Holes Definition and 1000 Threads

The thread https://www.physicsforums.com/threads/how-close-is-earth-to-the-closest-black-hole.939912/ reached a conclusion that there is a 65% confidence level that there is one black hole within 50 ly of Earth. The link http://www.solstation.com/stars/s20ly.htm says there are 25 stars bigger...

Yet the neutron degeneracy pressure is unknown correct? Said size of neutron is a variable? What if we view the pressure as a volume knob, why could not a BH be viewed as a NS with the volume turned up from higher pressure?

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...

https://www.forbes.com/sites/startswithabang/2018/02/14/black-holes-must-have-singularities-says-einsteins-relativity/amp/

If photons are light particles, and they lack mass, how is it possible that they are affected by gravitational pull from a black hole? Super sorry if this has been asked / answered before, I couldn't find it on this forum if it has... Caveat No.2: My physics knowledge was limited to high school...

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...

After searching elsewhere online I could not find any information about this thought and hope someone may offer some insight. Black holes seem to be generally discussed as having a single entrance point from the event horizon and down into its singularity. I am confused by how quasars have...

As we know the universe is expanding. Could this accelerating expansion contribute or cause black hole evaporation given that the strength of the gravitational force does not depend directly on time, while the distance of two given points in space increases with time? Sorry if my approach is...

I was asked this question... Honestly I do not know! Imagine a black hole. You get sucked inside the singularity Yes, you'd die instantly, but suppose you lived. Where would you end up in space & time if, when inside the singularity, you float to a wall containing it and pierced it and traveled...

If they are infinitely dense than, they would have infinite gravity, so if they have infinite gravity then the universe would have been sucked into a black hole. I was told that black hole has Infinite density so I want to clarify with you guys because it's logically didn't make sense to me.

Primordial Black holes (PBH) need to be collisionless to be considered a serious Dark Matter candidate. Indeed a population of PBH with masses about 30 solar masses and uniformly distributed in the galaxy have very low capture and direct collision rates. But these PBHs should also behave as...

From Wikipedia: Quark-degenerate matter may occur in the cores of neutron stars, depending on the equations of state of neutron-degenerate matter. It may also occur in hypothetical quark stars, formed by the collapse of objects above the Tolman–Oppenheimer–Volkoff mass limit for...

I am reading about Kerr black holes and non rotating black holes. But I am unable to understand what decides whether the black hole will not rotate or rotate. And if No Hair theorem suggests, we can know about a black hole through its angular momentum, what implications does zero angular...

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 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...

Holes have an effective mass. How is the mass of holes measured physically?

Given a tube that requires a series of holes to be drilled into it, in general terms, what would be the optimal pattern/shape/spacing of holes to maintain structural integrity, particularly against a force acting in an axial direction ie, on the end of the tube? That is, to prevent buckling?

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...

This video by PBS spacetime makes me wonder if one of the things it discusses, namely the possibility that a white hole can be home to another universe, is a worth to pursue question. Is there any advances in terms of discoveries on this area? What are your personnal opinions about that...

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"...

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...

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?

I get how to derive black hole equations mathematically. But conceptually, how does it make sense that the radius of a black hole is 2MG/c^2, for example?

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...

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...

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?

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...

Why is the parabolic shape for the hole broader than that of the electron?

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...

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...