Black holes Definition and 1000 Threads

From another post on this forum, we have an excerpt of Susskind's "The Black Whole War": To figure the increase in mass, let's figure the energy of the photon and then convert that to an equivalent mass. Photon energy is E = hf and if wavelength is R[sub]s/SUB], from v = f x...

Hi every1 My question is: we know nothing travel faster than light. Gravity travel at the speed of light, right? Now: light cannot escape from a black hole. So: gravity cannot escape from a Black Hole. Then... why can we feel the gravitational field of a black hole if gravity cannot be...

Locally, photons "blue-shift" when falling down a gravitational field. What happens when they arrive at the Planck frequency? Do they turn back into matter?

I know we haven't yet discovered that a technicolour force actually exists, but it seems to be worked out to some extent mathematically? (Not to say there hasn't been a false alarm, or two) I'm just curious that if it did end up existing, has the math been worked out far enough to see if it...

I'm pretty ignorant about astrophysics, but this made it into the newspaper today, and it seemed interesting. http://arxiv.org/abs/1106.3079 "Black hole growth in the early Universe is self-regulated and largely hidden from view," Treister et al. "The formation of the first massive...

I was wondering if black holes are insanely hot, my guess is they are because so much matter has been crushed together causing friction and energy. Is this right? Thanks. PS: if it's something a 14 year old wouldn't understand, please give me a url link to wikipedia where I can study it...

Hello! I'm redesigning my never-to-be-finish sci-fi novel, yet another futile to come up with scientifically based interstellar travel propulsion. My latest consideration is based on article[1] and possible extensions of those ideas. Anyway, I'm looking for an independent opinions on the...

Here's an idea I came up with recently, that I wanted to share: Physics is unitary and CPT symmetric, and therefore no true black holes exist, since they imply information loss and non-reversibility. Every "apparent" event horizon is really a separation of two mostly causally disconnected...

Here's an idea I came up with recently, that I wanted to share: Physics is unitary and CPT symmetric, and therefore no true black holes exist, since they imply information loss and non-reversibility. Every "apparent" event horizon is really a separation of two mostly causally disconnected...

Black holes suck in everything around them. My 5 year old knows that one. It's all over TV, etc. But what about the original star? Wouldn't that have just as much gravity? Wouldn't it do the same thing with the strength? Is it just that black holes are more exciting to talk about?

Jet propelled Black Holes by ion engine? Might asymmetry of jets for BH, together with Newton’s Third Law, result in high velocity over time, from an ion engine? Perhaps even several 100 km/s? Might Large Synoptic Telescope detect motion of associated binary massive star?

From reading various articles my understanding is that BH are gravitationally extreme - although from a distance they are gravitationally the same as any other object it is inside the Schwarzschild Radius EH where BH's differ from other large masses. The "singularity" is the point at which...

if black holes are 2 dimensional representations of our 3 dimensional universe, does that make our universe a 3 dimensional representation existing on the edge of (or entirely inside) a 4 dimensional universe? or to a 4th dimensional being would our 3 dimensional universe be considered a "black...

I look at time and space as a fabric, just as Einstein stated. However I look at time and space as a fabric moving through us. Moving through all organic matter like a river. So time is merely flowing past us just as space is. Is this the case? If we are moving around the sun in a trench of...

Homework Statement This problem is awesome! I like this chapter; Its really interesting. I think I just get a little impatient when I can't figure out the answer right away... I appreciate any help. Miniature black holes: Left over from the big-bang beginning of the universe, tiny black...

Is mass, angular momentum, and charge sufficient for black hole characterization? Or is also entropy, and hence surface area, also required? Thus is the shape for a given mass black hole also a required consideration?

How a quasar beam can get out of a black hole if no light is suppose to be able to get out of the event horizon of a black hole. ? Is it because the beam is created outside of the event horizon ? From what I understand quasar is created because of excess of matter on the black hole correct me if...

If you were to greatly increase the elctrical charge of an extremal Black Hole, (ie, drop a lot of electron in) what exactly would happen to it? I know the electrical repulsion would become more powerful than the gravity, so would it tear itself apart?

Hi, Lay questions again. What's the real story - is a black hole potentially a worm hole? If someone theoretically entered a black hole, the common portrayal is experiencing tremendous acceleration. But with time compression, how different would that acceleration feel to the traveler...

In trying to compute deflection angles for photons given their impact parameter (closest distance of trajectory to centre of black hole if unaffected) I am trying to numerically integrate the following equation (d^2/d(phi)^2)(u)+u=3Mu^2. However I am stuck as to how to work out the initial...

Hello everyone if black holes have a gravitational pull so strong that nothing can escape, then why is it that they do not continuously consume dark matter? Yes i know its called dark matter because it doesn't not interact with other matter but it does have an effect on the rotational curves...

I understand why you would be ripped apart if you enter a black hole, but I don't understand the fact that if the black hole is large enough, You would not be ripped apart if you passed the event horizon. And, some black holes you would be ripped apart outside of the event horizon? Can...

Hey all, I may be way out of the ballpark here, but its something I thought about today at one of my Astronomy lectures. How come Physicists view a black hole as "Something" rather than "Nothingness" ? The Physics about Black holes is still some what uncertain, and we try out best to...

Dokuchaev, "Is there life inside black holes?" I thought this was pretty cool. "Is there life inside black holes?" Vyacheslav I. Dokuchaev http://arxiv.org/abs/1103.6140 Abstract: Inside a rotating or charged black holes there are bound periodic planetary orbits, which not coming out...

