Holes Definition and 1000 Threads

A hole is an opening in or through a particular medium, usually a solid body. Holes occur through natural and artificial processes, and may be useful for various purposes, or may represent a problem needing to be addressed in many fields of engineering. Depending on the material and the placement, a hole may be an indentation in a surface (such as a hole in the ground), or may pass completely through that surface (such as a hole created by a hole puncher in a piece of paper). In engineering, a hole may be blind or through if it is partial or complete depth.

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  1. J

    Can Black Holes Consume Light Without Increasing in Mass?

    Hello, I was wondering a thing or two about black holes, now I'm not any kind of physicist or hobby astronomer for that. But can a black hole consume infinite amounts of, let's say gamma rays without increasing in mass or any other effect? However gamma rays haven no mass since they are pure...
  2. A

    White Holes: Real or Hypothesis?

    The White Hole is Real ? or Just a hypothesis with a mathematical model ? and Why the White Hole is the Opposite Of the Black hole ?
  3. C

    Question regarding maximum accretion of black holes

    So I've got a question that I can't seem to figure out. If the accretion efficiency of a black hole is L=εM(dot)c2 with ε=0.1 I have to set this to the Eddington luminosity which is Ledd = 4πcGMmp/σT to find the maximum rate at which a black hole can accrete by. I found that κ=mp/σT so I...
  4. A

    Collapsing Sun: Will It Get Smaller & Denser?

    When the sun is beginning to collapse will it get smaller and denser?
  5. Y

    Colliding Black Holes & Einstein's Equations

    I was watching Neil deGrasse Tyson video, in which he describes a scenario of colliding black holes. He mentions that when two black holes collide, there is a huge distortion of the space time between those two black holes as each of their even horizons intersect (i.e. each black hole has passed...
  6. E

    Do Schwarzschild Black Holes exist?

    The title says it all. Do static black holes really exist, or do the ones we know about seem to be spinning? ISTM unlikely that there could be any non-rotating black holes, but I don't really know, hence the question. Do we have the means to determine with any certainty what the answer is?
  7. M

    Why do black holes have such strong gravitational pull?

    Why are black holes black even though light(photons) has no mass? Gravity shouldn't affect it.
  8. A

    How can two Black holes fusion and consist a supermassive Black Hole

    How can two Black holes fusion and consist a supermassive Black Hole ?!
  9. N

    Gravitational non linearity: the glue of Black Holes

    Any comments on the following description from Kip Thorne, BLACK HOLES AND TIME WARPS, 1994, Box 10.1 would be appreciated. It seems odd to me that at some given curvature, gravity would become self sustaining...if that is what he is saying. We have previously discussed in these forums that...
  10. L

    Exploring the Mysteries of Black Holes

    Hi, I'm at high school at the moment and i have gotten really interested in black holes and the way they work as i have been reading books from Stephen Hawking. So we know that black holes absorb matter and photons by the pull of gravity. And we also know that it emmits radiation. But because...
  11. A

    Why don't black holes become stars again?

    1st post here - new to the forums - sorry if this is a stupid question.I was thinking, if the universe is approximately 98% hydrogen, you would think the matter a black hole consumes would be mostly hydrogen. So you have a black hole, it's consuming a ton of hydrogen, squeezing and condensing...
  12. H

    Black Holes Uniting: How Do They Crash?

    if black hole crash they unite to one b.h here, how can this two crash?? universe has a lot of dimension so i think it is hard to and when they crash, crash with only singularity??
  13. Hercuflea

    Are black holes explained by complex analysis?

    Is the center of a black hole essentially a pole, or a "point at infinity"? I always thought about this in my complex analysis class because one variable complex functions are 4 dimensional, which could translate into space-time. Black holes have to have infinite density in their center, too...
  14. I

    Black Holes in String Theory - calculation help needed

    I have a question about the paper: C. G. . Callan, R. C. Myers and M. J. Perry, “Black Holes In String Theory,” Nucl. Phys. B 311, 673 (1989). I have attached the relevant section. I am having trouble using equations (2.1) and (2.4) to derive (2.5) and (2.6). When I do the calculation...
  15. A

    Decent papers/articles on black holes

    Any decent papers/articles on black holes, their formation, dynamics, etc? Moderate amount of maths and derivations involved would be great!
  16. D

    Fermi Level of Electrons and Holes in Equilibrium and Non-Equilibrium

    Hi all, Why do the fermi level for electrons and holes coincide in equilibrium condition and why they separate as quasi fermi levels in non equilibrium situation?
  17. rjbeery

    Can Black Holes Truly Exist for Earth Observers?

