The Essence of Dark Energy and Theoretical Deduction Conjecture of Dark Matter ——Based on the First Principle Unified Theory of Light Strings (Revised Version)

Astronomical observations indicate that approximately 95% of the universe’s mass-energy is composed of dark matter and dark energy. Their physical essence cannot be fully explained by the existing Standard Model and General Relativity, making them core puzzles in contemporary cosmology. Based on the First Principle Unified Theory of Light Strings, this paper provides a self-consistent interpretation of the physical nature of dark energy: dark energy is the intrinsic spatial expansion tendency of free light strings in a vacuum, with no need to introduce unknown fields or unknown particles. On this basis, adopting a multi-dimensional elimination method and combining the core laws of the light string theory, this paper screens candidate schemes for dark matter and proposes a scientific conjecture: dark matter is an ultra-compact, highly stable, electrically neutral composite light string structure formed by neutrons binding electrons. This paper further supplements the stability mechanism of neutrons and the source of electrons, forming a closed logical loop without additional assumptions.