Blackhole

[LucidFlanders]

I know nobody knows, but what is the theory that makes the most sense about where the blackhole takes you? obviously you get sucked in, but after it crushes you, where do the remains go? I thought about this a few days ago "If i got sucked into the blackhole, and was not crushed, where would i go?"

[Bonsay]

You would die.
Other than that, your body would be compressed into an infinitely small and infinitely dense singularity.

[Invader]

Crushing implies outward forces that act in on the object. You wouldn't be crushed if you were to encounter a black hole. A black hole is also not technically a hole. It's a mass that takes up less space than it previously had as a star (and what an understatement that is!). Because you can get so much closer to the mass's center of gravity now the force of gravity can grow immensely, so much so that there is a distance from it that visible light can no longer escape (and we call this distance from the center the "event horizon"), although there are other forms of radiation that a black hole can give off. Whether or not a black hole is a singularity (a point in space, dimensionless) or not is beyond me.

[khh]

Crushing implies outward forces that act in on the object. You wouldn't be crushed if you were to encounter a black hole.
"Crushing" might imply outward forces, but do you have a better word to describe that you get compressed to virtually nothing?

[Invader]

"Pulled" into virtually nothing, I suppose, since gravity is doing all the work. Gravity does pull.

[slash112]

black holes dont take yo anywhere once you get "sucked in", they just compress you, its basically just really really really strong gravity

[Xei]

Yeah you have to understand that black holes aren't really holes.

They're essentially just infinitely small points with infinitely high gravitational fields which crush anything which enters them.

They appear bigger than points, as black circles, because light gets sucked into them.

[slash112]

They appear bigger than points, as black circles, because light gets sucked into them.

wow really?

although im probably misunderstanding what you said (as usual), and its probably not as amazing as im interpreting it.

[khh]

although im probably misunderstanding what you said (as usual), and its probably not as amazing as im interpreting it.
It is pretty amazing... According to general relativity the gravity is so strong that it bends spacetime in such a way that once you've entered the black holes, there are no way out. This is, from within a black hole no direction is outwards.

[Bonsay]

Yes there is a way out. Via hawking radiation. The way I understand it, annihilation between anti-particles and the particles inside the hole. Due to the creation of virtual particles in quantum vacuum.
wow really?

although im probably misunderstanding what you said (as usual), and its probably not as amazing as im interpreting it.

Well it's obvious since the strength the force gravity increases gradually (into infinity). There must come a point between 0 and infinite newtons (?) where there is enough strength to stop the light from escaping - it is the fastest thing according to relativity. So there is an event horizon or a black sphere of doom around the point of infinite power :bowdown: .

[khh]

Yes there is a way out. Via hawking radiation. The way I understand it, annihilation between anti-particles and the particles inside the hole. Due to the creation of virtual particles in quantum vacuum.
That's not a way out, really. That's antiparticles going into the black hole, decreasing it's mass, until there's not enough mass left for it to continue to be a black hole, at which point it explodes (I think).

[Bonsay]

That's not a way out, really. That's antiparticles going into the black hole, decreasing it's mass, until there's not enough mass left for it to continue to be a black hole, at which point it explodes (I think).
Well it's the only way out. You must remember that at a point before you even reach the event horizon you cease to be. You die. Your body is stripped atom by atom.

So, asking if there was a way out is, in a way, the wrong question, because you cannot get in. :)

I haven't heard of it exploding, don't see why it would though. But I don't know.

[khh]

Well it's the only way out. You must remember that at a point before you even reach the event horizon you cease to be. You die. Your body is stripped atom by atom.
Yes, I'm certainly aware of that fact :p
But my point is that it's awesome, and that this is why light gets trapped in it. Because there's physically no way out.

So, asking if there was a way out is, in a way, the wrong question, because you cannot get in. :)
No, no, you can get in. You just wouldn't survive the experience. But you - every particle in you, that is - could get in.

I haven't heard of it exploding, don't see why it would though. But I don't know.
Well, when the gravity no longer is sufficient to keep the remaining mass in a singularity, it's got to expand, doesn't it?

