Talk:Gravitational singularity

Suggestion for clarity in one sentence of the very first section; that section is not editable (for me, anyway)

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)

Energy-mass limit in given finite space

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)

Source

Gravity, by Thorne, Misner, and Wheeler

Naked Singularities

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)

The section on naked singularities (regarding the numerical simulations of Shapiro and Teukolsky) is very misleading - it seems to imply there is numerical evidence for naked singularities. However, shortly after their results, Robert Wald and Vivek Iyer showed that their findings were misinterpreted - that there was nothing out of the ordinary in the simulations. The name of the Wald-Iyer article is "Trapped surfaces in Schwarzschild geometry and cosmic censorship", 1991 in Phys. Review D. I am in favor of removing the reference to the Shapiro-Teulolsky simulations. Jjauregui (talk) 18:51, 3 March 2008 (UTC)

Time Dilation

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)

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)

Difference

The article doesn't explain what distinguishes a gravitational singularity from a mathematical singularity in GR equations. I put "sometimes" but someone took it away.

Here's the diff: mathematical singularities don't *always* means gravitational singularities because they can be artifacts of the coordinate system used.

I think, that there is practically, no difference between mathematical and geometrical singularity(ies). In fact, the latter is a practical phenonmenon of theoretical former.. --Krishnavedala 05:40, May 22, 2005 (UTC)

It seems that someone has been messing with the source, and data was lost. As for me the word "Hello" is rathewr unrelated to gravitational singularity ;). Please fix it...

Regards, Adam Hepner (not yet registered wikipedian)

The Gravity book, referenced at the top of this discussion, explains the differences between coordinate singularities, such as the North and South Poles, and real singularities, at length.

Gravitational singularities and entanglement?

Is it posssible that a pair of gravitational singularities can be entangled in a similarly to how electrons can be entangled?

If they cannot be entangled then can you explain why this concept doesnt work as I am curious to develop this idea?

Delving on the occult there dude ... . ---Mpatel (talk) 14:05, August 21, 2005 (UTC)

1. There are no gravitational singularities.

2. Black holes are not particles. They have the mass of several suns in the space of a proton at most.

This article Desperately needs complete overhaul

Need to clearly distinguish between geometric and coordinate singularities.

Among latter (aka gravitational singularities, although terminology nonstandard), need to point out that in exact colliding wave solutions, typically you have fold singularities which are geometric (not coordinate artefacts) but are not curvature singularities either.

I think should merge out some material into a new article on Curvature singularity, which should introduce some standard classifications:

• scalar versus nonscalar
• strong versus weak
• spacelike versus timelike versus null (doesn't apply to all curvature singularities)

Both article should link to appropriate examples illustrating these in the Category:Exact solutions in general relativity, which I need to populate myself.---00:04, 15 September 2005 (UTC)

From the first sentence too. You don't need matter, first of all -- vacuum solutions in GR have curvature singularities (eg the Kasner universe). Secondly, beyond the fact that volume is not a relativistically invariant quantity, it doesn't need to go to zero in a singularity, for example in a Big rip. Finally the curvature need not diverge either, as pointed out for the folds in wave collisions.

That said, I'm not sure what a better alternative would be. Maybe something along the lines of A gravitational singularity is a feature of a spacetime, so that the histories of obeserves that encounter it appear to end.? Sounds bad even to me. Any other suggestions? Wesino 15:43, 25 November 2006 (UTC)

Singularity existence

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)

First, The Schwarzchild solution that this discussion is based on is only valid in empty space. At some point you get to the matter even if it is squeezed to a point. There you cannot calculate curvatures invariants, etc., because you do not know what the solution is anymore, T!=0. Second, cannot extend TOV equation or any other equation of state-based solution because the equation of state is completely unknown at r=0 densities. Third, using T=0 anywhere near an event horizon is dubious because the extent of the matter is not known.Bscip (talk) 20:33, 28 April 2019 (UTC)

Intro

So, is this article about 'gravitational singularity' or 'spatial singularity' (as the intro puts it)? Ben Finn 11:54, 25 August 2006 (UTC)

People get confused (look around this discussion page), so we have to make the distinction.--Cherlin 10:17, 19 October 2006 (UTC)

Singularity exists or singularity existed?