    1) First we shall define to exist, relative to an observer, to mean that "the object in question lies in the observer's past light cone" 2) We define a black hole to be an "area of sufficiently compressed mass such that an event horizon of non-zero radius exists" 3) Next we make the...
  18. E

    Can We Really Understand Black Holes If Nothing Can Escape Them?

    How can we know anything about black holes if nothing, not even information can escape the event horizon? If we can know the mass and gravity of a black hole it is because some information is being sent by the black hole, but how can this be possible if nothing, not even light, can escape...
  19. Z

    Do Black Holes *actually* exist?

    So I found this article(albeit rather dated) questioning they physical existence of Black Holes and what really struck me were some of the comments by physicists Jose M Pecina-Cruz who may or may not be on physicsforums but nevertheless, this is what he had to say about it: So there is also a...
  20. S

    Logical Proof That Black Holes Can't Exist

    1. Three ships approach a 'black hole'. One ship continuously accelerates at a constant rate to keep itself stationary relative to the 'black hole'. One ship cuts off its engines and free-falls. The last ship accelerates away from the hovering ship and steadily increases its acceleration at an...
  21. R

    Percentage of stars that become black holes

    What percentage of stars become black holes? I tried to find this information through Google searching and the only thing I could find was a statement that said less that 1 in 1,000 stars in our Milky Way galaxy have enough mAss to become a black hole.
  22. S

    Equilibrium Distribution of Electrons and Holes

    Hello. I was studying the Semiconductor and I am confused with this diagram. I have attached the diagram. Please tell me briefly what does this diagram say. So that I could ask further. I have confusion with this diagram. I don't want to be specific so that you describe the whole diagram...
  23. A

    Virtual particle creation in black holes

    Hi, As I understand virtual particle pairs can be created outside of the event horizon of a black hole. I understand that they result from Vacuum Fluctuations. What creates these vacuum fluctuations? ***A side note: I hope I'm not violating any rules of the physics forums by creating two...
  24. Chronos

    Primordial black holes as DM candidates

    This paper, Constraints on primordial black holes as dark matter candidates from capture by neutron stars - http://arxiv.org/abs/1301.4984, appears to just about seal the coffin on primordial black holes as dark matter candidates. It does an admirable job summarizing the mass constraints on...
  25. C

    What is the effect of a massive, fast-moving planet entering a black hole?

    Hey all! Two things came to my mind about black holes, and I hope some of you can help me out :) 1. Say you have a non rotating, chargeless black hole of a certain size. Its radius will be R. If you go through the black hole, from your perspective then time will be fine, right? Then that...
  26. dbmorpher

    Can Black Holes Be Used for Faster-Than-Light Travel?

    Hello dbmorpher here, I am an avid Halo fan, and in the lore the ability to go faster than light is from the http://halo.wikia.com/wiki/Shaw-Fujikawa_Translight_Engine I wanted to know if miniature black holes and hawking radiation would be able to rip a hole in space-time. If not what are...
  27. T

    Why do smaller black holes emit more Hawking radiation?

    Why is it that the smaller a black hole is, the more Hawking radiation it emits? It seems counterintuitive to me. I would think that a larger black hole with a larger surface area would trap more antiparticles from virtual particle antiparticle pairs, hence emitting more Hawking radiation.
  28. G

    Black Holes: Mass, Schwarzschild Radius & Size

    If a black hole is a stellar structure that has collapsed on itself to a singularity does that mean it has no size? But is so defined by its mass and schwarzschild radius? Cheers
  29. P

    Black holes: Some astronomers detected flashes of x-ray in the cosmos

    Some astronomers detected flashes of x-ray in the cosmos. They say it can only be possible because matters temperature increases to million degrees to radiate into x-rays, and only objects entering into black hole could radiate x-rays in whole cosmos. How can you detected x-ray radiation from...
  30. shounakbhatta

    Exploring the Mystery of Black Holes: A Beginner's Guide

    Hello, I want to understand how black holes are formed. I don't have any idea of basic astronomy. Can anybody please guide me to a resource centre which gives the basic idea of astronomy. Thanks and regards, -- Shounak
  31. H

    Primes, pigeon holes, modular arithmetic

    Homework Statement The Attempt at a Solution Don't have a clue how to even start this one, sorry.
  32. S

    Black holes and General Relativity

    Hello everybody, I was watching a documentary about black holes the other day and I noticed something odd. General Relativity is said to break down when you apply the mathematics on a singularity. In this case, the center of the black hole. The radius of a singularity would be 0. Now there...
  33. S

    Does light aimed outward contribute to the pull of space-time in black holes?

