What is Singularity: Definition and 429 Discussions

A gravitational singularity, spacetime singularity or simply singularity is a location in spacetime where the density and gravitational field of a celestial body is predicted to become infinite by general relativity in a way that does not depend on the coordinate system. The quantities used to measure gravitational field strength are the scalar invariant curvatures of spacetime, which includes a measure of the density of matter. Since such quantities become infinite at the singularity point, the laws of normal spacetime break down.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/White Hole. Physicists are undecided whether the prediction of singularities means that they actually exist (or existed at the start of the Big Bang), or that current knowledge is insufficient to describe what happens at such extreme densities.General relativity predicts that any object collapsing beyond a certain point (for stars this is the Schwarzschild radius) would form a black hole, inside which a singularity (covered by an event horizon) would be formed. The Penrose–Hawking singularity theorems define a singularity to have geodesics that cannot be extended in a smooth manner. The termination of such a geodesic is considered to be the singularity.
The initial state of the universe, at the beginning of the Big Bang, is also predicted by modern theories to have been a singularity. In this case, the universe did not collapse into a black hole, because currently-known calculations and density limits for gravitational collapse are usually based upon objects of relatively constant size, such as stars, and do not necessarily apply in the same way to rapidly expanding space such as the Big Bang. Neither general relativity nor quantum mechanics can currently describe the earliest moments of the Big Bang, but in general, quantum mechanics does not permit particles to inhabit a space smaller than their wavelengths.

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  1. M

    I Some questions regarding the initial singularity

    I seem to have missed the opportunity to post my questions on a related thread so I hope this is okay. First, a request. I have read on this forum that ["Singularity" is just shorthand for "the place where the math model breaks down and we don't know WHAT is/was happening".]. Since the wiki...
  2. Aaron1947

    I Why did the singularity expand?

    The singularity before the big bang, was it anything like the singularities in the universe today? Did it have a black hole around it, with an event horizon? And what caused the singularity to expand? Why did it expand when the singularities in our universe don't do anything besides suck stuff in?
  3. V

    I Poisson Equation Neumann boundaries singularity

    I am trying to solve the poisson equation with neumann BC's in a 2D cartesian geometry as part of a Navier-Stokes solver routine and was hoping for some help. I am using a fast Fourier transform in the x direction and a finite difference scheme in the y. This means the poisson equation becomes...
  4. W

    I Why is the density infinite at the singularity?

    I always has the impression that the density of the universe is infinite at the singularity because its just amount of stuff divided by volume and if the distance between stuff is 0 then the volume is 0. So divide by zero and you get infinity. But I have been told by others that dividing by zero...
  5. wolram

    B The big bang singularity and black hole singularity

    In the big bang model the singularity is all ways quoted as being the start of the universe, but AFAIK scientists do not accept the singularity as real, the same with the black hole singularity, what is proposed to be in their place? from Wiki. The initial singularity was the gravitational...
  6. C

    Understanding Singularity Functions and Solving Equations with Assumptions

    Homework Statement http://me.erciyes.edu.tr/mkapalak/MKA-COURSES/STRENGTH-2/EXAMS/STR2-39-2.pdf How can (w/24)( <x-0.5L>^4 )= 0 ? by doing so, the author assume x <0.5L ? so that <x-0.5L> = 0 How do we know that? Homework EquationsThe Attempt at a Solution
  7. W

    I Relations resolves singularity -- new paper on arxiv

    A new paper on arXiv today claims that relationsism allows one to evolve the universe through the big bang. Alas I am not familiar with relationsism, is it related to shape dynamics? can anyone explain? https://arxiv.org/pdf/1607.02460v1.pdf
  8. L

    I Infinite Universe from Dimensionless SIngularity

    A significant number of physicists today postulate that the universe we reside in is infinite in size. It's also thought that if we extrapolate back in time to the big bang that the universe was a singularity of infinite density. Singularities are commonly thought of as a dimensionless point...
  9. Rishi Tharun

    B What Happens to the Singularity Inside a Black Hole When It Evaporates?

