Blackhole Definition and 125 Threads

Let's say Bob falls into a blackhole, and Alice is sufficiently far away that she is not falling in. She sees Bob's clock stop and his image fade away and all that. However, from Alice's perspective Bob never actually crosses the horizon. From her perspective, Bob is sitting frozen and invisible...

From what I understand about time dilation and the relativity of simultaneity; if we imagine two people near a black hole and one of them begins to approach the black hole on a trajectory that crosses the event horizon. The stationary observer will never see the moving observer enter the black...

I was wondering if someone can help explain to me what is happening in the image. Black holes have Light paths or something so i read here more accurate description is that within this horizon, all lightlike paths (paths that light could take) and hence all paths in the forward light cones of...

Has anyone else heard of that gravity waves may be the result of another type of supernova remains, called a Grav-Star? It seems almost to physically mimic a neuron star but stopped just shy of becoming a black hole, yet it still has enough of a gravity well to prevent light from escaping. Is...

Hello physics forum. I am not very well versed in physics, so this question could be a misfire, but I just wanted to clear this up. I watched one of Susskinds holographic principle lectures. So I get that Bob would see Alice turn into a hot mush of energy as she approaches an event horizon...

Yesterday, I attended the following presentation by Prof. Andrea Ghez. https://www.meetup.com/physicists/events/236886090/?gj=co2&rv=co2 In the Q&A session towards the end, there was a question she fumbled to give a proper answer. She mentioned that as long as the mass is compressed into...

So, a black hole has infinite gravity that even light can't escape from it, my question is, the gravitational field of a black hole can even pull light into it, then it means it is even faster than light, if not, light can escape from it. Does this argument make any sense, please tell me! thanks

When somebody crosses the horizon of a black hole, the person would have the privilege to travel backwards in time (as shown in the movie 'Interstellar'). What are the possiblities of such a person to even survive after getting in a black hole, and how does he even able to travel in the past...

If you fall into a black hole, that what is closer to the singularity, will fall faster that than what is further. However, space before and after you, is falling in with you. So from each General Relativistic perspective of "you", because there would be no inertial frame to orient yourself (you...

Homework Statement The radius Rh of a black hole is the radius of a mathematical sphere, called the event horizon, that is centered on the black hole. Information from events inside the event horizon cannot reach the outside world. According to Einstein's general theory of relativity, Rh =...

Is light can escape from Blackhole ??

Does this imply that we are looking at wormholes?

Do black hole singularities have 0 volume? What forces are keeping the particles from being in the same place?

Do black holes have an internal space? Consider the diagram. Inside the negative space, a "bubble" of sealed space, matter is free to move. https://dl.dropboxusercontent.com/u/109630018/temp/phys/blackholein.jpg

Homework Statement The problem is to calculate the temperature of a one solar mass black hole Homework Equations S = \frac{8\pi^2GM^2k}{hc} E = Mc^2 \frac{1}{T} = \frac{\partial S}{\partial U} The Attempt at a Solution [/B] My first solution I pulled out an Mc^2 Which left my...

I'm very new to the understanding of Hawking Radiation. I don't know much about this theory, but I do know that Hawking radiation works on a Quantum scale. I know that with black holes this theory proposes th idea that over time black hole lose mass because of "Spontaneous appearing positive and...

I understand that the coordinate system (CS) for a distant observer Od is different than that for an observer Of who is falling radially toward the event horizon of a non-rotating black hole (BH). Using the Schwarzschild metric, I would like to understand the transformation equations that...

Just a question originating from pure curiosity. But what would happen if we had a large ring in outer-space, akin to the ring world in the game "Halo", so massive that it's minutes from collapsing into a black hole. If it were to uniformly gain mass on all parts of its structure, how...

If you square both sides of the gravitational time dilation function for non-rotating spherical bodies, do you not get a "time travel function" that allows you to travel back in time with a massive enough body like a black hole?

I'm just wondering if a spacecraft or any kind of matter was swallowed by a black hole , where does the debris go? I know that it will disintegrate, but even the gravity in there is very strong will there be debris left? If there is, Will it go to other dimension or what? Thanks, Austin

Alrighty, this is my second attempt at this thread, as my first was removed due to speculating theories so i will try to keep this short and clear. Is it possible to apply the concept of Wave/Particle duality to explain the event horizon paradox in which a particle can cross the horizon in a...

For example a black hole is stable. As in Ts=Tu then what would be the uses of the BLACKHOLE. Would it have any such use ?

In my thought experiment (it seems that others have asked a similar question, but I have a more specific question in my list below), we have a physicist outside the event horizon of a black hole. He has many entangled particles and sends some into the black hole. Is / Could there be some...

I have always wondered various questions, out of which these 3 below are on the priority list including a previous topic I questioned here ofcourse without any answer to it. I am no science guy by the way, just curious! So the questions are: 1. Can a black hole contain a wormhole inside of it...

Let's imagine say, a spaceship is going through space at 99% the speed of light. Relativity says (to my understanding) that as the spaceship increases in speed it's mass will increase and it shall also get slightly shorter. Let's assume that energy isn't a problem, should the spaceship continue...

