Black holes Definition and 1000 Threads

Hi everybody, and thanks in advance. My doubt is: why should the mass go in the singularity? I'm thinking about this situation: imagine a sphere with radius R<2M; then that sphere generates a BH. Schwarzschild tensor metric is valid only in the exterior region of the mass and for this reason i...

I'd like to know people's views on the possibility of Black Holes being 'Gateways' or 'Portals' to parallel universes.

I saw a video of a talk by Susskind discussing his ER = EPR idea. This post isn't actually about that talk, except that it got me thinking about wormholes. Without exotic means, I understand that it is basically impossible to have a traversible wormhole connecting two distant points in space...

I have to 'question' the logic asked in the 'title question' asked in this artical: https://newatlas.com/most-distant-supermassive-black-hole/52508/?utm_source=Gizmag+Subscribers&utm_campaign=2151ebbb0d-UA-2235360-4&utm_medium=email&utm_term=0_65b67362bd-2151ebbb0d-91583997 It seems to me that...

I was reading up on the observation that occurred October of this year and started wondering what happens when two black holes collide do they merge to make one or do they collide as two separate objects kind of like two basketballs touching each other and also sort of a side question I've heard...

Hawking radiation formula shows the fact that when charge and angular momentum increases in a Kerr-Newman black hole (angular momentum in Kerr black hole) Hawking radiation decreases. Can someone explain this? Thank you.

Do Black Holes exist? after all the maths breaks down at the singularity Like the maths of the singularity breaks down at the beginning of the universe, what if there is no need for the maths to break down and these singularities do not exist?

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Surprisingly, I have not been able to find an answer to this question. How did scientists know where to build LIGO so that it would be able to find merging black holes in the sky? I assume LIGO is a permanent instrument so that it cannot be pointed to various parts of the sky, like an ordinary...

Beat this one up for me, please. I'm told it's an "against the mainstream" idea, so why that's true would be interesting to examine here. (Bear in mind I'm not an astrophysicist. That doesn't mean you can't post information that will leave me with a blank expression and a desire to find the...

Why is it believed that almost every big galaxy has a black hole on its center? Does the explanation rely on General Relativity?

I read an article today stating that the possible explanation for the near total absence of heavier elements such as gold and uranium in many galaxies may be due to those galaxies not forming around a central black hole that has in absorbing one or more neutron stars causing fusion of neutrons...

Would it be possible for an "extra" dimension to be created if a microscopic black hole was made and maintained until it sucked in a mass (a person) and was "turned on and off" infinitely quickly popping in and out of existence so that the gravity doesn't kill a human but the "extra dimension"...

Hello! If energy bends spacetime, then an object moving at high velocity will bend spacetime a lot around it due to its really big kinetic energy. It follows, that an object can become a black hole at extremely high enough velocities. But, since velocity is relative, we can find an observer for...

According to this article millions of Black Holes exist in our Galaxy, And within a few years mergers will be detected by Ligo, According to Kaplinghat, they may not have to wait too long, relatively speaking. "If the current ideas about stellar evolution are right, then our calculations...

I've been reading several ideas postulated by some researchers using either Dark Matter and or a micro Black Hole as energy sources to power a future spacecraft . 1) using dark matter as fuel to power a spacecraft by taking dark matter into a cavity and shrinking it to critical point using...

So, as one does, I have been pondering the nature of the universe and specifically black holes. I apologize for the rambling nature of this post...I haven't really put it into a coherent format because time is a bit limited. Also, English is not my first language and I apologize for any...

An earlier thread inspired me to imagine the following scenario. Consider observer A, black hole B and black hole C. A's past and future remains far enough away from any EH so that A is classical. In the past, A and B were stationary relative to each other. C approaches from infinity on a...

Hello all, To my knowledge, there are still a lot of questions regarding the specifics of black hole formation. My question is in regards to formation time. I've read that the actual formation takes "less than a second" according to the equations. Does anyone know where time shows up in the...

I'm wondering if black holes radiate antimatter as well as matter? If they radiate antimatter in equal amounts to matter, then would it all cancel out?

I have just started googling/youtubeing black holes. One point made repeatedly discussed is the loss of information in black holes. In particular quantum bits. What I have not yet found is very much explanation of what these potentially lost bits might be. So what I would like to know is...

Hello, I would really like a book like Susskind's "An Introduction To Black Holes, Information And The String Theory Revolution: The Holographic Universe" but not so condensed. If you have anything to suggest please do so. Also, if you know of any book that contains any part of the above book in...

light orbiting black holes If light can orbit a black hole, and it is continuously coming in from every direction, wouldn't it get "crowded" in there over billions of years?

Hi everybody, I am thinking of applying to the grad school at UCSB. I am interested in the theoretical studies of black holes and I’ve heard UCSB is very active in that area. Could someone give me an advice of how it is like? Also, I am a bit worried because of the rumour that it's extremely...

I didnt know much about black holes and also astrophysics but I want to know some general information about how they form.Well As massive star collapses the matter get so densed, then I guess internal pressure gets so high and as star explodes as supernova (maybe I described it wrong), ın any...