    Hello Friends... I just need a help... I want to kno what happens to the Singularity inside the black hole when it evaporates... Help me out[emoji5] [emoji5] [emoji5]
  10. MichaelLujan

    Writing: Input Wanted What would it take to crawl out of a black hole?

    As I understand it, the crux of the issue is: how is information preserved across the event horizon, in this case, the arrangements of subatomic particles, atoms, etc right on up through the individual parts, etc., of the creature in question. That, and the relativistic escape velocity required...
  11. Will Langas

    B Are Larger Black Holes Less Dense Than Smaller Ones?

    What has a higher density? Black Holes or Singularities? I looked online and all I saw was that they both have infinite densities.
  12. Bran

    B Expanding from and eventually to a singularity?

    I know this thread, about why the Universe can't expand inward, is fairly old; but I stumbled across it today and there was something mentioned here that sparked a question I feel like people here would be qualified to answer. What was mentioned, was that a singularity is a point at which our...
  13. T

    B Is the Big Bang a Result of a Spontaneous Singularity?

    It seems I remember hearing (either on tv or mag) that there was a theory that the original singularity which resulted in the big bang could have been created from essentially nothing by ripples or something in the space energy...or something like that. Can anyone point me toward any articles...
  14. O

    A Black Hole Paper Outlining Process of Singularity Formation

    Can someone point me to the seminal (or any other) paper explicitly showing and proving the formation of singularities in black holes? I'd like to learn about the exact physical processes which occur during the collapse of a star into a black hole and how the progress of those physical...
  15. D

    A Instability of Cosmology with Quantum Corrections

    A good year ago, quantum corrections have been proposed to the very early Universe. It was concluded that these quantum corrections contain a precise estimation for the cosmological constant and the so-called radiation term. The authors even have interpreted the latter as evading the big-bang...
  16. Mark Childerley

    Can anyone give me the equation symbol for a singularity please

    I need the symbol that discribes a singularity for a novel I am writing. Can anyone help? Many thanks Mark
  17. B

    Does time stop at the singularity?

    In the schwarzschild metric, inside the event horizon the r coordinate becomes timelike, and when when r=0 the coefficient of dr^2 is also 0. So time stops at the singularity, yet somehow it can move around and emit gravitons, i.e. "evolve" even when it's supposed to be frozen like a video...
  18. wolram

    What are Black Hole Singularities: Physical or Mathematical?

    https://en.wikipedia.org/wiki/Gravitational_singularity The two most important types of spacetime singularities are curvature singularities and conical singularities.[4] Singularities can also be divided according to whether or not they are covered by an event horizon (naked singularities are...
  19. ognik

    MHB What is an irregular singularity and how does it affect Laguerre's equation?

    Hi - I didn't really follow the book on Irregular singularities, so I have an example using Laguerre's eqtn - please use this to explain the concept... In standard form: $ y'' + \frac{1-x}{x}y' + \frac{\lambda}{x}y = 0 $ Clearly there is a normal singularity at x = 0 The book says there is...
  20. Feeble Wonk

    B Can entropy be measured in a singularity of infinite density?

    Please have pity for the idiot in the room. I've tried to look into this concept through a few papers I've found on-line, but the mathematics involved is too far over my head. I'm trying to wrap my head around the general concept of entropy as it applies to a singularity. In a singularity of...
  21. R

    How could the infant universe have existed as a singularity?

    A singularity is a region in which the curvature of space-time becomes infinite. But according to standard big bang models, at the initial point (at which T = 0) the pre-expansion space - as miniscule as it was - was filled uniformly with all energy that ever existed or will exist. But if all...
  22. J

    Singularity Theorems: An Accessible Reference

    I've read Hawking's introduction: http://arxiv.org/abs/hep-th/9409195v1, which are nice. I would like something that explains the other singularity theorems and how they are related to Big Bang. I've tried reading Hawking & Ellis but I can't understand most of the definitions.
  23. J

    Example of curvature scalar diverging at infinity?

