Black holes Definition and 1000 Threads

Assume we all accept that gravitational influence moves at the speed of light, just as EM radiation does. Light cannot escape from a black hole because the escape velocity from a BH exceeds the speed of light. If gravitons are a proposed particle-interaction based solution to explain gravity...

I've been fascinated by the posts and discussions here about "The Bounce" that seems to be emerging from some LQG models (thanks Marcus and others). I have a couple of questions, which I don't think I've seen in posts here (my apologies if they've been raised and discussed and I've missed it)...

I have recently been reading Moment of Creation by James Trefil, and I have stumbled upon the question, where has all the antimatter gone? I asked myself, what if micro black holes produced by the tremendous energy at the big bang are the answer? If you have an understanding in hawking radiation...

In January, a Vanderbilt University astronomer (I forget her name) found that there were probably hundreds of 'rogue' black holes flying about our galaxy. She surmised that the risk to the Earth from these RBH's was infinitesimal. She said that the only possible risk would be that one goes...

I had a brief conversation with a professor of mine and he presented, in short an argument against the existence of black holes. I'm sure you've heard it or a variation of it. It goes something like this: An advisor and his student are near a black hole. They are both wearing a watch, the...

I'm reading this paper "Exact Gravitational Quasinormal Frequencies of Topological Black Holes" ...By D. Birmingham and S. Mokhtari : http://arxiv.org/abs/hep-th/0609028v2" and now i confusing what are meaning of gravitational quasinormal modes of Topological Black holes?. Can...

http://blackholes.stardate.org/resources/articles/article.php?id=9 This presupposes that dark matter and dark energy interactions play no role?

This may strike some people as really weird but after reading the book, God and the New Physics by Paul Davies, I came across a paragraph where he explains what happens at the singularity of a black hole. At the singularity, there is no concept of time apparently. So it is impossible to leave a...

can someone Explain the NS-NS or NS-BH or BH-BH mergers proposed to explain short GRB’s. Thanks

what is the meaning of topological black holes? thanks

Hi, In the safety case for the new Large Hadron Collider (LHC), the possibility of creating artificial black holes is considered. The main argument for the case that there is nothing to worry about, is that cosmic rays collide regularly with atoms in the upper atmosphere with much higher...

From what I gather, only more exotic, extra-dimensional theories predict that there will be microscopic black holes produced in the Large Hadron Collider. And I get that even if they are produced they are very unlikely to be stable and even then they would probably be safe (just to let you know...

I was wondering about something. If a black hole has charge, would it be measureable? Does the electric field escape the black hole even when light cannot? Or if the field does not escape the black hole, how do we know that it's a charged black hole?

Sorry for the dumb question but... My friend and I were wondering how much energy is given off by an average black hole relative to its mass. (like X black hole gives off Y% of its mass as energy per second) Thanks in advance for your help.

Ok here is a thing I don't understand: How can a black hole exist? There are several things bugging me about black holes: 1) The more concentrated the matter is, the more deformed spacetime is and the slower the time is (from our point of reference). How can Black Hole be created in finite...

I am a total novice when it comes to quantum mechanics, but I was reading up on the phenomenon of entanglement and a question arose. Theoretically, could someone take two entangled particles and put one in a black hole, using the other to observe what happens to it? Wouldn't this violate the...

Given a Schwarzschild BH. A neutron fall into the BH. The neutron having non zero magnetic moment will carry a magnetic field B with it. How do I describe the new system, on which parameters will the metric depend? In term of classical GR, Kerr Newman solution provides a B in term of the...

Scientists are hoping to create tiny black holes here on earth, which they are pretty sure will evaporate almost immediately due to Hawking radiation. While they consider the risk to be almost nonexistent, I can envision some scientist saying "cool -- wonder if we can make a little bigger one"...

Here is the news: http://www.sciencedaily.com/releases/2008/05/080515092615.htm"

If black holes stretch the space-time fabric because of their mass existing in singularity, if you were near a black hole, wouldn't there be a time-stretch?

Well I read that points in space are indeed finite and intuitively they have to be because I guess we'd never be able to move from one point to the other. (intuitively this make sense) However, when a black hole is created it is said a singularity is formed i.e. and infinitesimal point in...

Hey all, Having stumbled across this forum completely by accident I thought I would stay for a while. As such I have a question. Would a black hole have a magnetic field? I would assume that magnetic fields are affected by gravity and therefore any magnetic field would be destroyed when...

i was reading about an article about the keck observatory and its use of a laser to observe super massive black holes at the center of the galaxy. they talked about how they found young stars near the black holes and how it wasnt possible. so it gave me an idea. is it possible for black holes to...

This may seem like a stupid question that's been brought up several times but it is regarding the possible creation of mini-black holes at the LHC. It's said that these MBH's pose no threat to the planet because of their small size and the fact that they will evaporate by Hawking radiation...

Im trying to describe a system of two kerr black holes and I was wondering if this was even possible? I am currently taking a GR course but I've looked through the textbook and we only seem to deal with stationary solutions to einstein's field question (and no two-body problems).

