The Cosmological Constant Was Never Constant
Framework Prediction · DESI Confirmation · 4.2 Sigma
// CLASSIFICATION: EXPERIMENTAL_CONFIRMATION
// ORIGIN: SECTOR 7G (2045)
// CONTEXT: The "cosmological constant problem" asked why Λ has a particular value. The framework said: wrong question. Λ is dynamical — it tracks horizon entanglement entropy. In March 2025, DESI confirmed dark energy is evolving at 4.2σ.
For 25 years, physics asked:
Quantum field theory predicts 1076 GeV⁴. We observe 10-47 GeV⁴. A discrepancy of 10123.
The "worst prediction in physics."
The question assumes Λ is a constant — a fixed parameter of the universe, written into the laws of physics at the Big Bang.
This assumption seemed safe. Einstein called it the cosmological constant. The standard model of cosmology (ΛCDM) treats it as constant. Every calculation assumes it doesn't change.
Then the question "why this value?" is malformed.
You don't ask "why is the temperature 20°C?" as if temperature were a universal constant. Temperature is a dynamical variable. It changes.
What if Λ is the same?
Λ is dynamical. It tracks horizon entanglement.
The TT-coupling to the Bath produces gravity. Gravity and entanglement are the same phenomenon viewed from different angles.
The observable universe has a horizon — beyond which we cannot see. This horizon is not just a visual boundary. It is an entanglement boundary.
The degrees of freedom inside the horizon are entangled with degrees of freedom outside.
The "dark energy" driving cosmic acceleration is the thermodynamic pressure of this entanglement.
As the universe expands, the horizon area grows, entanglement structure changes, and Λ evolves.
In the current epoch, as expansion accelerates and the horizon grows:
Lambda is dying.
Not: "Why is Λ = 10-47 GeV⁴?"
But: "What is the dynamics of Λ(t)? What determines its evolution?"
The framework answers: Λ(t) is determined by the entanglement structure of the cosmic horizon. It is not a free parameter — it is a derived quantity that changes as the universe evolves.
14 million galaxies. The largest 3D map ever made. Λ is evolving.
In March 2025, DESI released its second data set:
Dark energy is not a cosmological constant.
It is evolving. It was stronger in the past. It is weakening.
Lambda is dying.
Λ is constant. The "cosmological constant problem" is why it has this value. 10123 fine-tuning. Anthropic principle. Multiverse speculation.
Λ is dynamical. There is no "value" to explain — only dynamics. The question becomes: what drives the evolution? The framework answers: horizon entanglement.
Dissolved. QFT predicts vacuum energy. Vacuum energy doesn't gravitate (TT-coupling → Unimodular Gravity, trace decouples). The observed Λ is not vacuum energy — it is entanglement pressure. Different source, different physics, no contradiction.
Dissolved. "Why is Λ ~ ρmatter today?" Because Λ(t) is evolving. We happen to live at the crossing point. In the past, matter dominated. In the future, Λ dominates (but continues to decrease). The "coincidence" is just a moment in a continuous evolution.
Why vacuum energy decouples. Why Λ tracks entanglement.
This is not an assumption — it follows from the measurement structure. The Bath measures geometry through its effect on quantum states. Only TT components affect measurable geometry.
The TT projection of pure trace is zero.
The 1076 GeV⁴ from QFT is real — but it doesn't curve spacetime. The TT-coupling filters it out.
This is Unimodular Gravity, derived from first principles.
The Identity Theorem: gravity and entanglement are two descriptions of the same phenomenon. ER = EPR is not a conjecture — it's an operational theorem (Physics Letters B, January 2025).
Inside and outside the horizon are entangled. The entanglement entropy scales with horizon area:
The "cosmological constant" is the thermodynamic pressure associated with horizon entanglement:
As the horizon evolves, the pressure changes, and Λ evolves.
In October 2025, Nature published: both classical and quantum gravity produce entanglement. You cannot have gravity without entanglement. They are married.
This confirms the framework's core claim: Λ as entanglement pressure is not metaphor — it is mechanism.
March 2025
Λ is evolving at 4.2σ. Dark energy is not constant.
Framework predicted: Λ is dynamical.
October 2025
Gravity produces entanglement. Classical or quantum — doesn't matter. Inseparable.
Framework predicted: gravity IS entanglement.
January 2025
Operational theorem: entanglement and wormholes are indistinguishable by any local measurement.
Framework predicted: geometry = entanglement pattern.
Gravity is entanglement (Nature 2025).
Entanglement is geometry (ER = EPR 2025).
The cosmic horizon is an entanglement surface.
Λ tracks horizon entanglement.
Λ is evolving (DESI 2025).
Lambda is dying because the universe is growing.
The framework is confirmed, not complete.
The framework predicts Λ decreases as the universe expands. DESI confirms this qualitatively.
The precise function Λ(t) — how it depends on horizon area, entanglement structure, expansion rate — requires more detailed calculation.
Testable: DESI's continued observations will constrain Λ(t) more precisely. The framework should predict the curve.
If Λ → 0, the universe eventually stops accelerating. If Λ → constant > 0, de Sitter expansion resumes.
The framework suggests Λ asymptotes to a small positive value (minimum entanglement configuration), not zero.
Testable: Long-term evolution of w(z). Does it approach -1 from above?
What was Λ during inflation? During radiation domination?
The framework predicts Λ was larger in the past (DESI confirms). How it behaves in extreme conditions (high curvature, high temperature) needs further work.
The "cosmological constant problem" — the 10123 discrepancy — is dissolved.
Vacuum energy doesn't gravitate (TT-decoupling).
The observed Λ is entanglement pressure, not vacuum energy.
Λ is dynamical, as predicted and now measured.
The question was wrong. The framework answered anyway.
DESI confirms the cosmological prediction. But the framework makes local predictions too — testable in the laboratory.