Forgive the title. Long ago I was told that if two black hole traveling rapidly relative to each other "brushed" past each other they'd pull each other in. I find it odd that a massive object traveling near the speed of light would suddenly stop dead in its track. Instead consider two black...

I joined this site because I had questions and wanted to discuss topics on the subject of black holes. Lenny Susskind's lecture of this topic raised quite a few question a and ideas in my mind. I did write my concerns in the comments for the video, but I'll just paste that here as well. Here's...

We often hear about string theory requiring extra dimensions over and above our 4D spacetime. Does this shed any light on the singularity which is supposed to exist at the centre of a black hole? Does our normal spacetime simply join the other dimensions in their hidden (curled-up) form? This...

current proton decay experiments disfavor popular GUT like SU(5) Does the hiearchy problem for the higgs field require that the higgs couple to a GUT scale, if it exists, or to a Planck scale? does this require the higgs couples to Planck mass quantum mechanical black holes? since the Higgs...

The question is; After an object goes through the event horizon, is it possible for the object to reach the singularity? As far as i know, singularity, bends space down and actually space moves faster than light towards the singularity. But what tells us that the singularity's bending has a...

Hi, Physics Forum! I've been wondering what would happen in the following thought experiment. I am not physicist and may have made some incorrect assumptions. Please explain if any of these assumptions are wrong. What would happen if you threw a piece of (very long and strong) rope into a...

This paper https://arxiv.org/pdf/1705.06859.pdf says that PBHs were the start of galaxy formations at up to Z=10 what do you think? In this connection a natural idea may come to one’s mind, that the SMBH are not created in the galactic halos but, vise versa, galaxies are formed around the...

What would happen if you surrounded a black hole with water?

If you shrunk an atom down to a certain point would it become a black hole like all matter in the universe can? How big would it be?

From Wikipedia: So, assuming we have a massive ball of water that keeps growing, but somehow manages to remain at a fixed density, the moment the Schwarzschild radius overtakes the physical radius, will the gravitational properties of the ball of water undergo a sudden, dramatic change?

LIGO is reputed to have detected gravitational waves from the merger of 2 black holes (BHs). For an external observer of such an event, each BH would appear to approach the event horizon of the other, but never cross it in a finite time...is this correct so far? But the event horizons are...

Is it possible for the L.H.C. to have an atom size (or smaller) black hole from the collision chambers?? This will lead up to a bigger question if it a possible yes, I just don't want to sound like a moron right off the bat.

I was just wondering if there is anything to suggest that black holes are anything but giant neutron stars cloaked in an event horizon created by their own gravity. I mean if a neutron star is just on the cusp of having enough mass to be a black hole, and then gains that mass, what's to say it...

I recently studied about black holes and hiw they attract light too. But does light have mass? If it doesn't, I don't see any way how gravitational forces affect light. I have heard a bit about wave particle duality. But could you make it more clearer? I have no idea of relativity or particle...

Hey all! I'm new to Physics Forums. I'm going through Hawking's famous 1975 paper "Particle Creation by Black Holes" which presents the phenomenon later known as Hawking radiation. I'm going through it for the sake of my own learning and benefit since the paper is a bit ahead of my edge as a...

Assuming a wormhole exists, what would happen if one took one end of the wormhole into a black hole. Could they enter the wormhole and leave the black hole? What would be the result if they did?

Homework Statement In 2009, astronomers found convincing evidence of two such black holes orbiting as a binary system. From data collected, they estimated that the separation of the black holes was 3.2 × 1015 m and that their masses were 1.6 × 1039 kg and 4.0 × 1037 kg. The black holes orbit...

I have always been fascinated with black holes and information paradox. If quantum bits made up spacetime. Could the information getting inside a black hole be possibility encoded in its quantum bits? Look at https://www.quantamagazine.org/20150428-how-quantum-pairs-stitch-space-time/

After a quick and not fruitful Google Search I leave this question in better minds than my own. Q- Has there been any discussion linking the start of our Universe with a black hole? <Reason behind Question> I feel as if certain phenomenon seems quite similar to one another. A) star dies...

Black hole or more correctly the event horizon will not let anything past through it, from inside to outside, ok. But then we get to a particle with zero mass eg. photon. How can gravity act on that particle, surely for gravity to act there must be mass? Or does it act on the electromagnetic...

Gabriela Lemos and her team successfully entangled photons. Would it be possible to explore the interior of a black hole by letting one of the entangled photons enter beyond the event horizon and observe the impact on the other?

Since it is practically impossible to artificially create a perfect sphere, are black holes the closest thing?

I have never met such an idea... Can anyone comment?

Relativity, Elementary Particles and Black Holes by Thorne & 't Hooft Any idea what this book is and why it is unavailable? Is it a popular science book? I did not know that Thorne and 't Hooft co-authored a book.

Hi everyone,Every time I read an article about black hole evaporation through Hawking radiation, it seems to me that the writer didn't bother to connect all the dots so it will be clear for dummies like me.In many articles, I find 2 contradictory statements:1. Black hole emits a radiation (i.e...