Black Hole

[Chris Peterson]

Ok,

http://www.hawking.org.uk/into-a-black-hole.html

Although you wouldn't notice anything particular as you fell into a black hole, someone watching you from a distance, would never see you cross the event horizon. Instead, you would appear to slow down, and hover just outside. You would get dimmer and dimmer, and redder and redder, until you were effectively lost from sight.

The crossing of the event horizon is not observed but that doesn't mean that the object never disappears. That's what I needed. Otherwise black holes would be covered in red crap.

Right, I always get that backward.

And BTW, black holes sort of are covered in red crap. They are not at absolute zero- they radiate blackbody radiation. But the temperature is absurdly low- billionths of a kelvin above zero- so the wavelength of the emitted radiation is really, really long (which in astrospeak might be called "red", although it is obviously not in the visible spectrum at all).

[neufer]

Several articles do call the surface imaginary. I'm not sure why. I'm in agreement with Chris's assessment.

The Schwarzschild solution to Einstein's equations, which makes use of Schwarzschild coordinates and the Schwarzschild metric, leads to the well-known black hole singularity at the Schwarzschild radius.



Later it was realized that, in many (but not all) ways, this was no more a real singularity than the North Pole is a real singularity "in the latitude/longitude coordinates". A free falling observer will easily pass through a very large black hole event horizon and only die when he approaches the true singularity at the origin.

<<Karl Schwarzschild (October 9, 1873 – May 11, 1916) was a German physicist. He is also the father of astrophysicist Martin Schwarzschild. He is best known for providing the first exact solution to the Einstein field equations of general relativity, for the limited case of a single spherical non-rotating mass, which he accomplished in 1915, the same year that Einstein first introduced general relativity. The Schwarzschild solution, which makes use of Schwarzschild coordinates and the Schwarzschild metric, leads to the well-known Schwarzschild radius, which is the size of the event horizon of a non-rotating black hole.

Schwarzschild accomplished this triumph while serving in the German army during World War I. He died the following year from pemphigus, a painful autoimmune disease which he developed while at the Russian front.

Asteroid 837 Schwarzschilda is named in his honor.

[saturno2]

There are 4 types of black holes ( Physical properties)
1.- Black hole of Schwarzschild ( non-rotating and without electric charge)
2.-B. H. of Reissner-Nordstrom
3.-B.H. of Kerr
4.-B.H. of Kerr-Newman ( rotating and with electric charge)
Well
Wikipedia wrote ( In an article in English - Event horizon -)
" The < surface> at the Schwarzschild radius acts as an event horizon in a
non-rotating body that fits inside this radius ( although a rotating
black hole operates slightly differently ) "

[neufer]

---

<<The Black Hole of Calcutta was a small dungeon in the old Fort William in Calcutta, India, where troops of the Nawab of Bengal, Siraj ud-Daulah, held British prisoners of war after the capture of the fort on 20 June 1756. One of the prisoners, John Zephaniah Holwell, claimed that following the fall of the fort, British and Anglo-Indian soldiers and civilians were held overnight in conditions so cramped that many died from suffocation, heat exhaustion and crushing. He claimed that 123 prisoners died out of 146 held. However, the precise number of deaths, and the accuracy of Holwell's claims, have been the subject of controversy.

The dungeon was a strongly barred room and was not intended for the confinement of more than two or three men at a time. There were only two windows, and a projecting veranda outside and thick iron bars within impeded the ventilation, while fires raging in different parts of the fort suggested an atmosphere of further oppressiveness. The prisoners were packed so tightly that the door was difficult to close.

One of the soldiers stationed in the veranda was offered 1,000 rupees to have them removed to a larger room. He went away, but returned saying it was impossible. The bribe was then doubled, and he made a second attempt with a like result; the nawab was asleep, and no one dared wake him.

By nine o'clock several had died, and many more were delirious. A frantic cry for water now became general, and one of the guards, more compassionate than his fellows, caused some to be brought to the bars, where Mr. Holwell and two or three others received it in their hats, and passed it on to the men behind. In their impatience to secure it nearly all was spilt, and the little they drank seemed only to increase their thirst. Self-control was soon lost; those in remote parts of the room struggled to reach the window, and a fearful tumult ensued, in which the weakest were trampled or pressed to death. They raved, fought, prayed, blasphemed, and many then fell exhausted on the floor, where suffocation put an end to their torments.

About 11 o'clock the prisoners began to drop off fast. At length, at six in the morning, Siraj-ud-Daulah awoke, and ordered the door to be opened. Of the 146 only 23, including Mr. Holwell (from whose narrative, published in the Annual Register for 1758, this account is partly derived), remained alive, and they were either stupefied or raving. Fresh air soon revived them, and the commander was then taken before the nawab, who expressed no regret for what had occurred, and gave no other sign of sympathy than ordering the Englishman a chair and a glass of water. Notwithstanding this indifference, Mr. Holwell and some others acquit him of any intention of causing the catastrophe, and ascribe it to the malice of certain inferior officers, but many think this opinion unfounded.>>

[saturno2]

The black hole of Calcutta, it is right to be " blak hole"
This event is a crime of < against humanity >

[saturno2]

Error " blak hole "
Correct " black hole"

[Beyond]

Error " blak hole "
Correct " black hole"

ERROR--ERROR. Good thing you're not Nomad, saturno2, or you'd have to "Sterilize" yourself
http://www.youtube.com/watch?v=G6o881n35GU

[saturno2]

Error " blak hole "
Correct " black hole"

ERROR--ERROR. Good thing you're not Nomad, saturno2, or you'd have to "Sterilize" yourself
http://www.youtube.com/watch?v=G6o881n35GU

Error

[Markus Schwarz]

I sort of understand how a moving observer could not see itself crossing an event horizon. But the stationary observer dropping the object in? What's that about?

