/sci/ - Science & Math

A black hole is a singularity. A singularity is zero-dimensional. It has no volume, its just a single point. Around the singularity is the event horizon which is a 3D sphere beyond which light cannot escape because the gravity is too strong.

black hole is no different of a planet or a star (or a particle of dust, for what matters), just much denser.

>>2796563
>A singularity is zero-dimensional. It has no volume, it's just a single point.

Woah...

>>2796563
What I am picturing from your description is an invisible bubble. Thats it.

>>2796576
>>2796563
Also, if something is zero-dimensional how does it exists?

>>2796576

Sort of, the event horizon is not physical, much like how the fact that at sea level gravity here is 9.89 meters per second per second is not because of a limit.

>>2796563
Well, for that matter, there is also a gravitational singularity at the mass center of the Earth...

>>2796584
Forget that

If it is physical or not how can it exist if it isn't matter nor energy?

>>2796588
It is a point of nil volume and infinite mass.
A dirac distribution if you prefer.

A simple (non-rotating, non-charged) black hole has two main components - the singularity and the event horizon.
The singularity is the point where all of the mass of the black hole is located.
The event horizon is a 3-dimensional sphere centered on the singularity. When anything passes into the event horizon, it cannot escape.
Black holes are mass, and so are effected by gravity. (No idea where your pentagons came from)
We can learn about black holes spin by examining the accretion disk that forms around them.
On a macro scale, black holes behave just like regular stars, but this changes once you pass the event horizon.
For example, if the Sun were replaced by a black hole of equal mass, we would continue to revolve around it as normal.

>>2796606

NOT INFINITE. THE BLACK HOLE HAS NO MORE MASS THAN THE STAR IT ORIGINALLY WAS, AND USUALLY WILL HAVE SIGNIFICANTLY LESS UNTIL IT EATS MORE MATTER.

IF A BLACK HOLE HAD INFINITE MASS, IT WOULD AFFECT THE ENTIRE UNIVERSE UNIFORMLY.

>>2796606 It is a point of nil volume and finite mass, and infinite density.

I fixed it for you.

>>2796606
Newton's Philosopher's stone?

It's not there but it has infinite mass? This is a contradiction.

>>2796617
Agreed. So basically what a black hole does is take in a lot of stuff, matter, and packs it in super tight. Do black holes grow by doing this? Or do they stay the same size? If they grow that means that things have a certain amount of density that they can reach. If they don't grow that just means things are getting more and more mushed. Correct?

>>2796579

I would like an answer to this as well. As far as we know for something to exist it must be in some dimension... else it wouldn't be in our 3 or 4 dimensions!

Ideally, the resulting black hole of a supernova retains much the same gravitational field as the late star would. The only difference between the two is that you can reach deeper parts of the field of a black hole than that of the star, as there's none of that matter that's in excessive volume to get in the way.

>>2796623
tks.
>>2796626
That is the trick bothering physician : generally speaking such things are just mathematical models.
I have hard time believing it myself : when you have infinite things in physics, it is bad. I do believe (but I don't know enough to be categorical) that the theory is unclear on that, due to a mismatch between quantum physics and general relativity.

Captchka : Op high finite

>>2796652
*Physicists

Something to note is that it only theoretically has no dimensions, a real world example will obviously have some 3D dimensions of volume unless something else beyond our current knowledge is at play. Which it very likely is.

Best guess at this point is that the point at the very center of a black hole is so dense that it warps space-time sufficiently that a no dimension object is acceptable. However there is no way to falsify that.

>>2796623

Black holes have a very finite density. The center of the black hole maybe not, but the actual hole itself has since it's volume is defined at the event horizon boundary

>>2796636

THEY CAN "GROW" IN THE SENSE THAT THE MORE MASS THE DEVOUR, THE WIDER THEIR EVENT HORIZON BECOMES, BUT CONSIDERING THEIR ARE BLACKHOLES AT THE CENTERS OF GALAXIES THAT HAVE DEVOURED BILLIONS OF SOLAR MASSES AND THEY HAVEN'T "OUTGROWN" THEIR EVENT HORIZONS, IT'S FAIR TO SAY THE SINGULARITY GROWS NOT AT ALL, OR SLOWER THAN THE EVENT HORIZON DOES.

>>2796652
>>2796626
>>2796623
When he says finite mass what does that mean?

