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. bcrowell

    Dokuchaev, Is there life inside black holes?

    Dokuchaev, "Is there life inside black holes?" I thought this was pretty cool. "Is there life inside black holes?" Vyacheslav I. Dokuchaev http://arxiv.org/abs/1103.6140 Abstract: Inside a rotating or charged black holes there are bound periodic planetary orbits, which not coming out...
  2. mrspeedybob

    Black holes and conservation of charge

    Suppose you take a quantity of matter and separate the protons from the electrons, Now drop the electrons into a black hole. My understanding is that photons are the force carriers for the electromagnetic field. Since no photons can escape the black hole there should be no electrostatic...
  3. Pengwuino

    Hawking Radiation w/out black holes

    I stumbled upon an article while doing some research that had a statement saying that Hawking radiation can be found in places beyond black hole horizons. This lead me to this paper (which I'm not actually interested in beyond it's reference to the existence of hawking radiation outside of...
  4. T

    How can Block Holes form in finite time?

    I think this subject may have been discussed here already; please point to the thread if so. I am unable to understand how Black Holes can form within the lifetime of the universe. If nothing can cross an event horizon in finite time, then it seems clear that the horizon can't form (at...
  5. T

    Escaping Black Holes: Questions & Answers

    Several questions about escaping the event horizon of a black hole typical disclaimer: I am not a scientist so please don't scold me too much for curiosity. I imagine a large black hole with a less massive black hole in orbit around it. Light enters the event horizon of the more massive...
  6. N

    Can anyone please expand on white holes?

    "It is theoretically possible for a traveler to enter a rotating black hole, avoid the singularity, and travel into a rotating white hole which allows the traveler to escape into another universe." Can anyone please expand on white holes?
  7. S

    Black holes and only photons going in

    Build a Dyson sphere around a black hole (this is a thought experiment), so no more mass "falls in". Line the sphere with insanely bright lights. What happens to the black hole? I ask this because Prof. Sean Carroll in "From Eternity To Here" discusses whether there is a limit to the...
  8. N

    Black holes can be characterized by their event horizons.

    a) If the sun were compressed sufficiently enough so that it would turn into a black hole, what would be the event horizon of such an object expressed in km? b) What is the event horizon for a black hole with a mass of 10 9 Msol? c) What is the event horizon for the black hole with a mass...
  9. S

    Density of supermassive black holes.

    Wikipedia gives this description of supermassive black holes to distinguish then from stellar black holes: "The average density of a supermassive black hole (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be much less than the density of water...
  10. A

    The Schwarzschild Solution and how it led to the discovery of Black Holes

    I'm currently researching for the term paper of my class on black holes and the topic I selected is the one in the title. I've found some good information so far, but I don't feel like I have enough to get an A without a bit more. I'm curious if anyone has any resources that would aid this...
  11. soothsayer

    Is it Possible to Escape a Black Hole?

    I had a couple questions regarding the ability of objects and light to escape a black hole. 1) The even horizon is supposedly the boundary at which no object can escape from a Black Hole, as within this radius, the escape velocity is greater than c. This much I understand; If I throw myself...
  12. L

    Exploring the Fascinating World of Black Holes: Thoughts and Questions

    Hello there, I am new to the forums, and relatively new to physics. Please bear with me as I am still learning the intricacies of the subject. I have always been fascinated with science, but I missed several opportunities to study it academically. Most of my knowledge is self-learned through...
  13. A

    Exploring the Power of Magnetic Fields Around Black Holes

    recently i came to know that the jets of gases from black holes are due to magnetic fields...so in effect does this field overpower the effect of the gravitational pull of the BH?
  14. P

    Shockwave cosmology and white holes

    Now I’ve been trying to read up on this Shockwave cosmology model and wanted to see if I have the correct view since most of the math is over my head. Now from what I understand in this model is that there is a white hole singularity that explodes and instantly disappears and it produces a...
  15. S

    Exploring the Mysteries of Charged Black Holes

    So how do charged black holes work? If its photons that are the carriers of the electromagentic force, and photons can't escape from a black hole. How can anything external to a black hole tell if it's charged or not?
  16. R

    Are Black Holes Matter Sprinklers?

    Is the total jets mass emitted by a black hole to space smaller or larger than the total mass the black hole pulls in from the flat disk of gas that swirls around it? In other words, are black holes matter sprinklers that convert heat to matter and spray it to space?
  17. C

    Is the behavior of dark matter contradictory to the formation of black holes?

