Black hole Definition and 999 Threads

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...

if we teleport a small amount of millimeter cube of a neutron star outside it, will it remain still as a very dense heavy neutron clump or will it revert back into its components (iron) or will the neutron destabilize and turn into cosmic radiation of neutrons which then turn back into hydrogen?

Would a black hole whose density is lower than that of water, sink? The answer is likely over my head. So far, I've found 5 answers by "experts", with quite different opinions. For instance on this website, one reads . On IRC I was told by another expert that it would sink. Here are the...

Can a black hole be presented as a Heegaard decomposition or as the complement of a knot? I'll try and elaborate: If I understand correctly, the cross section of spacetime near a black hole can be thought of topologically as a manifold. What manifold is it? Can the manifold be decomposed?

Hi, I have the following problem: Given the 5-D generalization of the Schwarszschild solution with line element: ds^2=-\Bigg(1-\frac{r^2_+}{r^2}\Bigg)dt^2+\Bigg(1-\frac{r^2_+}{r^2}\Bigg)^{-1}dr^2+r^2[d\chi^2+\sin^2(\chi)(d\theta^2+\sin^2(\theta)d\phi^2)] where ##r_+## is a positive constant...

Hi! I have the following problem I don't really know how to approach. Could someone give me a hand? The line element of a black hole is given by: ds^2=\Bigg(1-\frac{2m}{r}\Bigg)d\tau ^2+\Bigg(1-\frac{2m}{r}\Bigg)^{-1} dr^2+r^2\Big(d\theta ^2+\sin^2(\theta)d\phi ^2\Big) It has an apparent...

Please forgive the awkward title. "Supermassive black hole" uses up a lot of the title character limit. Has anyone made a simulation of what would happen if a neutron star impacted a simplified (Schwarzschild) supermassive black hole? I've seen simulations of a neutron star colliding with a...

When neutron stars collide, heavy elements, such as gold, are created. Are these elements ejected from the system to be found, say, here on earth? Or do they fall back into the newly created black hole?

A star and a black hole again confirm Relativity. https://www.space.com/41291-relativity-revealed-milky-way-core.html

Is there a fundamental difference between the (speculative) understanding of a singularity arising from the creation of a black hole and the singularity which we think may have been at the origin of the Big Bang? Noteably, would there be two basic theoretical types of singularities...

Can a "thing" go through the event horizon of a black hole? I mean, everything inside a black hole can travel only in one direction: inward. That destroys the "thing" itself, since independent parts of the "thing" are no longer connected to one each others. Perhaps it's impossible for a "thing"...

Found this interesting interactive experiment. http://hubblesite.org/explore_astronomy/black_holes/encyc_mod3_q14.html In the interactive, it looks like the black hole is orbiting around something. What would it orbit around? Or am I looking at it wrong?

Let us imagine a photon circling around a black hole, as the picture shows. The gravity of the black hole curves the movement path of the photon into the shape of a circle. From point 0, geometric points A and B appear simultaneously with the photon, each in its own direction. The points travel...

According to Einstien's theory of evolution, the closer to the speed of light that an object travels, the slower it appears to move to an outside observer. (see https://www.thenakedscientists.com/forum/index.php?topic=40951.0) To take this to the next step once an object crosses the event...

What is the difference between mathematical singularity and black hole singularity[emoji780]

I am a hobby reader/listener of pysics, astronomy, special relativity, black holes and more. And a question arose that no amount of YouTube has touched on. Sorry if this is just a stupid question from a hobbist but it truly has me stumped. Or maybe I just have been taught by...

I'm trying to find how much energy will radiate when an object fell in a black hole. Is my calculations are correct or I'd committed mistake somewhere?

Greg Bernhardt submitted a new PF Insights post Calculating the Spin of Black Hole Sagittarius A* Continue reading the Original PF Insights Post.

Hey everyone, is anyone able to check the facts of this speech I wrote? I have 3 minutes max to say this, I might cut out tiny parts to save seconds. What do you guys think, is this correct? Should I change anything? Thanks! How Black Holes work Stars are massive collections of mostly hydrogen...

I'm reading Lambourne's <Relativity, Gravitation and Cosmology>, and I cannot get a result the book describes. It's on equation (6.7) in 173p. When a person free-falls into a non-rotating black hole from ##r=r_0## to some position ##r=r'##, the proper time becomes...

well since gravity waves are supposed to have mass, they are supposed to be effected by gravity itself, and :/ how are we supposed to detect gravitational waves emitted from a black hole when none can get out?

For Schwarzschild geomery $$ds^2=-(1-\frac{2GM}{r})dt^2+(1-\frac{2GM}{r})^{-1}dr^2+r^2d\Omega^2$$ For a Schwarzschild observer , the proper time and coordinate time are related by $$d\tau=(1-\frac{2GM}{r})^{1/2}dt$$ There is a often used relation between proper time and coordinate time $$d\tau...

we say everytime a couple of matter-antimatter particles get born near the edge of a black hole one of them falls into it and the other one escapes. And we everytime mention that the antimatter particle kind of eats a bit of black holes mass out...and by time the black hole gets smaller and...

How come the gravity of a stellar- mass black hole is strong enough to trap light but the gravity of a stellar-mass star (eg the sun) is not strong enough to trap light ?

What is the condition for a spherically symmetric solution represents a black hole? ##ds^2=\exp(\nu(r))dt^2-\mu(r)^{-1}dr^2-r^2 d\Omega^2## it is enough that it is fulfilled that ##\nu## and ##\mu## are nulled in the same value of r??. There are other conditions?