>>2796636
All of the mass of a black hole is located at the singularity, and moves there when it passes the event horizon, just as you move toward the earth after you jump.
The volume of the sphere contained by the event horizon is directly proportional to the mass of the black hole raised to the 4th power. (IIRC)

>>2796678

You can put a number on it.
"It weighs 10 solar masses" etc

an infinite mass would be just that, so huge that it cannot be quantified.

>>2796617
>THE BLACK HOLE HAS NO MORE MASS THAN THE STAR IT ORIGINALLY WAS, AND USUALLY WILL HAVE SIGNIFICANTLY LESS UNTIL IT EATS MORE MATTER

If matter gets sucked into a black hole at increasingly fast speeds, does it ever reach the center? Wouldn't the objects see the black hole dissipate just moments before reaching the singularity, since they're probably going 99.99% the speed of light by the time it gets there? I guess the matter doesn't need to reach the center to add to contribute to the black hole's gravity, though...

I asked this before in another thread a while back, but I didn't get a very clear answer. Thanks in advance.

>>2796636
The black hole's singularity does not grow. It has no size.
The event horizon will become slightly larger though.

Also, black holes do not ONLY come from supernovas. They're just the most visible event preceding one.
Also, your pic is inaccurate. There would not actually be a hole, just the distortion.

Pic related. Singularities form near-literal "holes" in the fabric of space-time.

>>2796690

Because there isn't one.

>>2796690
Why would the mass not reach the center? And why would the black hole dissipate?

Also it seems that everyone is saying black holes have infinite density, the singularity does at least. How is this possible? Can't things become so compact that electrons are pushed against nuclei? What state of matter would that be considered? Bose Einstein?

>>2796716
Its called degenerate matter
Good explanation here:
http://www.astronomynotes.com/evolutn/s10.htm#A2.1
Pic related

If the rate of time slows down with higher gravity how slow is time inside a black hole?

>>2796703
>Last stable orbit
Calls to mind a 'last gas for x miles' sign.

it isn't known if black holes are indeed singularities, they are only assumed to be because once the quark degeneracy force is overcome that there is no known force that would keep all the matter from collapsing further into an infinitesimal point.

>>2796703
shut the fuck up, you don't know what you're talking about.

That is a teaching tool to demonstrate the mechanics of relativity.

>>2796700
Why/how does the event horizon become larger?

>>2796703
Pictures like these are so hard to comprehend because of how undiemsional it makes space look. lol if that is a word. And also makes me wondering if there is a mass large enough to attract a blackhole of any size?

>>2796716
>why would the black hole dissipate?
http://en.wikipedia.org/wiki/Hawking_radiation#Black_hole_evaporation

>Why would the mass not reach the center?
Objects getting pulled into the black hole accelerate faster and faster, slowing them down relative to everyone else. We see the black hole evaporate in several million years, the mass being pulled in sees it evaporate in a much shorter time.

Actually scratch that, apparently a black hole the size of our Sun has a life expectancy longer than our universe:
http://library.thinkquest.org/C007571/english/advance/core8.htm

>>2796737
If it were physically possible to build a ship that could withstand the gravitational forces of a black hole (and you along with it), time would continually dilate as you approach the singularity, dilating more and more as you continue to spaghettify, possibly never ever actually reaching the singularity. (ex. If you were three meters from a stop sign, and every step you took halved in length, how many steps would it take to get to the sign? You would never reach the sign as the distance of the steps gets continually smaller) You would suffer an eternity of infinitely slowing time.

Black holes are like super deep spiraling funnels that lead into a singularity where all it's mass is concentrated. The farther down you get the slower you go because time is slowed by the overwhelming gravity.

>>2796745
>event horizon
It's not actually a physical construct, it's like the point of no return. On one side, something happens, on the other, something else. The size is dependent on the mass of the singularity.
>attract
Black hole is not fixed in space. It orbits stuff just like everything else does.

>>2796760
>We see the black hole evaporate in several million years

whoa there, off by a couple dozen orders of magnitude

WHAT IF INSIDE OF EVERY BLACK HOLE IS ANOTHER UNIVERSE

JUST SAYING

>>2796783

THAT IS A PLAUSIBLE THEORY, THAT IF YOU WERE TO MAKE IT THROUGH A BLACK HOLE AND THE SINGULARITY YOU WOULD BE TRANSPORTED TO ONE OF AN INFINITE AMOUNT OF UNIVERSES

>>2796745
If the gravitational fields of two blackholes were to intersect, it is not too unreasonable to think that they might "merge," although gravity does not work in just one direction. Both objects are attracted to each other; one is not attracted while the other is stationary. You, for example, actually exert a gravitational force upon the earth, much like it does on you, only it is of such an inconceivably small amount that the effects of your field are not noticeable.

