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

    Solve Oblique Asymptote & Graph: f(x)=x^3+3x^2-x-5/x^2-1

    Homework Statement Find the oblique asymptote and sketch the graph Homework Equations f(x)=x^3+3x^2-x-5/x^2-1 The Attempt at a Solution My question is that shouldn't there be a hole in the graph when x=-1 or 1? The denominator would end up being zero. When should i be using an...
  2. B

    How do massive stars like VY Canis not turn into black holes

    Apparently VY Canis Majoris is 30–40 solar masses, also there's R136a1 which is 265 solar masses. How do they remain stars with all that mass?
  3. F

    Question about semiconductors' holes.

    I know holes are made/present after electron leaves its place but are holes present in metals during photo electric effects? what is the mass of a hole (if it has any)? what are its characteristics are they exactly opposite of electron ( i mean its behaviour in electric and magnetic field ) ?
  4. A

    Why should radiation lead to loss in mass @ Black holes?

    According to theory of black hole radiation, black holes are expected to emit a thermal spectrum of radiation, and thereby loss mass, owing to the E=mc2 equation. Well, everything was clear to me till I got to the last point. why should there be loss only in mass?? couldn't the mass be same and...
  5. P

    Gigantic Black Holes vs White Holes: How Can We Know?

    Hello friends! Forgive me, I have another question for you physicists. We see those active galactic nucley which show enormous emission phenomena, so: How can we know that responsible are gigantic black holes and not white holes? I suppose we guess it, becouse we have some theory on the...
  6. G

    Two identical black holes, but rotating in opposite directions collide

    What would happen? Would the result be a non-rotating black hole? During their collision when their ergospheres overlap, would it generate an area where nothing could move in either direction along the plane of rotation? Also, since the force of their gravitational pull would be the same, would...
  7. M

    The Natural Dispersion of Black Holes

    Black holes are believed to be scattered throughout the universe. These ultra-dense bodies have a gravity field so dense that nothing, not even light can escape. If these bodies are able to consume everything that enters its event horizon than over the billions of years that the universe has...
  8. M

    The shape of black holes and their surroundings

    Hi Guys, Just a thought, if a job of a black hole is to suck everything in it's surrounding to nothing-ness. Then why are the there examples of black holes with jet streams flowing away from their axial poles? Apparently the Earth's gravity field is weaker at the equator, so why does...
  9. D

    How Can We See Light from Black Holes?

    Whenever I see any image of a black hole or in television or anywhere, I found there is a ring of light around the black hole. In discovery channel, I heard them saying that scientist found rings of light in space which had black region inside it. It was also one of the evidence with the help of...
  10. R

    What is the mechanism of small holes in auditorioms used as sound

    what is the mechanism of small holes in auditorioms used as sound absorbers
  11. I

    Black holes in tetrad formalism

    Where can i read about the solution of Einstein equations with spherical symmetry in tetrad formalism?
  12. A

    Why is it so accepted that matter falls into black holes?

    It seems like black holes could just as easily be expelling the matter they rip up. Couldn't a black hole just be something that rips matter apart atom by atom and then blasts it back into space? In this case there wouldn't be a need for a singularity. Quasars are one example of how they...
  13. K

    Searching for Microscopic Black Holes in the LHC

    Have we ever observed microscopic black holes in the LHC?
  14. Z

    Proof that micro black holes can't exist?

    I was playing around with some equations and I found a reason why I think micro black holes cannot exist. This proof requires a few assumptions which I have tended to find to be a scientific consensus. They are the following. 1) The smallest mass a black hole can have is the Planck mass which...
  15. T

    Is the Mass of Super-Massive Black Holes Factored into Dark Matter Calculations?

    When it comes to dark matter; Has the mass of the super-massive black holes residing at the core of every galaxy been taken into consideration? Could the total mass of all black holes account for the missing mass in the universe?
  16. K

    Laypersons problems understanding Black Holes

    A description of problems with the common understanding of black holes by this layperson: I have been contemplating black holes since I first heard about them at a lecture series by the then director of the Griffith Observatory in Los Angeles, by Dr. William J. Kaufman circa 1964. It seems...
  17. J

    Can we truly know the fate of objects in black holes?

    According to a recent published article, Physicist Leonard Susskind feels, along with Niels Bohr, that rather than try to come up with a mental picture of what objective reality is, scientists should limit themselves to creating hypotheses and testing them empirically. Susskind contends that a...
  18. C

    Black Holes Schwarzschild radius

    Is Schwarzschild radius trying to state the gravitational field on the event horizon of a black hole? If not, what is it trying to state? Can you give me a example using his formula to figure out the gravitational force of a black hole in the event horizon? Do you have any links I can...
  19. L

    Black Holes : Zero Volume, Infinite Density

    I didn’t believe it when I first heard it. I don't know how to reconcile this fact with what I understand about the known laws of physics. It appears to be one of the grandest mysteries I can think of. I understand that most of the universe is empty space but zero volume is different. Anyways...
  20. bcrowell

    Quantization of mass for black holes?