[slash112]

how can light be effected by it? i thought electromagnetic radiation (in this case visible light) isnt effected by magnetic fields

[khh]

how can light be effected by it? i thought electromagnetic radiation (in this case visible light) isnt effected by magnetic fields
Magnetic? We're talking about gravitational fields... That's something else entirely.

[slash112]

Magnetic? We're talking about gravitational fields... That's something else entirely.

oh wait, woops, i dont think i meant to say that. infact i was talking a load of crap either way, i was thinking about something else, but that turns out to be the same thing as i said basically.

but put that aside, how can light be effected by gravitational fields?

[slayer]

You'd die before you even got near a black hole.

I watched a really cool documentary on black holes a long time ago. They said your body would stretch out, and for a while it would feel good, then you'd get pulled apart limb by limb...

But this would only happen I think if you were still on earth because of conflicting gravitational pulls.


Black holes are awesome...I want to touch one.

[khh]

but put that aside, how can light be effected by gravitational fields?
The idea is that gravity warps space (or timespace, that is) itself. So that the shortest way for the light to travel no-longer is in a straight line. But when there is as much gravity as a black hole, then timespace is warped back in on itself, in a way, which traps the electromagetic waves inside.

[Bonsay]

No, no, you can get in. You just wouldn't survive the experience. But you - every particle in you, that is - could get in.
I... as in my soul has nothing to do with my atoms. Rather it's the interaction between them which creates me. If I get close, at a certain point I will cease to exist, before I even reach the event horizon. So I stick by my claim - you can't escape, because you can't get in. What does it mean for existence of matter/energy inside the singularity, who knows? It must be something awesomely incomprehensible.

Well, when the gravity no longer is sufficient to keep the remaining mass in a singularity, it's got to expand, doesn't it?
Why? it's infinitely strong. If you take a chunk away, it will still stay infinitely strong.

[khh]

I... as in my soul has nothing to do with my atoms. Rather it's the interaction between them which creates me. If I get close, at a certain point I will cease to exist, before I even reach the event horizon. So I stick by my claim - you can't escape, because you can't get in. What does it mean for existence of matter/energy inside the singularity, who knows? It must be something awesomely incomprehensible.
No, no, I quite agree that your self would cease to exist before you got there.

Why? it's infinitely strong. If you take a chunk away, it will still stay infinitely strong.
No, it's not infinitely song. Every black whole varies in diameter, after how much mass it has. It's just a lot of mass in one place, not an infinite amount.

[slash112]

he said infinitely strong not infinite mass

[khh]

he said infinitely strong not infinite mass
Well, yes, but the gravitational force is determined by the mass, and therefore it cannot be infinitively strong without infinite mass, which it doesn't have.

[slash112]

Well, yes, but the gravitational force is determined by the mass, and therefore it cannot be infinitively strong without infinite mass, which it doesn't have.

but it is also determined by the weight aswell, so say you were to have infinite gravitational feild strenght and infinite weight, you would get a mass of 1.

[Bonsay]

Well, yes, but the gravitational force is determined by the mass, and therefore it cannot be infinitively strong without infinite mass, which it doesn't have.
Then how is it that a singularity is infinitely small and infinitely dense?

[khh]

but it is also determined by the weight aswell, so say you were to have infinite gravitational feild strenght and infinite weight, you would get a mass of 1.
Uh... mass = weight. And you don't have infinite weight.

Then how is it that a singularity is infinitely small and infinitely dense?
Uh, there's a certain point at which the forces inwards (gravity) gets bigger than the forces outwards, and a mass implodes. Beyond that I don't know. I'm not a physicist :p

[slash112]

Uh... mass = weight. And you don't have infinite weight.

uh... mass = weight/gravitational field strength.

you obviously have never done even low level physics in school

and besides, i was saying hypothetically if you had infinate weight, because putting it in the equation gives you 1

[khh]

uh... mass = weight/gravitational field strength.
you obviously have never done even low level physics in school
Yes, that's quite obvious.
Except that when we say "weight" what we really mean is mass. If something weigh 1 kg, that that is it's mass.
edit: What you're talking about is force.
G = m * g
where G is the force, m is the mass and g is the gravitational field strength.

