Understanding higher dimensions helps make sense of spirituality, at least for those of us whose minds have a scientific bent.

Ordinary 3-D space is called 3-D because it takes 3 numbers to locate anything in it, no matter what the reference is. There are 3 directions. And 3 numbers to specify size -- length, width, height.

Adding another dimension to 3-D would mean adding another independent direction. We have trouble visualizing this, and scientists do too, so they think that if there's extra dimensions, they're curled up so small we can't see them. They don't care if it doesn't make sense; the math still works.

If there are higher dimensions, they include the lower dimensions as part of them. You can't have a 4th dimension all by itself, any more than you can have 3 dimensions without it containing 2 dimensions (surfaces) and 1 dimension (lines). If there are 10 dimensions to reality, they contain all the lower dimensions. There's no isolated tenth dimension.

Scientists have good reason to think that there are higher dimensions because the math says so, and they trust the math. Math doesn't lie. The math of general relativity, which expains gravity and is universally accepted as truth, requires 4 dimensions. If you add another (fifth) dimension, you are able to include the mathematics of electromagnetism, which also has been fully verified. Add still more dimensions, and you can include the math of the nuclear forces, which are inside the atom.

In the "string" theory of recent physics, "everything is vibration" is literally true. This theory says that the smallest pieces of physical reality are vibrating strings or loops of energy (whatever that means). Matter is just vibrating energy, and the frequency and mode of a vibrating string determines what kind of particle it appears to be. The math of string theory predicts the size and mass of particles, and it all agrees closely with what is seen experimentally. But the math only works if there are 10 spatial dimensions (the vibrations are complicated). You have to allow the strings to oscillate or wobble in 10 directions.

Science wonders why we can't see higher dimensions. I think our brains are designed to interface to 3-D only. And to perceive 4 dimensions we would need three eyes, and the eye would have a 3-dimensional retina. Still, there's the question of why we can't see "cross-sections" of 4-D shapes in our 3-D space.

In any case, I like to think that the realm of spirit is the higher dimensions, probably beyond the tenth, and that spirit can easily access the lower dimensions, including 3-D. But we in 3-D can't easily access the higher dimensions. To do so we have to raise our vibration (make it faster) to that of the higher dimensions. That's how the spirituality teachers put it. People who channel entities in spirit can do this.