Curse

Winterclaw · Mar 03, 2009, 10:20 PM // 22:20

Okay, a black hole is supposed to be something that has a gravity field so powerful that light cannot escape from it.

However that got me to thinking. C is supposed to be the absolute speed limit in the universe. That should mean that the max pull of gravity can only be C. However gravity has an inverse squared relationship in terms of strength vs distance. That would be that strong at the center of the black hole.

So my first question is, if I threw a led light that was pointed at me into a black hole, if the led light turns on one inch away from the black hole, I should be able to eventually see the photons correct?

Second question: since there is a limit to the pull of gravity, wouldn't a black hole have to have an internal pressure equivalent to C? Meaning shouldn't there be enough pressure to push something outwards at C?

Since there is a limit to G, how is it we can have normal black holes, where there is a G that is equal to C, and a super massive black hole?

In a slightly related question: shouldn't a hypothetical warp drive be impractical for FLT travel because I can only warp 1 light second of space towards me every second? I mean you can't pull space towards you faster than C, and then you'd still have to travel across that shortened distance.

Giga Strike · Mar 03, 2009, 10:38 PM // 22:38

Things aren't pulled by speed. They are pulled by a force. Speed is limited, but force is determined by more than just speed. Say that I have a cart moving at 100 mps with a weight of like 10 grams (or whatever the basic unit is) and it collides with another cart moving at the same speed but weighed 20 grams. The heavier one would have a greater force and would push the other back even though they are traveling at the same speed.

That was probably a horrible example, but whatever.

I guess what I'm saying is that it would slow down the light or redirect it to the point that it started going the other way.

Actually, imagine this: you have +10 health regeneration. Some necro then comes along and piles hexes on you with a combined total of -12 health degen. The degen would negate you regen and you would then be losing health at a rate of -2 as the only limit is what the rate at which you lose or gain health (+/- 10). The degen would be able to go beyond 10 because of the regen that prevented it from hitting the max.

Black Metal · Mar 04, 2009, 12:21 AM // 00:21

1st question: from what I understand, you mean the event horizon (the physical black hole is much smaller, but there's a surrounding sphere from where the speed of light can't escape. It's sort of like the escape velocity from earth. So, if your LED is outside the event horizon, you should be able to see it.

2nd question: I believe that a black hole's internal pressure isn't easily defined in Newtonian phsyical terms -- Newtonian physics break down inside black holes, as the four forces are at such high energy that they unify (there well may be more dimensions involved too). I think that string theory defines this better, not simple Newtonian concepts like pressure.

poobert · Mar 04, 2009, 06:07 PM // 18:07

Gravity is an acceleration, dv/dt. Even if v has a maximum, it does not put a limit on g. I think that answers most of your questions.

Second, the metric expansion of space is actually larger than c. Even though accelerating to c is not possible, it holds no meaning when talking about space itself. I suppose if you could manage to bend space however you liked, there would be no reason to limit the rate at which you could do it.

I don't quite understand the pressure question.

Kattar · Mar 04, 2009, 06:10 PM // 18:10

Quote:

So, if your LED is outside the event horizon, you should be able to see it.

This is correct, iirc. It's easy to see the event horizon, since it's really bright, then there's nothing.

zwei2stein · Mar 04, 2009, 08:03 PM // 20:03

Quote:

Originally Posted by Winterclaw

Okay, a black hole is supposed to be something that has a gravity field so powerful that light cannot escape from it.

However that got me to thinking. C is supposed to be the absolute speed limit in the universe. That should mean that the max pull of gravity can only be C. However gravity has an inverse squared relationship in terms of strength vs distance. That would be that strong at the center of the black hole.

So my first question is, if I threw a led light that was pointed at me into a black hole, if the led light turns on one inch away from the black hole, I should be able to eventually see the photons correct?

Second question: since there is a limit to the pull of gravity, wouldn't a black hole have to have an internal pressure equivalent to C? Meaning shouldn't there be enough pressure to push something outwards at C?

