Ahh, I gotcha. interesting.
On Fri, Sep 23, 2011 at 2:15 PM, Stephen A. Lawrence <[email protected]> wrote:
>
>
> On 11-09-23 02:42 PM, Alexander Hollins wrote:
>
> Wouldn't the light pulses only return at the same time if you also
> were at the center of the sphere?
>
> Sorry, I wasn't clear. The compact manifold in that case is the surface of
> the sphere. And in that case, you can't "be" at the center of the sphere;
> it's not part of the universe. (And all points on the surface are just like
> all other points on the surface.)
>
> The contents of the sphere, on the other hand, assuming you don't include
> the surface, wouldn't be compact -- it's an open manifold. (There's no
> well-defined edge, when you're inside looking out: any point which is inside
> the sphere can be surrounded by a tiny ball of stuff which is also inside
> the sphere.)
>
> The surface of the sphere, which is 2-dimensional, none the less can't be
> embedded in a flat 2-dimensional space.
>
> At least some cosmologists seem to think the "real universe" is like the
> surface of the sphere (but with more dimensions, of course): If you go far
> enough in a straight line you find yourself back where you started. The
> contents of a sphere isn't like that, of course -- if you're living inside a
> sphere, then you'd need to turn around at some point to get back to where
> you started.
>
>
> On Fri, Sep 23, 2011 at 11:12 AM, Stephen A. Lawrence <[email protected]>
> wrote:
>
> In fact, the questions aren't nonsense; they just need to be carefully posed
> to get sensible answers out of them in a universe where SR applies.
>
> There is a "distinguished frame" for the universe: The rest frame of the
> three degree background radiation. There just is one inertial frame of
> reference in which that's isotropic -- in all other frames it's red shifted
> in one direction, blue shifted in the other. That frame is (presumably) the
> frame which is at rest relative to the primordial fireball.
>
> Furthermore, if the universe is a compact manifold and "folds back on
> itself" -- such as the surface of a sphere -- then there is an intrinsic
> "rest frame" as well, which can be found by sending pulses of light
> simultaneously in opposite directions. If the universe is closed, and the
> light eventually comes back to the emitter, then there is just one inertial
> frame in which the two pulses will arrive back at the emitter
> simultaneously.
>
> More obscurely, if the universe is closed, then the frame just mentioned is
> the one in which the Sagnac effect is null. All other frames are (in
> effect) rotating (going 'round and 'round the universe).
>
>
> On 11-09-23 01:53 PM, Mauro Lacy wrote:
>
> Vorts,
>
> So, when I first heard about zero point energy years back, I assumed
> it was something I had already theorized myself when struggling with
> the concepts of relativity (which still bugs me, for the reasons I'm
> about to list) as I was mentally using the term Zero Point already.
> Imagine my dissapointment...
>
>
> Anyways, I'm a biologist and chemist more than a physicist, so PLEASE,
> correct me where I am wrong. As the velocity of an object increases,
> its apparent mass increases, and time slows, for that object, yes?
> And the time dilation and mass increase is "relative" to the velocity
> based upon the observer being a zero point. For 3 objects moving in a
> straight line in the same direction, one at .1 c, one at .2 c, one at
> .8 c, time dilation will be different for the .8 c object when vied by
> the other two objects, yes? because its traveling at .7 c compared to
> one, and .6 c compared to the other, correct?
>
> If that is the case, is there a zero point? is there an intrinsic
> velocity that pretty much EVERYTHING in the galaxy/universe shares?
> If so, what happens to mass and the flow of time as you approach that
> zero point?
>
> The "velocity of the vaccum". Does the vacuum moves? At which speed? And
> in relation to what? the immobile vacuum?
> Einstein's SR disregards all those questions as nonsense, or better said,
> "metaphysics". Speeds are only to be measured between material bodies, and
> not correlated against any absolute reference, because that absolute
> reference cannot be measured or determined.
> Does something that cannot be measured or determined exists? In which
> sense, or "where", it exists?
>
>
>
>
>