Suppose you take a quantity of matter and separate the protons from the electrons, Now drop the electrons into a black hole. My understanding is that photons are the force carriers for the electromagnetic field. Since no photons can escape the black hole there should be no electrostatic...

I stumbled upon an article while doing some research that had a statement saying that Hawking radiation can be found in places beyond black hole horizons. This lead me to this paper (which I'm not actually interested in beyond it's reference to the existence of hawking radiation outside of...

Several questions about escaping the event horizon of a black hole typical disclaimer: I am not a scientist so please don't scold me too much for curiosity. I imagine a large black hole with a less massive black hole in orbit around it. Light enters the event horizon of the more massive...

Build a Dyson sphere around a black hole (this is a thought experiment), so no more mass "falls in". Line the sphere with insanely bright lights. What happens to the black hole? I ask this because Prof. Sean Carroll in "From Eternity To Here" discusses whether there is a limit to the...

a) If the sun were compressed sufficiently enough so that it would turn into a black hole, what would be the event horizon of such an object expressed in km? b) What is the event horizon for a black hole with a mass of 10 9 Msol? c) What is the event horizon for the black hole with a mass...

Wikipedia gives this description of supermassive black holes to distinguish then from stellar black holes: "The average density of a supermassive black hole (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be much less than the density of water...

I'm currently researching for the term paper of my class on black holes and the topic I selected is the one in the title. I've found some good information so far, but I don't feel like I have enough to get an A without a bit more. I'm curious if anyone has any resources that would aid this...

I had a couple questions regarding the ability of objects and light to escape a black hole. 1) The even horizon is supposedly the boundary at which no object can escape from a Black Hole, as within this radius, the escape velocity is greater than c. This much I understand; If I throw myself...

Hello there, I am new to the forums, and relatively new to physics. Please bear with me as I am still learning the intricacies of the subject. I have always been fascinated with science, but I missed several opportunities to study it academically. Most of my knowledge is self-learned through...

recently i came to know that the jets of gases from black holes are due to magnetic fields...so in effect does this field overpower the effect of the gravitational pull of the BH?

So how do charged black holes work? If its photons that are the carriers of the electromagentic force, and photons can't escape from a black hole. How can anything external to a black hole tell if it's charged or not?

Is the total jets mass emitted by a black hole to space smaller or larger than the total mass the black hole pulls in from the flat disk of gas that swirls around it? In other words, are black holes matter sprinklers that convert heat to matter and spray it to space?

Hello, Firstly, i would like to say that i am by no means an educated person (as in taking specialty courses or an university degree in cosmology or physics), at least regarding this subject. From this point of view, what i am about to ask might seem silly or just plain stupid, so feel free...

Do you know any book written by a great physicist where he talks about black holes? I always enjoy reading the more relaxed way of talking that appears in popular scientific books such as The Fabric of Cosmos - B. Green.

Why doesn't dark matter fall into black holes ? Assuming it doesn't of course. If it did then surely huge amounts would have fallen into black holes. By now they'd be full of the stuff & more massive than they are. So I'm assuming for some reason dark matter doesn't fall into black holes. In...

Hello, I am aware that this question was the subject of a topic on this site, but it did not fully answer my question. My question is, why can't light escape from a black hole's gravitational pull, when, according to general relativity, the speed of gravity is equal to the speed of light? My...

I am curious to what extent black hole growth can be used to probe understanding of various particles/fields. 1] Dark matter: Let's consider dark matter to be so weakly interacting we can model it as a perfectly non-interacting gas. For even more simplification, let's assume dark matter...

I'm trying the exercises on p35 of the following: http://arxiv.org/PS_cache/gr-qc/pdf/9707/9707012v1.pdf I have done parts (i) and (ii) but was wondering if anybody can help me with (iii)? I had k \cdot D k^\mu |_{U'=0} = k^\nu D_\nu k^\mu |_{U'=0} = k^V' D_{V'} k^\mu since setting U'=0 means...

Interesting :o http://www.technologyreview.com/blog/arxiv/26316/?ref=rss

As i know them, black holes are dead remains of stars where the gravitational pull is so great that not even light can escape. Well, but light(electromagnetic radiation, in general) has no mass, then how does gravity effect light?

Is there any hard evidence that the inside of a black hole is simply an empty oblivion of nothingness? I've been mulling over some thoughts on time, and this has been grinding progress. I'm currently trying to find if the possibility of its center being a negative index of timespace is indeed...

I was reading about quasars, and what I got from it was that quasars are extremely far away (3 billion + light years according to wikipedia), they were common in the early universe, and they have a supermassive black hole in the center of it. My question is how did these quasars get such...

I can offer no further insight.

I'm not a physicist, just a mere philosophy grad, but I have some questions that may lead others to research, and I'm trying to find a place to ask them so that the information can be disseminated. They relate to the Holographic theory of the universe. Anyway, first question on this forum will...

Here it is, its probably an old one but as I am not a fully fledged scientist I don't know if it is. It relys on parallel universes. So what if the black hole sits over a valve beetween the sheets of these universes sucking in matter and compressing it through the valve into the parallel...

Im going to keep this very concise, mainly because i vaguely understand what I am discussing but anyways, as most informed people are aware black holes have an infinitely strong pull at their singularity and can even inhibit light. I am curious as towards the actual phenomena or reasons how an...