Its pretty tough to calculate the entire mass and weight of entire black hole.But how we will give a approximate value? How we will calculate its mass and weight? Could you list some stuffs that caught into the black hole? Has any scientist ever visited a black hole and collected data on it...

Thought experiment: single use of "magic" Setup: Let's assume we have a giant ball of water in space. Magic: Let's assume the water does not compress its center under its own gravity. (Constant density of 1 g/cm^3) Basic stuff: The mass of this ball of water, (since it does not compress)...

A star or a planet is a material object, while a black hole is an 'immaterial' spacetime object. Does the material or 'immaterial' nature of an object make any difference in how it curves or travels through spacetime as it manifests gravitation (apart from the powerful gravitation near a black...

Dear All Concerns Black Hole is formed at the end of life of a big star. The mass of such star should be equal to 5-10 solar masses. But I am imaging very small moving black hole coming to our solar system and passing between our Earth planet and the sun thereby creating solar eclipse of unique...

I recently re-read an article by Muller (https://arxiv.org/pdf/1606.07975.pdf) about the flow of time, and the possibility of time reversal given sufficient energy dissipation (basically during black hole evaporation, he concludes). Although the paper is on arXiv and not peer reviewed, Muller...

I read somewhere that it is not possible to prove that Our universe (from big bang to now) have different principles that inside of black hole. I think that one physicist said something like this. Or in different words: are principles of our universe different as inside of a black hole?

Could a particle near a black hole about to enter rid the string of its vibration?

If this is true where is the core of that star, either a neutron star or a black hole should exist near by, right?

Greetings, I've been thinking about the escape velocity having to be greater than c inside the event horizon for a particle to escape. Since this cannot happen, I picture the matter at the core as an insanely dense ball of atoms. But, could the pressure be so intense that atoms cannot hold such...

Hello everyone, "Does a charged particle radiate in free-fall?". I read many threads on this subject and I was surprised to find out that there is no unanimous "Yes or No" answer to this question. Here is an interesting answer from researchgate.net: The question is widely discussed in the...

What would spacetime look like near a black hole that was rotating at its extremal speed and had a ring of matter orbiting it at ultra-relativistic speeds (just outside the photon sphere), such that the ring was orbiting in the same direction as the black hole’s rotation? The ring would add to...

Conceptually, at least, this is a simple question, although I recognize that it might be hard to calculate in practice from available data. The matter-energy budget of the universe is measured (in a model dependent way) to consist of a certain percentage of dark energy, a certain percentage of...

So the Hawking radiation and the flinging of matter from the black hole, could this explain where all the matter goes? I am unsure of the theory for the second one, but if matter is broken to its quantum particles then why can't those quantum particles be in the Hawking radiation. Still very...

In simplified terms Hawking Radiation exists, because in the vacuum surrounding a black hole these subatomic-particle-pairs pop into existence and one of these particles manages to escape from the black hole. This stream of escaping particles is called Hawking Radiation, right?(Please correct...

Articles refer to white holes being associated with dark energy. What if dark energy is a larger version of the following process? Black holes banish matter into cosmic voids Some of the matter falling towards the [supermassive black] holes is converted into energy. This energy is delivered to...

How should we deal with the fact that GR predicts light not scaping from a BH while QM states BHs radiate?

Hello, Thank you for opening this thread. I am strongly interested in the universe, especially black hole. Though I am only eighteen years old, the more I read books about a black hole, the more my interest is getting powerful. Therefore, I want to know the latest and exciting news about...

Leonard Susskind said "everything that ever fell in, to make the black hole, [..] [is] all contained in [...] progressively thinner and thinner shells that approach the horizon asymptotically, never quite getting there" and from the perspective of someone outside the black hole "a shell, called...

If you were to condense an atom or group of atoms, the gravitational force would be very large because the atom is 99.9999999999996% empty, so making it 100% full would be like crushing a pound of tin foil into the size of a pen dot. If the density is so much it would make a huuuuge...

Suppose A is on a planet orbiting a black hole and B is far off such that due to time warp, every hour A experiences is equal to a year for B. Could they communicate using radio devices? Would an hour-long message from A be year-long for B? How much extra time it would take for a radio message...

Ordinarily a black hole’s Schwarzschild radius is linearly proportional to its mass. However, wouldn’t there be a deviation from this rule for extremely large black holes? Suppose we assume dark energy is due to a cosmological constant, whose value is the same everywhere (including inside the...

Is it astronomically known what the closest distance is between Earth and a black hole? (I was not able to locate an answer to this question searching the Internet.) If not, the article https://www.sciencenews.org/article/we-share-milky-way-100-million-black-holes says The Milky Way teems...

Black holes are amongst the most extraordinary objects that are known to exist in the universe. Jerome Gauntlett will discuss their fascinating properties and describe the dramatic recent observations of black holes using gravitational waves.

This is a possible science-fiction scenario, and I'm wondering if it is scientifically plausible. If someone wanted to take a one-way trip into future, say 1000 years from now, then SR gives you a possible way to do it without dying of old age: Just hop in a rocket ship, accelerate to nearly...

Where do the static electric field lines appear to originate from a charged black hole, non rotating, Reissner–Nordström metric? I've had a number of qualified physicists say they appear to come from the center of the black hole, but people on these forums have said that doesn't make sense...