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    1. #26
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      Quote Originally Posted by khh View Post
      Uh... mass = weight. And you don't have infinite weight.
      uh... mass = weight/gravitational field strength.

      you obviously have never done even low level physics in school

      and besides, i was saying hypothetically if you had infinate weight, because putting it in the equation gives you 1

    2. #27
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      Quote Originally Posted by slash112 View Post
      uh... mass = weight/gravitational field strength.
      you obviously have never done even low level physics in school
      Yes, that's quite obvious.
      Except that when we say "weight" what we really mean is mass. If something weigh 1 kg, that that is it's mass.
      edit: What you're talking about is force.
      G = m * g
      where G is the force, m is the mass and g is the gravitational field strength.
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    3. #28
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      someone get xei in here, im sure he would have something to say about this particular subject.

      in science, mass (m) is measured in Kg,
      gravitational feild strength (g) is measured in N/Kg
      and weight(W) which is the force, is measured in N

      mass and weight are completely different things

    4. #29
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      Quote Originally Posted by slash112 View Post
      someone get xei in here, im sure he would have something to say about this particular subject.

      in science, mass (m) is measured in Kg,
      gravitational feild strength (g) is measured in N/Kg
      and weight(W) which is the force, is measured in N

      mass and weight are completely different things
      Oh, we're talking past each other. I've never really heard anyone use the word weight about the gravitational force, but it seems I'm wrong about the linguistics here. English isn't my native language, after all.
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    5. #30
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      Quote Originally Posted by khh View Post
      Oh, we're talking past each other. I've never really heard anyone use the word weight about the gravitational force, but it seems I'm wrong about the linguistics here. English isn't my native language, after all.
      oh, that would make sense. because if you were to be taught english language you would probably be told weight is another name for mass. it is also what kids are told in school before they do physics. infact it is what is used everywhere except in science.

      but back to the original point...

      m=W/g
      so if you had infinite g and infinite W, you would get infinity/infinity=1

      which means infinite gravitational field strength doesnt necasirally mean infinite mass

    6. #31
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      Quote Originally Posted by slash112 View Post
      m=W/g
      so if you had infinite g and infinite W, you would get infinity/infinity=1

      which means infinite gravitational field strength doesnt necasirally mean infinite mass
      The extended formula is
      (γmM)/r^2
      In which γ is a constant (value 6.67 * 10^-11) m is the mass of one of the objects, M is the mass of the other and r is the distance between the two. Which means that either m or M, both masses, would have to be infinite.
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    7. #32
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      does (γmM)/r^2 equal g?

    8. #33
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      Quote Originally Posted by slash112 View Post
      does (γmM)/r^2 equal g?
      No, it equals G. Or the "weight" i guess :p

      What are we debating again? Whether or not it would explode if the mass got diminished?
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    9. #34
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      Quote Originally Posted by khh View Post
      No, it equals G. Or the "weight" i guess :p

      What are we debating again? Whether or not it would explode if the mass got diminished?
      oh right. and i was taught that weight is W, and i thought that symbols are the same throughout the world, oh well who cares i know what your talking about anyway.

      and, i dont know what we were debating, i was just commenting on things people say.

    10. #35
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      Quote Originally Posted by slash112 View Post
      oh right. and i was taught that weight is W, and i thought that symbols are the same throughout the world, oh well who cares i know what your talking about anyway.
      I've only seen W used about work, in joules.
      I thought that G is the symbol used throughout the world :p

      Quote Originally Posted by slash112 View Post
      and, i dont know what we were debating, i was just commenting on things people say.
      Hmm. Well cause if we're debating whether or not it would explode, that formula I just posted would mean that if the particles are actually at the exact same point, then the gravitational forces between them would actually be infinite and they should never be able to part.
      Or it just means the formula ceases to work then.
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    11. #36
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      Quote Originally Posted by khh View Post
      I've only seen W used about work, in joules.
      I thought that G is the symbol used throughout the world :p
      well where i come from work done in joules symbol is "Ew"

    12. #37
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      Quote Originally Posted by Xei View Post
      They appear bigger than points, as black circles, because light gets sucked into them.
      I remember learning this in my Stellar Astronomy class.
      naturals are what we call people who did all the right things accidentally

    13. #38
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      Quote Originally Posted by slash112 View Post
      well where i come from work done in joules symbol is "Ew"
      Huh, that's fun. We use Ek and Ep for kinetic and potential energy, but for some reason W for work. That's kinda funny.
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    14. #39
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      Quote Originally Posted by khh View Post
      Uh, there's a certain point at which the forces inwards (gravity) gets bigger than the forces outwards, and a mass implodes. Beyond that I don't know. I'm not a physicist :p
      That doesn't explain the infinite gravity.

      You said:
      "Well, when the gravity no longer is sufficient to keep the remaining mass in a singularity, it's got to expand, doesn't it?"