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))

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)

I did an overhaul

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))

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)

Jumble

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)

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)

I have to weigh in on Plumbago's side. I like the discussion of various crises in physics, but I think they belong in their own article. It's not made clear what features they share with gravitational singularities, and I would argue that in fact there are no essential similarities (beyond "something becomes infinite"). I don't want to offend anyone, but here are the issues I see with this first section --

The examples have more to do with infinities than they do with singularities. Olber's paradox, the ultraviolet catastrophe, and the electron self-energy issue all result from adding up an infinite number of contributions, resulting in infinity, in a sense similar to a infinite series that doesn't converge. In these examples, there's a quantity that you compute at any point in space (total light from stars, energy density in blackbody radiation, energy in electron field) and it's infinity, everywhere. This isn't at all the same as the singularity in a black hole, for example, which is localized.

The only example that comes close, I think, is the electron one. Here you get one singularity comes from the fact that the potential energy of the electron-nucleus system would be infinite when the electron radiates away all of its energy and ends up in the nucleus (with everything considered as a point). You also get an infinite radiated energy. But the fact that point charges have infinite potential energy when they're sitting on top of each other is just regular, 19th-century electromagnetism and has nothing to do with quantum mechanics. Also the connection with gravity isn't clear.

There are also a few factual errors in the paragraph -- for one, the Pauli exclusion principle doesn't have anything to do with preventing the inspiral of electrons. It's true that it's related to electrons and atoms, which are also discussed in the paragraph, but the reason you don't get electrons spiraling in rapidly is not because of Pauli blocking. Secondly, you can "confine an electron in the space of a nucleus," or in any other finite region; you just get higher energy states for the electron (see square well). Finally, electrons do spiral into the nucleus in a manner perfectly consistent with quantum mechanics -- see electron capture.

The goal of making analogies to help the reader understand a gravitational singularity is admirable. But as it is, the intro paragraph talks about other historical problems in physics, then moves on to discuss things that aren't singularities (like problems with coordinate patches), and then concludes with talking about experimental tests of string theory. At this point, the reader's information about a gravitational singularity is still limited to the one-sentence intro at the top of the page.

So how about breaking this bit out onto another page, as Plumbago suggests? Wesino 15:35, 25 November 2006 (UTC)

Huh?

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)

Belief

I am still reluctant to believe that singularities exist, because of the zero demision problem. I am a theorist, it is hard for me to swollow things I can't see or imagine. maybe someone could point me in the right direction.-MJH 20:39, 8 October 2006 (UTC) Other theorists have problems with zero dimentions. Someone typed that a black hole singularity is smaller than a proton. Even at this size I see a major traffic jam of matter trying to enter the singularity. Matter would spiral toward the sigularity, minutely slower than the speed of light; it would miss by a few nanometers and collide with other particles trying to enter the singlarity: Failing to collide it would do a sling shot manuver which would carry it back to event horizon where it would turn around for another unsuccessful try at entering the singularity. Ccpoodle (talk) 18:04, 5 May 2008 (UTC)

If the Universe was limited by what we can imagine or see, there wouldn't be a Universe at all.

The article argues that there are no singularities in physics, no matter what the math says.--Cherlin 10:17, 19 October 2006 (UTC)

The article says General Relativity shows both coordinate singularities in metrics, and absolute singularities wherever a point mass turns up in the equations, usually in considering the evolution of a Black Hole. Changing to a different metric disposes of coordinate singularities. Getting rid of the infinite density, infinite force of gravity, and infinite curvature of space around a point mass requires changes in known physics. (Simonapro 12:08, 24 October 2006 (UTC))

I agree with Ccpoodle, about the zero dimension problem. Or even if a singularity has zero volume, how can we calculate the density? Density is defined as Mass/Volume, and attempting to solve with a Volume of zero results in division by zero, which is undefined. Tolkien fan (talk) 14:53, 1 July 2008 (UTC)

