Black holes Definition and 1000 Threads

I would like a discussion to quantify just how much mass is ejected at the poles (including the mass equivalence of the photons) when jets form. In quasars the black hole presumably reaches over a Billion solar masses, where the mass is proportionate to the mass of the galaxy and is also related...

Intriguing and informative story on gravity wave detection. Are gravastars an alternative to black holes? Is it possible the there are NO black holes? The collapse of mass into a ball of energy that presses out and stabilizes the incoming mass is a thought provoking alternative to the common...

OK, so it's time to start a new thread. I heard many times that there exists only one black hole solution for a given mass and angular momentum, but I know already that this is not true. We all know that if we throw something into an existing black hole, its event horizon starts to ripple. So...

I take an interest in physics in my spare time (in IT during the day). I have a query regarding the 'problem' of information loss at a black hole, and would be grateful for some enlightenment. It seems generally regarded that any information going past the horizon of a black hole is...

It is my understanding of black holes that nothing can escape them because their escape velocity is higher than the speed of light. The place at which the escape velocity becomes higher than the speed of light is known as the event horizon. My question is what happens if there is a normal force...

This is something I've been curious for some time. I've heard that there is a relation between gravitational waves and black holes. Moreover, this year the quite important paper "Observation of Gravitational Waves from a Binary Black Hole Merger" was published. Now, I'm starting to study...

Homework Statement Calculate the number of white dwarf, neutron star and black holes the galaxy will have after 5Gyr of evolution. M<8(solar mass) for white dwarf 8(solar mass) < M < 40(solar mass) for neutron star M > 40(solar mass) for black hole Initial mass function is ξ(M) = AM-s...

Black holes suggest anti-matter has negative matter but is this true? I think anti-matter has positive mass - e.g. a positron and electron annihilate giving off 0.5MeV + 0.5MeV photons where these photons have a huge positive energy. If the positron had negative mass then there would be no...

In scientific daily. https://www.sciencedaily.com/releases/2016/04/160411130033.htm How can a cosmic strings align black holes , or any other process,

Hey guys, I'm currently doing a project on black holes and need some input on what you believe to be the biggest misconceptions about black holes, thanks! You can read more about the guidelines of the project at: http://www.aqa.org.uk/subjects/projects/aqa-certificate/EPQ-7993

A bit over two years ago, Chris Adami et al. published their solution to the firewall paradox (referred to without source in http://msutoday.msu.edu/news/2014/plugging-the-hole-in-hawkings-black-hole-theory-1/, perhaps referring to http://arxiv.org/abs/1310.7914). But what has happened in the...

If the sun disappear right now, we won't notice before 8 and something minutes due to the speed of light. The Earth will keep going it's way on it's orbit because, as everything, gravity cannot exceed light speed. The same would apply if we were orbiting à black hole. I often heard of the...

Hello, I didn't know if this is the right place for this question but here it is. I have a thesis due by June sometime. The thesis is in an astronomy course so I would like to do something on physics. I have just started learning the basics and would like to impress the teacher (this might help...

I'm a structural engineer in Mississippi and I love all aspects of cosmology. I want to learn all I can about gravity wave technology. I was not expecting the level of detail that a single event is revealing. It's very interesting that they expect to see gravity waves from objects other than...

Questions. 1. As protons will eventually decay, will objects made with protons orbiting black holes that are time-dilated remains? 2. What happened at someone's perspective if he/she fell into a super massive black holes? Will he/she be free instantly? (Time dilation) 3. What happens after the...

Is there a limit as to how much a black hole gathers mass and how much it losses mass via hawking radiation so that the black hole becomes in equilibrium, neither gaining mass or loosing mass How long would it take a hypothetical isolated black hole to loose one solar mass due to Hawking radiation.

Naive reading on the web says that stellar collapse is halted by quantum mechanical processes called "degenerate pressures" that arise when gravity tries to force fermions such as electrons or neutrons into the same quantum state. White dwarfs are propped up by electrons, neutron stars by...