    Hello, Firstly, i would like to say that i am by no means an educated person (as in taking specialty courses or an university degree in cosmology or physics), at least regarding this subject. From this point of view, what i am about to ask might seem silly or just plain stupid, so feel free...
  18. G

    Black Holes: B. Green's The Fabric of Cosmos

    Do you know any book written by a great physicist where he talks about black holes? I always enjoy reading the more relaxed way of talking that appears in popular scientific books such as The Fabric of Cosmos - B. Green.
  19. R

    Why doesn't dark matter fall into black holes ?

    Why doesn't dark matter fall into black holes ? Assuming it doesn't of course. If it did then surely huge amounts would have fallen into black holes. By now they'd be full of the stuff & more massive than they are. So I'm assuming for some reason dark matter doesn't fall into black holes. In...
  20. E

    How Many Holes Are Needed in a Bottle to Effectively Water a Garden?

    A garden is watered with a watering homemade consist of a plastic bottle, with numerous holes r of diameter, lying on the garden and conected to a hose. Asumme that a bomb water is responsible for generating a flow of water constant Q. How many holes must have the bottle to get water to wet...
  21. V

    Why can't light escape black holes?

    Hello, I am aware that this question was the subject of a topic on this site, but it did not fully answer my question. My question is, why can't light escape from a black hole's gravitational pull, when, according to general relativity, the speed of gravity is equal to the speed of light? My...
  22. J

    Black Holes: growth affected by Higgs or Dark energy/matter

    I am curious to what extent black hole growth can be used to probe understanding of various particles/fields. 1] Dark matter: Let's consider dark matter to be so weakly interacting we can model it as a perfectly non-interacting gas. For even more simplification, let's assume dark matter...
  23. L

    Black Holes computation homework

    I'm trying the exercises on p35 of the following: http://arxiv.org/PS_cache/gr-qc/pdf/9707/9707012v1.pdf I have done parts (i) and (ii) but was wondering if anybody can help me with (iii)? I had k \cdot D k^\mu |_{U'=0} = k^\nu D_\nu k^\mu |_{U'=0} = k^V' D_{V'} k^\mu since setting U'=0 means...
  24. I

    Do Black Holes and Dark Matter Interact?

    Interesting :o http://www.technologyreview.com/blog/arxiv/26316/?ref=rss
  25. T

    How Does Gravity Affect Light in Black Holes?

    As i know them, black holes are dead remains of stars where the gravitational pull is so great that not even light can escape. Well, but light(electromagnetic radiation, in general) has no mass, then how does gravity effect light?
  26. P

    Evidence of inexistence in black holes?

    Is there any hard evidence that the inside of a black hole is simply an empty oblivion of nothingness? I've been mulling over some thoughts on time, and this has been grinding progress. I'm currently trying to find if the possibility of its center being a negative index of timespace is indeed...
  27. F

    How did quasars form with such massive black holes?

    I was reading about quasars, and what I got from it was that quasars are extremely far away (3 billion + light years according to wikipedia), they were common in the early universe, and they have a supermassive black hole in the center of it. My question is how did these quasars get such...
  28. L

    Does nuclear decay apply to atoms of matter consumed by black holes?

    I can offer no further insight.
  29. A

    A questions about black holes among other things

    I'm not a physicist, just a mere philosophy grad, but I have some questions that may lead others to research, and I'm trying to find a place to ask them so that the information can be disseminated. They relate to the Holographic theory of the universe. Anyway, first question on this forum will...
  30. B

    Black holes, a simple theory, has it been looked into

    Here it is, its probably an old one but as I am not a fully fledged scientist I don't know if it is. It relys on parallel universes. So what if the black hole sits over a valve beetween the sheets of these universes sucking in matter and compressing it through the valve into the parallel...
  31. S

    Objects collapsing to black holes

    Im going to keep this very concise, mainly because i vaguely understand what I am discussing but anyways, as most informed people are aware black holes have an infinitely strong pull at their singularity and can even inhibit light. I am curious as towards the actual phenomena or reasons how an...
  32. A

    Understanding Charged Black Holes

    Can anyone explain to me what exactly is a charged black hole?Where is the charge?Is it on the singularity or somewhere else?
  33. Eagle9

    Novel-Travel inside the Black Holes

    Good day! The famous American scientist Kip Stephen Thorne once wrote a novel the name of which probably is like this: “The travel inside the Black Holes”. I wrote probably because I have not read it in English language, I read its translation in one of European languages. This is little story...
  34. L

    Formation of neutron stars and black holes.