    Reading Geroch's "What is a Singularity in General Relativity?", it seems that polynomial scalar invariants constructed from the Riemann tensor can diverge if we are at infinite distance, and not in a true singularity. Can someone give an example of space-time whose scalar invariant diverges...
  24. bcrowell

    Curvature singularity with well-behaved Kretschmann scalar

    Does anyone know of an example, preferably a simple one, that can be used to demonstrate that we can have a curvature singularity without a singularity in the Kretschmann scalar?
  25. N

    Singularity of spacetime/singularity of the riemanian tensor

    Hello, I have a question to the singularities of spacetime (where the metric tensor is infinite, but not the coordinate singularities which can be removed be a change of coordinate) It's easy to show that a singularity of the riemanian tensor scalar RαβμνRαβμν leads to a singularity of the...
  26. Bob Bartlett

    Singularity of atomic particle characteristics.

    At any instant in time, for an atomic particle, are its characteristics singular?
  27. Invutil

    Black Holes: Volume & Forces Explored

    Do black hole singularities have 0 volume? What forces are keeping the particles from being in the same place?
  28. C

    Transitioning from Finite to Infinite Mass in a Black Hole

    So, according to physicsoftheuniverse.com, "In the centre of a black hole is a gravitational singularity, a one-dimensional point which contains infinite mass in an infinitely small space, where gravity become (sic) infinite and space-time curves infinitely, and where the laws of physics as we...
  29. B

    Why is Schwarzschild singularity not real

    It seems to me that the Schwarzschild singularity is generated by the metric function which is an invariant and so has the same value in any coordinate system, so why is it not equally valid?
  30. S

    Find and classify singularity?

    Homework Statement Find and classify the singular point for f(z) = 1/ ( sin z - sin a) Where a is an arbitrary real constant. Homework Equations f(z) = 1/ ( sin z - sin a) Where a is an arbitrary real constant. The Attempt at a Solution There will be infinite number of singularities of sin z...
  31. bcrowell

    How to prove that something is a non-curvature singularity?

    In general, what methods are there for proving that something is a non-curvature singularity? As a specific example, take the 1+1-dimensional version of the NUT metric, ##ds^2=t^{-1}dt^2-t d\theta^2##, which is discussed in Hawking and Ellis in two places. H&E's treatment is long and...
  32. MTd2

    Removing Static Black Hole Singularity without QM (paper)

    I thought of posting this on astrophysics or general relativity forums since it seems completely classical, but given the extraordinary claim, I am posting here. Note that one of the guys is a notable string theorist. http://arxiv.org/abs/1510.03396v1 Journey Beyond the Schwarzschild Black...
  33. thorq

    Building a "slider crank"-style lifting platform. Need help.

    Hi, I am trying to design a lifting platform for light duty loads (3d printing build platform) that only uses rotation for its actuation. I have a design that uses a mechanism similar to the slider crank and I want to maximize the total height the platform can travel. This is a sketch of my...
  34. S

    Curve integral, singularity, and parametrization

    Well, it's physics friday! (carpe diem etc, what else) :) 1. Homework Statement I present to you this (not so) pleasant expression that seemingly appeared on a page out of nowhere. \vec{F}(r, \theta, \varphi) = \frac{F_0}{ar \sin\theta}[(a^2 + ar \sin\theta \cos\varphi)(\sin\theta \hat{r} +...
  35. Hybrid

    If we restarted the Universe n Times from T=0......

    Would it always be identical? Would it ever be identical? Essentially with the current state of physics and taking quantum fluctuations into consideration, would it always be the same? Is there motion at T=0?Another question: If we restarted the Universe from the big bang and let it play out...
  36. newjerseyrunner

    What's the difference between a point and singularity?

    When an neutrino is observed, it becomes a point particle, but it has mass. Is that mass not concentrated into a point? Why doesn't it collapse down to a micro black hole? What's the difference between a neutrino and a micro black hole of the same mass? I know it has 1/2 spin and other...
  37. P

    What is a nonscalar curvature singularity?