Since there is a limit to G, how is it we can have normal black holes, where there is a G that is equal to C, and a super massive black hole?

In a slightly related question: shouldn't a hypothetical warp drive be impractical for FLT travel because I can only warp 1 light second of space towards me every second? I mean you can't pull space towards you faster than C, and then you'd still have to travel across that shortened distance.

0) First, speed is not unit of force, you cant affect anything by force equal to "c" that is (wtf?). Anyhow, Force does not have limit. Gravity pull of black hole depends on its mass, which can be infinite. That is what makes black holes "work".

1)Yes. But only those that get out of in cone whose axis traverses center of black hole. angle of cone depend on distance from horizon. The closer the smaller, being exactly 360 in infinity and 0 at zero distance and *negative* under horizon (thats, nothing gets out.).

2) C, a speed of light is not even unit of pressure. (wtf did you mean with pressure anyway?). BH does not have "pressure" inside that we know off. It is empty except singularity, which is point with zero dimensions, anything getting under horizon is sucked to that point and destroyed.

3) Super massive black holes are normal black holes, except for mass which is super bigger. bigger mass translates to larger event horizonths, nothing more, nothing less. Nothing else "exotic".

Stop comparing incomparable things! Stop misusing c to grade things that not speed!

Winterclaw · Mar 04, 2009, 10:52 PM // 22:52

0. The force of gravity as I've seen it sometimes gets expressed in terms of FPS or MPS. In other words shouldn't the limit of that pull top out at C, that you can't pull something to you faster than that?

2. In terms of pressure, what I'm trying to imagine is that then in order for a black to remain a point in space, no matter how small, there must there must be some kind of internal pressure (force) pushing outwards equal to the gravity pulling inwards.

Since F = M*A, A must be equal to C. Now because A has an absolute limit and as you approach that limit M approaches 0, it stands to reason that the maximum force anything can exert, including gravity and black holes, is also capped out.

If a black hole exists, it has to take up at least a little bit of space, even if that amount of space is as small as the smallest particle. Now if it has zero dimensions as you suggest, how can be be sure it even exists at all? Likewise, energy can't be destroyed and it has to take some form and there has to be mass/energy in order for it to have gravity. Likewise if all the mass is destroyed, then there should be no mass within it. If a black hole has no mass, it can't have gravity because gravity requires mass in order to exist. You can't have nothing that produces something, that's a physical impossibility. You have to have something there in order to produce it. You have to have something there creating the gravity because gravity doesn't exist on it's own.

3. Since there is a limit to speed and force, and a standard black hole meets those definition, a supermassive one makes no logical sense. You've met the known limit to things such as force and gravity with a standard black hole so a bigger one can't exist.

BTW, I'm not misusing C because 1. there probably is some unified theory that equates all things such as light, mass, gravity, etc. 2. C is a component of force (gravity) which has a stated limit. The only way to increase force is to either increase mass or acceleration. However you can't increase C past a certain point and as you get too close to that point, you start decreasing M until it hits zero. Thus C is intrinsically connected to things such as force and gravity. It represents not just a limit to speed, but a limit to everything.

poobert · Mar 04, 2009, 11:26 PM // 23:26

Quote:

Originally Posted by Winterclaw

0. The force of gravity as I've seen it sometimes gets expressed in terms of FPS or MPS. In other words shouldn't the limit of that pull top out at C, that you can't pull something to you faster than that?

Gravity is expressed as an acceleration. Not a speed. eg g =9.81 ms^-2.

The rate of change of velocity has no limit unlike the velocity, which is capped at c. Hence a force can technically be as large as it likes. The force however will never be able to accelerate anything past the speed of light because an infinite force is required to reach it.

the mass of an object = rest mass times the lorentz factor. As F=ma as v increases, m increases. As v tends to c, m tends to infinity. Hence F must go to infinity in order to keep on accelerating it.

This is why c is the upper bound for velocity. As the force tends to infinity, the speed can never exceed c. This is how c ties in with force/acceleration. It does not create a limit for acceleration. It just defines what that acceleration can do.

