Talk:Black hole

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Semi-protected edit request on 22 July 2020

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[b]Black hole in mythology[/b]

Black hole in Puranas is called as third eye of god Shiva & also called as Vishnu Chakra Or Krishna Chakra - Black hole is also known as Goloka abode of god Krishna. Gita Says abode of god Krishna is where light cannot reach.

Black hole in Puranas is also known as Rudras - Puranas Says there are countless Rudras but only 11th(Eleventh) Rudra is known as god Shiva. God Krishna says in Gita that I am god Shiva.

In Ramayan god Rama was king for 11,000(Eleven Thousand) years & some Ramayan says nobody knows how many years god Rama was king - It means god Rama was immortal & he is still king & he is Still Living Somewhere. It means god Rama was avtar of god Shiva. There is no other information of 11th(Eleventh) number found in any texts books of hindu mythology.

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Please Remove These Lines

I Have Studied At Least 200 Books On Hindu Mythology.

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Please Remove These Lines Vikram ght (talk) 14:29, 22 July 2020 (UTC)

 Already done. These line don't appear in the article, so there's nothing to remove. –Deacon Vorbis (carbon • videos) 14:35, 22 July 2020 (UTC)

Supernovae

Do my eyes deceive me? Is there no mention of the word "supernova" in the entire article? Lithopsian (talk) 19:37, 27 August 2020 (UTC)

I have just added some info and a link to supernova, in the gravitational collapse part. --JimenaAstro (talk) 22:11, 27 August 2020 (UTC)JimenaAstro

I removed part of what you added because it included an incorrect definition of what a planetary nebula is. Planetary nebulae are not supernova remnants and they aren't related to black hole formation. It would still be useful to have a little more text on the connection between supernovae and black hole formation though. Aldebarium (talk) 22:21, 27 August 2020 (UTC)

I just (preliminary) restored properly sourced content that was removed by user Aldebarium (talk · contribs). Comments welcome. - DVdm (talk) 22:26, 27 August 2020 (UTC)

Hi Aldebarium (talk · contribs), thank you for your comments and edits. The mention to planetary nebulae was there before, I did not add it. I just expanded on the supernova event, but did not feel like removing the planetary part completely. I agree that planetary nebulae are not supernova remnants (and are not related to black hole formation). I added a brief mention to supernova in the introduction and will now have a look at the gravitational collapse part to see how we can express it better. Thank you! JimenaAstro (talk) 22:32, 27 August 2020 (UTC)JimenaAstro

OK- sorry then, I misunderstood where that text came from. I agree with including more information on the connection between supernovae and black hole formation in general, so my main reason for the deletion was just to remove the incorrect stuff about planetary nebulae. Aldebarium (talk) —Preceding undated comment added 22:35, 27 August 2020 (UTC)

 Jood job here! - DVdm (talk) 22:37, 27 August 2020 (UTC)

Aldebarium (talk · contribs) Please try to conform closer to what's directly stated in reliable sources. Rolf H Nelson (talk) 05:04, 28 August 2020 (UTC)

I'm not sure what you're referring to, but if you mean the part about Type Ia supernovae, I was working on removing that in my next edit. I didn't write that, it was there before, and I agree it doesn't belong there. Aldebarium (talk) 05:07, 28 August 2020 (UTC)

It would probably be appropriate to also mention something about the (upper) mass gap that sets an effective maximum mass for stellar black holes.TR 06:49, 28 August 2020 (UTC)

Semi-protected edit request on 7 October 2020

Recently, a quantum thermodynamical description for the interior of a Reissner-Nordström black hole, was proposed by Musmarra and Bellini. J. I. Musmarra, M. Bellini. "Quantum thermodynamics in the interior of a Reissner-Nordström black-hole". Physics of the Dark Universe. vol. 30, 100710 (2020).[1]. Mago.ratanga (talk) 22:55, 7 October 2020 (UTC)

 Not done. It's not clear what changes you want to make. –Deacon Vorbis (carbon • videos) 22:56, 7 October 2020 (UTC)

Temperature proportionality

Regarding this and this edit by user Spyglasses and this and this revert by user Deacon Vorbis, see Kip Thorne who writes that Hawking concluded that the temperature is proportional to the hole's surface gravity. So it looks like Deacon Vorbis is correct. - DVdm (talk) 14:17, 10 October 2020 (UTC)

References

Semi-protected edit request on 3 November 2020

The reference no. 177 Shipman, H. L.; Yu, Z; Du, Y.W (1 January 1975). "The implausible history of triple star models for Cygnus X-1 Evidence for a black hole". Astrophysical Letters.

 is incorrect in detail: Shipman appears to be the single author of the article, see

https://ui.adsabs.harvard.edu/abs/1975ApL....16....9S/abstract

It should read e.g.