>>2796775
Yeah, I just pulled that number out of my ass.

dem quasars, dem quasars baby

A Black hole is easiest explained by calling it remnants of what was before the big bang, "holes" in reality,time and matter, a sort of peephole where we can glimpse into what was before time

simply nothing.

>>2796790


GUYS, WE ARE INSIDE A BLACK HOLE RIGHT NOW D:

>>2796764
You just blew my fucking mind. Thank you, sir.

>>2796804
Except that's completely wrong because a singularity has no volume and therefore cannot be 'peeped into'.
You can't even 'look at' it, just in it's general direction.

>>2796815

If you were to look at the spaceship go through the Event Horizon and eventually into the Black Hole, it would suddenly appear to stop. It would be lost in time.

Yet if you yourself were to go through, that wouldn't exactly be the case.

>>2796818

how do you know?

your guess is as good as mine

>>2796803
I don't think people truly understand how awesome these are.
Pic related, its the energy jet from a quasar (3C321) destroying a neighboring galaxy. That blue stuff is gas blasted off from the galaxy hit by the energy jet.

>>2796843

The fact that it is impossible to take a picture of the black hole directly proves that it cannot be "peered" into

It seems to me that white holes could only exist if the universe was a sphere and there was an unimaginably massive black hole that managed to create a dent in space that stretched all the way to the opposite side. I'm sure the effects of something that massive existing would cause the entire universe to feel it.

>>2796849
"Behold! The magnificent power of nature; the beauty in complete annihilation."

>>2796843
Y'see, that's the difference between you and me.
I'm not 'guessing', though 'guessing' here seems to mean 'pulling this out of my ass'.
But you go ahead and 'guess' and I'll just be over here, 'evaluating available information and attempting to formulate a logical hypothesis'. You'd probably call that 'magic'.

>>2796849

Holy shit

<3 quasars

Too lazy to look up, but is there a general length that the gas is shot up?

>>2796876

>>2796864
>White hole
GOD FUCKING DAMNIT
IF THEY EXISTED WE'D FUCKING KNOW IT
SPITTING OUT ALL THAT FUCKING MATTER AND RADIATION
NO
FUCK YOU

>>2796849
enlighten me plox

Fuck man, I was talking to my friend about this shit today... how awesome black holes are and we were just discussing them and some religious fag is like

>HEY GUYZ WHAT MAKES A BLACK HOLE

Explain that a super nova explosion does

>WELL WHAT CREATED THE SUPER NOVA THEN LOL

Explain how super novas are created

>LOL THEN HOW DID THE UNIVERSE BECOME

Well, shit.

>>2796913

Quasars are quite common, NASA actually sent out a camera in space to take pictures of them to learn more about quasars and black holes and found at least one per day in the small region they were studying.

Basically, from my understanding (which is pretty limited), a black hole at the start of the creation of a galaxy starts to absorb all the gas and dust around it and stars and shit start to form around it. Eventually the black hole is like fuck this and releases all that energy in a HUGE FUCKING RAY OF LIGHT. As you can see, the energy from that shit can destroy a galaxy.

But after that the black hole becomes "more mature" and slows down and so does the galaxy.

Be free to correct this, I'm not expert

>>2796913
http://www.astronomynotes.com/galaxy/s12.htm
and
http://www.astronomynotes.com/galaxy/s13.htm
and
http://www.astronomynotes.com/galaxy/s14.htm

should give you a basic idea

>I get that black holes are formed from super novas. Any thing else?
well you can get them from anything
you just need enough mass and enough energy to shrink it past it's Schwarzschild radius
if the mass is too low the "forced" black hole would evaporate and explode
if the energy is not enough you will succeed in creating a short lived neutron star that would explode in a nova when the compressing force is gone

>Also is a black hole three dimensional?
they're 3 dimensional

>Can you measure its area, volume, or circumference?
the only thing you can measure is it's mass and it's diameter at the event horizon

>What shape is a black hole, since they aren't affected by gravity are they pentagons?
well we guess or i should rather say scientist and astronomers guess that they're round or point like
they ARE affected by gravity and they can merge into super black holes like in the center of our galaxy