Quote:

2. In terms of pressure, what I'm trying to imagine is that then in order for a black to remain a point in space, no matter how small, there must there must be some kind of internal pressure (force) pushing outwards equal to the gravity pulling inwards.

Probably a force resulting from the pauli principle (the same thing that prevents two electrons from existing on top of each other).

Quote:

Since F = M*A, A must be equal to C. Now because A has an absolute limit and as you approach that limit M approaches 0, it stands to reason that the maximum force anything can exert, including gravity and black holes, is also capped out.

A is not equal to C. C is a velocity. A is an acceleration.

Quote:

If a black hole exists, it has to take up at least a little bit of space, even if that amount of space is as small as the smallest particle. Now if it has zero dimensions as you suggest, how can be be sure it even exists at all?

Black holes occupy a finite space. I think they are mostly the size of the moon.

Quote:

. Since there is a limit to speed and force, and a standard black hole meets those definition, a supermassive one makes no logical sense. You've met the known limit to things such as force and gravity with a standard black hole so a bigger one can't exist.

Limit to speed. No limit to force. Super massive black holes make perfect sense.

Quote:

2. C is a component of force (gravity) which has a stated limit. The only way to increase force is to either increase mass or acceleration. However you can't increase C past a certain point and as you get too close to that point, you start decreasing M until it hits zero. Thus C is intrinsically connected to things such as force and gravity. It represents not just a limit to speed, but a limit to everything.

LRN2DIMENSIONALANALYSIS

Let me try dumbing it down a bit. Lets say we accelerate something from standing to 60 miles per hour. There is no limit to the rate at which we can do this (dv/dt has no upper bound). This rate is acceleration. There can be an acceleration greater than 2.99x10^8 m/s-2 and it is not forbidden.

wheew I'm tired. Hope that helps. I am going to sleep

zwei2stein · Mar 05, 2009, 07:34 AM // 07:34

Quote:

Originally Posted by Winterclaw

0. The force of gravity as I've seen it sometimes gets expressed in terms of FPS or MPS. In other words shouldn't the limit of that pull top out at C, that you can't pull something to you faster than that?

2. In terms of pressure, what I'm trying to imagine is that then in order for a black to remain a point in space, no matter how small, there must there must be some kind of internal pressure (force) pushing outwards equal to the gravity pulling inwards.

Since F = M*A, A must be equal to C. Now because A has an absolute limit and as you approach that limit M approaches 0, it stands to reason that the maximum force anything can exert, including gravity and black holes, is also capped out.

If a black hole exists, it has to take up at least a little bit of space, even if that amount of space is as small as the smallest particle. Now if it has zero dimensions as you suggest, how can be be sure it even exists at all? Likewise, energy can't be destroyed and it has to take some form and there has to be mass/energy in order for it to have gravity. Likewise if all the mass is destroyed, then there should be no mass within it. If a black hole has no mass, it can't have gravity because gravity requires mass in order to exist. You can't have nothing that produces something, that's a physical impossibility. You have to have something there in order to produce it. You have to have something there creating the gravity because gravity doesn't exist on it's own.

3. Since there is a limit to speed and force, and a standard black hole meets those definition, a supermassive one makes no logical sense. You've met the known limit to things such as force and gravity with a standard black hole so a bigger one can't exist.

BTW, I'm not misusing C because 1. there probably is some unified theory that equates all things such as light, mass, gravity, etc. 2. C is a component of force (gravity) which has a stated limit. The only way to increase force is to either increase mass or acceleration. However you can't increase C past a certain point and as you get too close to that point, you start decreasing M until it hits zero. Thus C is intrinsically connected to things such as force and gravity. It represents not just a limit to speed, but a limit to everything.

0) difference between m*s^/-1 and m*s^/-2 is huge. they are totally different things. lets do unit-proof:

m*s^-1 = m*s^-2 | divide by m
s^-1 = s^-2 | multily by s^2
s = 1

Congratulations, in your universe time is universal constant! Nothing can ever happen!

