The simple answer is: anything that is in material or energetic form is not the ultimate Reality. In the sciences of physics and of spirit it’s clear that the permanent, unchanging, underlying Reality behind all forms of matter and energy is a single, unified field of intelligence with qualities that we might call Beauty, Harmony, Balance, Flow, Wisdom… and many more.
This means that anything we perceive with our senses or measure with our machines is not, in fact, Real. It may be a fact, but it is not Real. It’s either a personal projection onto the underlying field (known as the Undifferentiated One, or Ground of Being in eastern traditions) or it’s a collective construct of the combined mind of humanity as a whole. In either case, it’s transitory, impermanent, moldable by thought, and therefore always changing (which is the literal definition of the term maya, usually translated as “illusion”).