Re: Calabi-Yau
I've got something in mind...It might be manifestly ridiculous...
The universe as we know it is merely a three-dimensional "brane" (not brain) suspended in a four-dimensional bulk.
We live on a brane; a brane is like a membrane. Imagine the skin that forms on your soup when it gets cold, a brane is like that. A brane is some sort of lower-dimensional thing (2-D) sitting in a higher-dimensional space (3-D soup). However our brane sits in a 4-D space called the bulk, like so much congealed fat we are prevented from escaping the brane and going into the higher-dimensional soup. However only "gravity" is allowed to do that!
Some think that gravity is the strongest thing around; it moves planets and clusters of galaxies, not to mention keeps us pinned to the ground. But rather "gravity is weak"!
When you compare it to the other forces, say the electromagnetic force, gravity is incommensurably less powerful. Think about the simple refrigerator magnet and the forces acting on it as it pins a photo to the fridge. There's the combined gravitational force of the entire Earth pulling the magnet down to the ground and the magnetic attraction of a little strip of iron anchoring it to the fridge. Those few grams of magnetic material WIN; not even a planet-size helping of gravity is enough to overcome its intrinsic weakness.
Which leads me to look back again at nature. There is only one physical process that determines how things happen, one truth, the (big T) of the universe, and that is particle physics to describe the workings of gravity.
Particles interact by exchanging particles with other particles. Take for example an electron exerts a force on another electron by shooting a little photon (particle of light) out to the other electron, which the second electron catches and responds to. Yes particles "communicate"! Forces using "mediating" particles like photons. This what the process looks like in my head: (Electron-photon-Electron.) The two electrons "communicate" by tossing the ball like photon back and forth to each other. This tossing pushes the electrons apart, which agrees with what we see in the world, negatively charged electrons repel one other. With particles other than electrons, the net effect can be attraction, not repulsion, but the principle remains the same in that a force, "any force" is caused by things throwing particles at other things. The more particles that are thrown/caught, the stronger the force will be.
Gravity fits into the whole scheme of thing because it's caused by massive particles throwing "gravitons" attractive particles at each other. These gravitons work to pull massive particles closer together invoking the exchange of subatomic particles.
Now to really get a grip on gravities weakness, there is a symmetry between the graviton and the other force carrying particles in that the strength of both the electromagnetic and gravitational force diminishes with distance and in magnitude.
Now enter "brane" theory where we are trapped in our 3-dimensional world, which is itself floating in a higher dimensional space. We cannot travel into this higher dimensional space and nothing we know of can travel into it, not electrons, quarks or even exotic muons except for the "graviton". It alone can journey into the higher dimension, and as gravitons spread out in to that extra dimension there are fewer here to do the work of pulling heavy things together as the result of particles throwing particles at other particles. When there are fewer particles being caught, that force gets weaker. Now in brane theory, we lose gravitons out into the fourth dimension, the results, gravity is weak! And if you were a graviton, and each extra dimension is curled up in a circle, you would be able to move in this circular direction at every point in space while still moving in a straight line through the three dimension we are familiar with, we would arrive at the 4th dimension.
So in all theory only "gravitons" can escape into the extra dimension.
Somebody really smart might be thinking of how to "grow" a space-time fabric to dissipate weakness...
Any good cooks around here?