title:  Huh? 

message: There's one thing I've never understood about black holes. It was explained to me years ago that as matter approaches the 'event horizon' (Schwartzschild radius or whatever you prefer to call it), time is distorted in the same manner that space is, and in fact for a particle exactly at the event horizon, time no longer passes as seen from this universe. There's a certain syncronicity to that explanation that makes me believe it's true. If so, then how does matter ever actually ENTER a black hole? It seems like it would take infinitely long for a particle to fall into a black hole, even as it continues being accelerated by the immense gravity (since of course space is distorted as well.)  Even as the black hole is being formed, the density near the center would increase infinitely slowly, and I would think that no event horizon could ever actually form. The density would increase continuously, and would approach arbitrarily closely to the density necessary to form an event horizon, but never actually achieve or exceed that density. An observed black hole, then, would be nothing more than a collection of particles that are exceedingly close to, but not quite, dense enough to form a singularity. It truth there can be no event horizon in our universe for the simple reason that it would take literally infinitely long to form.
Crackpot enough of a theory?  Middlenamefrank 21:37, 27 October 2006 (UTC)
replies: text: I think the fact that Zeno's paradox seems to be superceded by some force in the universe of motion would apply here too, and it would form regardless for the same reason that Zeno's paradox does not restrict movement, it would not restrict time here either. 66.243.213.232 (talk) 22:08, 4 September 2011 (UTC)
thread_title:  A question for the cosmologists 

message: "In the Stargate SG-1 episode 200, in a parody scene, it is mentioned that a singularity is about to explode. One of the characters even points out that this is impossible. This is used to great effect as a nod to scientific errors made in science fiction."
I thought Steven Hawking proved that singularities [i]could[/i] explode.
:They don't explode, they (may) evaporate due to Hawking radiation - Fosnez 03:08, 24 July 2007 (UTC)
replies: text: Depends on semantics. The end-phase evaporation of a singularity would be very rapid and emit alot of radiation. One could say that this is an explosion. 70.55.203.112 (talk) 10:01, 25 September 2008 (UTC)

text: It is impossible because it would require whatever is inside to travel backwards through time, what we consider the radius as a direction through space in external coordinates becomes "the past" in internal coordinates. George Dishman (talk) 14:23, 24 February 2023 (UTC)
thread_title:  SG-1 Reference 

message: Assuming that the smallest physically meaningful unit of distance/space is the Planck length, or to put it another way, that the universe is composed of Planck-length time-space "units", what is the theoretical minimum density of a black hole mass compressed into this unit volume? Likewise, on the other end of the scale, what would be the density of the primordial Big Bang singularity, assuming current estimates of the mass of the observable universe? In other words, can we put numbers on the possible range of singularity densities, assuming that a singularity is not actually infinitely small? — Loadmaster 18:39, 2 October 2007 (UTC)
thread_title:  Infinitely small vs. Planck scale 

message: Would a gravitational singularity be the same as a spacial singularity (even just in certain terms)? I've also heard of the condition giving rise to the big bang construed as a "singularity in time" or a "time singularity" (though conceivably, and technically understood as, spacial as well I presume). Could there be an article on a "time singularity" as it would be theoretically understood? How would this relate to the quantum foam as the condition prior to the big bang? The quantum foam article does not delve into what I've observed to be speculated as the quantum foam state of the imminently-prior-to-big-bang condition. 66.243.213.232 (talk) 21:56, 4 September 2011 (UTC)
thread_title:  space singularity versus time singularity 

message: The contents of a black hole should be ultra relativistic. If the pressure P of ultra relativistic material is (rho)c2/3, the total thermal or viral energy of this star would be ∫PdV = (Mc2)/3, meaning a whopping 1/3 of the mass energy of the star would be used just to oppose the force of gravity. The star radius should be calculable using the viral equation. The best information I have is the gravitational potential energy of ultra relativistic material is very slightly higher than the Newtonian value, or about (1.1 GM2)/R.  Using the viral equation (thermal energy equals half the gravitational potential energy) gives a star radius  of about R = (1.65GM)/c2, or 0.82 times the Schwarzchild radius. A 0.82 Schwarzchild radius star would contain light. For this ultra-relativistic star both surface gravitational acceleration and core pressure decrease as size increases. It does not collapse.
Observational evidence of significant star radius in a black hole: Black holes have measurable spin. If a 5 solar mass object of 12 kilometers radius spins at 1000 revolutions per second, the equatorial velocity is a significant fraction of the speed of light. If a 5 solar mass object of 1 centimeter radius spins at 1000 revolutions per second, angular momentum is isn't conserved. 172.163.36.231 (talk) 00:34, 30 December 2012 (UTC)
replies: text: Debating the physics behind (or the validity of) the subject matter of the article does not belong on this talk page. Do not expect to get a response to your argument here. — Quondum 08:20, 6 January 2013 (UTC)
thread_title:  Arguements against a point singularity and infinite density 

