Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
Drexel University or The Math Forum.



Re: closed universe, flat space?
Posted:
Apr 29, 2013 3:56 PM


On Apr 29, 12:05 pm, Dan <dan.ms.ch...@gmail.com> wrote:
> What matters is what the observers living "inside" the space notice.
The observers look like that are housed inside a cylinder. When one goes around the world, if he pays more attention, he will notice that he is not moving in a straight line. <shrug>
> Let's say I have a flat , plastic blanket, and some people living > purely within the world of the plastic blanket , with normal time > (same as our time ) . Now , I proceed to 'fold the blanket' . What > would the observers living 'inside the blanket' notice? Has anything > changed 'inside the blanket' ?
Nothing has changed except being enclosed by this blanket. <shrug>
> Light along the blanket still travels > its shortest path , that is , along whatever fold I made in the > blanket , as to be a straight line in the 'unfolded blanket' .
This is not right. Light will stop at where the blanket starts to curve. Please experiment for yourself. If you have observed light travel along with the curvature of the blanket, please check yourself in for the thorough psychological checkup. <shrug>
> The > observers wouldn't notice anything has changed . In fact, for them , > nothing has changed .
Besides according to GR, all geodesic motions follow the paths that result in the least amount of spacetime (not time and not space). Light always travels/propagates with the exact null spacetime. So, to any observers, light will not propagate with a coherent path. Since interferometers work that require light to propagate with a coherent and timely path, the hypothesis known as GR is completely wrong from the ground up. <shrug>
> Let's say our observers are living in a perfect sphere (or a surface > with 'spherelike' internal geometry ) . That means it has the same > nonzero 'intrinsic curvature' everywhere . But, can our observers > notice the 'intrinsic curvature' ?
No, he can never tell if his own local space is curved or not since the curvature of space is relative. <shrug>
> Yes . Inside a sphere , they can build a triangle with three angles of > 90 degrees . That clearly means something funky is going on with the > space .
This is not an example of curved space. A good example is here on earth. Can you find a triangle that adds up its angles greater than 180 degrees? After all, the surface of the earth is under the effect of curvature of spacetime influenced by the earth itself and even more so by the sun. That is if the curvature business is valid in the first place. <shrug>
Koobee Wublee thinks the selfstyled physicists are way over their heads on the curvature of space or spacetime mumble jumbo. <shrug>