Shipman, H. L. (February 1975). "The implausible history of triple star models for Cygnus X-1 Evidence for a black hole". Astrophysical Letters. Intophysics (talk) 19:22, 3 November 2020 (UTC)

Agreed. Looks like the doi link is bad? VQuakr (talk) 20:02, 3 November 2020 (UTC)

 Done Fixed. XOR'easter (talk) 20:14, 3 November 2020 (UTC)

Black hole definition refinement

According to me, the current definition for a black hole ("A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it.") should be refined to be able to cope with the observations of two black holes merging together. According to the current definition, recently observerd merging of black holes would not possible since none of the merging black holes would be able to loose matter to the other black hole. The refinement could be something like: "without the nearby presence of any other significant object". WDeeraa (talk) 23:47, 26 January 2021 (UTC)

If some reliable source would directly support that, there would be no problem to add it. Without a source this would be wp:original research, which is not allowed on Wikipedia. - DVdm (talk) 00:02, 27 January 2021 (UTC)

Definitions are arbitrary. We already have List of gravitational wave observations, LIGO observations of inspiral events, which document mergers of black holes with other black holes (such as GW150914), and other mergers of black holes with neutron stars, etc. In other words, these objects are observed to entrap each other; there is no need for definitions to allow their existence. --Ancheta Wis   (talk | contribs) 01:56, 27 January 2021 (UTC)

In a BBH merger nothing escapes from within the black holes. There is no need to change anything.TR 13:29, 27 January 2021 (UTC)

In a Binary Black Hole system you could argue that nothing escapes between the two black holes (although I believe that the ultra-strong gravitational fields will influence each other, therefore also both event horizons, which will allow exchange of matter at a certain stage).

But when the two black holes merge to become one bigger black hole, the current definition of a black hole does not hold.

Also since the mass of the resulting black hole is less than the sum of the two merging black holes (for example GW190521: 85 M_☉ + 66 M_☉ → 142 M_☉), there is a significant loss of mass which cannot be explained with the current definition.

Maybe the addition of a note to solve the lack of a source? WDeeraa (talk) 21:54, 28 January 2021 (UTC)

We solve the lack of a source by not doing adding the content. All content, including footnotes, needs to be verifiable. VQuakr (talk) 22:13, 28 January 2021 (UTC)

I repeat, there is nothing wrong with the current description of a black hole as "a region of spacetime from which nothing can escape", in the case of merging black holes. In fact, this remaining true is instrumental in certain approaches to numerical relativity used to model such a merger. If you wish to claim otherwise you will need to provide a source.TR 15:37, 29 January 2021 (UTC)

Semi-protected edit request on 7 February 2021

We need to add Paul Murdin's wiki page this Wiki page. Basically, changing 'Paul Murdin' in this article to a link to his page. 213.104.97.175 (talk) 23:18, 7 February 2021 (UTC)

 Done. ◢  Ganbaruby!  (Say hi!) 00:35, 8 February 2021 (UTC)

New image

Should a section be added about imaging of black holes and should the latest image of a black hole be added? ([2]) Cynosure-NULL (talk) 21:11, 26 March 2021 (UTC)

IMHO any in-depth coverage (that is, beyond a sentence or two) of the EHT Messier 87 imagings should go under Event_Horizon_Telescope#Messier_87* instead. Rolf H Nelson (talk) 20:56, 27 March 2021 (UTC)

Black-holes and Quantum Dynamics

The continued contraction of a normal star, compressed by an unrelenting level of gravity, can be arrested by restrictions imposed by the Heisenberg Uncertainty Principle (HUP). Gravitational energy acting on a star is normally transformed into a star’s internal particle-energy, which opposes a star’s contraction. Prevailing black-hole theory asserts that an unsuppressed level of gravitational energy can overwhelm a star’s internal-energy, thereby producing a black-hole “singularity” of infinite density. However, HUP restrictions will not allow this to happen.

The internal particle dynamics of a star are initially random and constituted by multiple degrees of dimentional freedom. But particle collisions gradually assume an oscillatory momentum indicative of a wave.

