The universe is holographic with each level reflecting all other levels. The universe is coherent. Nothing stands alone. Everything is connected to everything. Change one thing and you change everything. Resonance and frequency are the keys to the universe. We exist in a reality created by energetic vibration.
As we study metaphysics, we come to understand the multidimensional nature of our soul's experience. Every person is his or her own universe, fragmented into every possible/probable manifestation in order to explore that which called you into existence at this level of vibration. As we become more aware, we can connect with other aspects of our own soul existing in parallel 'programs of reality' or parallel universes which exist in different frequency vibrations.
Each of our infinite 'fragments' is insulated, separated by a Veil of Forgetfulness, that allows each component part of that scenario to assume a point-of-view, and provide a unique perspective of what is transpiring within that 'Now' moment.
Your senses are not 'windows' to an 'objective' universe. They are really filters, blocking from your awareness what you have no desire to see. 'Out there' consists of an endless array of everything imaginable. But here, in this 3D universe, you have assigned for yourself a specific focus, and your veil makes sure that you stay with it until that focus is complete.
For example, when you enter into a sleep state, you experience a parallel or multidimensional life. It is real, continual, and meaningful. You might think of it as a 'past or future' life. You may experience profound relationships with others, remember well-traveled paths and places that are not consciously known to you in your current reality program. Some have experienced being absolutely heartbroken over someone deeply 'familiar' in a dream only to awaken and wonder why they would feel such things for someone not in their current state of consciousness. What you are experiencing is yourself in a parallel or multidimensional reality. Your current 'reality channel' has just temporarily changed frequency. They are all equally real and playing simultaneously.
'List ye, O man, and hear a mystery
stranger than all that lies 'neath the Sun.
Know ye, O man, that all space
is filled by worlds within worlds;
aye, one within the other yet separate by Law.'
~ The Emerald Tablets of Thoth - Tablet X: The Key of Time