does the univerce have an end, a limit?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Shadow1, Jan 1, 2010.

  1. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    There are for most practical purposes only three space dimensions, but three more velocity dimensions are required to fully specify a system of particles. This set of 6 specifications (or really 6n coordinates, 6 for each of the n particles) is usually called "phase space." Some important theorems are stated for phase space.

    For example one can define a constant energy surfaces in phase space (more that just Vx^2 + Vy^2 + Vz^2 sum for all particles, if some particles are charged and there are electric fields) The ergotic theorem states that if you wait long enough, then the system will pass as close as you like to any given point in phase space. This then allows one to makes certain probability calculations more easily, allows gas laws to be derived from first principles, etc.
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  3. Emil Valued Senior Member

    You're right.My English is not good.

    You're right.
    But how do you define a movement?Coordinate is not changing with time?
    If in space 3D coordinates does not change with time,this means it is no movement?
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  5. sifreak21 Valued Senior Member

    very true but everything we know as of now is it is endless hard to comprehend the size but we will never know.. just think if this was the entire universe ( ) then whats out here ->

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  7. Fraggle Rocker Staff Member

    We don't "know" anything about that at all! This is simply an assumption. We've learned from the mistakes of our ancestors. They assumed that the earth was a plane rather than a sphere because it seemed that way from their point of view. Thanks to them, we are smart enough to not assume that the universe is a hyperplane rather than a hypersphere.

    We have absolutely no information to support an assumption either way. In other words, "everything we know" about it is insufficient to make a hypothesis. Let's be humble and admit our ignorance!

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