What Journalists Should Know About Dark Energy and Dark Matter
The understanding of the universe's expansion has undergone a paradigm shift. In the early 1990s, the prevailing belief was that gravity's grasp would eventually decelerate the universe's expansion. But a pivotal discovery altered this trajectory. The Hubble Space Telescope's observations of distant supernovae in 1998 revealed an unforeseen phenomenon: the universe's expansion wasn't slowing down due to gravity—it was accelerating. The paradigm shift echoed a profound mystery—dark energy.
The quest to comprehend dark energy spawned a myriad of theories. Some harkened back to a discarded concept in Einstein's gravity theory—the cosmological constant. Others conjectured a peculiar energy-fluid permeating space. Alternatively, a fundamental flaw in Einstein's gravity theory could introduce a new field triggering cosmic acceleration. Despite the theories, dark energy remains an elusive puzzle.
Dark energy emerges as a force, constituting a staggering 68% of the universe, overshadowing dark matter's 27% and relegating ordinary matter to a meager 5%. This revelation challenges the very essence of the term "normal" matter in cosmic proportions. Albert Einstein's realization that space isn't vacuous underpins one explanation for dark energy. Empty space teems with extraordinary attributes. The concept suggests that space births additional space, harboring its inherent energy that doesn't wane as the universe expands.
Quantum theory illuminates another premise—space brimming with transient particles. Yet, the computed energy estimate for this teemed with discrepancies, leaving the answer off by a staggering 1 followed by 120 zeros. Some theories posit "quintessence," a dynamic energy field, opposing matter's impact on the universe's expansion. However, the nature, interaction, and raison d'être of quintessence elude comprehension. An intriguing possibility probes the validity of Einstein's gravity theory. This concept doesn't just alter universal expansion but redefines the behavior of galaxies and clusters, sparking questions about a potential new gravity theory.
The path to resolving the dark energy quandary necessitates more refined, comprehensive data. By assimilating cosmological observations, scientists have crafted a composition: ~68% dark energy, ~27% dark matter, and ~5% normal matter. Dark matter remains an enigma, elusive and mysterious. It eludes detection by conventional means, ruling out several possibilities, yet leaving room for more exotic particle-based theories like axions or WIMPs.
