It is not another dimension, it is not even a parallel Universe. We exist in quantum reality, only we consider our building blocks of human form to be larger and consequently more significant. Thus we may not notice the invisible world of energy around us.
Some have reported that as they felt life slipping away that they encountered an unusual dimming of light, a sensation of sliding into gradual darkness.
This is the physical experience of the mind and senses witnessing the light leaving.
How many times has your intuition told you the answer even if you ignored it? What you are looking for is within. You are your own universe.