>Also can you map a black hole's spin if it has one and the distance it travels if it does travel?
yes the current theory of gravity predicts that every spinning object creates an ergosphere (a region of spacetime that is being dragged by the spinning mass) and you would be able to throw something towards the black hole and see the direction that of it's spin
they do travel inertia is still a law that governs them
we can detect a black hole's position by looking at the stars behind it or detecting the gravity change if we can feel it or detect it by looking at nearby objects

you can think of black holes as stars that don't emit light
it's basically the same thing
also the existence of an ergosphere around a black hole makes us believe that it does not collapse into an infinitely small point

also you may want to check this:
http://en.wikipedia.org/wiki/Black_hole_information_paradox

Rei because cute

>>2796955

>paradox theory

Wasn't that shit presented by Hawkings and shot down by a bunch of scientists?

>>2796977

Edit: Didn't he say himself that he was wrong about the Information Paradox?

>>2796977
i think they proved that no information is lost but i'm not sure
my memory is kind of bad..

>>2796993

Yeah isn't that the whole theory?

That information is lost at the event horizon?

Black holes... Interesting stuff, here's something I'd like to know.

Assume for a moment that one lived in a 2 dimensional universe (technically 3 if we include time. Essentially, assume the universe is a sheet of graph paper.)

Now, it seems to make sense that so long as any phenomena in this universe manifest within that 2 dimensional space-time, then to an observer, it would be possible to conjecture on or otherwise attempt to explain any 2-dimensionial phenomena.

Now, assume a 3-dimensional obstruction intersects with the 2-dimensional spacetime; would this three dimensional obstruction then appear just as inexplicable to a 2-dimensional observer as a black hole seems to be for us?

>>2796942
Not exactly. Whats actually happening is that in Active galactic nuclei (AGN), there is a large amount of dust and gas (called an accretion disc) circling around the supermassive black hole. As the matter falls toward the black hole, its gravitational potential energy is converted into kinetic energy, which through friction with all of the other particle becomes heat. The gas heats up enough that it begins to emit electromagnetic radiation.
It isn't exactly clear how this radiation is focused into the jets of energy emitted (like in 3C21).

>>2797006
I think it would be like trying to explain the concept of time having a y axis to it or something. You can't even really perceive time flowing backwards let alone in another axis.

>>2797015

Interesting... so in laymens terms the dust falls in towards the black hole and the energy of the dust is converted to kinetic energy and released as radiation (the quasars)?

>>2797031
Essentially, yes.
Here's a video by Sal
http://www.khanacademy.org/video/quasars?playlist=Cosmology%20and%20Astronomy

>>2797031
>kinetic energy is converted into thermal
>thermal is converted into GIANT LAZOR PYEW

>>2797006
Go to youtube and type in the search bar:
Carl Sagan Flatlandia.

Live and learn.

Can someone explain the definition of physical information in terms of quantum mechanics etc.

Things like "Information is not lost at the Event Horizon" means what? What information?

>>2797076
> me

for you:
>>2797006
http://www.youtube.com/watch?v=UnURElCzGc0

>>2797079
Anything, nothing can move faster than c, so if the escape velocity is greater than c, NOTHING can escape, no info.

>>2797079
explaining gravity in terms of quantum mechanics is the million dollar question.

If the black hole itself has infinite mass, then according to the diagram shown at
>>2796703
there is no ending if you enter the event horizon.
Note: Unless the theory that the universe is bent, then entering the horizon will result in an endless "time warp".

>>2797093
>>2797096

So physical information is everything?

>>2797098
>If the black hole itself has infinite mass

Ah, the folly of accepting everything in pop sci as fact.

>>2797093
>nothing can move faster than c
BZZZZT. Wrong. Nothing WITH MASS can ACCELERATE TO c from less than c.

>>2797098
>infinite mass
HOW MANY TIMES DO WE NEED TO COVER THIS IN ONE THREAD
MASS = FINITE
DENSITY = INFINITE
VOLUME = ZERO

>>2797104
Learn to read.
It clearly says "if".

>>2797093
If nothing can move faster than C why do so many physicists claim that for a brief amount of time the universe expanded at a speed higher than C following the big bang?

Also, isn't there an observationally verified type of radiation which occurs as a result of the energy created from something moving faster than C, and then slowing down to C?

