What is Holes: Definition and 1000 Discussions

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. F

    Does how black holes inside galaxies orbit around the central black hole tell us

    Does how black holes inside galaxies orbit around the central black hole tell us anything useful? Could be my noobness, but the idea of a bunch of black holes orbiting a central black hole just seems messy. ha. Have we got the jist of what would happen if a black hole ate another black hole? if...
  2. W

    Can flat spacetime model Black Holes?

    I'm asking because some of you state that flat spacetime can't model black holes... meaning even between the Planck scale and event horizon, but yet atyy said spin-2 field in flat spacetime is equivalent to General Relativity for spacetime that is covered by harmonic coordinates which atyy...
  3. J

    Can Black Holes Grow and Merge?

    Do black holes become larger and larger with all the matter and light they consume? And is it possible for a black hole too merge with other black holes?
  4. J

    Relative Black Holes: Can Particles See Universes of Them?

    Is it possible that a particle traveling so close to c from its reference frame observes objects within their schwarzschild radius? In other words is it possible that in these particles reference frames is a universe primarily comprised of black holes? If so then would gravity be relative?
  5. M

    Exploring the Possibility of Elementary Particles as Black Holes

    Is there any theory for which "elementary" particles are "small" black holes or/and for which the electron and the proton would be a pair of associated black holes? Does such question even be meaningful ? Or is it just science-fiction, the fruit of any crazzy imagination?
  6. P

    Time, simultaneity, black holes & entropy

    I'm a newbie, and I've got some questions that are raised by Leonard Susskind's "The Black Hole War," a fascinating non-technical book about his argument with Stephen Hawking about whether or not information is conserved even if it is dropped into a black hole. I've read several threads and the...
  7. P

    Neutrinos Interaction with EH of Black Holes

    Hi all, While the articles I have been reading are about a year old (which can be considered relatively outdated in terms of particle physics) I have been looking at the possibility of Neutrinos being able to travel at FTL (Experiments conducted by CERN and OPERA). I understand in the articles...
  8. C

    Pauli Exclusion Principle and Black Holes

    I understand that there may be no answer to the question "Why is Pauli Exclusion Principle not applied beyond a Neutron Star's mass?" since there may not be a full quantum gravity theory yet, however, I'm thinking, what if Pauli Exclusion Principle is not really a principle, but an indication...
  9. P

    When did black holes first started to appear in the universe?

    I need to know when did the first black holes appear?
  10. T

    Do balck holes violate the constancy of the speed of light

    I read that the speed of light is constant, that everyone measures the same speed of light from their own reference frame. Yet I have also read that light can't escape from a black hole, because of the gravitational effects. How can you measure it's speed at 'c' and yet at the same time not...
  11. S

    Black Holes: Observation of an astronaut falling

    Hey guys, I'm a new guy in this forum. I've been visiting it for 1 year actually but never decided to register and so I did. I am having a presentation on black holes at school and I want some clariffication of what's going on when falling into a black hole. Well let's assume that an...
  12. F

    Electrons and holes: how can holes have a mass?

    Hello Forum, in semiconductors, there are two types of charge carriers: electrons and holes. Holes are fictitious positive charges...How can they have a mass? thanks, fisico30
  13. A

    What Happens to Photons Near a Black Hole?

    1. Photons approaching a black hole will initially a. all of the above are possible depending on distance from the event horizon b. pass by with their direction changing (bending/curving) c. fall into the black hole d. go into orbit around the black hole e. pass by without...
  14. P

    Black Holes Relation to an Accelerated Expanding Universe

    Hello, Let me first start off by saying that I have no formal Education or background in Physics or Astronomy save for one course during college. This is simply posing an idea I had while reading an article on the acceleration of the expanding universe and how it could have a correlation with...
  15. R

    Doesnt information travel faster than light in case of black holes?

    hi, i was wondering, for a black hole, as everyone knows,the escape velocity is greater than light. this means that the information about the existence of the black hole in terms of light never reaches the observer. so if the black hole were the cease to exist at an instant of time, the...
  16. T

    On the rotation of black holes

    My question is this: Does the direction of spin of a supermassive black hole exert an affect on the spin of its surrounding galaxy (given that the above described black hole is at the center of such a galaxy)? Is there a direct or correlative effect? If so, can an in-depth explanation be...
  17. S

    Understanding Black Holes: Quantum Physics and Hawking Radiation Explained

    Hey everyone, I have some questions about quantum physics and black holes. For starters, what happens to an entangled particle as it enters a super massive black hole? Would gravity just break the entangled state because of the extreme forces? The only issue i see with that is that...
  18. S

    Acceptable misalignment between holes on mating parts?

