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Implications of Infinity

  1. Aug 4, 2004 #1
    What are the implications of Infinity in Physics, such as QP, GR, SR.

    Like i know infinity leads us to black holes and other things.

    Do they do not pose a serious problem to physics.

    If anyone can give me some insights of dealing with infinity please do because to me the implications are bad when it comes to the mathematics behind the notion.

    To me inifinity is an abstract mathematical issue, and i understand that it is a must, because it will sooner or later come into the picture, but if all math breaks down at infinity or a lot of it, it's hard to reconcile with it.

    So i guess what I am asking for is for a knowledgable person to explain to me how infinity works in physics. How it can be treated. How solutions can be understood.
  2. jcsd
  3. Aug 4, 2004 #2


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    Staff: Mentor

    Have you had calculus yet? Its real useful in calculus.
  4. Aug 4, 2004 #3
    In many situations, infinity is used more as an approximation, a way to simplify calculations, or a way to downright allow them. Here are examples.

    -Although we know a solid is made of atoms, classical electromagnetics uses functions such as density as a fonction of position in the solid, as if the solid was continuous (continous <=> infinite amount of infinitely small atoms).

    -When a sine wave is used to represent a wave, it is an approximation of reality, since a true sine is infinitely long over time and/or space.

    - Integrals are often done over an infinite range because it allows a compact and ready solution.

    - Crystal theory assumes crystals are of infinite dimensions, since a random atom inside a crystal wouldn't know the difference.

    - The electric field E at (x,y,z) is define as V/q, when there is no q. No one denies the existence of something at (x,y,z) when there is no q, so the notion of infinity (limits) is essential to define a field.
  5. Aug 4, 2004 #4
    Actually I have had all of Calc I II and III, and I understand and have covered that gonzolo described so well, I see where infinity helps, i guess what I am asking is where it hurts, such as singularities where you have infinite density and gravity.

    And MOST of all I wanted to know if infinity was real or just abstract mathematical concept which help us engineers and phys. and others with problems like gonzolo mentioned.
  6. Aug 4, 2004 #5
    If you are standing a specified distance from a pretty girl, and incrementally move half your current distance toward her, it will hurt.

    Sorry. It was all I could think of.
  7. Aug 4, 2004 #6
    that doesnt make any sense, sounded like you were gonna start zeno's paradox and then you stopped.
  8. Aug 4, 2004 #7
    he's talking about this joke:
  9. Aug 7, 2004 #8


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    Staff Emeritus
    Science Advisor

    Infinities in a theory are a bad thing, usually indicating a flaw in the theory.

    However, dealing with infinity in the form of infinite groups (Lie groups) is becoming very important for anyone wanting to get into physics.

    So in my opinion one should not shy away from learning the abstract properties of infinite sets in math class, because infinite sets do have many useful appications in physics.
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