Black holes Definition and 1000 Threads

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So Alice and Bob are hanging out near a really large black hole. It's quiet. Nothing has entered the BH is a while. Alice tosses Bob in and then waits long enough for him to collide with the singularity. Of course, Bob is keeping time differently than Alice - so I rather doubt that the time...

The other day my friend asked me a really interesting question regarding the scene from interstellar where they go down to Miller's planet, where every hour on this planet is 7 years of Earth time. He asked me if they were to send a signal to the spaceship where Romilly was, what would happen...

Here is a presentation on the discovery of two colliding neutron stars and the resulting phenomena such as gravity waves, gamma ray bursts, and synthesis of high atomic number elements. The author is a theoretical physicist who is involved in the research. He says that the neutron stars most...

Recently there have been a lot of studies of black holes colliding and the gravitational waves that they produce. My question is: What is the effect on the space between the two black holes before they collide. The stress must be extraordinary. That stress should be measurable by radiation...

Dark matter passes through everything, but is only influenced by gravity, so in the case of a neutron star, since dark matter doesn't interfere with ordinary matter, it can just pass through it, but neutrinos might be stopped by it's density, as neutrinos can just pass through stars almost as if...

How long would it take for an object, stationary with respect to a black hole (mass of the sun), to fall from 1 AU into it beyond its event horizon? From our frame of reference can we observe over time, a black hole growing in size as matter falls beyond the event horizon? From our frame of...

The thing is that this is an exercise that I have to show my teacher but I don´t know how to get the answer.The exercise says: "A body of mass m moving in the Keplerian field V = −M/r (in G = 1 units) has a total conserved energy, Etot = 1 /2( m r˙^2 + r ^2ϕ˙ ^2 )− mM/r. Show that the...

The laws of physics breaks down at an atomic level, it also breaks down around black holes. could the two be related? could a black hole be an atom with a periodic number in the (insert ridiculous number here) ? If it were true that black holes where atoms / elements it'd turn two problems...

From what I understand, a black hole can exist that was formed entirely from antimatter. If this antimatter black hole were to collide or merge with a black hole that has the exact same mass, but was made of regular matter, what would happen? Obviously the matter and antimatter would...

There is some confusion on my part what the actual reality is at the Event Horizon, since there appears to be different answers in using Kruskal-Szerrkes coordinates or Schwartzschild coordinates. Reality does not have two answers. There is only one right one. Asked multiple times on this...

Can someone post links to the popularly accepted theories on black holes? Just about all of the information I come across is presented as scientific fact, regardless of how far-fetched some of these ideas may seem, or contradict each other

I have been curious if there is anything that would prevent a star that has the mass to supernova from going supernova at the end of its life. If that were possible could it then also be possible that black holes are not actually holes but something so massive that light and anything that comes...

Is it fair to say that all energy from a Gravitational Wave that enters the photon sphere of a Black Hole is destine to become part of that BH? And other parts that remain just outside of the photon sphere would experience gravitational lensing? Perhaps focusing the GW to an area of much...

Summary: Expansion of matter in the visible universe, total volume of space outside the visible universe, black hole mechanics, and general questions from an uneducated but extremely interested evolved monkey. Hello everyone! I do not know the rules of this forum, or any forum for that matter...

Last night PBS showed two shows on Black Holes. In the shows the host traveled on a supposed warp drive spaceship. A question occurred to me. Suppose for the argument that the Alcubierre drive were possible. Then suppose you were in a ship contained in a warp bubble moving through space at say...

Do black holes precess? I added some marks to a picture of quasar 3c175... can the highlighted distortion of the jet be interpreted as black hole precession?

I wonder why electromagnetic waves don't escape from a black hole while gravitational waves (obviously) do. What is the difference between the two kind of waves? And between gravitons and photons? thank you for your attention

So, for the end of this semester's introductory couse in General Relativity (undergrad) I have to do a project on "The analogy between the mechanical laws on a black hole and the laws of thermodynamics". I couldn't find much (at least on my own) about this particular topic in my university's...

Summary: I don't get it, why can we be sure, that black holes evaporate My simplified imagination about Hawking radiation is that when the vacuum fluctuation creates a matter-antimatter particles pair at the event horizon, thay are ripped appart by the tidal force and do not manage to split...

The first law of thermodynamics states that matter can only be transferred from one state to another, and cannot be truly destroyed. What happens to matter consumed by a black hole? What happens to it and where does it go? Does the first law still hold true?

Imagine two black holes at great distance. They are both spatially separate and both completely collapsed to a singularity. Gravity begins to pull them together. According to the equation for the gravitation potential energy of two objects at distance… Ug = -GMm/r …These two objects begin...

I am wondering if an object can fall into a black hole at faster that the speed of light. I have heard that the expansion of the universe can make distant galaxies appear to recede from one another at velocities faster than the speed of light.

 Intuitively, this makes sense to me. I am...

Summary: Thanks to CERN, we now have huge particle accelerators such as the LHC. We use them to enhance our understanding of quantum physics. As everyone know,particle accelerators are huge machines that smashes atoms into pieces at near the speed of light. I have heard making antimatter by...