When I saw the report of a gamma ray burst associated with the LIGO GW event, my immediate thought was that the obvious explanation is that the compact massive objects were not in fact black holes, and the gamma ray burst was from the energy of the final collision and merger. This would...

Quite unexpectedly, it seems that the Fermi Gamma-ray Burst Monitor spotted what appears to be a hard gamma-ray burst about 0.4s after the LIGO GW event, lasting about 1s: http://arxiv.org/abs/1602.03920 This is not expected from a black hole merger (and as a black hole sceptic, I find it very...

As we all know, the LIGO collaboration published a paper recently on the first direct observation of a binary merging black hole system. From the observed signal, they were able to infer the black holes' masses and their distance from Earth. However, the fact that they can estimate masses and...

a related thought experiment to a tunnel through Earth through which a person falls to the other side, is what if it was a pendulum falling through the planet? first, a pendulum is at 90 degs to the G field; 2nd, as soon as the pendulum BEGINS to fall through, it is in free fall, and it will...

OK, in solar mass terms, 29+36=62 with 3 left over. Or make that 3 left out. This is a little-advertised mechanism for pulling mass from a black hole. And, since the output is gravity waves, it doesn't seem to be directly related to Hawking Radiation. Somehow intense gravity can scoop out...

This question is in context of the recent gravitational wave detection by aLigo. Apparently aLigo has detected the entire process, including the before merger, during merger, and aftermath of the completed merger. My understanding is that two black holes should not be seen to be merging in...

Since we think that 85% of the matter in the universe is Dark Matter, does it follow that around 85% of the mass of a typical black hole should be of dark matter origin? If not, why not? And if so, black holes are defined by only 3 parameters, mass, electric charge and spin. As far as we can...

It appears that black holes do exist in our universe, in the sense that there are objects so massive and so small that there must be an event horizon. Is it generally accepted that there is "really" a singularity inside these event horizons, or that we just don't know, and may never know?

Would it be possible that you could create a black hole from heating something really hot. I heard Vsauce said if you heat something hot enough that it's wave length of the light released is smaller than the plank length, it would become a black hole. That means that the energy would be on the...

First of I am not a scientist, just a big fan. So I am sorry for any incorrect terminology. A few years back I remember reading a article on the various theories pertaining to Dark energy. I think it may have been in a Scientific American. After the article was done talking about the most...

The tittle says it all really, how did Black Holes appear so early in the universe, why not stars? arXiv:1601.05473 [pdf, ps, other] The Early Growth of the First Black Holes Jarrett L. Johnson (LANL), Francesco Haardt (Universita dell'Insubria) Comments: 13 pages, 9 figures, invited review...

I don't know if this question makes any sense, sorry if it doesn't. I have often read that any matter (say an object, for more mundane clarity) falling into a black hole (providing it radiated) would be perceived by an outside observer as never actually crossing the event horizon. It's "image"...

I feel like this could go in quite a few of the Physics subforums (Quantum Physics, Beyond the Standard Model, Special and General Relativity, or High Energy, Nuclear, Particle Physics) instead of Astronomy and Cosmology, but hopefully this will work. This is my first question I've posed here...

Soft Hair on Black Holes Stephen W. Hawking, Malcolm J. Perry, Andrew Strominger (Submitted on 5 Jan 2016) It has recently been shown that BMS supertranslation symmetries imply an infinite number of conservation laws for all gravitational theories in asymptotically Minkowskian spacetimes. These...

Apparently rare - only 12 galaxies are known to exist with two black holes in their midst, according to Dr. Julie Comerford. Comerford reported a recent observation of a double black hole galaxy at the American Astronomical Society's annual meeting in Kissimmee, Florida. One of the BHs is...

If a black hole had a mass similar to the Sun (I know black holes tend to be at least three times larger but let's assume an unusual series of events) how far would the are of extremely distorted bent gravity around it be could it cause closely orbiting bodies to be pulled or pushed out of orbit...