[slash112]

someone get xei in here, im sure he would have something to say about this particular subject.

in science, mass (m) is measured in Kg,
gravitational feild strength (g) is measured in N/Kg
and weight(W) which is the force, is measured in N

mass and weight are completely different things

[khh]

someone get xei in here, im sure he would have something to say about this particular subject.

in science, mass (m) is measured in Kg,
gravitational feild strength (g) is measured in N/Kg
and weight(W) which is the force, is measured in N

mass and weight are completely different things
Oh, we're talking past each other. I've never really heard anyone use the word weight about the gravitational force, but it seems I'm wrong about the linguistics here. English isn't my native language, after all.

[slash112]

Oh, we're talking past each other. I've never really heard anyone use the word weight about the gravitational force, but it seems I'm wrong about the linguistics here. English isn't my native language, after all.

oh, that would make sense. because if you were to be taught english language you would probably be told weight is another name for mass. it is also what kids are told in school before they do physics. infact it is what is used everywhere except in science.

but back to the original point...

m=W/g
so if you had infinite g and infinite W, you would get infinity/infinity=1

which means infinite gravitational field strength doesnt necasirally mean infinite mass

[khh]

m=W/g
so if you had infinite g and infinite W, you would get infinity/infinity=1

which means infinite gravitational field strength doesnt necasirally mean infinite mass
The extended formula is
(γmM)/r^2
In which γ is a constant (value 6.67 * 10^-11) m is the mass of one of the objects, M is the mass of the other and r is the distance between the two. Which means that either m or M, both masses, would have to be infinite.

[slash112]

does (γmM)/r^2 equal g?

[khh]

does (γmM)/r^2 equal g?
No, it equals G. Or the "weight" i guess :p

What are we debating again? Whether or not it would explode if the mass got diminished?

[slash112]

No, it equals G. Or the "weight" i guess :p

What are we debating again? Whether or not it would explode if the mass got diminished?

oh right. and i was taught that weight is W, and i thought that symbols are the same throughout the world, oh well who cares i know what your talking about anyway.

and, i dont know what we were debating, i was just commenting on things people say.

[khh]

oh right. and i was taught that weight is W, and i thought that symbols are the same throughout the world, oh well who cares i know what your talking about anyway.
I've only seen W used about work, in joules.
I thought that G is the symbol used throughout the world :p

and, i dont know what we were debating, i was just commenting on things people say.
Hmm. Well cause if we're debating whether or not it would explode, that formula I just posted would mean that if the particles are actually at the exact same point, then the gravitational forces between them would actually be infinite and they should never be able to part.
Or it just means the formula ceases to work then.

[slash112]

I've only seen W used about work, in joules.
I thought that G is the symbol used throughout the world :p

well where i come from work done in joules symbol is "Ew"

[AirRick101]

They appear bigger than points, as black circles, because light gets sucked into them.

I remember learning this in my Stellar Astronomy class.

[khh]

well where i come from work done in joules symbol is "Ew"
Huh, that's fun. We use Ek and Ep for kinetic and potential energy, but for some reason W for work. That's kinda funny.

[Bonsay]

Uh, there's a certain point at which the forces inwards (gravity) gets bigger than the forces outwards, and a mass implodes. Beyond that I don't know. I'm not a physicist :p
That doesn't explain the infinite gravity.

You said:
"Well, when the gravity no longer is sufficient to keep the remaining mass in a singularity, it's got to expand, doesn't it?"

Gravity is infinite. How can it be no longer sufficient to keep the remaining mass.

[slash112]

Huh, that's fun. We use Ek and Ep for kinetic and potential energy, but for some reason W for work. That's kinda funny.

well i think our way makes more sense lol. no just kidding, im just surprised because i thought it was the same everywhere

and yea we use them for the energies too

[khh]

You said:
"Well, when the gravity no longer is sufficient to keep the remaining mass in a singularity, it's got to expand, doesn't it?"