    "Black Hole Masses are Quantized," Gia Dvali, Cesar Gomez, Slava Mukhanov, http://arxiv.org/abs/1106.5894 There is a nontechnical summary on the arxiv blog: http://www.technologyreview.com/blog/arxiv/ , along with some inflammatory and uninformed speculation about safety at the LHC, including...
  21. E

    Exploring the Reality of Black Holes: Event Horizons vs. Singularities

    Hello to all physics community! I have a question concerning black holes. Are black holes, real holes? And which is the difference between black holes and wormholes?
  22. J

    Exploring the Cosmic Ocean: Water Vapor Around a Feeding Black Hole

    I have read that it is possible that primordial black holes could have formed in many different sizes, from micro black holes to hundreds of solar masses, my question is this. What is the smallest black hole that could survive from this time until now, without being destroyed by hawking...
  23. B

    An upper limit to the size of black holes?

    In an earlier post I make the controversial suggestion that the universe was very heterogeneous in the early stages. I have another conjecture that goes along with that one. Please try to read this with a bit of an open mind. Imagine that there is an upper limit to the size of a black...
  24. P

    Primordial Black Holes: Could Spacetime Form BHs?

    Could the primordial black holes that seeded the first galaxies have been formed from spacetime that never expanded below the critical threshold for black hole formation? If quantum jitters caused the variation in densities seen in the cosmic background radiation, could islands of higher density...
  25. L

    Are black holes theoretical or real?

    The news always depicts them as real http://www.bbc.co.uk/news/science-environment-13964767 But as far as I gather from reading this forum and wikipedia, black holes are always said to be "candidates" Has it been proven "beyond a reasonable doubt" that they exist?
  26. S

    What Causes the Increase in Area of Black Hole Horizons?

    From another post on this forum, we have an excerpt of Susskind's "The Black Whole War": To figure the increase in mass, let's figure the energy of the photon and then convert that to an equivalent mass. Photon energy is E = hf and if wavelength is R[sub]s/SUB], from v = f x...
  27. B

    Why Can We Feel the Gravitational Field of a Black Hole?

    Hi every1 My question is: we know nothing travel faster than light. Gravity travel at the speed of light, right? Now: light cannot escape from a black hole. So: gravity cannot escape from a Black Hole. Then... why can we feel the gravitational field of a black hole if gravity cannot be...
  28. K

    Do planck frequency photons form near black holes?

    Locally, photons "blue-shift" when falling down a gravitational field. What happens when they arrive at the Planck frequency? Do they turn back into matter?
  29. D

    Could Technicolour Play a Role in Black Hole Collapse?

    I know we haven't yet discovered that a technicolour force actually exists, but it seems to be worked out to some extent mathematically? (Not to say there hasn't been a false alarm, or two) I'm just curious that if it did end up existing, has the math been worked out far enough to see if it...
  30. bcrowell

    Black holes in the early universe

    I'm pretty ignorant about astrophysics, but this made it into the newspaper today, and it seemed interesting. http://arxiv.org/abs/1106.3079 "Black hole growth in the early Universe is self-regulated and largely hidden from view," Treister et al. "The formation of the first massive...
  31. C

    Are Black Holes Hot? A Deeper Look

    I was wondering if black holes are insanely hot, my guess is they are because so much matter has been crushed together causing friction and energy. Is this right? Thanks. PS: if it's something a 14 year old wouldn't understand, please give me a url link to wikipedia where I can study it...
  32. X

    Can Charged Black Holes Propel Interstellar Travel?

    Hello! I'm redesigning my never-to-be-finish sci-fi novel, yet another futile to come up with scientifically based interstellar travel propulsion. My latest consideration is based on article[1] and possible extensions of those ideas. Anyway, I'm looking for an independent opinions on the...
  33. S

    Possible non-existence of black holes and its consequences

    Here's an idea I came up with recently, that I wanted to share: Physics is unitary and CPT symmetric, and therefore no true black holes exist, since they imply information loss and non-reversibility. Every "apparent" event horizon is really a separation of two mostly causally disconnected...
  34. S

    Possible non-existence of black holes and consequences

    Here's an idea I came up with recently, that I wanted to share: Physics is unitary and CPT symmetric, and therefore no true black holes exist, since they imply information loss and non-reversibility. Every "apparent" event horizon is really a separation of two mostly causally disconnected...
  35. J

    Black Holes and their original star

    Black holes suck in everything around them. My 5 year old knows that one. It's all over TV, etc. But what about the original star? Wouldn't that have just as much gravity? Wouldn't it do the same thing with the strength? Is it just that black holes are more exciting to talk about?
  36. C

    Can Black Holes be Propelled by Ion Engines?