2) It is already compressed to singularity. you can't get anything less unless mass starts to disappear ... and it can't (conservation of energy from thermodynamics.).

A - acceleration. C - speed. A can not equal to C.

(hint, if maximum force was capped, nothing would ever be able to reach speed of light - yet some things are naturaly at speed to light.)

It still can interact with surroundings and form observable artifacts - like horizon which people againt and again mistake for hole itself. Mass is not destroyed, it is still there (hence effects on surroundings).

3) supermassive is just a normal, but big black hole. really. the only difference is that supermassives are generally in centers of galaxy with huge acretion disks which means that we can observe them over large distances, unlike normal black holes which we can't detect well outside our galaxy.

You you do misuse, unified theory unifies what can be unified. different types of base interactions. not mass, speed and acceleration. if it has different unit, it can not be unified unless you can prove those units are equal. GL with that, crackpots were trying for 100 years.

imnotyourmother · Mar 05, 2009, 08:14 PM // 20:14

WOW what great theories. One great person said that in science a Theory is better than fact? They used this to try and prove that God does not exist because of the theory of evolution is a theory. boy oh boy.

SO let us go back to the question if you can stretch out space or the heavens if you will.

Now GO EASY on me. It will be scary I know. OPEN your mind not jump all over me as I present THE FACTS...

The Hubble tellescope is used to measure the universe and map it. The hubble was directed to the edge of the known universe and then moved off so that it could calculate the rate of expansion of the universe. So they calculated a spot to focus the telescope where the universe WAS NOT and took a picture for a point of reference.

THE Telescope found that the and I quote "Universe was STRETCHED" is the exact phrase used. They could not explain it in mathematical terms.

I how ever found the answer...the bible says that the LORD stretched out the heavens so there is your answer. The bible says that with GOD nothing is impossible.

So I say tell me how the worlds tallest trees - 900 feet or more - get nutrients to the upper most parts. Science can not answer this as the pressures needed would split the bark and the tree should die.. but there the tree is standing right in front of me. Science can not explain it but I can touch it.

So the answer has not yet been reveiled to us.

Rhamia Darigaz · Mar 05, 2009, 08:51 PM // 20:51

itt: op acts as if force has dimensions length/time
troll?

Winterclaw · Mar 05, 2009, 09:15 PM // 21:15

Not a troll, just curious about the subject.

Zwei, are normal black holes and super massive the only two kinds there are?

And since I'm asking "stupid" things, I'll ask another that's related to gravity. Supposedly, if you look at all of the visible mass in the universe, you won't get everything needed to account for all of the observed gravity. Now a number of people have called the missing matter dark matter in order to make up for the extra gravity. What I'm curious about is that is this the only hypothesis that has been considered or if anyone has thought maybe our knowledge of gravity is off.

poobert · Mar 05, 2009, 10:27 PM // 22:27

Gravitational models are very good. Much more than people realize. That is why for a given set mass, the total force of gravity is very accurately calculated.

But it is very likely that the total mass estimates of the universe are off rather than our knowledge of gravity. In fact I would say they are very off. Because you can't see all the universe from Earth, you have to use the fact that the universe is isotropic (the same in all directions). Then you can get an average density of the universe and scale it up. (actually it gets a bit more complicated).

The stuff that is there but you can't see throws it off even more. I suppose the ultimate test of current theories of quantum gravity is to find the higgs boson (what they wanted the hadron collider to do).

By the way. I actually agree with notmymother. God did it. Everything above is inspired by the devil.

second edit. Now that you mention it, I am curious about this too. I shouldn't have dropped cosmology. Our knowledge of gravity is pretty damn good when it comes to predicting the slight oscillations in a star on the other side of the galaxy, but for the structure of the entire universe?

MisterB · Mar 06, 2009, 12:00 AM // 00:00

I was under the impression that our understanding of what gravity does, the effect, is rather well understood, but not the cause. I've yet to see an actual definition that does not simply describe the effects of gravity.

