Fresh DESI data hints that dark energy might 'toggle' like an invisible pendulum. Scientists built a model where dark matter and dark energy exchange signals, causing a double crossing of the phantom line. This naturally predicts unimaginably lightweight particles. What other secrets does the dark cosmos hold?
When a car on cruise control hits a bump, the speed jumps for a moment, but the engine runs smoothly. Something similar was recently noticed with dark energy — the force that makes the Universe expand faster and faster. Scientists describe it with the parameter w: if it drops below -1, the Universe would accelerate toward the 'Big Rip.' DESI project data showed that w twice briefly dipped into this dangerous zone, but without disaster. Usually, such behavior requires weird physics, but a new model gives a simple explanation.
In it, dark matter particles interact with dark energy like a bump in the road: their coupling gently nudges the system, and the parameter w temporarily falls below -1, while dark energy itself remains stable. The model was checked against three sources: distances to galaxies (DESI), properties of the cosmic microwave background (Planck), and the brightness of distant supernovae. Everything matched.
The most unexpected conclusion: dark matter particles must be incredibly light — around 0.002 electronvolts. The electron's mass is almost half a million times larger. Such 'fluffs' might be part of an unknown family of particles yet to be discovered.
🎯 Dark energy behaves like water that momentarily boils without forming bubbles — pressure spikes, but the system quickly settles down.
🎬 The idea of unstable dark energy spawned many stories about the 'Big Rip,' such as in Paul McAuley's novel 'The War with the Remotes'.