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Gravity/mass concept

  1. Jun 8, 2005 #1
    in einstein's famous gravity model - gravity is caused by a disruption of some fabric by an object with mass (i.e. the ball on the fabric causes the fabric to "expand" creating an inward force toward the ball for other objects).

    i was thinking about this and wondering the following:

    1) if gravity is indeed this - i.e. a disruption or interference of something with the space-time fabric - could "mass" be described in the same way. i.e. - the mass of the object is defined by the way it interferes with the space-time fabric.

    2) the speed of light could also be related then as such ... the light particles/waves - don't interact with the space-time fabric in the same way that "massive" objects do. light perhaps passes through the fabric as if it were a vacuum of space-time. in other words - imagine that a ball that falls down a tube - the ball's velocity is restricted by the friction of the tube. the tighter the tube (or the bigger the ball) - the slower it falls. but - if the tube is big enough, or the ball small enough - the friction of the tube becomes irrelevant - and the ball's velocity has a maximum potential. to tie this back to the previous concept- imagine that light is the ball - and space-time the tube - and in this case, the light particles/wave is not restricted by/influenced by the space-time fabric - and so reaches a maximum velocity.

    3) a follow-on concept is that light particles/waves are only two-dimensional - i.e. they exist in only two dimensions instead of three (or three instead of four if you include time). thus - mass, or interference of the space-time field is defined by three space dimensions. i.e. in the same way that a box has an area but no volume - light has velocity - but no "real" mass. if that is the case - then perhaps, mass-energy equivalance is only true for certain dimensions. i.e. energy could exist in 1d and 2d particles/objects - even though they may have no mass.

    any thoughts?
  2. jcsd
  3. Jun 10, 2005 #2
    The bowling ball on a sheet model of gravity is not very useful when trying to find a fundamental definition of mass and inertia, IMHO. The model is incomplete and a tautology. Consider, what holds up the edges of the sheet? Consider, what is the sheet made of? Consider, what is the force that pushes the bowling ball into the sheet? The force of gravity is part of the model, so the model cannot be used to help understand what gravity is.

    You are juggling these ideas with some skill, but we are all waiting for someone to show us how they all fall together in a neat pattern. Keep thinking.

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