      Gravity is infinite. How can it be no longer sufficient to keep the remaining mass.
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      Quote Originally Posted by khh View Post
      Huh, that's fun. We use Ek and Ep for kinetic and potential energy, but for some reason W for work. That's kinda funny.
      well i think our way makes more sense lol. no just kidding, im just surprised because i thought it was the same everywhere

      and yea we use them for the energies too

    16. #41
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      Quote Originally Posted by Bonsay View Post
      You said:
      "Well, when the gravity no longer is sufficient to keep the remaining mass in a singularity, it's got to expand, doesn't it?"

      Gravity is infinite. How can it be no longer sufficient to keep the remaining mass.
      Yup, I said that. I might have changed my mind, though. If there's no distance between the particles then the formula I posted earlier says that you've got something divided by zero, which may or may not yield infinity. I can't remember the math for this.
      If it does, and if the mass of the black hole is indeed at one, single point with no distance between it (oh, and the formula is correct), then the gravitational forces holding the black hole itself together would be infinite and it would not expand even if it lost mass.

      Quote Originally Posted by slash112 View Post
      well i think our way makes more sense lol. no just kidding, im just surprised because i thought it was the same everywhere
      I think it's supposed to be.
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    17. #42
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      Thanks guys.

    18. #43
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      Quote Originally Posted by khh View Post
      Yup, I said that. I might have changed my mind, though. If there's no distance between the particles then the formula I posted earlier says that you've got something divided by zero, which may or may not yield infinity. I can't remember the math for this.
      If it does, and if the mass of the black hole is indeed at one, single point with no distance between it (oh, and the formula is correct), then the gravitational forces holding the black hole itself together would be infinite and it would not expand even if it lost mass.


      I think it's supposed to be.
      Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.

    19. #44
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      Quote Originally Posted by Licity View Post
      Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.
      i thought it does give infinity. ive seen all the smart ones talk about it on DV.

    20. #45
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      Quote Originally Posted by Licity View Post
      Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.
      Yeah, that's possible. I don't know. As I said, I don't really remember that math.
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    21. #46
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      Quote Originally Posted by Licity View Post
      Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.
      http://en.wikipedia.org/wiki/Division_by_zero



      The function y = 1/x. As x approaches 0 from the right, y approaches infinity (and vice versa).

      Neither am I well versed in mathematics. But this is what I think of.
      Last edited by Bonsay; 06-13-2009 at 09:46 PM.
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    22. #47
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      Quote Originally Posted by Bonsay View Post
      The function y = 1/x. As x approaches 0 from the right, y approaches infinity (and vice versa).
      There is a difference between approaching infinity and being infinity. At times, we use the "extended real numbers" or "one point compactification" of the reals, which do include -inf, +inf and inf respectively, but those aren't really relevant in physics, afk.
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    23. #48
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      Quote Originally Posted by Licity View Post
      Division by zero does not yield infinity; the operation is undefined. This means that it is impossible to have no distance between particles.
      This isn't a valid inference anyway. In the extended reals, x/0 is defined to be infinity for all real x != 0. It is possible, within our current models, for bosons but not fermions to occupy the same space. It's refered to as boson condensation. I don't know if this would be possible within the conditions of a black hole. The reason that we say it has infinite gravitational attraction is because the graph looks sort of like the one bonsay pointed. Any time a function "blows up" or goes to infinity then we call it a singularity. Quantum theory is full of them and it is one of the major problems to juggle the mathematics around to make them go away.
      Last edited by PhilosopherStoned; 06-13-2009 at 11:02 PM.
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    24. #49
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      This explains my point pretty well.

      "However, there are some theoretical circumstances where the end result is infinity. One example is the singularity in the description of black holes. Some solutions of the equations of the general theory of relativity allow for finite mass distributions of zero size, and thus infinite density. This is an example of what is called a mathematical singularity, or a point where a physical theory breaks down. This does not necessarily mean that physical infinities exist; it may mean simply that the theory is incapable of describing the situation properly. Two other examples occur in inverse-square force laws of the gravitational force equation of Newtonian Gravity and Coulomb's Law of electrostatics. At r=0 these equations evaluate to infinities."
      http://en.wikipedia.org/wiki/Infinity

      In reality, or physics there is no such thing as "infinity". Only because the mathematical proofs allows these theories to include infinity do not mean that theory or model is in fact reality.

      When we gave a particle or a black hole zero size it makes sense mathematically, and it seems that these models are appropriate enough to still be useful to science. But I am sure that this "point/zero size" model will get replaced when the opportunity arise.

    25. #50
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      Getting back to the original question, there is a theory (not sure of the name) that what happens in a black hole has to do with perception. From the outside, a person who "falls" into a black hole is destroyed, while the person would perceive themselves to be whole, continuing on their straight trajectory.

      Another example, two perfectly synchronized watches are on the wrists of two people. One person (victim) starts to fall into a black hole just before midnight. If the outside person could watch the time on the victim's watch, and the victim is "destroyed" at exactly midnight, the victim's watch would never reach midnight. However, the victim would perceive time to pass as normal.

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