Black Metal · Mar 06, 2009, 04:20 AM // 04:20

Gravity is well understood in a Newtonian sense, but gravity on a quantum level is not. Gravity is well modeled above quantum levels, but below that, it's not been unified with the other forces. String theory attempts this, but it's so complex, untested, and incomplete that it's just not there yet.

For all but the most extreme cases (quantum level, black hole type densities and extreme spacetime warping), Newtonian gravitational concepts are virtually perfect.

zwei2stein · Mar 06, 2009, 08:10 AM // 08:10

Quote:

Originally Posted by Winterclaw

Not a troll, just curious about the subject.

Zwei, are normal black holes and super massive the only two kinds there are?

And since I'm asking "stupid" things, I'll ask another that's related to gravity. Supposedly, if you look at all of the visible mass in the universe, you won't get everything needed to account for all of the observed gravity. Now a number of people have called the missing matter dark matter in order to make up for the extra gravity. What I'm curious about is that is this the only hypothesis that has been considered or if anyone has thought maybe our knowledge of gravity is off.

Again, they are the same, jut bigger numbers. There are other theoretized things like kugelblitzes, black holes made from energy, but that does not really matter because once it forms, its just another good old black hole as energy is basically different kind of mass. E = mc^2 and stuff.

About dark matter, it is only one hypothesis, but from evidence most likely one. And yes, everything is questioned because if we apply our models universe-wide it can be revealed that we could have missed something that won't show in lower scale applications.

I wonder, are you trying to write sci-fi stuff or something? Writers always have these kids of weird questions.

Quote:

So I say tell me how the worlds tallest trees - 900 feet or more - get nutrients to the upper most parts. Science can not answer this as the pressures needed would split the bark and the tree should die.. but there the tree is standing right in front of me. Science can not explain it but I can touch it.

Worlds tallest tree is 380 feet. And we very much understand how it works: Nature, issue 428, pages 851-854. (thank my biologist buddy!)

Anyhow, we thought we do not know how bumblebee could fly, but eventually found out.

Anyhow, better be content with lack of answer and keep looking for it than just cowardly use one-size-fits-all answer. Better be able to shred wrong answer when confronted with contradictory facts and start looking for new one than keep at it.

Fril Estelin · Mar 06, 2009, 08:43 AM // 08:43

Winterclaw: I won't (yet) provide hints at answers, but just want to mention that the answers to your questions are quite far from "common sense" (as in "we're going to look at this problem as if I was standing in front of the black hole with my torch light"), they require mathematical equations and deep understanding of advanced physics (which I don't have, but I have enough baggage to help and get a rough understanding answers from experts). For example, C is not an absolute limit as you can see from the wiki page:
http://en.wikipedia.org/wiki/Speed_o...nd_experiments

But as you can see from the wiki page, we need to get quite far from "common understanding" of physics, and delve deeper into the theoretical constructs (particle, wave, etc.).

Winterclaw · Mar 06, 2009, 09:04 AM // 09:04

Quote:

I wonder, are you trying to write sci-fi stuff or something? Writers always have these kids of weird questions.

When I do write sci-fi, it isn't about black holes and isn't the hard type of sci-fi. I think I'm curious about it because I've always wondered if Relativity fails to explain things past a certain point like newtonian physics fails past a certain point.

Fril, I've heard about that one experiment with the gel but in general light has its limits.

Fril Estelin · Mar 06, 2009, 09:23 AM // 09:23

Quote:

Originally Posted by Winterclaw

Fril, I've heard about that one experiment with the gel but in general light has its limits.

Yes because photons have a mass.

Re-reading your OP: "I mean you can't pull space towards you faster than C", yes you can, see how the galaxies do it the wiki link (and this is how quantum computer scientists hope to use particle entanglement too).

I don't know if you've come accross that wiki link too:
http://en.wikipedia.org/wiki/Black_h...black_holes.3F

zwei2stein · Mar 06, 2009, 11:36 AM // 11:36

Quote:

Originally Posted by Fril Estelin

Yes because photons have a mass.

And because they carry information.

Anything that has either mass or carries information cannot exceed speed of light.