    Hi, I am working on a design that has a stack of CSK PC/104 pcb boards fastened togther using HEX spacers. One of the PCB boards is being designed by an different design team. They have already manufactured their board but it turns out that the screw holes for the Hex spacers are...
  19. A

    Grazing collision of two black holes

    Suppose two black holes graze one another in a high speed encounter. The collision is glancing such that the event horizons merge and then separate. Q1) I assume this is possible? Now suppose that the collision is nearly but not completely collinear. Q2) Is it true in this case that...
  20. K

    Evidence that black holes gain in mass?

    Please correct me if I am wrong, as I have little more than a high school knowledge of physics until I start at university this year - virtually no knowledge of the quantum side of things just yet. ^^ My thought is, as spaghetification occurs as you approach the centre (not using singularity...
  21. A

    Black Holes and Thermodynamics: Exploring Entropy and the Second Law"

    I read in a book that since the area of a black hole increases, the entropy increases, so black holes are consistent w/ the second law of thermodynamics. So...I have a really stupid question on black holes and the second law of thermodynamics: Consider an ideal gas of non-interacting...
  22. B

    How can Black Holes emit radiation?

    I know that black holes are still not entirely understood, but I do know that it's generally accepted that they emit Hawking radiation. But I've also heard that the gravitational pull of a black hole is so strong that nothing can escape, "not even light". So how is it possible that Hawking...
  23. C

    How do black holes relate to physics?

    I have to write a research paper on a topic of my choice for physics class, I chose black holes simply because they interest me and it was one of the few topics unchosen. Can anyone with more scientific intellect then myself provide some insight as to how black holes relate to physics? Just some...
  24. X

    Are Black Holes Deceivingly Still?

    To my understanding, as an object approaches the event horizon of a black hole, the light that is seen by a relatively static observer slows down more and more until the light is eventually "trapped" on the event horizon, making it appear to the observer as though the object is standing still...
  25. Elroch

    Rotating black holes, causality and time travel ramble

    It is well-known that associated with the Kerr solution which represents a rotating black hole, there can be a region of space-time where there are loops in space time (non simply connected paths which are navigable in principle). If this is so, it breaks causality and permits time travel in...
  26. R

    First post a question about Black Holes and Gravity

    Hi everyone. I have a very keen interest in physics. Unfortunately at school I was made to do a combined qualification in science which didn't allow me to pursue what I was interested in most. I still try and read and understand what I can about physics and cosmology... but one thing has...
  27. S

    Are supermassive black holes just big stars?

    Simple enough question. I know there are two types of black holes; the type formed after a star collapses in a supernova and the supermassive variety like the one at the center of the milky way. If a star continued to grow by swallowing up other stars and solar systems is it possible that at a...
  28. Elroch

    Large black holes and information

    Hawking and others suggest that it is a very special deal that macroscopic black holes lose quantum information, but I only partially agree. It is clearly important that they do not preserve most quantum numbers - black holes may be a way to break a lot of conservation laws of particle physics...
  29. F

    Black Holes: Falling in and Looking out?

    I think we're all familliar with the old "What if you fell into a black hole?" Event horizons, time dilation (I think is the right term), and spagettification. There is however one thing these thought experiments never seem to cover that I'm really curious about. As I understand this...
  30. J

    How Electromagnetic Waves Pass Through Holes

    Hi everyone I have a question that has been bothering me for a while now. I have basically built a Faraday cage using wire mesh. I know there is a relationship between the mesh hole size and the wave suppressing ability of the cage. As I understand it an electromagnetic wave can be thought of...
  31. J

    Can Neutrinos Escape from a Black Hole and Affect Its Lifespan?

    If neutrinos can move faster than light speed, then can they escape from a black hole? If so, then would the life of a black hole be reduced?
  32. C

    Are black holes really the cookie monsters of the universe?

    http://whoknew.news.yahoo.com/who-knew/black-holes-27425876.html
  33. S

    Why don't we see a lot of matter around black holes? And can we observe it?