Gravity is infinite. How can it be no longer sufficient to keep the remaining mass.
Yup, I said that. I might have changed my mind, though. If there's no distance between the particles then the formula I posted earlier says that you've got something divided by zero, which may or may not yield infinity. I can't remember the math for this.
If it does, and if the mass of the black hole is indeed at one, single point with no distance between it (oh, and the formula is correct), then the gravitational forces holding the black hole itself together would be infinite and it would not expand even if it lost mass.

well i think our way makes more sense lol. no just kidding, im just surprised because i thought it was the same everywhere
I think it's supposed to be.

[LucidFlanders]

Thanks guys.

[Licity]

Yup, I said that. I might have changed my mind, though. If there's no distance between the particles then the formula I posted earlier says that you've got something divided by zero, which may or may not yield infinity. I can't remember the math for this.
If it does, and if the mass of the black hole is indeed at one, single point with no distance between it (oh, and the formula is correct), then the gravitational forces holding the black hole itself together would be infinite and it would not expand even if it lost mass.


I think it's supposed to be.

Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.

[slash112]

Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.

i thought it does give infinity. ive seen all the smart ones talk about it on DV.

[khh]

Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.
Yeah, that's possible. I don't know. As I said, I don't really remember that math.

[Bonsay]

Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.
http://en.wikipedia.org/wiki/Division_by_zero


http://upload.wikimedia.org/wikipedia/commons/thumb/4/43/Hyperbola_one_over_x.svg/300px-Hyperbola_one_over_x.svg.png
The function y = 1/x. As x approaches 0 from the right, y approaches infinity (and vice versa).

Neither am I well versed in mathematics. But this is what I think of.

[PhilosopherStoned]

The function y = 1/x. As x approaches 0 from the right, y approaches infinity (and vice versa).


There is a difference between approaching infinity and being infinity. At times, we use the "extended real numbers" or "one point compactification" of the reals, which do include -inf, +inf and inf respectively, but those aren't really relevant in physics, afk.

[PhilosopherStoned]

Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.

This isn't a valid inference anyway. In the extended reals, x/0 is defined to be infinity for all real x != 0. It is possible, within our current models, for bosons but not fermions to occupy the same space. It's refered to as boson condensation. I don't know if this would be possible within the conditions of a black hole. The reason that we say it has infinite gravitational attraction is because the graph looks sort of like the one bonsay pointed. Any time a function "blows up" or goes to infinity then we call it a singularity. Quantum theory is full of them and it is one of the major problems to juggle the mathematics around to make them go away.

[Specialis Sapientia]

This explains my point pretty well.

"However, there are some theoretical circumstances where the end result is infinity. One example is the singularity in the description of black holes. Some solutions of the equations of the general theory of relativity allow for finite mass distributions of zero size, and thus infinite density. This is an example of what is called a mathematical singularity, or a point where a physical theory breaks down. This does not necessarily mean that physical infinities exist; it may mean simply that the theory is incapable of describing the situation properly. Two other examples occur in inverse-square force laws of the gravitational force equation of Newtonian Gravity and Coulomb's Law of electrostatics. At r=0 these equations evaluate to infinities."
http://en.wikipedia.org/wiki/Infinity

In reality, or physics there is no such thing as "infinity". Only because the mathematical proofs allows these theories to include infinity do not mean that theory or model is in fact reality.

When we gave a particle or a black hole zero size it makes sense mathematically, and it seems that these models are appropriate enough to still be useful to science. But I am sure that this "point/zero size" model will get replaced when the opportunity arise.

[Sesquipedalian]

Getting back to the original question, there is a theory (not sure of the name) that what happens in a black hole has to do with perception. From the outside, a person who "falls" into a black hole is destroyed, while the person would perceive themselves to be whole, continuing on their straight trajectory.

