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Gravity , Dark energy and Atoms

  1. Aug 8, 2007 #1

    Hi , I am rather new to this (well just found the site today) and I was wondering weather any of you knew the answers to my questions? I have searched the internet for any theories on the questions bit without and success, and I would like to hear your views.

    My first question is about gravity, where does it come from , how does it work (I know it is the force between two masses)? On earth how does it work, does it come for the centre, if so what happens at the centre? Does it travel in a straight line or in a wave? If it does come from the centre how is it possible for it the simultaneously affect every single atom at the same time?

    Secondly I would like to understand dark matter? What on earth (well not on earth) is it. how does it fill 78% of our universe with us being able to see it. where does it come from, is dark energy what is emitted from dark holes?

    Thirdly I would like to understand the simple atom. What is truly inside neutrons and protons? If atoms are mainly made up of space are they kept together by their own gravity field, being pushed and pull simultaneously? How is it possible that all these uncountable atoms, for some reason decide to drift together randomly to form what we know, to form you? When they are mostly (in the mostly liberal term) air and when the inter atomic forces are always changing, why in this split second (in the big scheme of things) they make what they are?

    I know that most of these questions have not been scientifically proven, I was curious of any theories you might have? Thanks :smile:
  2. jcsd
  3. Aug 8, 2007 #2


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    May I suggest that to avoid confusion, and to ensure your post is in the appropriate forum, that you ask ONE type of question at a time and wait for the ensuing discussion before posting another question (which may or may not fit into the existing thread). If not, you will have a jumbled answer covering various things from different places. This isn't the way to get a clear, coherent answer, at least, not in a public forum such as this.

    In addition, please make sure you have reviewed the PF guidelines.

  4. Aug 8, 2007 #3


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    Forty Two!
  5. Aug 8, 2007 #4


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    Firstly as Zapper said, having the whole of astrophysics explained to you in one post is unlikely!
    Second physics generally doesn't explain how things are - it explains how they appear to behave. We have a series of models which we believe are the best explanations of observed behaviour - but there is a always a deeper level of 'but why does it do that'.
    You should read some popular explanations of space and physics, look for a series of books called "in search of ..." by John Gribbin.

    Gravity is a property of space. Space is distorted by the presence of mass which bends space. Particles in and moving through space feel the effects of the bends and move along them.
    Gravity doesn't have to travel to effect a particle because the particle is moving through space that is already bent. Changes in gravity do travel at the speed of light.

    Dark energy is not a very good term - and is nothing to do with black holes etc. 'Dark' just means doesn't light up.
    It seems to be a property of space which causes otherwise empty space to repel other empty space. Because of quantum effect, empty space isn't really empty. It is possible for pairs of particles to appear from no-where and repel each other, it seems that this effect is causing the universe to expand at a faster rate than we expect.

    Inside neutrons and protons are other particles called quarks, at the moment we don't know what is inside quarks - or even if there is anything.
    Gravity is much too weak a force to hold atoms together. The protons in the nuecleas are all positively charged and so would try and fly apart, they are held together by a much stronger force, similairly the quarks in individual protons and neutrons are held together by a different force.

    We have theories which predict the behaviour of these forces - but that doesn't explain what they are or why they should be there.
    I know this has raised more questions than it answered - thats physics!
    You should probably look at some popular science books and magazines.
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