Black Holes

[Dubbelosix]

1 minute ago, dimreepr said:

I mean I don't really understand, 157 km? How was that created?

You know what a wavelength is right?

[dimreepr]

2 minutes ago, Dubbelosix said:

You know what a wavelength is right?

That wasn't my question.

[Dubbelosix]

read what he said again, and tell me your question again, for clarity, please.

Now I have looked back, you are not asking what it is, or what it means? But you are asking, (maybe) how the wavelength is created?

[Strange]

13 minutes ago, dimreepr said:

I mean I don't really understand, 157 km? How was that created?

The Schwarzschild radius is defined by: [math]r_s = \frac{2 G M}{c^2}[/math]

The mass of the black hole was 53 solar masses: https://www.sciencealert.com/new-ligo-virgo-gravitational-waves-neutron-stars-space-news-sept-2017

Plugging that In to the equation gives 157km: http://xaonon.dyndns.org/hawking/

 

 

Edited September 28, 2017 by Strange

[Dubbelosix]

Just now, Strange said:

The Schwarzschild radius is defined by: [tex]r_s = \frac{2 G M}{c^2}[/tex]

The mass of the black hole was 53 solar masses: (sorry, link for that not working at the moment)

Plugging that In to the equation gives 157km: http://xaonon.dyndns.org/hawking/

 

 

No I made the same mistake, he isn't actually asking about the wave, he seems to be asking why its created. 

[dimreepr]

10 minutes ago, Strange said:

The Schwarzschild radius is defined by: [tex]r_s = \frac{2 G M}{c^2}[/tex]

The mass of the black hole was 53 solar masses:

 

That was kinda my point, surely a black hole has a minimum mass?

8 minutes ago, Dubbelosix said:

No I made the same mistake, he isn't actually asking about the wave, he seems to be asking why its created. 

How? was my question...

Edited September 28, 2017 by dimreepr

[Strange]

Just now, dimreepr said:

That was kinda my point, surely a black hole has a minimum mass?

I'm not sure it does. Although, I don't suppose GR is valid for black holes with sizes approaching the Planck length. (Which would be about 27 micrograms.)

[Dubbelosix]

I don't know, you tell me, I am confused now, as I am sure other people will be. 

[Strange]

5 minutes ago, dimreepr said:

How, was my question...

Now, I'm not sure what the question was either!

[Dubbelosix]

1 minute ago, Strange said:

I'm not sure it does. Although, I don't suppose GR is valid for black holes with sizes approaching the Planck length. (Which would be about 27 micrograms.)

Perhaps... not any conventional black hole. Mind you, Wheeler was convinced his Geon was a possibility. I have shown, it could be.

Others have speculated on small, extremal black holes. Wheeler, went all out and said there was a Planck foam... but all these physics, requires more evidence. 

https://en.wikipedia.org/wiki/Extremal_black_hole

https://en.wikipedia.org/wiki/Quantum_foam

http://iopscience.iop.org/article/10.1088/1742-6596/222/1/012038/pdf

[J.C.MacSwell]

2 hours ago, Dubbelosix said:

 

 

Emmm... No. Gravity follows the same speed rules as general speed of light, which are made of photons. 

 

Gravity couldn't possible tug to rip apart the inside. 

Stated from a different reference frame to give you a different perspective:

 So you are saying a blackhole could not possibly enter a larger mass, and exit without absorbing the whole mass? (underlying assumption is that the relative velocities are very high, and the distant parts of the larger mass never get inside the event horizon)

Or are you saying something else?

[zapatos]

Quote

The revolutionary discovery of space-time ripples may have come from two black holes colliding while inside the belly of an enormous star, whose subsequent collapse launched powerful jets of gamma rays.

https://www.newscientist.com/article/2077783-ligos-black-holes-may-have-lived-and-died-inside-a-huge-star/

 

 

[MigL]

Geon is short for 'Gravitational Electromagnetic Entity'

The term was coined by J A Wheeler in the 50s to describe EM, or even gravitational waves, held together and confined by gravity.
They are not a minimal sized BH but are a theoretical constructs of any size.

If you consider any particle as having zero dimension ( point particles ) but a finite mass, then all particles will be Black holes and have an associated event horizon. ( and we don't see any event horizons )
Heisenberg says a particle cannot be localized to one point, and IIRC, 'torsion' in Einstein-Cartan theory, and the Dirac equation in a gravitational field impose a finite size to particles such that they cannot be Black Holes.

[beecee]

7 hours ago, dimreepr said:

I'm sure there is no mathematical theoretical size limit for a black hole, but I would assume, given the science that if the parent star of the singularity was big enough to go supernova; how could it be small enough to exist in our solar system and not affect us? 

Primordial Planck size BHs have been hypothetically suggested to have formed at near the BB epoch by Stephen Hawking. Other then that, and as far as I know, more recent BHs need be by definition stellar size, Intermediate size and of course the SMBHs at the cores of galaxies.  