Another example, two perfectly synchronized watches are on the wrists of two people. One person (victim) starts to fall into a black hole just before midnight. If the outside person could watch the time on the victim's watch, and the victim is "destroyed" at exactly midnight, the victim's watch would never reach midnight. However, the victim would perceive time to pass as normal.

[Oneironaut]

Getting back to the original question, there is a theory (not sure of the name) that what happens in a black hole has to do with perception. From the outside, a person who "falls" into a black hole is destroyed, while the person would perceive themselves to be whole, continuing on their straight trajectory.

Another example, two perfectly synchronized watches are on the wrists of two people. One person (victim) starts to fall into a black hole just before midnight. If the outside person could watch the time on the victim's watch, and the victim is "destroyed" at exactly midnight, the victim's watch would never reach midnight. However, the victim would perceive time to pass as normal.

Well, from the way I understand it, the victim wouldn't really perceive very much, for very long, because he would be "spaghettified"; in that his body would begin to stretch, once he passes the event horizon, and thin itself out (crushing all of your bones and internal organs).

The observer would see the victim approach the event horizon, and then that person would seem to suddenly freeze in place, and his image would slowly begin to fade away.

[Bonsay]

... in that his body would begin to stretch, once he passes the event horizon, and thin itself out (crushing all of your bones and internal organs).

It starts before it reaches the event horizon. The event horizon is just the point at which light can't escape. Which obviously goes way faster than a human.

[Oneironaut]

It starts before it reaches the event horizon. The event horizon is just the point at which light can't escape. Which obviously goes way faster than a human.

Correct. I worded that wrong. :oops:

(Was hammered last night. Heh.)

[Xei]

Note that black holes don't have infinite mass, by the way.

The strength of gravity is proportional to 1/r^2, where r is the distance between you and the centre of gravity of the object. The thing about the actual mass of black holes is that it's condensed into a point with pretty much 0 volume: therefore, as you can get arbitrarily close to the centre of gravity, the gravitational field strength will tend to infinity.

The boundary of a black hole is just where light can't escape, not the boundary of its mass. Most people are aware of the idea of escape velcocity. This is the minimum velocity you'd need to travel to never fall back to a massive body, such as Earth. You can work it out by equating kinetic energy and potential energy,

1/2 mv^2 > r*GMm/r^2
so v > sqrt 2GM/r

the thing with the event horizon is that sqrt 2GM/r is so large that the escape velocity is greater than the speed of light, and as nothing can travel faster than light, nothing can ever escape.

[Specialis Sapientia]

Black hole = Finite mass and Zero volume

This gives us infinite density and a gravitational singularity.

Of coarse I stress again, mathematically and not in reality.

[Lord Bennington]

*headwall*

infinity/infinity=/=1

It's undefined.

infinity=2infinity, right?

divide by infinity

2=1? No, because /infinity is undefined.

For the record, even though we've WAAAAAAAy passed the point when someone divided by infinity in a proof.

[slash112]

*headwall*

infinity/infinity=/=1

It's undefined.

infinity=2infinity, right?

divide by infinity

2=1? No, because /infinity is undefined.

For the record, even though we've WAAAAAAAy passed the point when someone divided by infinity in a proof.

good point.

and i take it you're talking about when i divided by infinity earlier on

[Xei]

Dividing by infinity is normally fine, but dividing infinity by infinity is certainly not and requires a thorough analysis of the situation before an appropriate answer, if any, can be given.

[slash112]

can i just ask a slightly related question which would be pointless to make a whole new thread about.

im talking to this guy on the internet, and he is saying that gravity travels at the speed of light. i am saying that gravity doesnt travel at all because its a force.

which one of us is right? or are we both wrong?

[Specialis Sapientia]

can i just ask a slightly related question which would be pointless to make a whole new thread about.

im talking to this guy on the internet, and he is saying that gravity travels at the speed of light. i am saying that gravity doesnt travel at all because its a force.

which one of us is right? or are we both wrong?

In short, yes gravity travels at speed of light.

Part of explantion here: http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html

[Sesquipedalian]

I have heard that the 11th dimension is the source of gravity, and we are affected by leaks from that dimension. (possibly why gravity is the weakest fundamental force)

The speed of light is also the "speed limit" for this universe, right?