I think much confusion is caused by a misuse of terms. Space is first an abstract concept; things take up space, there is space between points and around them. But when discussing topics in Relativity, people tend to use the word space to mean spaces that have been measured. In relativity we often say "space" contracts, which is not meaningful using the first definition. Instead we should say that the thing we were using to measure spaces with contracted. Similarly with time. Things take time to happen. We measure the time something takes against something else. That's how measurements work; they are comparisons. Something can slow down or speed up. Often we say "time" slowed down, which has to refer to the thing we were measuring with, as that is the only physical option. In general relativity we say gravity curves spacetime, meaning the thing we were using to measure spaces and times with has curved. This is like saying the thing we are using to measure spaces and times with has curved. So a gravitational singularity isn't when Euclidean/Newtonian space and the concept of time curves into a paradox, it is when the thing we are using to measure those spaces and times ceases to be useful for making those measurements.

I have added a short paragraph to the introduction hoping to clear up this subtle difference. In case it becomes necessary later, here is one place these definitions are discussed. — Preceding unsigned comment added by 74.179.164.249 (talk) 22:22, 9 April 2014 (UTC)

Please sign your talk page messages with four tildes (~~~~). Thanks.

I have removed the paragraph per wp:UNSOURCED. - DVdm (talk) 13:16, 10 April 2014 (UTC)

Good to hear voices that don't run with the herd. I think a finite sized star larger than the Schwarzchild radius resides in a black hole. Containing light or ultra relativistic material is not that difficult, a 2 solar mass neutron star almost does it. A point singularity is a simplistic explanation to explain a black hole and an inflationary universe. Unfortunately many millions of dollars or prize money and awards have been given out based on a point singularity and it will be hard to open people's minds. There is an establishment that supports a point singularity. Phrases like "the golden age" of black hole theory indicate the situation.72.69.11.171 (talk) 14:36, 23 July 2014 (UTC)BG

There might be a way to measure if a singularity exists in a black hole. When matter falls into a black hole, wouldn’t infalling matter emit radiation or jets differently if the black hole contained a finite sized star instead of a point singularity? A black hole star of 3GM/(c^^2) radius should contain light, but not as effectively as a Schwarzchild radius star or point singularity. There could be formulas for the radiation ejected from a black hole based on internal star radius.72.69.11.171 (talk) 02:06, 28 July 2014 (UTC)BG

Scientists are aware that mathematical infinities are unlikely to represent reality. What maths describes as an infinitely small, infinitely dense point, is more likely to be "very very small" and "very very dense". Infinities however are a very useful mathematical tool, and as much as the general public hates to believe it, mathematical tools are very powerful things for exploring the world around us. So if a theory involves infinities, this is not a sign that the science behind it needs to be completely re-worked.178.15.151.163 (talk) 10:08, 4 February 2016 (UTC)

A question for the cosmologists

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)

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)

Maybe but from another point of view how about this: A Black Hole consists of whatever material produces gravity (call it matter if you like) which has managed to exclude through the effect of gravity both energy and space (or distance when you break down the speed of light as a distance traveled over time). A Black Hole is then from this perspective the composite manfestation of absolutes, i.e., absolute temperature (zero) absolute energy (also zero owing to absolute zero temperature requiring absolute zero energy) and absolute time meaning that when you cross the event horizon you are no longer traveling - you are already there - all points within the event horizon are reached simultaneously when time within the event horizon is infinite and distance zero. Adaptron 12:31, 3 November 2006 (UTC)

I think it works like this. From the outside observer it appears to never enter. Its not time that slows, its the speed of the light moving away from the black hole. The photons at the very edge of the event horizon leave the object with a very slow speed and, therefore, take a long time to reach the observer. The object that enters the event horizon notices no difference in the flow of time. So, to an outside observer the object appears to be moving slower and slower as it approaches the black hole. (and I would imagine would be red-shifted because of a longer wavelength, eventually leaving the visual light spectrum and actually becoming invisible to the human eye) 66.142.246.134 23:21, 4 January 2007 (UTC)

Myself, I have wandered through the same problem, but MORE importantly than the question of Event Horizon, the question should be maintained to the actual singularity: There does not exist a single singularity in the current time in our universe because the particles which are in their way to form the singularities of any given black hole are accelerating to infinite through time. For an outside observer, if he "could" watch the black hole through the event horizon, he would see an "almost" complete singularity, but not quite, and its particles would be seen almost stopped. To this outside observer, the moment the black hole would reach singularity would reside in an infinite point in time axis. To an inside viewer, though, if he could turn his "head" towards the outside of the hole, he would see a decreasing viewing disk of incoming matter and light, and he would see, in a finite span of time, the whole time span of the universe till the infinite reach his eyes as he reaches the singularity. He would have reached a point in the universe where space and time would be over, in a finite amount of time.

