Orchid Win7 v1 <voi### [at] devnull> wrote:
> > That one is easy. Simply because our eyes can only see in 2d. We can
> > perceive 3d images because of the stereoscopic effect of having 2 eyes.

Perceiving three-dimensional space is not related to stereoscopic vision.
It helps, but it isn't what makes it three-dimensional perception.

> That doesn't explain why visible objects around us only move in 3 
> dimensions. If there were more dimensions and we should somehow only 
> "see" 3 of them, we should see objects constantly zipping into and out 
> of the 3D slice we can perceive.

Talking about slices is, as I see it, nonsensical. A camera doesn't see
a "slice" of the three-dimensional space. It sees a *projection*, which
is a completely different thing. If there were a fourth dimension that's
like the other three, we would likewise see a three-dimensional projection
of it, not a slice.

Anyway, according to general relativity, spacetime *is* four-dimensional,
and everything actually moves in the fourth dimension all the time.
Moreover, the reason why gravity (seemingly) accelerates objects is
because of this movement in 4-dimensional spacetime. (The spacetime is
curved, which is what causes the apparent acceleration. In reality it's
not acceleration but inertia.)

So, technically speaking, when you drop an object, you are seeing movement
in the fourth dimension (or, more precisely, the effects of the curvature
of spacetime, from which we see a 3-dimensional projection, which is what
causes us to perceive it as accelerating motion, even though in reality
it's just inertial motion. It's a similar idea as how a railroad seems
to converge at the horizon in a photograph.)

-- 
                                                          - Warp

Post a reply to this message