One more, what about wormholes? I have seen some places that describe them as black holes connected to another point in the same universe or to another universe.

[slash112]

In short, yes gravity travels at speed of light.

Part of explantion here: http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html

ah, thanks, that helps me for my arguement (even thoguh i was wrong, that wasnt the point i was trying to make)

[Licity]

I have heard that the 11th dimension is the source of gravity, and we are affected by leaks from that dimension. (possibly why gravity is the weakest fundamental force)

The speed of light is also the "speed limit" for this universe, right?

One more, what about wormholes? I have seen some places that describe them as black holes connected to another point in the same universe or to another universe.

I think that's what M-theory says about gravity, the more widely-accepted theory of GR states that gravity is the result of matter and energy bending spacetime. Light speed is the upper limit on speed in the universe. No one knows for sure exactly why it is the strange number it is, but the very short answer to why you can't exceed it is because it takes infinite energy to raise mass to the speed of light, let alone exceed it.

Wormholes are not known to exist, but are valid according to GR.

[Posquant]

But if you had a soul, immaterial and not squishable like your body ... it could pass through ... to another universe.

[Licity]

But if you had a soul, immaterial and not squishable like your body ... it could pass through ... to another universe.

The question is, are souls subject to spacetime curvature?

[Posquant]

Egyptians said we have several souls.

Not all of same density.

http://www.kheper.net/topics/Egypt/egyptian_soul.htm

Maybe some would get squished? Peeled? No fun.

I sometimes imagine the interstitial spaces crowded with all these lost souls, victims of failed transits, traumatic ejections, painful separations.

Imagine, assume you have a soul, if you were burned at the stake, burned alive, like a back in the day. What would happen to your soul? If I was a soul, I might not stick around.

Ugh.

PQ

[Jookia]

Your atoms get smeared onto the black hole's ring.

[Sesquipedalian]

Well, the black hole has no ring around it, unless you count matter orbiting at near light speed a ring. A black hole is an unimaginably dense ball. (ex.: a black hole with the mass of the earth, I think about 17 septillion tons, would be about the size of a player marble [the small marbles that you hit with the shooter] For simplicity, a black hole can be described as an infinitely small point that acts as a matter drain.) To give you another idea of how dense this is, a white dwarf star is a super dense star. One tablespoon of a white dwarf star, subjected to 1 G, would weigh 1000 pounds. A black hole is MANY more times as dense. (often considered infinitely dense)

[RedfishBluefish]

Technically I don't think black holes would actually have 0 volume (ie. be a singularity). Because for us looking from the outside, as all the particles of the black hole get closer when it implodes under gravity, time would slow down by the increasing local gravity in the black hole. So eventually the black hole would look like it was frozen with some finite but extremely small volume. Or it would if we could see through the event horizon haha. Of course this depends whether time slows down enough under gravity to offset the increasing acceleration of the particles under that gravity.

[Vampyre]

Although I'm not an expert by any means, I'll mention a couple things I've seen about black holes that might clarify some things.

A black hole is a point, of an unknown size, and has a very powerful gravitational force, strong enough to bend light. It has an event horizon, which is the distance from the black hole at which point, the gravitational pull is so strong that light can no longer move away from the black hole. It is black because it has no light or colour emitting from it.

Current technology has no way of observing what happens within the event horizon. All we can observe is what happens outside the event horizon. Because of this, it is uncertain what happens within the event horizon. However, because of the strength of it's gravitational pull, it's assumed that it compresses anything that enters it to singularity.

Because it's unobservable and we don't know for certain what happens, the creative mind invented the wormhole: a passage between black holes or dimensions. However, this is quite unlikely, since the gravitational pull is strong enough to break anything we know exists and the mass of the black hole increases as things enter it. This is why, disregarding the gravity, it is unlikely for a wormhole to exist, because we can tell that some part of the things that enter it remain there.

As for its effects on a soul ... I won't get into that.