Have I written this clearly, or does it all sound BS? I really believe this should be the case. Anyone? 195.23.224.61 12:13, 23 February 2007 (UTC)

SG-1 Reference

"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)

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)

Why is it impossible? —Preceding unsigned comment added by 81.178.39.81 (talk) 16:03, 7 September 2010 (UTC)

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)

A better question is "Why is it possible?" 178.15.151.163 (talk) 10:04, 4 February 2016 (UTC)

Infinitely small vs. Planck scale

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)

Who claims that a distance of the Planck-length is the smallest physically meaningful unit of space ? If energy is high enough you might be able to explore sub-Planck-scales, aren't you? Secondly I don't understand your reformulated question. minimum density of a black hole mass compressed into this unit volume ? There is an one-to-one mapping of the mass of a black hole to its volume (preciser to the volume encapsulated by its event horizon), if we neglect charge and angular momentum of a black hole. And of course you can easily compute the mass of a black hole whose event horizon has a radius of the Planck length. And the mass density of a black hole is strictly decreasing by a 3rd power on its mass (event horizon radius is a linear function of its mass).

Moreover I like to know whether my added section of "Uncertainty principle" should be renamed "Compton wavelength of a black hole" and should be better (or also) be put into the article considering black holes? Thanks in advance. —Preceding unsigned comment added by Achim1999 (talk • contribs) 16:14, 17 June 2009 (UTC)

space singularity versus time singularity

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)

Did the universe start with a singularity?

The article states: "According to general relativity, the initial state of the universe, at the beginning of the Big Bang, was a singularity." However, I maintain that if people extrapolate backward in time far enough they reach not a singularity, but a point at which our knowledge of the laws of physics does not indicate what the previous state would be. Claiming that there must have been a singularity at the beginning or even that there must have been a beginning seems more like superstition than science. Who has ever seen such a singularity? I have called for a citation. - Fartherred (talk) 03:17, 3 October 2012 (UTC)

Compare the article to what NASA publishes here. "It [the Big Bang Model] postulates that 12 to 14 billion years ago, the portion of the universe we can see today was only a few millimeters across." That is just a theory, but one I respect. The claim that the universe started with a singularity has no observational basis. - Fartherred (talk) 03:37, 3 October 2012 (UTC)

Roger Penrose mentions "comprehensive theorems" that certain conditions are necessarily associated with a singularity under the mathematics of general relativity. The Big Bang is presumably one of them. This does not mean that the big bang started with a singularity in reality: these are conditions in which general relativity is known to be inaccurate (the quantum realm). But, aside from the lack of citation, the statement is presumably correct. — Quondum 14:44, 3 October 2012 (UTC)

Are you sure that a singularity is indicated by general relativity as a general case and not just a particular formulation that describes the big bang? As far as taking the trajectories of distant galaxies and extrapolating them backwards, we do not know the trajecctories well enough to be sure that they would meet in a point. The universe might have net angular momentum and the extrapolation, if based on accurate enough information would reveal a rotating universe as the original maximum density state.

From what you write, it seems that the beginning from a singularity is a mathematical convenience that does not necessarily describe the universe. The big bang generation of protons and electrons from all energy is in theory accompanied by anti-protons and positrons, which we see in smaller numbers than would be indicated by theory. General relativity and some descriptions called Big Bang might include a singularity in the mathematics but just mentioning that without indicating the apparent departures from reality seems to give a false impression of scientific knowledge about the early state of the universe. Not long ago acceleration of the rate of expansion was first discovered. If there could be a little acceleration, why not more, earlier. It seems to me that this talk of a singularity at the start of the universe is taken much to seriously for the shaky ground it stands on. - Fartherred (talk) 20:01, 4 October 2012 (UTC)