    Hello! I just want to start off by saying that I am no physicist or astronomer, so my apologies if my questions are really basic lol (although I am an engineer so I do have some technical background). I am very interested in it though, and I had some questions that I was hoping someone could...
  34. D

    Unraveling the Mysteries of Black Holes and the Big Bang

    Am I correct in saying that in theory Time, Matter and presumably Energy are compressed to a singularity at the centre of a black hole? If that is so then wouldn't they be "transported" back to the state and position they were in at the very beginning of time. In other words the instant of...
  35. D

    Sound wave in a tube of air with holes (lab)

    Homework Statement I had a Physics lab with the following setting: A signal generator is connected to a speaker which is located on one end of a tube. This creates the sound wave. The tube is open on both ends. A micro is movable along the tube and it is connected to an occsilator which...
  36. narrator

    Entropy, heat death and black holes

    Talking about the big bounce and black holes in another thread made me wonder about the life span of black holes, especially in the heat death scenario. If the U went through heat death, does that mean that black holes would also exhaust their energy? Do black holes die, and if so, what...
  37. X

    Can time slow down infinitely in black holes?

    It is my understanding that time within black holes is slowed down incredibly, and all of the mass is found within this slowed down area. How then could a black hole move if time is slowed down so much (possibly infinitely)? Shouldn't this slowing of time also reduce the speeds of the mass...
  38. T

    Space-Time Black Holes: Measuring Warped Space/Time

    Can the amount of space/time warped by a black hole be measured and if so, where can I find measurements of previously measured black holes?
  39. D

    Black holes and time dilation around the event horizon

    As I currently understand it from the point of view of an observer falling into a black hole it takes a finite time to cross the event horizon and reach the singularity. From the point of view of a far away observer the person falling into the black hole never actually crosses the event horizon...
  40. R

    Black holes, dark matter, the expansion of the universe, and unifying theories.

    A thought experiment I have been thinking about this for twenty years and I would like to hear your opinions. It relates to black holes, dark matter, the expansion of the universe, and unifying theories. This is very simple and beautiful to me. Forgive my lack of formal training, my goal...
  41. B

    Is there a limit to information storage on the surface of a black hole?

    Hello, I'll try to explain this as well as I can... I was watching NOVA's special on The Fabric of the Cosmos and the segment on how information is both lost in the black hole and stored on the surface got me wondering "Is there a limit to how much information can be stored on the surface...
  42. Rlam90

    Exploring My Ideas of Black Holes: Matter & Energy

    I don't like the idea of anything crossing the event horizon of a black hole from any observer's view point. The closer something gets to the event horizon, it either appears to slow down, or the event horizon appears to stretch and move further away. How can anything cross it? For this...
  43. G

    Exploring the Formation of Black Holes: A Curvature in Space-Time

    If gravity is a distortion between space and time, then how come black holes are formed, only the surface of an object should then exert gravity, right?
  44. J

    What Happens When Two Black Holes Collide?

    what happens when two black holes collide?
  45. J

    Neutron Stars vs Black Holes: What's the Difference?

    what is the difference between a neutron star and a black hole?
  46. E

    Using Black holes to view our solar system

    Has anyone figured out or tried this: It seems to me that since light is bent by G fields, that looking close enough to the side of a black hole, some of that light near the event horizon may have escaped its G field after its trajectory has changed significantly... possibly redirected enough...
  47. D

    Those Jets from the poles of black holes

    Can anyone point me to a journal article that describes, mathematically or otherwise, how those jets shoot from the poles of some black holes with accretion discs and AGN. Also, if you will forgive the additional question, is there any reason why the physics that describe the ejection from...
  48. 2

    How do black holes radiate if nothing can escape?

    Hi. So, as title says, how can black holes radiate if nothing can escape from them?
  49. H

    I'm writing a novel involving worm holes and asteroids/meteors

    Please Help! I'm writing a novel involving worm holes and asteroids/meteors I thought it would be best to ask the experts in the field to make sure I don't get lynched when this book comes out. Please help however you can. The date during this particular incident is Feb 14, 2016, 11:47 pm...
  50. mrspeedybob

    Thoughts on electrically charged black holes

    Suppose there exists a black hole with a large + electrical charge. The escape velocity for any given particle will depend on the net force on it, gravitational + electrical. It seems logical that the more positive a particles charge the lower its escape velocity will be from any given point. If...
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