Answer: It’s very simple. To date many scientific articles have been written on this subject.
We feel everything within us. The upper Light constructs these feelings in us. The physical or spiritual waves (it makes no difference what they are called since they all have the same nature) perform certain actions upon us, and we sense them. It follows that everything that we feel depends upon our Kelim (vessels), our senses.
If our senses are on the most minimal level, in them we feel different ranges, objects, and events, which we call our world. But if the senses are expanded, instead of these volumes we begin to feel additional ranges that engulf the present ones. Ultimately everything dissolves, everything disappears into the waves.
Baal HaSulam presents a very simple example. If we cool water, it transforms into ice, which is to say that from a liquid state it passes to a solid state. If we heat water, it evaporates; it transforms into vapor, into a mist. But this is the same entity that was once in a liquid or solid state and now has transformed into a gaseous state. That is, everything changes relative to us.
If we had other senses, then, for example, we might feel the air as if it were concrete, like an insurmountable obstacle. It follows that it is our senses that portray the world as it is for us.
Read what scientists have written about the perception of reality. After Einstein there was Everett and other great physicists who have written that everything is perceived relative to the observer, and this has been proven experimentally.
Therefore, if our senses change, even matter becomes something else. It is only a wave of light. Whereas we need to be involved with the aspiration for the Creator, for this force, since its discovery is what makes all the changes in us.
From the European Convention in Germany 3/23/13, Lesson 3