Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Just an Idea

  1. Mar 19, 2004 #1
    According to Einstein's theory of general relativity, gravity bends or warps space-time. this is because the gravitons, or gravity waves, contain no mass and therefore exert their force over large distances with infinite speed. in other words, light from a star that passes by a large body, like our sun, could appear in a place that it is not. the gravity from the sun would bend space time so that even though light may seem to follow a striaght path, it is actually following a curved one. the gravity of large bodies doesnt affect places lightyears away at this magnitude because gravity's force diminishes as it gets farther away from its source. this has led many physicists to believe that if one went in a straight line, they would eventualy end up at the same place after a period of time. this is because all the matter in the universe has warped space time so much, that space time would appear like the earth or sphere. (as if looked through a 2d space) i would agree that at some point in time, all the matter in the universe was very hot and dense. (the big bang) let us go through what i think will happen throughout the expansion of the universe. first, the big bang would take place obviously. next, like it has been found, galaxies that were formed would expand from the point of the big bang. since there is much evidence to say that gravity will not stop this expansion and conclude in an event known as the big crunch, it is logical to say that the universe would continue to excpand forever. however, since the matter in the universe bends space time so much, they would eventually meet either halfway around the universe, or back at were the big bang took place. this wouold result in another big bang. i accept this because it seems that everything that is clear to us is very similar. for example, atoms have a nucleus in which electrons revolve around. the moon revolves around the earth. the earth revolves around the sun along with all of the planets in our solar system. the sun revolves around the center of our galaxy. wouldn't it be safe to say that the galaxies in our universe revolve around the center of the universe. it is very hard to imagine such a thing in 3d space so i will use 2d space for now. galaxies could be represented as electrons and the center of the universe is represented by the nucleus of an atom. this would imply that the universe is finite, but spacetime is infinite. our universe is contained in space time.

    fire away people!
  2. jcsd
  3. Mar 19, 2004 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    One of the first thing you must learn is to use some paragraph structure, reading your post is painfull.

    Next you need to understand, that much of which you think you understand, you do not.

    For example:
    1. gravity is not instantenous, it travels at c.

    2. According to Quantum Mechanics, atomic structure is NOT isomorphic to the structure of a solar system. This, first model, of the atom is good only for basic concepts, it simply does not work for real applications. I wish that they would never even mention this model simply because it leads novices far astray.
  4. Mar 19, 2004 #3


    User Avatar
    Science Advisor

    Hi. You have unfortunately got many things wrong. (But don't blame yourself, it's not easy to get a clear picture of this in the beginning.)

    The speed is c, not infinite.

    There is no single point where we can say Big Bang started. The singularity is now everywhere.

    No. All matter will move further and further away from each other.
    Compare with a 2D-universe existing ON the surface of a balloon which is expanding.

    No, because there is no center to move around!
    Last edited: Mar 19, 2004
  5. Mar 20, 2004 #4
    I read in a Brief History of Time that gravity is instantaneous. Wouldn't that mean that the gravitons travel at an infinite distance?
  6. Mar 20, 2004 #5


    User Avatar
    Science Advisor

    "because the gravitons, or gravity waves, contain no mass and therefore exert their force over large distances with infinite speed."--threewood14

    No. Keep in mind that photons also "contain no mass" and they move (in vacuum, and as measured by an inertial observer) at constant speed c, which is most definitely finite.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook