The universe is a strange place: only 5% of everything in existence is made up of ordinary matter. The rest is made up of 25% dark matter and 70% dark energy. Dark matter is already a mystery (thought to be made of particles that don't interact with light), but dark energy is even more puzzling. Scientists know that dark energy must exist, but the deeper we look, the weirder things get.
Why must dark energy exist?
Dark energy is confirmed by its effect on the expansion of the universe. Observing distant celestial objects with fixed brightness, scientists have found that the universe is not only expanding, but also expanding at an increasing rate. Dark energy is considered to be the driving force that accelerates this process.
New mystery: Dark energy changes over time
Dark energy was originally thought to be constant, but recent research has found that it appears to be stronger in the early universe than it is today. Many suspected this was just a measurement error, but new data from the three-year-long Dark Energy Survey suggests that dark energy is indeed changing — a finding that could upend current models of physics.
The research project used data from:
- The Dark Energy Camera on the Víctor M. Blanco 4m Telescope in Chile.
- The Dark Energy Spectroscopic Instrument (DESI) on the 4m Nicholas U. Mayall Telescope in Arizona.
Hundreds of researchers have collaborated to create a 3D map of the universe, revealing the structure formed by gravity (as shown above). The results show that dark energy was stronger in the past and has weakened over time — contrary to models that view it as a fixed force like gravity.
Suggestions for a scientific revolution
Dr. Juan Mena-Fernández (Laboratory for Nuclear and Space Physics, France) commented: " This result suggests insights beyond the standard cosmological model. If confirmed, we could be on the verge of a major turning point ."
While scientists are not yet ready to dismiss existing theories, they are continuing to gather data from DESI (which can observe thousands of galaxies at once) to clarify the nature of dark energy. This discovery opens up new avenues of research for theorists. Whatever dark energy is, it will shape the future of the universe. It is amazing that we can look up at the sky and find the answer to one of humanity's biggest questions. Not only is dark energy mysterious, it can also "shapeshift" — a clue that has scientists both excited and 'headaches'!