    Black holes can pull photons in although they move at the speed of light. So, does this means that black holes pull space-time in faster than light and if so, why can space-time "travel" faster than light?
  34. A

    Can Black Holes Truly 'Grow' in the Lifetime of the Universe?

    A lot of scientific literature states that black holes 'grow' in size (which I think is equivalent to saying 'grow their Schwarzschild radius or event horizon'). They apparently do so by consuming external matter that falls into them. However, any matter that does fall toward a black hole...
  35. A

    Quantum tunnelling and black holes

    Just a quick question, that I'm not completely clear about; Quantum tunnelling allows particles to overcome barriers that they classically shouldn't be able to overcome, my question is simply, do/can particles escape a black hole after passing the event horizon due to tunnelling? If not, why...
  36. A

    Can Black Holes Bend Time?

    how can black holes bend time if time bending is impossible ?
  37. B

    Completeness axiom as having no holes in the set

    Completeness axiom as having "no holes" in the set My textbook describes the completeness axiom as essential to showing that there are no "holes or gaps" in the real numbers. That is, for any two reals A and B, there exists a real C such that A<C<B. Of course, we all know that the actual...
  38. J

    Size of Black Holes: A Closer Look

    So are all black holes infinitely small, which is what they call the singularity point? I'm talking about the actual distance the matter of a black hole takes up. Does a super massive black hole have the same physical size as any other black hole(which i guess would be infinitely small) and just...
  39. P

    Will object with speed near the speed of light become black holes?

    . http://en.wikipedia.org/wiki/Black_hole and we know that when object travels near the speed of light it gains infinite mass, so does it means that it becomes a black hole?
  40. S

    Speed of light enough to escape black holes ?

    I wad thinking since black holes are so dense ... lights speed would get slow significantly , so isn't it that if you are at light speed ( 3 x 10^8 m/s ) then you might come out of a black hole ? Its the same concept we learn in 10 grade ! Am i right ?
  41. S

    Observable Universe and Black Holes

    Hi, my first post here! Galaxies outside the observable universe (that we can't see their light) can affect us with their gravity? If the answer is no, we can say that gravity information travels at the speed of light. So, in a black hole how gravity information from an object inside...
  42. M

    Frame Dragging & Galactic Rotation: Implications for AGN & Black Holes

    Hi, I am interested in the issue of frame dragging used in a number of galactic rotation models. However, I wanted to first make sure that I have a better understanding the relativistic implications of frame dragging. While the issue of galactic rotation is not the subject of this thread, it is...
  43. M

    Electric Quadrupoles, Micro Black Holes & String Theory

    I had an exchange with Lubos Motl about this topic, in the comments here. Very briefly, there is a 2004 paper in which the author (Kjell Rosquist) considers the old idea that the electron is actually a spinning, charged (i.e. Kerr-Newman) micro black hole. Using a purely classical model for...
  44. M

    Black holes, universe boundaries and geometry

    A quick novice question. What sort of shape would project a holographic reality (Kind of like water spraying from the inside walls of a sphere) from the boundaries of the universe and at the same time contain drains (black holes) that feed the shower?
  45. M

    Filling holes or gaps in mathematical knowledge.

    I graduated high school nine years ago. The highest math I took then was Algebra II, as I had little interest then. After a seven year career, I was able to go back to school and have made it to Calculus I this semester. I struggled some in college algebra, finding out that there were...
  46. U

    Does temperature affect black holes

    Is there a temperature that black holes cease to emit non-zero mass particles.
  47. R

    Naive question regarding black holes.

    so, when it comes to EM or strong force or weak force, you cannot tell the difference it some object exists inside a black hole or if it does not. nothing from that object gets out from behind the event horizon. except for gravity. if a black hole swallows up a massive star, the gravitational...
  48. C

    Holes in a 2-D surface and holes in 3-D space

    I was watching a panel discussion on YouTube in which Neil DeGrasse Tyson made a very interesting remark about black holes. He said that we traditionally think of holes as indentations in a 2-D surface, such as a hole dug into the ground, and that it didn't make sense to imagine a hole floating...
  49. T

    Do Tidal Forces in Black Holes Affect Matter at the Quantum Level?

    Theoretically; As any mass approaching the core of a black hole, then would the tidal force difference effect the quantum level and rip apart matter? Also at the very centre of a black hole would gravity cease to exert its force since in any direction the "pull" would be equal?
  50. D

    How do holes in semiconductor carry heat?

    This question is about seebeck effect. If the movement of hole(positive charge) happens because of electrons moving in opposite direction, how is the heat carried by hole when one side of p-type semiconductor is heated? Is it from lattice vibration?
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