Dark Energy: From Brake to Engine ⚡ экспресс
In the new Ph-ΛsCDM model, researchers realized the idea of flipping the sign of the cosmological constant using a phantom scalar field within general relativity. The field, with an unusual kinetic term (a so-called 'wrong sign' of energy), evolves on a bounded potential, providing a smooth transition from a state with negative energy density (like anti-de Sitter) to positive (like de Sitter). Surprisingly, the field becomes repulsive even when its energy is still negative, while the total energy stays positive. This model offers an elegant mechanism that could explain discrepancies in modern cosmological observations.
The universe is expanding faster and faster thanks to dark energy. But measurements of the rate give contradictory results. A new explanation: in the past, dark energy acted as a brake, slowing the galaxies' recession, and then switched to acceleration. Like a car that first rolls backward and then lunges forward. This transition is described by the Ph-ΛsCDM model, based on the theory of gravity by Einstein. It uses a phantom field — a substance capable of smoothly changing the sign of energy from attraction to repulsion. This avoids the 'Big Rip' that previous theories threatened. This is a development of ideas that emerged after the discovery of acceleration by Perlmutter. Most unexpectedly, the field starts accelerating even while the energy is still attracting — as if the engine started working before the clutch engaged. The model promises a stable future despite the grim predictions of standard cosmology.
🎯 Phantom energy is so named for its ability to violate physical laws, like a ghost passing through walls.