This is probably because BHs are formed when massive objects such as stars, undergo gravitational collapse after exhausting their available fuel. Even then the star needs to be of very large size, much larger then the Sun to eventually go supernova and produce a BH.

SMBHs get to be that size by accreting matter and merging with other BHs.

BHs form when a given mass is squeezed to within its Schwarzchild radius, which creates a situation that further collapse is compulsory according to GR, at least up to the quantum/Planck level, where GR itself fails. Most cosmologists today believe that the singularity and the infinite quantities associated with it does not really form. When approaching a BH, depending on its size, a body/mass will undergo what is called spaghettification caused by tidal gravity effects, and sees the body/mass stripped down to its most basic constituents as gravity eventually overcomes the other three forces, including the strong nuclear force. This means that the mass that makes up the BH, is of a nature that has not existed since the early seconds after the BB. 

The larger a BH, say a SMBH, the less are these tidal gravity effects, so much so that one could effectively cross the EH, without feeling any ill effects, until and when one approaches and gets closer to the "singularity".

Edited September 28, 2017 by beecee

[Mordred]

1 hour ago, MigL said:

 

Heisenberg says a particle cannot be localized to one point, and IIRC, 'torsion' in Einstein-Cartan theory, and the Dirac equation in a gravitational field impose a finite size to particles such that they cannot be Black Holes.

Bingo

[Dubbelosix]

7 hours ago, MigL said:

Geon is short for 'Gravitational Electromagnetic Entity'

The term was coined by J A Wheeler in the 50s to describe EM, or even gravitational waves, held together and confined by gravity.
They are not a minimal sized BH but are a theoretical constructs of any size.

If you consider any particle as having zero dimension ( point particles ) but a finite mass, then all particles will be Black holes and have an associated event horizon. ( and we don't see any event horizons )
Heisenberg says a particle cannot be localized to one point, and IIRC, 'torsion' in Einstein-Cartan theory, and the Dirac equation in a gravitational field impose a finite size to particles such that they cannot be Black Holes.

 A geon for all intents and purposes, was a black hole. It is about waves being trapped by its own gravitational field - so yes, there are similarities with black hole theory and the concept of the geon.

 

Secondly, can you clarify what you mean by the following:

 

'''Heisenberg says a particle cannot be localized to one point, and IIRC, 'torsion' in Einstein-Cartan theory, and the Dirac equation in a gravitational field impose a finite size to particles such that they cannot be Black Holes.''

 

 

 

[MigL]

Sure...
The Heisenberg Uncertainty Principle says that if an electron ( as an example ) is localized within a very small box then its momentum, and energy, become more and more indeterminate. If it can be localized within a dimensionless box, then its momentum and energy could be infinite. IE although we treat them as point particles,quantum effects place a limit on their lower spatial extent.

I don't recall where I read the details of the other assertion, but found this in the Wiki entry on Micro Black Holes, and it's much clearer than what I posted...

" Elementary particles are equipped with a quantum-mechanical, intrinsic angular momentum (spin). The correct conservation law for the total (orbital plus spin) angular momentum of matter in curved spacetime requires that spacetime is equipped with torsion. The simplest and most natural theory of gravity with torsion is the Einstein-Cartan theory.^[7][8] Torsion modifies the Dirac equation in the presence of the gravitational field and causes fermion particles to be spatially extended.^[9] The spatial extension of fermions limits the minimum mass of a black hole to be on the order of 10¹⁶ kg, showing that mini black holes may not exist."
Reference:
(9) ^ Nikodem J. Popławski (2010). "Nonsingular Dirac particles in spacetime with torsion". Phys. Lett. B. 690: 73–77. Bibcode:2010PhLB..690...73P. arXiv:0910.1181 . doi:10.1016/j.physletb.2010.04.073.

Edited September 29, 2017 by MigL

[Dubbelosix]

No I am sorry, not that, I know what the uncertainty principle is and what it means. 

 

I mean this bit ''and IIRC, 'torsion' in Einstein-Cartan theory, and the Dirac equation in a gravitational field impose a finite size to particles such that they cannot be Black Holes.''

Ok... I thought this was related to torsion smearing particle size. I just needed to hear it from you because I wasn't sure. Torsion is interesting for this reason - and is appealing. 

Torsion is also capable of removing any initial singularities to the universe, which was one motivation for me studying Friedmann cosmology with torsion.

I have at least once wrote in the past that torsion can remove pointlike dynamics for particles. 

[Mordred]

2 hours ago, Dubbelosix said:

 

. I thought this was related to torsion smearing particle size.
 

It would be more accurate to express the above as particle wave function boundary confinements. ( just an interjection :p)

[Dubbelosix]

Go take a look at my statistics thread Mordred, in maths, I think you might be able to help?

5 minutes ago, Mordred said:

It would be more accurate to express the above as particle wave function boundary confinements. ( just an interjection :p)

 

hell, why not? lol