New data suggests the unknown, unobservable force responsible for the universe’s expansion may be weakening.
Dark energy is a dynamic entity, rather than a matter-of-fact constant in the universe’s rapid unfurling, a team of scientists announced this week.
The Dark Energy Spectroscopic Instrument, or DESI, is an international effort involving more than 900 researchers. The project has produced gargantuan sky maps and helped reveal some of the universe’s largest structures, including the source of the universe’s largest known jets. The latest DESI release shakes up the foundational understanding of dark energy and its role in the universe.
As best scientists can tell, the vast majority of the universe is made up of dark matter and dark energy. Dark matter is the catch-all term for about 27% of the universe that is only known to exist because of its gravitational effects on other matter. The stuff is so infinitesimally small or otherwise elusive that it cannot be observed with telescopes, which take in wavelengths of light emitted by objects to better understand those sources.
Observable matter–everything from the coffee cup on your desk, to distant planets, to the largest and most ancient galaxies—makes up just 5% of the cosmos, meaning that dark energy is responsible for a whopping 68% of everything we think exists in the universe.
The notion of dark energy as a constant—which is to say, it manifested the same way 10 billion years ago as it does today, and as it will 10 billion years from now—is “baked into” the predominant model of the universe, Lambda-CDM, according to Rossana Ruggeri, a physicist at the University of Queensland who was involved in the DESI analysis.