The fuzzball proposal for black holes Authors: Kostas Skenderis, Marika Taylor Comments: 106 pages, invited review for Physics Reports Subjects: High Energy Physics - Theory (hep-th); Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc) The fuzzball proposal states that...

Wouldn't the very center of black holes have zero gravity? For example, if I was at the very center of the Earth wouldn't I be weightless because the pull of gravity was equal and opposite in all directions? Wouldn't this be true for any massive body including black holes? And of course I am not...

I am interested in the theoretical shape(s) of black holes. I read that they may be cone shaped, they made be "shells", they may be two dimensional, etc. Can i get some clarification? thanks, jlr

I understand that if black holes were created in the LHC, they should evaporate in 10^-100 seconds and be created at 1 black hole per second. The collider produces 10^8 collisions per second. The lifespan of a black hole increases with mass^3. I was wondering whether it would be possible for a...

Does this apply to a black hole? What would be the consequences of it? Thanks

Black holes irresistibly suck things in. That is a common misconception in science fiction. In fact, a spherical black hole of mass M attracts exterior mass no more strongly than a spherical star of mass M. Their exterior spacetimes are the same Schwarzschild geometry. But there is a sense in...

Over 200 planets have been discovered by the radial velocity technique. Why no black holes? For similar periods, the signal amplitude should be much greater. TIA. Jim Graber

In regard of frame-dragging within the ergosphere of a rotating black hole, what effect would this have on gravity? It seems accepted that with frame dragging (or lense-thirring), the fabric of space is dragged around with the black hole but that light within the ergosphere still travels at...

Hypothetical scenario: A small black hole passes by a much larger black hole at a velocity large enough to avoid capture. Is there any chance that the tidal forces generated by the gravitational field of the larger black hole could cause part of the smaller black hole's mass-energy to...

My physics professor told us that string theory correctly predicts the entropy ofa black hoole. that leaves me wondering...how do u even measure what it's entropy is to even confirm a theoreticla calculation? is S= k ln W even used at all?

Does anyone know where I might find a good beginners guide to black holes? I know its a big topic to start from scratch - but I'm a quick learner.

If two black holes with equal mass and angular momentum, but the latter in opposite directions were to collide, they would release a great deal of radiation and would subsequently lose energy and the resulting black hole would have a lower total mass than the two previous ones combined. But how...

hi I am new here. i don't really know much about physics but i was thinking... A Supermassive Black Hole pulls in all this matter due to its gravitational pull. my question is due to the super high mass of the black hole and the curvature of time and space, would it be possible for the black...

What initially attracted me to this book was how easy it was to read, or atleast how easy it said it was to read... I have read the first few pages and I am really enjoying it. For anyone that has read it, I would like to know if any of it is dated. It was published in 1999, or that is the case...

Good day to you all, I am total amateur so people with high physics degree don't need to waste their time since this question is very easy to answer I am sure... Time gets slower and slower (atleast relative to us) as the gravitational field gets stronger and stronger right? (If I am wrong...

For this to happen there must have been two stars that went super nova in close proximity, if so i find hard to think that a star would survive a very close companion going nova, so how do the two black holes get close enough to collide?

We know that something with a big mass will collapse and will become a black hole. We know also that an "easy" black hole is the Schwarzschild solution of the Einstein's equations. An object free falling into a black holes will pass the event orizont without problems but for an external...

My question is related to black holes, well there are many books and writings that explain what a black hole is and all AFTER collapse but i have seen few that explains the BEFORE collapse; exactly how is that matter can be squeezed to an infintesimal point, ¿what effects could one expect to...

Correctly speaking all particles having mass should be a black and should have a small but finite swarchild radius,for example the electron,quarks etc are all black holes. But what would happen if two particles come within their swarzchild radius?

This is theoretical, but if we had a black hole with event horizon of radius R, and passed in a continuous stream of stellar matter with a radius of 99% of R or so, would the black hole take in everything, no matter how fast it was moving? For example, we have a sufficiently long rod of a...

if BB is true then there should be black holes which should also explode like the big bang...Do we have evidence for this type of small bang black holes...

Detecting large extra dimensions via "mini black holes"? Occasionally I come across something explaining that one of the possible discoveries at the Large Hadron Collider might be the production of "mini black holes", which if found would demonstrate the existence of large extra dimensions. The...

I just wanted to ask and I'm sure I'm wrong but i thought of it last night. if some models explain a mutlieverse (such as m-theory), is it possible that black holes in one universe are white holes in another universe? now i am no physicist, but as a lay-man thinking if a black hole warps space...

I know that there exist 4 types of material: solid, liquid, gas and plasma. Black holes are also some kind of material and probably not one of the above. Then, how can we describe the material of black holes?

I have been recently wondering about black holes and the laws of thermodynamics. So I would like to ask: Can there be physical movement without thermal radiation in other words loss of energy in thermal form? Every particle in the universe that have mass will be in movement. I am in belief...