An outside observer does see objects cross the event horizon. If you yourself fell into a black hole, however, it would take infinitely long to reach the event horizon- in your reference frame- due to time dilation. From your viewpoint, you would asymptotically approach the horizon but never reach it.

Sorry, but it's the other way around. For a static observer it takes a particle an infinite amount of his coordinate time to cross the horizon. The light he receives from the particle gets more and more red-shifted as it approaches the horizon. A free falling observer, however, reaches the event horizon in a finite amount of his proper time.

When the free falling observer crosses the horizon, nothing special happens to him. The event horizon is not like a wall of bricks . If he has a window in his spaceship, he will certainly see the sky change and can thereby deduce if he has crossed the horizon or not.

[Chris Peterson]

Sorry, but it's the other way around.

Yes, Markus, I noted above that I got it backwards.

[saturno2]

The center of a black hole has a high density. ( A maximum
value that tends to infinity).
But the average density of a black hole super-massive
( thousands of times the mass of Sun), is less then 1, lighter
than the density water on the Earth.
However, in the center of the < singularity> we could find
high density and high rotation

[THX1138]

This may very well be the same question that was asked some years ago but to my knowledge no definitive answer was ever given. Where there are a number of black holes (Four, five or more) in very close proximity to each other what would this be called.
A group of holes?
A cluster of holes?

[Chris Peterson]

This may very well be the same question that was asked some years ago but to my knowledge no definitive answer was ever given. Where there are a number of black holes (Four, five or more) in very close proximity to each other what would this be called.
A group of holes?
A cluster of holes?

I'm not sure that such exist. But if so, what they would be called would probably depend on the presumed mechanics of their creation. Are they supermassive black holes brought together by galactic mergers? Stellar mass black holes that are simply some sort of evolved multiple star systems?

[saturno2]

What time of " life " can have a black hole ( not supermassive)

[Chris Peterson]

What time of " life " can have a black hole ( not supermassive)

For the lowest mass black holes known to exist, the lifetime is very long- more than 10⁶⁵ years. If primordial black holes exist, they could be much lower mass, and have lifetimes as short as a few billion years, making their collapse potentially observable.

[saturno2]

Chris Peterson
Thanks for your note

A black hole of 1 solar mass slowly lose mass and delay in
1 x 10 E 65 years to disappear.
While a subatomic black hole disappear almost instantly.

[Doum]

NASA space telescope discovers 10 monster black holes

http://www.nbcnews.com/science/nasa-spa ... 8C11131462

So is it a bunch of black hole? Or a group or a gang or......

[BMAONE23]

I would call it a Doum of Black Holes

[tadekkoks]

NASA space telescope discovers 10 monster black holes

http://www.nbcnews.com/science/nasa-spa ... 8C11131462

So is it a bunch of black hole? Or a group or a gang or......

It is very interesting news, monster black holes... Monster!

BTW - I don't know, whether it is a bunch, whether the group, or the gang - but perhaps it is simply... family?

[BMAONE23]

Since everything vanishes beyond the EH perhaps A VOID of Black Holes

[wonderboy]

My theory on blackholes (and I mean theory in its most loose of forms) is that everything returns to them. Every Galaxy has a supermassive black hole at its centre. As it grows the gravitational pull on everything surrounding it becomes stronger until everything surrounding the black hole returns to its centre. once this has been done by all galaxies all that will remain is the graviational pull of the black holes. they will eventally collide and conjoin until they are all (if not mostly all) one massive blackhole with the overwhelming majority of the universes' mass at its centre. when this happens, the universe is poised for another big bang! just one of my very many thoughts on all things astronomy.


Paul

[Chris Peterson]

My theory on blackholes (and I mean theory in its most loose of forms) is that everything returns to them. Every Galaxy has a supermassive black hole at its centre. As it grows the gravitational pull on everything surrounding it becomes stronger until everything surrounding the black hole returns to its centre. once this has been done by all galaxies all that will remain is the graviational pull of the black holes. they will eventally collide and conjoin until they are all (if not mostly all) one massive blackhole with the overwhelming majority of the universes' mass at its centre. when this happens, the universe is poised for another big bang! just one of my very many thoughts on all things astronomy.

No matter how massive a black hole can realistically get, there is nothing that results in most surrounding material crossing its event horizon. Most of the material outside a black hole, and which is in a closed orbit, will simply end up in a smaller orbit. But an orbit still. Black holes don't suck in the material around them any differently than other massive objects, like stars.

Statistically, all matter could eventually end up in black holes just by random collisions. But that will take a long time- many orders of magnitude longer than the age of the Universe. All the black holes could theoretically collide randomly and coalesce, as well, but that would take longer than their evaporation time. So the Universe will die a cold death, and not be reborn in another cycle.

[Beyond]

So the universe will die a cold death, and not be reborn in another cycle.

Click to play embedded YouTube video.

[saturno2]

Chris Peterson wrote:
"So the Universe will die cold death, and not be reborn in another cycle"
The matter in the Universe will condense at dark matter cold and super dense and is ready to new Big Bang and other cycle...

[Chris Peterson]

Chris Peterson wrote:
"So the Universe will die cold death, and not be reborn in another cycle"
The matter in the Universe will condense at dark matter cold and super dense and is ready to new Big Bang and other cycle...

All the evidence suggests otherwise. Matter is not going to condense, but will spread out. There will be no collapse, no future Big Bang cycle. Just never ending expansion and cooling.