Hey guys. I've been wondering, what would happen if a star around 13 solar masses and a black hole 10 solar masses were drifting towards each other? Since the star is heavier, It would absorb the black hole, But i think when it reaches the event horizon It would meet Mr.Singularity, and what...

PeterDonis submitted a new PF Insights post Do Black Holes Really Exist? Continue reading the Original PF Insights Post.

Over the years I've watched Science try to deal with the Information Paradox regarding black holes. http://news.sciencemag.org/physics/2015/12/physicists-figure-out-how-retrieve-information-black-hole I've always been curious how we got to the point where we see this as a problem in need of a...

Why is it that the smaller the black hole is, the more quickly it supposedly evaporates? It seems like a black hole should radiate energy proportional to the surface area of the event horizon. To me it seems like the evaporation should slow down the more the black hole shrinks because the energy...

What do you think about the following blog post about a recent paper by Alex Vilenkin about the possibility of black holes containing inflating universes? http://fqxi.org/community/forum/topic/2589

According to LQC, did the universe before the bounce contain black holes? If so, would they still be around? What I'm getting at is this: I've read that LQC predicts that the high densities around the bounce tend to smooth out inhomogeneities. If I understand correctly, this is quite promising...

self-dual loop quantum gravity results when the immirizi parameter y=i has been the subject of many recent research papers here is a partial listGravitational axial perturbations and quasinormal modes of loop quantum black holes M.B. Cruz, C.A.S. Silva, F.A. Brito (Submitted on 26 Nov 2015)...

Hi, layman here, I have often read that because of time dilation, we would never see any infalling matter actually crossing the event horizon, it would just look more and more redshifted towards becoming invisible, even for infrared or microwave / radio detectors, but never becoming part of the...

Does this imply that we are looking at wormholes?

http://www.space.com/28664-monster-black-hole-largest-brightest-ever.html Astronomers have discovered the largest and most luminous black hole ever seen — an ancient monster with a mass about 12 billion times that of the sun — that dates back to when the universe was less than 1 billion years...

I have heard that, given the energy of a quantum of Hawking radiation, we can extrapolate backward in time to its 'creation' near the event horizon. When we do this we find that, because of time dilation and conservation of energy, the wavelength of the emitted particle becomes smaller than the...

I understand how the neutron stars are formed, and why the electron degeneracy pressure collapses as electrons are absorbed by protons, by photo disintegration. However, I'm struggling to grasp what happens when the gravity is large enough to overcome neutron degeneracy pressure. Apparently a...

So, according to physicsoftheuniverse.com, "In the centre of a black hole is a gravitational singularity, a one-dimensional point which contains infinite mass in an infinitely small space, where gravity become (sic) infinite and space-time curves infinitely, and where the laws of physics as we...

[Moderator's note: Spun off from previous thread on different topic.] I'm still a bit new here and haven't studied much astronomy (being an electronics dude) so can anyone give me a good link(s) for what we know about existing black holes. That is size, location, and other physical...

For this we need a thought experiment: imagine you're on a gedanken planet manning a gedanken laser cannon, and it's pointing straight up. The light doesn't curve round, or slow down as it ascends, or fall down. It goes straight up. Now let's keep you safe in a bubble of artistic licence, and...

http://arxiv.org/abs/1510.03066 String condensation: Nemesis of Black Holes? Michael Hewitt (Submitted on 11 Oct 2015) This paper puts forward a conjecture that there are no black holes in M theory. We will show that a mechanism to prevent black hole formation is needed in 4 dimensions to make...

Homework Statement Muscle can be torn apart by a force of 100,000 N applied across an area of 1 m2. A 10 cm2 muscle therefore will be torn by a force of 100 N. If a student of average size were being lowered into a black hole of 1 solar mass, at about what distance from the hole's center will...