The critical point at which a star is transformed into a black-hole is triggered by the HUP wave-equation relating the uncertainty of a particle’s position ‘Δx’ to its range of momentum ‘Δp’: ΔxΔp ≥ h, where ‘h’ is the Planck constant. When the product of particle uncertainty approaches the value of ‘h’, Newtonian physics no longer works as a description for particle dynamics.

The reason for this is that the distance between particle collisions, driven by gravity, approaches zero. As the volume of a star is compressed by gravity, the degrees of freedom available for particle motion decreases, and particle dynamics can be described by a one dimensional, quasi-harmonic motion, whereby a particle’s wave-function assumes the form of a planck-level ‘spike’.

The width of this spike represents the extreme limit of particle frequency, as well as particle wavelength, velocity and momentum. As particle velocity approaches the speed of light, the rate-of- change of momentum (dp/dt) approaches zero, and particles assume the form of unaccelerated objects, dp/dt=0; particles thereby attain a state of definite energy.

Although a reservoir gravitational potential may still exists, its action on particle dynamics can no longer have an effect, since Δx (collision distance) approaches zero, and particle KE has reached a maximum value. The potential energy term disappears from the Schrodinger equation, and a particle’s momentum can be expressed in terms of its energy, p = E/c. This equation represents a photon. Details governing a particle’s change-of-state from a material object to a photon will, hopefully, be forthcoming in the near future.

A black-hole is unique; it presumably represents the maximum energy-density (E/r) that nature is capable of producing (energy-density is defined as ‘E/r’: energy/radius). Since particle energy-density, restricted by HUP, cannot get larger, Newtonian physics can no longer translate gravitational energy into particle kinetic energy. At this point, a star is transformed into a black-hole.

But unrelenting gravitational energy persists in acting on a black-hole. Nature solves this problem by a change-in-state in particle dynamics; Newtonian dynamics is replaced by quantum-dynamics. Inertial particles, with an indeterminable energy of p²/2m, are replaced by a wave-function, ‘Ψ’, presumably in the form of photons with a precise energy (pc} but with a location that’s largely indeterminable.

The QM change-of-state in a star’s Newtonian principles is coincident with the formation of an event-horizon (EH) envelope, governed by the laws of general relativity. The total energy of quanta trapped within the EH is equal to the initial total, particle kinetic-energy of a star prior to its change-of-state: Σ(n)pc = 1/2(Σp/m), where ‘n’ represents the number of interior particles. The resulting black-hole consists of an object composed of emprisoned photons but with the properties of mass and momentum in the classical sense.

As additional gravitational energy is acquired by an expanding black-hole, its volumetric energy will increase. However, it’s expansion (its radius) is a unique function of its energy-density. This, together with its escape-velocity, will remain constant: MG/r = E/r = c² = constant. A black-hole has the greatest energy-density (E/r) for any object produced by nature. This concentration of energy-per-unit-radius cannot increase or decrease as a BH get bigger; black-holes cannot get smaller.

Additional gravitational-energy acquired by a black-hole serves as work to increase its size, rather than contributing to an increase in gravitational force, as in a normal star. The energy-density of an expanding black-hole is a function of its radius; energy-density determines the gravitational properties of a black-hole; therefore, gravity should remain at a constant, maximum value allowed by quantum mechanics, regardless of the size of a black-hole. This is because the gravitational force at the boundary of a BH does not change as it expands: the additional energy absorbed by a black-hole serves to expand its dimensions, rather than contribute to its boundary forces, as in a normal star.

Black-hole gravitational force is the same for all black-holes, regardless of their size. This property should be varifiable by astronomical observation; the velocity of object’s orbiting very close to a black-hole should approach the speed of light. — Preceding unsigned comment added by Robert E Osborne (talk • contribs) 00:39, 12 April 2021‎

Alternatives section

I suggest that the Alternatives subheading should get its own separate section, outside of the Observational Evidence section. Reason being, alternatives are more theoretical rather than observational. If not a separate section, perhaps a subheading under Open Questions. Assambrew (talk) 19:42, 15 April 2021 (UTC)

I tend to agree. The current organization dates back to a time when the observational evidence was much more circumstancial, and this subsection served as a summary of alternative hypotheses for the available observational evidence (at the time). We now have pretty overwhelming evidence from various sources (e.g. LIGO and the EHT), and this organization is a bit dated. The section would also benefit from a critical update.TR 14:20, 16 April 2021 (UTC)