    First of all, I know that that very large stars tend to form black holes, and smaller stars, but still massive in comparison to our sun, tend to form neutron stars. My question is, if matter is lost when a star collapses into a black hole, but can still form one, why is it that it is a star...
  35. H

    A little help here with black holes

    Well I'm a senior in high school have an independent study to finish for my physics class. I have started my research, however I am still needing to know how I am going to pull a good 10 pages of information from this project (which is how many the teacher is asking for). I just need to know...
  36. P

    Question about black holes and gravity

    The black hole is surrounded by an event horizon. No matter which fell under the horizon will never escape, even in the form of information (in the classical theory of relativity). So why is the star orbiting a black hole moving at the correct speed and trajectory, as if they knew the mass of a...
  37. G

    Do Electron Holes Have Spin Angular Momentum?

    Do holes (i.e. electron holes) have spin angular momentum like electrons do? Thanks for any insight you can give and if you can recommend any literature on the mater that would be great! Thanks!
  38. E

    Conceptual ramifications if black holes do not exist.

    My question here is to ask what would be the consequences to theoretical physics if, it was discovered, that black holes do not exist in nature. For example, as gravity and pressure increases beyond neutron star, new, previously unknown quantum principles, similar in spirit to loop quantum...
  39. D

    Planets Surviving Black Hole Formation: A Scientific Inquiry

    Can there be planets revolving around black holes? I'm not asking about black holes at the center of galaxies, but other black holes.
  40. I

    Exploring Light's Path Between Two Colliding Black Holes

    I'm going to have trouble stating this question exactly in the language of GR, but I'm going to try my best. We have a manifold with two identical black holes falling into each other from a large distance with no angular momentum, both spin and around their collective center of mass. A ray of...
  41. S

    Body-centered-cubic # and types of holes?

    In the Body-centered-cubic (BCC) unit cell which types of holes (interstices) are there? (tetrahedral, octahedral, or cubic) How many of each type? Thanks!
  42. G

    Calculating Gas Particle Effusion Rate Through Two Holes

    Homework Statement A gas effuses into a vacuum through a small hole of area A. The particles are then collimated by passing through a very small circular hole of radius a, in a screen a distance d from the first hole. Show that the rate at which particles emerge from the second hole is...
  43. S

    What would happen if two black holes collided?

    What would happen if two super-massive black holes collided with each other? I know it may be a very unlikely scenario. I just started thinking about this for about a week and I wanted to see what anyone had to say about it. Thanks!
  44. W

    What is the Purpose of Black Holes?

    A little philosophical question. What would you say is the purpose of a black hole? To create another universe? To somehow balance the distribution of mass? Any guesses or hunches? Just curious.
  45. P

    Question about Black Holes and Speed

    Hello everyone this is my first post. I just recently started getting interested in physics but just from a very theoritical view and in very simple ways My problem goes like this: As far as i am concerned according to Relativity Theory nothing can go faster than light. So then we have the...
  46. T

    Exploring the Mystery of Black Holes

    hi, i was just wanting to get a few opinions on where and maybe even when a black hole goes to. It's something I've read into a lot in the past few months; and I'm really interested to find out what others think. Thanks
  47. S

    Existence of super-massive black holes

    Imagine that you are an astronaut standing very far from a black hole.Now you throw a luminous body (a bulb may be) directly towards it.Now as it gets nearer the black hole,the light from the bulb as you observe it becomes more red-shifted.Eventually from your frame(consider it is an inertial...
  48. P

    Do Black Holes Grow? Investigating the Lifecycle of a Galaxy

    I know that this can not be true because if it was, the universe would be mainly black hole by now but I can't seem to fathom how if something has an increase in mass (law of conservation of mass) from an external object, it does not increase in size. My next thought would be, if gravity is...
  49. M

    Question about Big Bang and Black Holes

    After the Big Bang it was a short period of inflation. After that the physics that we know is supposed to apply. After inflation the speed of the expansion was smaller than the speed of light and all the mass of the universe was in a relatively small volume. Why was not the universe a black...
  50. P

    Is Time Travel Possible Through Black Holes?

    Black holes-- time travel? Is it plausible for something to time travel by means of a black hole, or is that entirely science fiction?
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