    Jet propelled Black Holes by ion engine? Might asymmetry of jets for BH, together with Newton’s Third Law, result in high velocity over time, from an ion engine? Perhaps even several 100 km/s? Might Large Synoptic Telescope detect motion of associated binary massive star?
  37. C

    Black Holes & Gravity: Exploring Photons & the Singularity

    From reading various articles my understanding is that BH are gravitationally extreme - although from a distance they are gravitationally the same as any other object it is inside the Schwarzschild Radius EH where BH's differ from other large masses. The "singularity" is the point at which...
  38. C

    Drilling Holes in Pressure Vessel Flanges

    Hello, I have been designing a pressure vessel for the last week. I have based all my maximum allowable stresses on ASME code but can't figure out how to include drilled holes. I plan to be using a pipe welded to a cap at one end and attached to a blind flange with holes drilled in it at the...
  39. K

    Moving electrons and moving holes? How does a hole move?

    Hi all. I understand that a hole is the absence of an electron. I have come across textbooks with instances where they talk about movement of minority carriers, and movement of majority carriers. Since the hole has to be one of them, they are referring to moving holes. But, how can a hole...
  40. P

    Black holes and higher dimensional universe

    if black holes are 2 dimensional representations of our 3 dimensional universe, does that make our universe a 3 dimensional representation existing on the edge of (or entirely inside) a 4 dimensional universe? or to a 4th dimensional being would our 3 dimensional universe be considered a "black...
  41. S

    Is time and space moving through us? Do black holes rotation create time?

    I look at time and space as a fabric, just as Einstein stated. However I look at time and space as a fabric moving through us. Moving through all organic matter like a river. So time is merely flowing past us just as space is. Is this the case? If we are moving around the sun in a trench of...
  42. G

    Miniature Black Holes: Calculating Distance from Person

    Homework Statement This problem is awesome! I like this chapter; Its really interesting. I think I just get a little impatient when I can't figure out the answer right away... I appreciate any help. Miniature black holes: Left over from the big-bang beginning of the universe, tiny black...
  43. C

    Are Black Holes sufficiently characterized?

    Is mass, angular momentum, and charge sufficient for black hole characterization? Or is also entropy, and hence surface area, also required? Thus is the shape for a given mass black hole also a required consideration?
  44. L

    Exploring Quasars and Black Holes

    How a quasar beam can get out of a black hole if no light is suppose to be able to get out of the event horizon of a black hole. ? Is it because the beam is created outside of the event horizon ? From what I understand quasar is created because of excess of matter on the black hole correct me if...
  45. K

    What Happens When You Increase an Extremal Black Hole's Charge?

    If you were to greatly increase the elctrical charge of an extremal Black Hole, (ie, drop a lot of electron in) what exactly would happen to it? I know the electrical repulsion would become more powerful than the gravity, so would it tear itself apart?
  46. narrator

    Black Holes and Wormholes: Fact or Fiction?

    Hi, Lay questions again. What's the real story - is a black hole potentially a worm hole? If someone theoretically entered a black hole, the common portrayal is experiencing tremendous acceleration. But with time compression, how different would that acceleration feel to the traveler...
  47. T

    Deflection angles of photons passing by black holes

    In trying to compute deflection angles for photons given their impact parameter (closest distance of trajectory to centre of black hole if unaffected) I am trying to numerically integrate the following equation (d^2/d(phi)^2)(u)+u=3Mu^2. However I am stuck as to how to work out the initial...
  48. S

    Unraveling the Mystery of Dark Matter and Its Relationship with Black Holes

    Hello everyone if black holes have a gravitational pull so strong that nothing can escape, then why is it that they do not continuously consume dark matter? Yes i know its called dark matter because it doesn't not interact with other matter but it does have an effect on the rotational curves...
  49. nukeman

    Black holes and Event Horizon: Q's ?

    I understand why you would be ripped apart if you enter a black hole, but I don't understand the fact that if the black hole is large enough, You would not be ripped apart if you passed the event horizon. And, some black holes you would be ripped apart outside of the event horizon? Can...
  50. nukeman

    Why Do Physicists Consider Black Holes Something?

    Hey all, I may be way out of the ballpark here, but its something I thought about today at one of my Astronomy lectures. How come Physicists view a black hole as "Something" rather than "Nothingness" ? The Physics about Black holes is still some what uncertain, and we try out best to...
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