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Black Hole?

  1. May 13, 2015 #1
    Can someone please explain what a black hole is? I hear everyone speaking about it but have no idea what it is.
    Is it something where even speed of light becomes 0? How?
  2. jcsd
  3. May 13, 2015 #2
    You can search in google.
  4. May 13, 2015 #3


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    Indeed. PF is a poor substitute for an encyclopedia or other source of general information about a subject. Try searching 'Black Hole' in wikipedia, reading the article, and then coming back here if you have specific questions. Google is also a good source of information IF you can avoid any pseudoscience.
  5. May 13, 2015 #4
    A black hole forms when a high-mass star dies. It basically emits no radiation (light) hence the name black hole. It's gravitational field is so strong that matter in its vicinity gets pulled in and lost forever. Nothing can escape its gravitational pull - not even light.

    I'm sorry I just skimmed through your post and didn't even read the last question. Since speed of light is the fastest speed allowed in physics, which means nothing can exceed the speed of light. There is a concept called escape speed, which is the speed needed for one object to escape from the gravitational pull of another object. An object's escape speed is proportional to the square of the body's mass divided by the square root of its radius. So the more compressed an object is, the more escape speed is needed to escape that object's gravitational pull. Now a black hole is basically the core of a high-mass star that collapsed on itself and is compressed down to a point where even the required escape speed exceeds the speed of light. But remember, nothing can exceed the speed of light since it is the fastest allowed speed in physics. Therefore, the conclusion is nothing can escape from that compressed object, or in other words, a black hole.
    Last edited: May 13, 2015
  6. Jul 5, 2015 #5


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    I've had to remove multiple posts from this thread whose information is almost entirely wrong or have been crackpot theories. Time to lock this thread.
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