message: Please mention all views and enrich the article. By the way, there are no "singularities" in nature, but simply a "degenerate particle". Read what "degenerate matter" is, if "degenerate matter" gets more compressed, it simply becomes a quasi-fundamental indivisible particle. Due to the "holographic principle", the "black hole degenerate particle" is "ALMOST" (I said "almost" and it is hyper-extremely important so keep it in mind) a point, but never an actual one due to the "uncertainty principle" (no uncertainty = no existence). The "holographic chromodynamic data" always demand some "range of uncertainty" to be described, matter that enters faster than it can be absorbed by the black hole jets out at almost luminal (light-speed) speeds.  — Preceding unsigned comment added by 2A02:587:410A:4200:7907:4615:761E:BA72 (talk) 17:00, 3 February 2016 (UTC)
thread_title:  not all mentioned here, German and US Universities teach alternative theories also 

message: I have no idea if this is the right place for this comment, and I have no idea how to remove a GIF, but there is currently a GIF here so distracting it makes the article nearly impossible to read.  Will someone please remove it?  — Preceding unsigned comment added by Rickmoede (talk • contribs) 18:12, 8 August 2016 (UTC)
thread_title:  Extremely Distracting GIF Must Go 

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thread_title:  External links modified 

message: I changed the opening sentence to include simply singularity since this is how they are usually referred to... A gravitational singularity, spacetime singularity or simply singularity is a location in spacetime where the gravitational field of a celestial body becomes infinite in a way that does not depend on the coordinate system. 73.85.206.211 (talk) 20:55, 15 January 2019 (UTC)
thread_title:  Gravitational Singularity, Spacetime Singularity or simply Singularity  

message: The section on black hole entropy confuses Hawking radiation with black hole entropy and black hole thermodynamics. It says the idea of black hole entropy was ignored before Hawking came up with Hawking radiation. This is false; Bekenstein, Hawking, and others had spent a lot of time thinking and writing about black hole thermodynamics and concluded that black holes had quantities that behaved like entropy and temperature, but it wasn't known if these were the same as entropy and temperature from "ordinary" thermodynamics. The idea that black holes had entropy was driven by the idea that if they didn't, they could be used to violate the second law of thermodynamics, and Hawking's thinking about black hole radiation was driven by that, not the other way around.
The best thing to do is probably to turn this section into a summary of the Black hole thermodynamics page and link to that as the main article. That article should probably also have its history section expanded a bit. I may do it when I have some more time and focus available. -Sean r lynch (talk) 23:38, 26 August 2019 (UTC)
thread_title:  Entropy 

message: "Since such quantities become infinite within the singularity, the laws of normal spacetime break down." - 73.85.203.44 (talk) 14:15, 23 November 2019 (UTC)
thread_title:  Re: Singularities, the laws of physics break down 

message: What is the targeted educational level for proper comprehension of these and similar articles? G12, undergraduate, graduate? How does this effect accessibility, and how can it be enlarged? Oceanic84 (talk) 20:59, 11 February 2021 (UTC)
thread_title:  Targeted comprehension level 

message: I'm far from an expert in this field, but I suspect the sentence
"A conical singularity occurs when there is a point where the limit of every diffeomorphism invariant quantity is finite, in which case spacetime is not smooth at the point of the limit itself. "
in the conical singularity section of the article is a typo. Surely at a non-singular point, the limit of every diffeomorphism-invariant quantity is finite, so why should this indicate the existence of a singularity?
I suspect the sentence should read something like
"A conical singularity occurs when there is a point where the limit of some diffeomorphism invariant quantity is infinite, in which case spacetime is not smooth at the point of the limit itself. "
Or possibly
"A conical singularity occurs when there is a point where the limit of some diffeomorphism invariant quantity does not exist, in which case spacetime is not smooth at that point.",
but I'd be more comfortable if someone who understands this better than I made the edit. Andylatto (talk) 17:03, 21 October 2021 (UTC)
replies: text: It looks ok at it is. The metric can be finite everywhere the coordinate system is used, so all these limits exist and are finite. - DVdm (talk) 21:47, 10 February 2022 (UTC)
thread_title:  Typo in conical singularity section? 

message: The problem of singularities has been solved. See article Quantum gravity, § 5. 178.120.19.87 (talk) 14:46, 16 April 2024 (UTC)
thread_title:  The problem of singularities has been solved.