In many vortex's, the center has low pressure, from the center of a stirring cup of tea to the centere of a hurricane or storm system. I'm trying to crudely model how this might apply to the center of a spiral galaxy. If the behavior is similar, and the center has a low pressure void...

What is the most general method of obtaining the event-horizon from the given black hole metric. Let us consider Kerr black hole in Kerr coordinates given by ds^2 = -\frac{\Delta-a^2sin^2\theta}{\Sigma}dv^2+2dvdr -\frac{2asin^2\theta(r^2+a^2-\Delta)}{\Sigma}dvd\chi-2asin^2\theta d\chi dr +...

Let's start off with what we know about black holes; It is formed through a colossal explosion of a star. So, I want you and your silly little friends that work in the Physics department to think about this deliberately: The Big Bang tells you that the universe was formed through a explosion...

say you fell beyond the event horizon of a black hole can another black hole passing close enough pull you out?

I know this is far from what a strict obeyance to the principle of occoms razor may result in and its probably wrong. is it theoretically possible that as a star contracts to result in a black hole, the contraction does not stop when its just a point hole, but continues, expanding in a negative...

I have this crazy and goofy dream to construct an artificial black hole. Not a crude analogue, but the actual astronomical object. Would that entail using a particle accelerator to accelerate particles to huge velocities, gaining mass, and then smashing together and then turning into a black...

Hawking said that the horizon area of a black hole never decreases and illustrated that in his Hawking Are Theorem: dA/dt ≥ 0 Does anyone know why is it like that. Why doesn't the area decrease?

How fast do we expect the hypothetical graviton to travel? It seems that if the graviton were to mediate the gravitational force then it wouldn't be subject to the normal FTL rules otherwise black holes would have no gravitational effect on the rest of the universe. What's the current...

Would it be possible for the universe to exist as a white hole within a black hole? I know about the whole black hole universe theory, though I never really looked into it.

Why does time stop in the event horizon of a black hole? Or at least slow down, from what i know.

Can someone help me on this: Hawking Bernstein radiation can cause a BH to evaporate. The second law of BH dynamics says that the area of the event horizon cannot decrease. Isn't this a contradiction? Also when considering the size of the event horizon, is it different depending on wheather...

Hello everybody, this is my first post to the forum. I am trying to learn concepts in physics at the moment. According to the theory, the concentrated mass of a black hole warps space-time so much, that not even light can escape the event horizon. I have a thought experiment. Say, half the...

first, what I know about black hole is; It has so much mass that collapse into itself create gravity field so strong that even light can't escape. and normally, black hole born only in giant star explosion. but what 'IF' normal rocky planet happen to collect mass (by asteroid, gas or...

Are there any cool simulations of an object traveling into a black hole from the objects point of view? Thanks.

Has anyone studied the effects of the central black holes in the galaxy's, on the rotation of the galaxy's spiral arms. When the black hole spins, do the stars in the surrounding galaxy spin in the same direction, does the speed of the spinning black hole affect the rate of rotation in the outer...

Its said there up on the universe, black hole which even can trap the whole light entering through it, exists. But if anyone, I mean any living things, trapped there...I'm confused how can they go beyond the black hole...or will be they trapped, if so what happen their bodies?

Singularity Spin Mechanics Okay I within the last week too a look at a article about black hole spin and in this article it was said by a scientist that black hole's spin near the speed of light that are supermassive blazars I was thinking if a object is spinning wouldn't that make this...

destroy a Blackhole? !? http://arxiv.org/abs/1304.6592 What the? I nominate this for the most outlandish arxiv article I've seen yet lol. I couldn't think of which forum to post this but its definitely is worth laughing about.

Does the mass of a black hole remain the same if it is not "feeding"? If matter in a black hole keeps crushing down in size to infinity, does the mass stay the same, but the volume decreases? Isn't a black hole constantly shrinking in size? Thanks in advance for the help!

hi guys, i have an elementary question about the black hole..recently i have read in a science magazine that even the lights from other stars can not reach to the black hole ( event horizon) rather bends in other direction due to its gravitational force..now my question is if i point a light...

Hello, New to this forum. Very fascinated with physics. Started as a fascination with waveforms, sound, acoustics, and quickly spiraled into an infinite fascination with physics in general, specially particle physics at a quantum level and general relativity at a cosmic level and nuclear...

From a GR perspective, how does the event horizon of a black hole know how to behave? Consider a simple scenario of a shell of material outside the event horizon of a black hole, in free fall. Once the material is consumed by the black hole, the event horizon will be greater, but my...

Hi, This is my first post and first of all I would like to thank all the contributors to this forum for the amazing amount of information provided here. I’m not a physicist, but I like physics (although I have only a qualitative understanding of it) and I like to smash my brain on difficult and...

Thought this article may spark some interest if it works out we may gain a better understand of BH's. http://www.sciencedaily.com/releases/2013/01/130130132324.htm

Ok I am wondering what would happen if an anti-black hole collided with a black hole of the same mass. Would they annihilate and release energy or would it become a more massive or less massive black hole?