Well the singularity in the general relativity treatment of the Big Bang theory seems well enough known to not require a citation. It is referred to in the reference in Crux007's edit of 4 October. Whether these theories describe the real world or not is something that could be discussed in the article if reliable sources are found discussing that. I will remove the call for citation that I added. - Fartherred (talk) 00:56, 5 October 2012 (UTC)

Yes, my impression is that the general conclusion is that general relativity itself is considered incomplete, rather than that there may be solutions to the unmodified general relativity that could escape singularities. I've just noticed the link to Penrose–Hawking singularity theorems. I see that article indicates that inflation complicates the picture. — Quondum 02:29, 5 October 2012 (UTC)

Thanks for the referral to [[Penrose–Hawking singularity theorems]] which in turn led to A Brief History of Time in which Stephen Hawking gives a negative evaluation of the likelihood of a singularity at the beginning of time. This seems like something which probably belongs in the article, but I have not even gotten the book yet to evaluate the meaning of the reference. I will not be slighted if someone else puts a mention in the article before me. I have too much to do anyway. - Fartherred (talk) 02:22, 22 October 2012 (UTC)

"According to general relativity, the initial state of the universe, at the beginning of the Big Bang, was a singularity." Einstein didn't believe in a point singularity and he was presumably knowledgeable about general relativity. 72.69.11.171 (talk) 20:47, 23 July 2014 (UTC)BG

And your point is? —Quondum 22:35, 23 July 2014 (UTC)

If Einstein was alive should he be told to study general relativity more so that he would understand why there is a point singularity?72.69.11.171 (talk) 10:24, 25 July 2014 (UTC)BG

This is off-topic with regard to the editing of of the article. It is known that general relativity cannot be a complete theory of the physical universe (i.e. it must become inaccurate under certain conditions, including at singularities). That we don't have all the answers is no surprise. —Quondum 13:37, 25 July 2014 (UTC) Yes, general relativity is not accurate at singularities if singularities exist. 72.69.11.171 (talk) 17:47, 30 July 2014 (UTC)BG

A singularity would be obtained by extrapolating the scale factor during the radiation-dominated era back in time. The scale factor is proportional to the square root of time so goes to zero at some fiducial t=0. That extrapolation has been invalid since the hypothesis of an era known as inflation gained acceptance in the 1980s. During inflation, the scale factor depended exponentially on time so there is no longer a singularity in the current consensus model and this should be removed from the article. — Preceding unsigned comment added by GeorgeDishman (talk • contribs) 14:29, 24 February 2023 (UTC)

Arguements against a point singularity and infinite density

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) BG

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)

Quondum- I am impressed with the articles on Gravitoelectromagnetism and Einstein field equations you were involved with. If a fraction of the effort on these subjects was applied on what happens inside a black hole a lot might be accomplished. The Tolman-Volkoff equations don't work for a black hole; they even give the wrong results for a neutron star. Maybe we could discuss this somewhere else. 172.162.18.21 (talk) 14:06, 9 January 2013 (UTC)BG

Inside a black hole and at the BIG Bang-Bit Bang, at their centers is a point singularity that reaches infinite density. Thus, the two are connected. 2601:580:10A:946E:6865:7117:AFC7:9D55 (talk) 21:51, 15 January 2019 (UTC)

not all mentioned here, German and US Universities teach alternative theories also

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)

If you are going to make claims like that, please include sources/references, otherwise all must assume it is just BS - this is the internet after all. You claim to know what is happening inside a black hole, a claim I have never heard any other scientist make. 178.15.151.163 (talk) 09:59, 4 February 2016 (UTC)

Extremely Distracting GIF Must Go

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)

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Gravitational Singularity, Spacetime Singularity or simply Singularity

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)

Entropy

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)

This final sentence does not make sense to me. "This will occur at a cosmological redshift of more than one million, rather than the thousand or so since the background radiation formed". One Million what? Gooobster (talk) 21:27, 10 February 2022 (UTC)

Re: Singularities, the laws of physics break down

"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)

Targeted comprehension level

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)

Typo in conical singularity section?

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)

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)

The problem of singularities has been solved.

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