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Help with the fundamental forces.

  1. Jan 11, 2014 #1
    Could someone help me understand the four fundamental forces?

    I'd like to set up a thought experiment as well:

    Let's break up our solar system into individual atoms, and create a gas cloud about the size of our solar system. All things like they are, the gas should slowly come together, and form something similar to what we have, right?

    Now, in an effort to understand dark matter, along with what the fundamental forces do, what happens if we individually take away one of the fundamental forces from the gas? How will the cloud evolve over time? Such as, without electromagnetism, is it possible for a star or planet to form? What do the strong and weak forces do? How will the matter change as we remove a fundamental force?

    I know this may not be the best approach, but maybe you can help me find a better way to think about it?

    Thanks for your time!
  2. jcsd
  3. Jan 12, 2014 #2


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    Staff: Mentor

    Probably much smaller (natural collapsing gas clouds are quite large), and a bit less massive, but it depends on the angular momentum you give that cloud.

    Dark matter is irrelevant for the formation of individual stars.

    Should look like this:

    Without gravity the gas cloud does not collapse at all.

    Without electromagnetism there are not atoms, electrons and nuclei just pass through each other and there is no pressure. Nuclear reactions happen as there is no repulsion between the nuclei, forming increasingly larger nuclei (I don't think there is an upper limit on stability now as there is no repulsion between protons any more). I guess you would create a large, thin cloud of really exotic nuclei, with a few electrons hanging around (unless they start with sufficient energy to escape).

    Without the weak force, no nuclear reactions can happen. The gas cloud heats and collapses, and the new sun gets a white dwarf quickly as there is no additional source of energy.

    Without the strong force, there are no nuclei or hadrons (like protons and neutrons) at all, it is unclear how the initial state is supposed to look like.
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