    What is a nonscalar curvature singularity, in the context of "the https://en.wikipedia.org/w/index.php?title=Wave_of_death&action=edit&redlink=1 is a gravitational plane wave exhibiting a strong nonscalar null...
  38. M

    A Question Regarding Black Holes

    Hello people, I have a question regarding black holes. The way i understand it, black holes form in supernovas, and they occur because the gravitational pull of the stellar remnant is so great that nothing can stop it, and it basically collapses down to a singe point, virtually nothing... Now...
  39. ion santra

    What is the Nature of Singularity in the Function f(x)=exp(-1/z)?

    what is the nature of singularity of the function f(x)=exp(-1/z) where z is a complex number? now i arrive at two different results by progressing in two different ways. 1) if we expand the series f(z)=1-1/z+1/2!(z^2)-... then i can say that z=0 is an essential singularity. 2) now again if i...
  40. L

    Is an electron considered a singularity by some physicists?

    I read this book called How To Teach Relativity to Your Dog by Chad Orzel. In the book he discusses how an electron is known to have mass but is also considered a point like particle. He said that some interpretations consider the electron thus to have an infinitely dense mass which should...
  41. Rupert Young

    B Big Bang & Infinite Universe: Evidence & Discrepancies

    Following on from this thread. If the universe is infinite and was at the time of the big bang does that not mean that the size and contents was infinite? In other words at the BB there was already infinite amount of galaxies. I had understood that at, or just after, the BB the mass of the...
  42. J

    Predicted Heat Death of the Universe

    Predicted Heat Death of the Universe In his thought provoking documentary “Wonder of the universe” ( ) Professor Brian Cox explains the thinking behind current predictions for the “Heat death of the universe”. He explains the predictions through the effect of the second law of thermodynamics...
  43. Stephanus

    What is the limit of classical GR in describing the singularity of a black hole?

    What is the size of the singularity? 1. Is it 0 cm? 2. Is it below Planck length? 3. Is "the size of singularity" the wrong question, such as asking "what is the length of 500 celcius"? What does that mean? From event horizon all the way, just before, the centre, is vacuum? And suddenly there...
  44. Stephanus

    Schwarzschild, Singularity, Density

    Dear PF Forum, I have a question about the size of "singularity" This question has already been asked here, Question about Schwarzschild radius But what I want to know is this density thing that I'd like a confirmation. Actually it's 2.9511896078372906 KM according to his...
  45. Mohan Nivas

    Space-Time Singularity: What, How, and Is It Possible?

    What is space-time singularity? How it formed...? Is singularity possible..?
  46. Baddness

    Can time equal 0 in a Singularity?

    First off, I want to say hello. I have been interested in gravity for most of my life, I've just taken forever to do anything about it. Better late than never. That's my story and I'm sticking to it. :) By no means do I consider myself a professional by any means, but I have been putting out an...
  47. Bray420

    What supported the singularity during the Big Bang?

    If the Big Bang created space time, what did the singularity of the Big Bang "rest" on?
  48. R

    Supernova Explosion near a black hole

    What would happen if there was a supernova explosion near a black hole ? Would it just sit there and absorb all the energy incident on it ? Or would it simply vaporize into elementary particles ? And if it does vaporize, could the remnants give us a clue as to the quantum state of matter inside...
  49. binbagsss

    Curvature Singularity: Necessary & Sufficient Conditions

    For a physical singularity I think it is sufficient that anyone scalar quantity blows up, Why is it not a necessary condition that all blow up? For a curvature singularity am I correct in thinking that it is a sufficient condition to find a coordinate system in which the metric coefficient no...
  50. Buzz Bloom

    Understanding Big Bang Singularity: Physics Forums Q&A

    Question TO: Physics Forums – March 17, 2015 Various sources I have read talk about the big bang origin as a point singularity. Here is one example:
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