I am sure there is I saw people talking about it here on /sci/ yesterday.

So how can nothing be faster than c and yet a specific type of radiation which can only exist as the result of something moving faster than c and than accelerating down to the speed of c, also exist and be provable in a lab?

How can it be both impossible and yet the universe itself expanded at a higher rate than C during the initial expansion of the big bang, and its own slowing also caused this same type of observable radiation?

How can someone contradict actual observation and say that faster than C is impossible just because our equations say so when in fact we have observed these phenomenon, and when prevalent theory is that the universe at one point in time expanded at a higher rate than the movement of C (if you shot a beam of light out the universe would have beat it in a race for that brief period of time)?

?????

>>2797116
>It clearly says 'if'
WHICH IS CLEARLY WRONG. THERE IS NO 'IF', BLACK HOLES HAVE FINITE MASS, END OF STORY. IT IS ONE OF THE FEW THINGS WE ARE CERTAIN OF ABOUT THEM.

>>2797107
What about the initial moments of the big bang, where all the mass in the universe accelerated outward at faster than C?

I think pic is related btw.

If black holes had infinite mass then all other mass in the universe would be pulled towards it instantly.

>>2797136
Ok then,
although wrong.
WHAT THE FUCK HAPPENS TO THE SHIT THAT ENTERS THEM?

>>2797143
>accelerate outward
No. It DEcelerated outward. There was no acceleration, it went from 0 to >c instantly.

>>2797162
I thought it was still accelerating?

>>2797162

Acceleration is the correct term, "decelerate" is a misnomer and implies a failure of understanding of what "acceleration" is.

0 to greater than C did not occur "instantly" as you suppose, by the way, the prevailing theory says that it occurred in an extremely short period of time. "Instant" is not a real thing.

>>2797170

It's still moving and expanding outward, just slower than before. It is decelerating but still accelerating but not accelerating.

WHAT THE FUCK IS C HOLY SHIT I HAVE NO IDEA WHAT IS GOING ON

>>2797133
http://en.wikipedia.org/wiki/Cherenkov_radiation
>at a speed greater than the phase velocity of light in that medium
>IN THAT MEDIUM

>>2797181
Yes, this is known as surpassing C.

Everything is a medium.

C is the speed of light.

let's send da monkeys to find out what is beyond dat hole.

>>2797179
'c' is the universal constant, the speed of light, as represented in the famous Einsteinian relativity equation, E=mc^2

>>2797161
It gets squished and fried. Some of the fried bits get spat back out.
>>2797170
It decelerated, then started accelerating again. NO I DON'T KNOW WHY MAYBE DARK MATTER DID IT.
>>2797173
For purposes of this debate, assume 'instant' means 'one unit of planck time'. IF YOU ARGUE THAT PLANCK TIME DIDN'T EXIST AND IS THEREFORE IRRELEVANT I AM LIABLE TO SPONTANEOUSLY COMBUST.
>>2797179
C is the speed of light
>>2797194
IN A PERFECT VACUUM JESUS FUCK

UNTIL SOMEONE GOES TO A BLACK HOLE YOU GUYS ARE ALL EQUALLY WRONG AND FULL OF HORSE SHIT

>>2797239

>DOESN'T THOUGH THAT IS FACTUALLY EXPLAINED IN THE MATHEMATICS

>>2797247

>THOUGH

HOW THE FUCK DID I TYPE THAT I MEANT KNOW

>>2797239
>thinks that black holes are unable to be observed without flying up to it in a spaceship

Do you live in a cave or something?

>>2797239
SPACE MONKEYS!

>>2797259
Even if you sent a tin can filled with monkeys hurtling to their doom in a black hole, how do you plan to gain any useful information out of it? You would never be able to observe the monkeys, nor would they return.

>>2797269

Strap a Kodak on those bitches

>>2796549
>A black hole is a theoretical singularity. A singularity is zero-dimensional. It has no volume, its just a single point. Around the singularity is the event horizon which is a 3D sphere beyond which matter and energy cannot escape because the force of gravity is too strong.

Fixt.

>>2797269
>until we observe da black holes, we are all full of "horsy poo".

>>2797283
>A singularity is zero-dimensional...its just a single point.

Doesn't that make it 1-dimensional

>>2797306
1D is a line
2D is a square
3D is a cube
4D is WE WON'T NEED EYES TO SEE

Singularities are string size.