Holes Definition and 1000 Threads

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...

Can anyone explain to me what exactly is a charged black hole?Where is the charge?Is it on the singularity or somewhere else?

Good day! The famous American scientist Kip Stephen Thorne once wrote a novel the name of which probably is like this: “The travel inside the Black Holes”. I wrote probably because I have not read it in English language, I read its translation in one of European languages. This is little story...

First of all, I know that that very large stars tend to form black holes, and smaller stars, but still massive in comparison to our sun, tend to form neutron stars. My question is, if matter is lost when a star collapses into a black hole, but can still form one, why is it that it is a star...

Well I'm a senior in high school have an independent study to finish for my physics class. I have started my research, however I am still needing to know how I am going to pull a good 10 pages of information from this project (which is how many the teacher is asking for). I just need to know...

The black hole is surrounded by an event horizon. No matter which fell under the horizon will never escape, even in the form of information (in the classical theory of relativity). So why is the star orbiting a black hole moving at the correct speed and trajectory, as if they knew the mass of a...

Do holes (i.e. electron holes) have spin angular momentum like electrons do? Thanks for any insight you can give and if you can recommend any literature on the mater that would be great! Thanks!

My question here is to ask what would be the consequences to theoretical physics if, it was discovered, that black holes do not exist in nature. For example, as gravity and pressure increases beyond neutron star, new, previously unknown quantum principles, similar in spirit to loop quantum...

Can there be planets revolving around black holes? I'm not asking about black holes at the center of galaxies, but other black holes.

I'm going to have trouble stating this question exactly in the language of GR, but I'm going to try my best. We have a manifold with two identical black holes falling into each other from a large distance with no angular momentum, both spin and around their collective center of mass. A ray of...

In the Body-centered-cubic (BCC) unit cell which types of holes (interstices) are there? (tetrahedral, octahedral, or cubic) How many of each type? Thanks!

Homework Statement A gas effuses into a vacuum through a small hole of area A. The particles are then collimated by passing through a very small circular hole of radius a, in a screen a distance d from the first hole. Show that the rate at which particles emerge from the second hole is...

What would happen if two super-massive black holes collided with each other? I know it may be a very unlikely scenario. I just started thinking about this for about a week and I wanted to see what anyone had to say about it. Thanks!

A little philosophical question. What would you say is the purpose of a black hole? To create another universe? To somehow balance the distribution of mass? Any guesses or hunches? Just curious.

Hello everyone this is my first post. I just recently started getting interested in physics but just from a very theoritical view and in very simple ways My problem goes like this: As far as i am concerned according to Relativity Theory nothing can go faster than light. So then we have the...

hi, i was just wanting to get a few opinions on where and maybe even when a black hole goes to. It's something I've read into a lot in the past few months; and I'm really interested to find out what others think. Thanks

Imagine that you are an astronaut standing very far from a black hole.Now you throw a luminous body (a bulb may be) directly towards it.Now as it gets nearer the black hole,the light from the bulb as you observe it becomes more red-shifted.Eventually from your frame(consider it is an inertial...

I know that this can not be true because if it was, the universe would be mainly black hole by now but I can't seem to fathom how if something has an increase in mass (law of conservation of mass) from an external object, it does not increase in size. My next thought would be, if gravity is...

After the Big Bang it was a short period of inflation. After that the physics that we know is supposed to apply. After inflation the speed of the expansion was smaller than the speed of light and all the mass of the universe was in a relatively small volume. Why was not the universe a black...

Black holes-- time travel? Is it plausible for something to time travel by means of a black hole, or is that entirely science fiction?

Hi, I'm not a physicist so the answer to this question may be elementary but I can't figure it out for myself. I posted this elsewhere before finding this particular part of the forum. Black holes are famous because (almost) nothing can escape from them. Once an observer has crossed the event...

Hi, I'm not a physicist so the answer to this question may be elementary but I can't figure it out for myself: Black holes are famous because (almost) nothing can escape from them. Once an observer has crossed the event horizon, no more contact may be made with him or her. Thus it will...

Hey guys. If the string theory is correct (and strings are fundamental and the last building block) I had a thought that if and when a star collapses (due to whatever reason) it can reach neutron star status. Add more mass and it can collapse to a quark star. Now say that we add more mass and...

-------------------------------------------------------------------------------- Hi All, I just wanted to be sure I am calculating this correctly: In a golf game, Player A and Player B are competing in 4 holes of golf. The probabilites for 4 holes are below: Player A Prob. Draw Player B...

From watching "The Universe" on the History Channel, I have heard that there is a theory suggesting that on the "other side" of black holes may lie white holes that spew everything back out into another universe. I'm not sure how great of a source that show is, but that's not the issue here...

How we can prove the existence of black holes? And how they are located in in the space as they can absorb light too?

Hi, I've recently finished a course on GR, and would like to read up more on wormhole and white hole. May I ask if there are any papers, websites or books that introduces the mathematical and physical structure of these stuffs?

I am trying to reconcile three things: (1) The entropy of a black hole is proportional to the logarithm of the number of possible states of that object to give the same event horizon. (2) The only parameter for a S. black hole is its mass, since its electric charge and angular momentum are...

Is it possible for a cloud of gass to condense around a black hole and for fusion to start? Or another way to ask. Is it possible for a star to have a black hole at it's center?

I am sure this must have been asked before but here goes. If two black holes were on a collision course with each other or would pass close to each other. Would the smaller one get pulled into the bigger one?