I realize that my understanding of this matter and it's vast number of related concepts is rudimentary and incomplete. Kindly forgive my ignorance and try to explain your thoughts in layman's terms. Thank you for your time.

Hello. I'm trying to study primordial black holes for my work, but I still can't understand what are abundance and mass spectrum? Could you explain? Thanks in advance.

Trying to understand radiation near black holes, specifically sgr-a, and more generally "radiation in space" and its general threat to the survival of spaceship occupants. Please let me know if this would be more appropriate in a different section here, eg astrophysics. In my little story the...

Not sure where best to post. Local paper has had a couple of articles about the black hole image over the past couple of days. They quote Walter Isaacson “Einstein did not believe, then or later, that these results actually corresponded to anything real,” . Is that true? I couldn't imagine...

Does anyone know, and is there an instrument that could?

Good morning. Not sure if I am doing this right, but I just wanted to ask a question.

I’m very new and uneducated but extremely interested in astrophysics. That said, I’m also tainted by popular science fiction with my theories. My question...is it possible that since black holes carry so much mass and with said mass slow space time down to a degree that we are moving too fast...

Hello. In chapter 3 (Quantum Black Holes) of this book... https://www.amazon.com/dp/069116844X/?tag=pfamazon01-20 ...Stephen Hawking writes... "The no-hair theorem, proved by the combined work of Israel, Carter, Robinson and myself, shows that the only stationary black holes in the absence of...

According to the Big rip theory if Black holes tear apart after a very long time, then according to the theory of relativity an object that reaches the event horizon should see time passing infinitelty and by the time the object was swallowed wouldn't the black hole not exist anymore because of...

Scenario: You have two black holes approaching, one from the left (A), one from the right (B), each at speed S. They are offset vertically. S is sufficiently high that they will deflect passed each other without merging. Question: Suppose the speed S is high enough so that the event...

I am under the impression, there is no unique solutions to Einstein's field equations for a cosmological constant, or for higher dimensional spacetimes. Has anybody got a counter example for a solution including the cosmo constant to show there are multiple solutions, for example, i know of the...

I am working on a research project where I intend to describe what the Penrose process would like in a sonic black hole. I have found what a rotating (Kerr) black hole looks like in the sonic analog: https://arxiv.org/pdf/1802.08306.pdf I have also found that the analog of massless particles...

Whether it be through Hawking radiation, miniature black holes, or even white holes, is it possible that one day energy could be harnessed from black holes and used on earth?

Stephen Hawking theorized the creation of virtual particle pairs at the event horizon of a black hole, with one of the particles escaping the event horizon (Hawking Radiation) and the other particle falling into the black hole. Sean Carroll states on page 272 of From Eternity to Here that "if...

Are there any theories on Blackholes becoming so massive that the forces generated by the matter within them exceeds the forces compressing them and the tipping point leads to a Big Bang?

It seems that the super-massive black holes at the centres of galaxies formed very early in the history of the galaxies (e.g ULAS J1342+0928, which had about 800 million solar masses 13.1 billion years ago). Presumably, in the very early days, matter in the universe was much less clumped than...

If they could solve the information loss paradox in black hole https://en.wikipedia.org/wiki/Black_hole_information_paradox What other related problems it could solve in Beyond Standard Models or unsolved quantum questions, etc.? If the LHC could no longer detect new particles, could beyond...

When we approach a black hole, the effect of gravity is such that relative to us, time far from the black hole would approach infinity as the distance to the Event Horizon approaches zero. But what happens when we cross the Horizon? How do we measure time outside? Will infinite time have have...

Yes, I understand that this is all kind of hypothetical, there have been no black holes discovered with a naked singularity. A black hole which is spinning beyond the speed of light is said to expand its event horizon to drop below the speed of light again. When it does that, it creates a...

I was musing about black hole mergers and what an observer might see for a particularly simple (i.e. blatantly contrived) scenario. Suppose that there are two (non rotating, un-charged, bog standard) black holes of dissimilar masses heading for a head-on collision. They will accelerate towards...

I read that 1. dark matter has to be concentrated in galaxies; 2. McGaugh & Co discovered a precise relationship between visible-ordinary matter and the calculated sum of ordinary + dark matter from thorough observation of actual acceleration of more than 150 galaxies. 3. First experiments to...

I'm sure this is a really basic question for the black hole experts here. Consider a situation where a star approaches and then crosses the event horizon of a super massive black hole, the star gets torn apart eventually undergoing spaghettification as it approaches the singularity. My question...

Hi Everyone, I'm interested in how to annihilate black holes (they are like blenders separating all the things apart and agglomerate like "tumors/cancers" in the universe). However, I'm new to this field and need some clarifications on some of the basic concepts like "annihilation" and...

I read about a theory (https://en.wikipedia.org/wiki/Magnetospheric_eternally_collapsing_object) (https://arxiv.org/pdf/astro-ph/0602453.pdf) that proposes that collapsing massive stars never actually form a singularity, and instead they end up as "magnetospheric eternally collapsing objects"...

I am working on a presentation for a course in general relativity and my topic is the stability of black holes. In many of the references and articles that I have found, the author asserts the importance of the conjecture but offers no reason. So I ask: Why is the black hole stability conjecture...

Are there theories to explain the formation of supermassive black holes?